ORNl-4844
- Annual PROGRESS REPORT
^citiod finding ^Decemfaej 31.1972 mm BLANK PAGE Printed in the United States of America. Available from National Technical Information Service U.S. Department of Corrmerce 5285 Port Royal Road Springfield, Virginia 22151 Price: Printed Copy $3.00; Microfiche $0.95
This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. ORNL-4844 UC 34-Physic;
Contract No. W-7405-«ng?6
PHYSICS DIVISION ANNUAL PROGRESS REPORT For Period Ending December 31,1972
J. L. Fowler, Director G. R. Satchler, Associate Director P. H. Stelson, Associate Director Felix E.Obenshain, Editor
NOTICE This report was prepared as an *ccowt of sponsored by the United States Government. Neither the United States nor the United Sates Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, at their employees, maini any warranty, express or impned, or srtamrt any legal habihly or responsmiity for the accaracy. com pleteness or nirfalnraj of any information, apparatus, prodact or procem disclosed, or represents that its as* wontd not infringe privately owned rights.
APRIL 1973
OAK RlOGE NATIONAL LABORATORY Oak Ridge, Ttnntmm 37830 OMrtHcdby UNION CARBIDE CORPORATION forth* US ATOMIC ENERGY COMMISSION MASTER!
WOT^m* tf THis wmM is UWUHJA Reports previously issueu in this section are «s follows:
ORNL2718 Period Ending March 10. 1959 ORNL-2910 Period Ending February 10, 1960 ORNL-3085 Period Ending February 10, ! 961 ORNL-3268 Period Ending February 1C, 1962 ORNL-3425 Period Ending January 31, 1963 ORNL-3582 Period Ending January 31,1964 ORNL-3778 Period Ending December 31,1964 ORNL-3924 Period Ending December 31,196S ORNL-4082 Period Ending December 31,1966 ORNL-4230 Period Ending December 31,1967 ORNL-439S Period Ending December 31,1968 ORNL-4513 Period Ending December 31,1969 ORNL-4659 Period Ending December 31,1970 ORNL-4743 Period Ending December 31,1971 Contents and Summary
FOREWORD xxiii
MONTHLY REPORTS OF THE PHYSICS DIVISION 1 1. THEORY
NUCLEON TRANSFER FORM FACTORS CALCULATED WITH REALISTIC INTERACTIONS Y. K. So, W. T. Pinkston, and K. T. R. Dawes 7 Abstract of paper to be published in Nrtides 6 Nudei.
HIGHER-ORDER CORRECTIONS TO BRUECKNER-HARTREE-FOCK BINDING ENERGIES AND RADII K.T. R. Danes, R. J McCarthy, and P. U. Sauer 7 Abstract of paper to be published in Physical Renew.
RENORMAUZED BRUECKNER-HARTREE-FOCK CALCULATIONS USING DIFFERENT PRESCRIPTIONS FOR THE INTERMEDIATE-STATE SPECTRUM K.T. R. Davies, R. J. McCanhy, and P. U. Saner 8 Abstract of published paper: Phys. Rev. Co, 1461 (1972).
HARTREE-FOCK CALCULATIONS OF BUBBLE NUCLEI K. T. R. Davies, C. Y. Wong, and S. J. Krieger 8 Abstract of published paper: Phys. beit. 4IB, 455 (1972).
THE RENORMAU^ED BRUECKNER-HARTREE-FOCK APPROXIMATION Richard L. Becker 8 Abstract of paper to be published in the proceedings of Symposium on Present Status and Novel Developments in the Many-Body Problem, Rome, Italy, Sept. 19-23,1972. (Proceedings to be published in nNuovo Cimento.)
DEFORMED BRUECKNER-HARTREE-FOCK CALCULATIONS W. F. Ford, R. C. Braky, R. L. Becker, and M. R. Patterson 8 Abstract of paper to be published in the proceedings of Symposium on Presen Status and Novel Developments in the Many-Body Problem, Rome, Italy, Sept. 19-23,1972. (Proceedings to be published in llNuovo Cimento.)
RENORMAUZED FOLDED DIAGRAM EXPANSION FOR THE NUCLEAR GROUND STATE Richard L. Becker, Robert W. Jones, and Franz Molding 9 The extension of our earlier folded diagram expansion in the core interaction to one in the Bmeckner reaction matrix has been obtained. It includes the factorization of a renormahzed Broeckner-Hartree-Fock potential energy for "particle" states.
PREDICTED INTERMEDIATE STRUCTURE IN HIGH-RESOLUTION DEEP-HOLE SPECTRA Richard L. Becker 10 The admixture into a deep single-hole state of 2 hofe-1 particle states nearly degenerate with it is shown to give rise to an intermediate structure in quasi-free knockout or pickup spectra. Detailed Bnieckner theoretical calculations are presented for a Or hole in '*0. Higher-resolution (pjp) data are urged.
iii IV
ML-EOCXEMZATKKi OF TwC BRANDO* SEMES WITH A NEW PROPAGATOR-RENORMALIZED REACTION MATRIX Ricked U tet&c? ...... 17 bttrod^ction oi a propagator-re noinuiacd reaction operator Bluj) yields an expa«k>n in B which possesses the stationary properties of Brando* \ series in the hare interaction.
TARGET EXCITATIONS AND THE OPTICAL POTENTIAL FOR PROTONS SCATTERING FROM NUCLEI C. L. Rao. M. Reeves III. and G. R. SatcMer 18 Abstract of paper submitted tor publication in Nuclear Physics.
EXCHANGE EFFECTS ON THE FXCITATION OF 20Ne BY PROTONS G. R. SatcMer !8 Abstract of paper to be published in Articles 4 Nuclei
INTERFERENCE NEAR THE COULOMB BARRIER AND COMPLEX INTERACTIONS FOR INELASTIC SCATTERING G. R. Satrhler 18 Abstract of published paper: Phys. Lett. 39B, 492 (1972).
THE FOLDING AND DEFORMED POTENTIAL MODELS FOR INELASTIC SCATTERING S. R. Satchler 19 Abstract of published paper: Phys. Lett. 39B,495 (1972).
RADIAL MOMENTS OF FOLDING INTEGRALS FOR NONSPHERKAL DISTRIBUTIONS G. R. Satchler 19 Abstract of pubhshed paper: / Math. Phys. 13,1118 (1972).
THE OPTICAL MODEL G. R. Satchler and F. G. Perey , 19 Abstract of paper to be published in the proceedings of Conference on Nuclear Structure Study with Neutrons, Budapest, Hungary, July 31 -August 5,1972.
EXCITATION OF GIANT MONOPOLE RESONANCES BY PROTON SCATTERING G. R. &t*Ier 19 Abstract of paper to be published in Particles 6 Nuclei NUCLEAR GIANT RESONANCES, SUM RULES, EFFECTIVE CHARGES, AND SUCH-LIKE G. R. Satchkr 19 Abstract of paper submitted for publication in Comments on Nuclear d Particle Physics,
EXCITATION OF GIANT DIPOLE AND GIANT QUADRUPOLE STATES IN NUCLEI G. R. Satchler 20 Abstract of published paper: NucL Phys. A195,1 (1972).
EFFECTTVE HAMLTONIANS FOR TRUNCATED SHELL MODELS B. R. Barrett, E. C. Halbert, and J. B. McGrory 20 Several methods for determining appropriate effective Hamfltoniatts to be used in truncated shaft-model calculations are discussed. In particular, we discuss die determination of an effective Hamitonian which will reproduce in the <'s/2'fi/2 two-orbit space the results of a calculation with a given (1 + 2)-body HamiHonian in the ^5/2^ 1/2^3/2 three-orbit space.
A PROGRAM FOR EXTENDED WEAK-COUPLING CALCULATIONS L. B. Hubbard and J. B. McGrory 21 A computer program for making shell-model calculations in a basis of states formed from coupling of eigenstates in meqtavaJent spaces is described.
SHELL-MODEL CALCULATIONS OF NUCLEI IN THE 208Pb REGION J. B. McGrory, C. M. Ko, and T. T. S. Kuo 22 SbeB-model calculations for 2,°-2,2Pb, 204"206Fb, 2,0Po, 2I !At, and 2,2Rn have been carried out. In general, results are in excellent agreement with experiment. V
COULOMB ENERGY DIFFERENCES IN *rf-SHELL NUCLEI IN THE CONVENTIONAL SHELL MODEL J. B. McGrury 22 Coulomb energy differences for isobark multipiets in A = 19. 20. and 21 nuclei have been calculated in terms of a conventional shdt-modd calcination in a neutron-proton formalism.
ALPHA-PARTICLE SPECTROSCOPIC AMPLITUDES AND THE SW3) MODEL Munetake khnnura, Akito Arima. E. C. Halbert. and Tokuo Terasawa 23 Abstract of paper submitted for publication m Nuclear Physics.
AN ANALYSIS OF SHELL-MODEL WAVE FUNCTIONS FOR *4 AND/* SHELL NUCLEI IN TERMS OF SU<3) REPRESENTATIONS J. B. McGrory , , 23 Nuclear shell-model wave functions for nuclei with A ~ 18-22, 34-38, and 42-44 ha -e been transformed into a basis of states which carry representations of the SU<3). As expected, SIK3) is a good representation for low-tying states in the nuclei with A = 18-22. It is not a good representation for the heavier nuclei, mainly because of effects due to the singk partide span-orbit spitting.
SHELL-MODEL CALCULATIONS KM MASSES 27,28, AND 29: GENERAL METHODS AND SPECIFIC APPLICATIONS TO 27AL 2*SL AND **Si B. H. Wldenthal and J. B. McGrory 24 Abstract of paper to be published in Physical Renew.
SHELL-MODEL CALCULATIONS FOR ,4 = 18,19, AND 20 NUCLEI WITH CORE EXCITATION INCLUDED EXPLICITLY J. B. McGrory and B. H. Widenthal 24 Abstract of paper to be published in Physical Review.
ANALOG AND CONFIGURATION STATES IN 4'Sc if = 3/2" AND 1/2) AND THE LOW-LYING LEVEL STRUCTURE IN 4SSc S. D. Bloom, J. B. McGrory. and S. A. Moszfcowski 25 Abstract of paper to be published in Nude* Physics.
ON THE TRANSITION FROM SHELL STRUCTURE TO COLLECTIVE BEHAVIOR: A SIMPLIFIED SHELL-MODEL STUDY K. T. Hecht, J. B. McGrory, and J. P. Draayer . 25 Abstract of published paper: NucL Phys. AI97,369 (1972).
WHERE UES THE INTERACTION BARRIES? C. Y. Wong 26 Abstract of paper submitted for publication in Physical Review Letters.
ON SUPERHEAVY NUCLEI SYNTHESIS BY THERMONUCLEAR EXPLOSIONS C. Y. Wong 26 Abstract of paper submitted for publication in Physical Review "Comments 4 Addenda."
STABILITY OF A ROTATING TOROIDAL MASS C. Y. Wong 26 Abstract of paper submitted for publication in Astrophyskal Journal.
FUSION THRESHOLD ENERGY IN HEAVY-ION REACTIONS C. Y. Wong 27 Abstract of published paper: Phys. Lett. 42B, 197 (1972).
TOROIDAL NUCLEI C. Y. Wong i 27 Abstract of published paper: Phys. Lett. 4IB, 446 (1972). VI
BUBBLE NUCLEI C. Y. Wong 27 Abstract of published paper: Phis. Leu. 4IB.451 (1972».
TOROIDAL LIQUIC STARS C. Y. Wong 27 Abstract of paper submitted for publication in Nature.
A PEDESTRIAN APPROACH TO THE INTERMEDIATE STRUCTURE IN PHOTON UCLEAR REACTIONS IN LIGHT NUCLEI F. B. Malik and M. G. Mustafa 28 Abstract of paper to be published in Proceedings of the V Symposium on the Structure of Low-Medium Mass Nuclei.
A THEORY OF INTERMEDIATE STRUCTURE, OVERLAPPING RESONANCES, AND PHOTONUCLEAR REACTIONS IN LIGHT NUCLEI M. G. Mustafa and F. Bary Malik 28 Abstract of paper submitted for publication in Helvetica Physica Acta.
THE GAMMA-RAY ABSORBED FRACTION FOR SMALL OBJECTS Lincoln B. Hubbard 28 For objects whose dimensions are of the order of a mean free path or has the absorbed fraction for internally emitted gamma rays can be calculated to reasonable accuracy with the most simple model. 2. HIGH-ENERGY PHYSICS
EVIDENCE FOR A NEUTRON HALO IN HEAVY NUCLEI FROM ANTIPROTON ABSORPTIONS W. M. Bugg, H. O. Conn, G. T. Condo, E. L. Hart, and R. D. McCuDoch 30 Measurement of the ratio otpp to pn interactions in C, Ti, Ta, and Pb yield evidence for the presence of a neutron halo in heavy nuclei.
THE FOUR-PION DECAY OF THE/0 MESON W. M. Bus. G. T. Condo, E. L. Hart, H. O. Conn, R. D. McCuIIoch, R. J. Endorf, C. P. Home, and M. M. Nussbaum 32 Abstract of paper submitted for publication iu the Physical Review.
MULTIPION DATA ON THE T REGION W. M. Bugg, G. T. Condo, E. L Hart, H. O. Cohn, R. D. McCuIIoch, M. M. Nussbaum, C. P. Home, and R. J. Endorf 32 Abstract of paper submitted for publication in Physics Letters.
HIGHER-MASS BOSONS FROM 7.87-GeV/c » V INTERACTIONS W. M. Bugg, G. T. Condo, E. L. H*rt, H. O. Cohn, R. D. McCuiloch, M. M. Nussbaum, R. Endorf, and C. P. Home 33 Abstract of published paper: Phys. Rev. 6D, 3047-50 (1972). 3. NUCLEAR STRUCTURE, REACTIONS, AND RADIOACTIVITY 3a. Systematics
ORELA NEUTRON CAPTURE AND STELLAR NUCLEOSYNTHESIS B. J. ADen and R. L. Macklin 34 Abstract of paper submitted for publication in Australian journal Atomic Energy.
STATUS REPORT OF THE NUCLEAR DATA PROJECT D. J. Horen, R. L. AuWe, F. E. Bertrand, Y. A. Ellis, W. B. Ewbank, B. Harmatz, M. B. Lewis, M. J. Martin, S. Raman, M. R. Schmorak, and D. C. West 34 The work of the Nuclear Data Ptoject for the calendar year 1972 is reviewed. In addition to the data compilation and research efforts, services rendered by the Project to both basic and applied users of nuclear data are discussed. Vll
EVIDENCE FROM INELASTIC PROTON SCATTERING FOR A GIANT QUADRUPOLE VIBRATION IN SPHERICAL NUCLEI M. B. Lewis and I-. E. Bertrand 36 Abstract of published paper: \ucl. Phys. AI96. 337 (1972).
REACTION LIST FOR CHARGED-PARTTCLE-INDUCED NUCLEAR REACTIONS. Z = I TO Z - 99 (H TO Es). JULY 1971 -JUNE 1972 F. K. McGo^n and W. T. Milner 36 Abstract of published paper: Nuclear Data TaHes Al 1,1-126 (1972).
REACTION UST FOR CHARGED-PARTICLE-INDUCED NUCLEAR REACTIONS. Z = I AND 2 (H AND He), MAY 1969-JUNE I97I:Z= 3 TO 99 (Li TO Es), 1948-JUNE 1971; COULOMB EXCITATION, IV56-JUNE !9?1 F. K. McGomn and W. T. Milner 36 Abstract of paper to be published in Atomic and Nuclear Data Reprints, Vol. I (Academic Press).
3*. A <22
IMPROVED UPPER LIMIT FOR THE ELECTRIC DIPOLE MOMENT OF THE NEUTRON W. B. Dress, P. D. Miller, and N. F. Ramsey 37 Abstract of paper submitted for publication in the Physical Review.
PROGRESS REPORT ON THE EXPERIMENT TO DETECT AN ELECTRICAL DIPOLE MOMENT OF THE NEUTRON P. D. Miller, W. B. Dress, P. Perrin, R. Bouchez, N. F. Ramsey, and R. Mossbauer 37 The neutron intensity from the reactor at Institut Laue-Langevin will allow a sensitivity of i0~ cm as compared with the present upper limit of 1.0 X 10~23 cm.
THE p-p FINAL-STATE INTERACTION IN THE 3He(4,r)2j> REACTION R. W. Rutkowski and E. E. Gross 37 Abstract of published paper: Phys. Lett. 35B, J51 (1971).
CHARGE-ASYMMETRY EFFECTS !N* THE REACTION 2H(4He,3He)3H E. E. Gross, E. Newman, M. B. Greenfield, R. W. Rutkowski, W. J. Roberts, and A. Zucker 37 Abstract of published paper: Phys. Rev. C5,602 (1972).
SEARCH FOR A 3He + 3He RESONANCE IN *Be; ASTROPHYSICAL IMPLICATIONS M. L. Halbert, D. C. Hensiey, and H. G. Bingham "3 The reaction 6Li(3He,f)6Be* shows no evidence for a 3He + 3He resonance just above threshold. Therefore, some othr.i solution to the solar neutrino problem must be sought.
ISOSPIN CONSERVATION IN COMPLICATED REACTIONS C. D. Goodman, D. C. Hensiey, A. van der Woude, and S. Raman 39
6 7 6 7 The reactions '' B * d-* He + Be or Li* + Li have been studied and the ratio o6(0)/o7(0) has been compared with a prediction based on isospin symmetry.
ABSOLUTE NEUTRON YIELDS FROM THICK-TARGET NATC(o,n) J. K. Bair 42 Abstract of paper submitted for publication in Nuclear Science and Engineering, Technical Note.
TOTAL NEUTRON YIELD FROM THE REACTIONS ' 3C(o^r)160 AND ' 7'! *O{aji)20A 1 Ne J. K. Bair and F. X. Haas 42 Abstract of paper submitted for publication in the Physical Review.
THE LEVEL STRUCTURE OF ' 70 FROM NEUTRON TOTAL CROSS SECTIONS J. L. Fowler, C. H, Johnson, and R. M. Feezel 43 Abstract of paper submitted for publication in the Physical Review. Vkll
rt MATRIX ANALYSIS WITH A Mm St EDGE POTENTIAL FOR 160 + n DATA ( >t Johnson, i. I Fowler, ami R U. I ee/ei 43 •\bvrac! r.t published paper p,». 2 3 m Contributions Conference on Xuclear Stmcturt Study with Seutn is (Budapest. Hungary. July August 1972». Os'ra Research Institute for Physics. Budapest. 1972.
A INIFIED/r MATRIX PLiS POTENTIAL ANALYSIS FOR i60 + n CROSS SECTIONS C. H. iohnvon 43 Abstract of paper to be published in the Physical Review.
NEUTRON CAPTURE IN FLUORINE BELOW 1500 keV R. L Micklin and R R. Winers 44 Absiraci of paper sumbitted iVr publication in Physical Review C.
TOTAL NEUTRON YIELDS FRtHH THE PROTON BOMBARDMENT OF 17-,80 J. K. Bail 44 Ab-;tract of paper submitted or publication in the Physical Review.
THE ENERGY LEVELS OF 2I Na F. X. Haas. C. H. Johnson, and J. K. Bair 44 Abstract of published paper: Nuci. Phys. AI93,65 (1972).
HEAVY-ION NEUTRON YIELDS J. K. Bair, W. B. Dress, C. H Johnson, and P. H. SteJson 45
16 I8 NAT 16I8 63 65 The cross sections for nrutron production by « 0 bombardment of C, 0, ' Cu, 58.60,6 i,62,64Nj and
•«,».s16?,6».702n>l?w beef) mMtted for bombardiffi energies below 55 MeV.
TOTAL NEUTRON YIELD FROM THE (o^i) REACTION ON 2 * '22Ne F. X. Haas and J. K. Bair 47 Abstract of paper subm.ited for publication in the Physical Review.
(3He,n) REACTION AT 25 McV M. B. GreenTield, C. R. Bingham, E. Newman, and M. J. Saltmarsh 47 Abstract of published pape.r: Phys. Rev. C6, 1756 (1972).
3c. 22
NEUTRON TOTAL CROSS SECTIONS FOR KILOVOLT NEUTRON ENERGIES W. M. Good and J. A. Harvey . , 4T High-resolution total neutron cross section measurements have been made at OREL A upon 21 nuclides from 1 to 100 keV. keV NEUTRON TOTAL CROSS SECTION MEASUREMENTS AT ORELA J. A. Harvey 49 Abstract of Invited Paper publisl ed in Proceedings of ANS Topical Meeting on New Developments in Reactor Physics and Shielding Calculatiom, Kiamesha Lake, New York. Sej umber 12-15, 1972, USAEC CONF-720901, Book 2, pp. 1075-86 (1972).
TW ,OK,eO,<0,10B(,60,«K AND ' *«' 60,a) REACTIONS J. L. C. Fold, Jr., !>. Gomez del Campo, S. T. Thornton, R. L. Robinson, and P. H. Stetson 50 The '^Bf'^O^J), ,0B(l6Oyc»), and I2C(,60,a) reactions have been investigated using a 60-cm-long position-sensitive proportional detector at the focal plane of the Enge split-pole spectrograph. States at high excitation energies in 23Na and 34Mg were populated.
OPTICAL MODEL FAMILY AMBIGUITY RESOLVED FOR HELION ELASTIC SCATTERING FROM 60Ni C. B. Fulmer and J. C. Hafele 55 Abstract of piper to be published in Physical Review C. IX
ENERGY DEPENDENCE OF THE OPTICAL MODEL FOR HELrON SCATTERING FROM 60Ni C. B. Fulmer, J. C. Hatele.and C. C. Foster 55 Abstract of paper to be published in Physical Review C.
SPIN-ORBIT AND TARGET-SPIN EFFECTS IN HELION ELASTIC SCATTERING C. B. Fulmer and J. C. Hafele 55 Abstract of a paper to be published in Physical Review C.
6365Cu<»^'7) REACTIONS G. G. Slaughter, G. L. Morgan, and J. K. Dickens 56 Gamma-ray spectra from the («.«'?) reaction on * Cu were used to deduce energy levels in *65Cu. Excitation functions obtained relatively were normalized to absolute data obtained with a Nal crystal, with excellent agreement.
NEUTRON CAPTURE CROSS-SECTION MEASUREMENTS FOR F6Sr. 87Si, AND 88Sr G. J. Vanpraet, R. L. Macklin, B. J. Allen, and R. R. Winters 57 Abstract of paper to be published in proceedings of IAEA Conference on Nuclear Structure Study with Neutrons, July 29-August 4,1972, Budapest, Hungary.
NEUTRON RESONANCE PARAMETERS OF 92Mo 0. A. Wasson, B. J. Allen, R. R. Winters, R. L. Macklin, and J. A. Harvey 57 Abstract of paper submitted for publication in Physical Review C.
VALENCY NEUTRON CAPTURE IN 92Mo(ii.7)93Mo O. A, Wasson and G. G. Slaughter 58 Abstract of paper submitted for publication in Physical Review C.
VALIDITY OF THE VALENCE-NEUTRON MODEL FOR 98Ko G. W. Cole, R. E. Chrien, R. C. Byrd, S. F. Mughabghab, J. A. It. .ey, and G. G. Slaughter 58 The validity of the valence neutron model for predicting partial radiation widths in the 98Mo(n,7)99Mo reaction is good for resonances with large reduced neutron widths, and seems to be less good for smaller resonances where statistical effects would be more important.
THE 9' Ziipj) REACTION AND THE LEVEL STRUCTURE OF 89 It J. B. BaU 59 Abstract of published paper: Phys. Rev. C6,2139 (197?V
SYSTEM ATICS OF L = 0 TRANSITIONS OBSERVED IN THE <#>,*) REACTION OF NUCLEI NEAR N = 50 J. B. Ball and J. S. Larsen 59 Abstract of published paper: Phys. Rev. Lett. 29,1014 (1972).
A REMARK ON THE LEVEL STRUCTURE OF 93Mo AND THE FAILURE OF/ DETERMINATION BY SPECTROSCOPIC FACTOR RATIOS NEAR CLOSED SHELLS J. B. BaU 59 Abstract of published paper: Phys. Lett. 4IB, 55 (1972).
ENERGY LEVELS OF 94Ru OBSERVED WITH THE 96RuTHE LEVEL STRUCTURE OF 92Mo AND 94MO STUDIED WITH THE (?,() REACTION J. S. larsen, J. B. Ball, and C. B. Fulmer 60 Abstract of paper to be published in Physical Review C.
CALCULATED ENERGY LEVELS FOR 89Y, 90Zf,91 Nb, 92Mo, 93Tc, AND 9*Ru J. B. Ball, J. B. McGrory, and J. S. Larsen 60 Abstnct of published paper: Phys. Lett. 41B, 581 (1972). I
X
EXCITATION FUNCTIONS FOR HEUON4NDUCED REACTIONS IN IRON C. B. Fulroer, 1. R. Wdiams, W. C. Palmer, and G. Kindred 60 Abstract of published paper: toys. Rev. C6, 1720-30 (1972).
ELASTIC SCATTERING OF HEUONS AND ALPHA PARTICLES AT AND NEAR 180° W. W. Eidson, C. C. Foster, C. B. Fulmer, J. C. Hifde, D. C. Hensky. and N. M. OTaflon 61 Values of aid) were measured for elastic scattering of alpha particles and hetions over the range 155-18>* for a number of mrident particle energies and target nuclei.
INTERFERENCE BETWEEN COULOMB AND NUCLEAR EXCITATION IN INELASTIC SCATTERING OF ' *0 IONS F. Videbaek, I. Chernov, P. R. Christensen, and E. E. Gross 67 Abstract of published paper: toys. Rev. Lett. 28,1072 (1972).
TOTAL CROSS SECTION OF CALCIUM C. H. Johnson, J. L. Fowler, and N. W. Hill 67 The total cross section of calcium has been measured in the range 60 to 100 keV with energy resolution of 0.1 to 1.0 keV.
NEUTRON SHELL STRUCTURE IN 98Zr, 9SZr, AND 97Zr BY (dj>) AND (a,3He) REACTIONS C. R. Bingham and G. T. Fabian 69 Abstract of paper accepted for publication in Physical Review C.
GIANT RESONANCES IN THE HIGH-ENERGY INELASTIC SCATTERING CONTINUUM M. B. Lewis 69 Abstract of published paper: toys. Rev. Lett. 29,1257 (1972).
RULES FOR SPIN AND PARITY ASSIGNMENTS BASED ON LOG// VALUES S. Raman asd N. B. Gove 69 Abstract of paper to be published in the Physical Review.
LOG/if VALUES FOR SECOND-FOR31DDEN BETA TRANSITIONS AND THE DECAY OF 24Na S. Raman, N. B. Gove, J. K. Dickens, and T. A. WaOdewkz 70 Abstract oi published paper: toys. Lett. 40B, 89 (1972).
6I 63 ,6 CROSS SECTIONS FOR THE Ni, CU( OTY) REACTIONS R. L. Robinson, J. C. Wells, Jr., H. J. Kim, and J. L. C. Ford, Jr 70
Cross sections for the various exit channels of the 61Ni,63Cu(16OJC) reactions are reported for EI6Q= 38.5-48.5 MeV.
INTERPRETATION OF THE 58'60Ni(,6O;r) REACTIONS R. L. Robinson and H. J. Kim 71 The cross sections for the reactions produced by bombardment of 58'60Ni with 38-46 MeV l60 ions are compared to predictions of the optical model and for statistical decay of a compound nuclear system.
IK-BEAM GAMMA RAYS FROM THE '60 AND ' 2C BOMBARDMENT OF SILICON ISOTOPES H. J. Kim, R. L. Robinson, W. T. Milner, and J. C. Wells, Jr 75 Properties of the high-spin states populated by the (,60,2»), (160,2p), and (12C,2p) reactions on Si isotopes were investigated. Preliminary results deduced from the gamma-ray singles, gamma-gamma coincidence, and partide-gamma coincidence studies are reported.
THE '' °Pd,»l *C4p4>'y) REACTIONS J. A. Deye, R. L. Robinson, and J. L. C. Ford, Jr 76 Abstract of paper submitted for publication in Nuclear Physics.
ELASTIC AND INELASTIC PROTON SCATTERING FROM "Sr A. V. Ramayya, J. L.C. Ford, Jr., R. L Robinson, and J. H. Hamilton 77 Abstract of published paper: Nud. toys. A193,186-92 (1972). XI
M /4>100 TOTAL REACTION CROSS-SECTION MEASUREMENTS FOR 30- TO 60>MeV PROTONS AND THE IMAGINARY OPTICAL POTENTIAL J. J. H. Menet. E. E. Gross. J. J. Mabrafy. and A. Zucker 77 Abstract of published paper: Phys. Rev. C4,1114 (1971).
PROPERTIES OF THE 2' AND 2" STATES IN ,06'!' 2Cd ATD ' MC4 Z. W. Grabowski and R. L. Robinson 77 Abstract of paper to be submitted for publication in Nuclear Physics.
PROTON EXCITATIONS IN I09Ag R. L Auble, D. J. Horen, F. E. Bertrand, and Y. A. Ellis 78 Proton states in 109Ag are being studied by means of the ,08Pd(3He/f) reaction using 27-MeV 3He ions from the ORIC.
PROTON EXCITATIONS IN l0*'' l0Cd FROM (3He^) REACTIONS R. L. Auble, D. J. Horen, F. E. Bertrand, &nd J. B. Ball 78 Abstract of published paper: Phys. Rev. C6,2223 (1972).
SEARCH FOR A ZERO-PHONON GAMMA-RAY TRANSITION IN l0*Pd AND ' 34la P. H. Stetson, S. Raman, J. A. McNabb, R. W. Lide.and C. R. Bingham 78 Abstract of a paper submitted for publication to the Physical Review.
THE ' ,0Pd,! %6Cd(p4>'j) REACTIONS J. A. Deye, R. L. Robinson, and J. L. C. Ford, Jr 79 Abstract of paper submitted for publication in Nuclear Physics. p-WAVE RESONANCES IN ''! Cdf*?)1' 2Cd O. A. Wasson and B. J. Allen 79 Abstract of paper submitted for publication to Physical Review C
COULOMB EXCITATION OF f 17'! l9Sn P. H. Stelson, W. T. Mflner, F. K. McGowan, R. L. Robinson, and S. Raman 80 Abstract of published paper: NucL Phys. A190,197-217 (1972).
NEUTRON SHELL STRUCTURE IN ' 2SSn BY (dj>) AND (a,3He) REACTIONS C. R. Bingham and D. L. Hiliis 80 Abstract of paper submitted for publication to Physical Review C.
NUCLEAR SPECTROSCOPY OF NEUTRON DEFICIENT LANTHANUM, DYSPROSIUM, AND ERBIUM ACTIVITIES B. Harmatz and T. H. Handley , 80 Abstract of published paper: NucL Phys. A191,497 (1972).
NEUTRON HOLE STATES IN '38U AND' 40Pi V. D. Helton, J.C. Hiebert,and J. B. Ball , 81 Abstract of paper submitted for publication to Nuclear Phywics.
ENERGY LEVELS IN ,42Nd S. Raman, J. L. Foster, Jr., O. Dietzsch, D. Spalding, L. Bimbot, and B. H. Wudenthal 81 Abstract of paper to be published in Nuclear Physics A.
THE LOW-LYING EXCITED STATES OF l4SNd POPULATED BY THE CAPTURE OF THERMAL NEUTRONS D. A. McCiure, S. Raman, and J. A. Harvey , 82 Abstract of paper to be published in proceedings of Conference on Nuclear Structure Study with Neutrons, Budapest, July 1972. xu
NEURON SHELL STRUCTURE OF ,4$N4 FROM {dj>) AND (a,3He) REACTIONS C. R. Bingham. D. L H»»,and J. B. Ball 82 Frehnisary results for the study of the 14sNd(4j>) and ,4$Nd(<*,3He) reactons indicate that a large fraction of the • strength for the JV = 82-126 shell has been located.
DECAY OF 5.9-DAY l4$Eu TO LEVELS IN i45Sm E. Newman, K. S. Toth, and I. R. Wihams 84 Abstract of paper accepted for publication in Physical Renew C.
HIGH LYING 2* STATES IN >48Sm OBSERVED IN THE DECAY OF 5~ ,4*Eu K. i. Toth and E. Newman 84 Abstract of paper accepted for publication in Physical Review C.
THE L0W4.YING EXCITED STATES OF 14sNd POPULATED BY THE CAPTURE OF THERMAL NEUTRONS D. A. McQure, S. Raman, and J. A. Harvey 84 Abstract of paper published in Contributions to IAEA Conference on Nuclear Structure Study with Neutrons, July 31-August 5, J972. Budapest, Hungary, p. 128 (1972).
STUDY OF HAFNIUM ALPHA EMITTERS: NEW ISOTOPES ' S9Hf, 160Hf, AND ,M Hf K. S. Toth, R. L. Harm, C. R. Bingham, M. A. Ijaz, and R. F. Walker, Jr 85 Abstract of paper submitted for publication in Physical Review C.
NONSTATISTtCAL EFFECTS IN THE As GIANT RESONANCE S. F. Mugbabghab, M. R. Bhat, G. A. Bartholomew, R. E. Chnen, G. W. Cole, O. A. Wasson, and G.G. Slaughter 85 Abstract of paper published in Contributions to IAEA Conference on Nuclear Structure Study with Neutrons. July 31-August 5, J972, Budapest, Hungary, p. 214 (1972).
LIFETIME MEASUREMENTS OF 8% 10% AND 12* ROTATIONAL STATES IN 164Dy G. B. Hagemann, E. EichJer, D. C. Hensky, N. R. Johnson, W. T. Miner, and L. L. Riedinger 85 Lifetimes of the 8*, 10% and 12* rotational states in I64Dy were deduced from the shapes of the corresponding Doppkr-broadened gamma transitions.
EVIDENCE FOR THE ALPHA DECAY OF THE NEW ISOTOPE l69Os K.S.Toth, R. L. Hahn,C. R. Hngteni, M>. A. Ijaz,and R. F. Walker, Jr 86 Abstract of published paper: Phys. Rev. C6,2297 (1972).
ALPHA-DECAY PROPERTIES OF THE NEW OSMIUM ISOTOPES ! 70Os AND '7I Os K. S. Toth, R. L. Hahn, M. A. Ijaz, and R. F. Walker, Jr 87 Abstract of published paper: Phys. Rev. C5,2060 (1972).
SEARCH FOR INTERMEDIATE-STATE STRUCTURE FROM RESONANCE NEUTRON CAPTURE IN lssRe AND 1>7Re J. A. Harvey, N. W. Hil, A. Stolovy, and A. I. Namenson 87 Gamma rays with energies >4 MeV from neutron capture have been measured at ORELA for ~1200 resonances m 1 ,$,,87Re op to 3000 eV in search of intermediate-state structure.
COMMENTS ON THE DOORWAY STATE IN 20*Pb B. J. Aien, R. L. Macklin.C. Y. Fu, and R. R. Winters 88 Abstract of paper submitted for publication in Physkal Review C, Comments and Addenda.
INVESTIGATION OF THE "'P*12C,'' B)20*P AND 20,Pb(, 2C,* 3C)M1Pb REACTIONS AT HIGH BOMBARDING ENERGIES J. S. Larsen, J. L. C. Ford, Jr., R. M. Gaedke, K. S. Toth, J.B. Bel, and R. L. Hahn 88 Abstract of published paper: Phys. Lett. 42B, 205 (1972). ZU1
GIANT RESONANCES IN THE HtGH-ENERCY HEUUMINELASTK SCATTERING M. B. Lewis Abstract of paper to be pubtwhrd in Physical Review Letters.
INVESTIGATION OF THE 20*Fu<»,»*) REACTION AT E - 54 Mf V M. B. Lewis, F. E. Bertrand, and C. B. Tulmcr 88 Abstract of paper to be published in the Physical Review.
POSSIBILITY OF STRONG MULTtPOLE VIBRATIONS IN THE LOW-EXCITATION REGION OF THE NUCLEAR CONTINUUM M. B. Lewisand F. E. Bertrand f9 Abstract of published paper: Phys. Rev. C6, 1108 (1972).
THE SIGN OF THE HEXADECAPOLE MOMENTS OF 233Th AND 338U NUCLEI E. Eichfcr, N. R. Johnson, R. O. Saver, D. C Hensley, and L. L. Riednger 89 Abstract of paper submitted for publication in Physical Review Letters.
COMPOUNIVNUCLEAR AND TRANSFER REACTIONS IN l3C REACTIONS WITH 33,U AND 23*Fu R. LHahn.f.F. Dittnet, K.S. Toth,andO. L. Ketter 89 Angular and range distributions were measured for 2*4Cf and 345Cf re-oils produced in the reactions 33*U(,3Cgut) and 23,Pa( Cvorn). The evidence indicates that the first set of reactions proceeds via uanrwund-ancleus fonaatio*, whne the second set involves transfer of a part of the incident 12C, foBowed by neutron emission from the excited
NEUTRON TOTAL CROSS SECTION OF 34*Cm AND 343Pn FROM 0.5 TO 5000 eV J. A. Harvey, N. W. Hal, P. W. Benjamin, C E. AhtfeM, F. B. Simpson, O. D. Simpson, and H. G. Mater 90
Transmission measurements have been made at ORELA upon 24*Cm and 342Pu from 0.5 to 5000 eV.
ELECTRIC HEXADECAFOLE MOMENTS IN THE ACTTNIDE NUCLEI F. K. McGowan, C. E. Bemis, Jr., J. L. C. Ford, Jr., W. T. Miner, F. H. Stetson, and R. L. Robinson , 91 Large contributions to the excitation of 4* rotational states from £4 transitions have been observed in precision Coulomb-excitation experiments with i7-McV 4He ions for 12 evea-4 actnwV nuclei (230 STUDIES OF 23SU AND 337Np SMALL-SAMPLE FISSION CROSS-SECTION MEASUREMENTS ON 34,Cf J. W. T. Dabbs, C. E. Bemis, N.W. Hill, M. S. Moore,and A. N. Has 100 A very large resonance at 0.7 eV accounted fcr ~7S% of all fission events observed between 0.3 eV aad 1 MeV.
ASYMMETRIC FISSHJN IN THE TWO-CENTER MODEL M. G. Mustafa, U. Mosel, and H. W. Schmitt 102 Abstract of published paper: Phys. Rev. Lett. 28,1536 (1972).
ASYMMETRY IN NUCLEAR FISSION M. G. Mustafa, U. Mosel, and H. W. Schmttt \ 102 Abstract of paper submitted for publication in Physical Review C nv rO^XnALENEXGYFOKT1IERSSIONOFASlJI¥nCAVY?«UCLEUS M- G. Mntfafa. U. Ifoarf. and H. W. Scaantt 102
Tag* anttBafJBntJBan1 d^MMW -iiifiJ1* &HT faBs* AMBMMI tftf tana* «9jRBnM4nn*.apVV unanaT^PWC ^^^X RttC aaaVBR r-naarnHnVaavPai
DEPENDENCE OF FBSMN MASS ASYMMETRY ON THE INTERNAL EXCITATION ENERGY OF THE FSSMNWG NUCLEUS •L C. Mastataaad H. W. Sckautt 103 ft raw in ay calculations baaed oa the asyntnwtric two-center atodel hate begin ia an effort to study changes in the effective potential energy surface for fosm.< with iacieaarg compoaad auclcnj excitation energy.
REAIJSTIC SINGLE -PARTICLE K MATRIX FOR DEFORl*^ AND FKSIONE*; NUCLEI R. Y. Cum, D. Kokand H. W. Schnutt 106 cafcabtjess based cs the BweiLaeA-GoteTnra density-dependent nd nwcnrum dependent snaXoarOiJe Haunaoaiaa hate been perforated for aght nuclei from 4He to 49Ca and are in progrcs for heavy aactei.
SYSTEMATKS OF FRAGMENT MASS AND ENERGY DOTRIBU110NS FOR PROTON4TOUCED FBSMN OF 23,U, 23$U. AND 23*U Robert L. Ferguson. Franz final. Fiances Heawaton. S. C. Burnett, and H. W. Schnutt 106 Abstract of paper submitted for pnbheation ia Physical Rewiew C
FBKMON OF 2#*Bi »Y Ju-l-MeV PROTONS: SEARCH FOR AN ASYB1MET1UC COMPONENT IN THE MASS nSTRnUTION, AND NEUTRON EMBSMJN RESULTS Fiaav PlnnL Rohm L Ferguson, Fiaaca 106 Abstract of paper sakatt ied for publication ia Physical Review C
MASS AND TOTAL KINETIC ENERGY DISTRIBUTIONS FROM THE SPONTANEOUS FBSMN0FM'O» Frances Pkaaoaton, Robert L. Ferguson, Franz final, and C L. Beans, Jr 107 Fragment nans and total kinetic energy dhtinmlioai hate been deternuued in an energy-energy correlation experiment on spoataneoBS tanua of 24*Cm.
NEUTRON MULTBTLKITY IMSTRDUTtONS IN THE SPONTANEOUS FISSION OF 24*Cm, 24*Cm, AND 252Cf R. W. Stoagfcton, J. Haiperin, C. E. Bern*, Jr., and H. W. Schautt 109 Abstract of paper accepted tor pabheatior in Mtdlaa^ ^^
233 235 PROMPT GAMMA RAYS EMiTTED IN THE TllERMAL4«IEUTRON4NDUCED FISSION OF Uf U, AND 2MFu AND THE SPONTANEOUS FSSSsON OF 2S2a Frances Pkasonton, Robert L. Fergnson, and H. W. Schautt 109 Rcsntts are given for the average energy and average nantber of ganuna rays emitted within ~5 usee after fission as functions of faaantatana^Siaaa^itJesm noted •
LIMITS OP ANGULAR MOMENTUM IN HEAVY40N COMPOUNl>NUCUUS REACTIONS U. Bban and Franz Paul 112 Abstract of pubadwd paper: Phys. Ret. Lett. 29,303 (1972).
PREDICTIONS FOR HEAVY-ION REACTIONS RASED ON THE ROTATING LIQUID DROP MODEL Franz Plasil 113 Abstract of paper pubhshed in procecdiags of European Conference on Nactear Physics, Aix-en-Provence, June-Jury 1972, vol. II, p. 51,/ Phys. Paris, France (1972).
EQUILIBRIUM CONFIGURATIONS OF ROTATING CHARGED OR GRAVITATING LIQUID MASSES WITH SURFACE TENSION. PART II S. Cohen, Franz Plant, and W. J. Swiatecki 113 Abstract of paper submitted for publication to Annals of Physics. »
XV
5. MOSSBAUER SPECTROSCOPY
EXPERIMENTAL TEST OF HEWS GAUGE-INVARIANT GEOMETRY t G. Hams. Pari G. Hnray, F. E. Ob-mhiin. J. O. Thomson, and R. A. Vdfccco 114 Abstnct o»" paper accepted for paNkarioa a the Physical Review.
GIANT MAGNETIC HYPERFINE FIELDS OF *' Ni ON TETRAHEDRAL SITES OF SPINELS JohnC. Loteand Fekx E. Obemfcaai 114
The **Ni nadear pawn resonance (NCR) spectrum of the nickel chroaule (NiCrI04) spinel shows both the largest magnetic dipok and electric quadrupok hyperfme (hi) interactions yet leported for nickel in any host lattice.
THE *'Ni MOSSBAUER EFFECT IN NICKEL-PALLADIUM ALLOYS JohnE.Tamfl US Abstract of ORNL-TM-3930.
MOSSBAUER STUDIES OF ELECTROSTATIC HYPERF1NE INTERACTIONS IN z3*U, 23*U, AND M4U Joyce Anne Mound 115 Abstract of ORNL-TM-3931.
6. ATOMIC AND MOLECULAR PHYSICS
ELECTRON-OPTICAL FACTORS LIMITING RESOLUTION IN TRANSMISSION ELECTRON MICROSCOPES T. A. Wetton 116 Abstract of pnbbhhed paper: pp. 125-157 in Ptoceedmgs of Workshop Conference on Microscopy of Ouster NuckH at Defected Crystals (CTntt Riser. Cmmde. September 19711, CRNL-622 -1, edited by J. R. Parsons (1972L
RELATIVE ENERGIES OF THE LOWEST LEVELS OF THE/V3./**2. AND/** V ELECTRON CONFIGURATIONS OF THE LANTHAMDE AND ACTTNSDE NEUTRAL ATOMS K. L Vander Sans and L. J. Nugent 116 Abstnct of pubushed paper: Phys. Rep. 60A, 86 (1972).
SYSTEMATKS IN THE RELATIVE ENERGIES OF SOME LO%f^YrNC EI-ECTRON CONFIGURATIONS IN THE GASEOUS ATOMS AND IONS OF THE LANTHANIDE AND ACTfNIDE SERIES K. LVanderSfcus and L. J. Nugent 117 Abstract of paper submitted for publication in the Journel of the Optical Society of Americm.
STUDIES ON THE ORIGIN OF THE JdOfron'1-REGION INFltARED RANDS OF NATURAL AND SYNTHETIC ALPHA QUARTZ O. C. Koppand P. A- Stoats 117 Results of doping experiments on synthetic quartz crystals zse gncn. Boron has been shown to prodnce a band in synthetic quartz similar to one foand in natural quartz.
VIBRATIONAL DETERMINATION OF CRYSTAL STURCTURES John M.Sprii»»CT,E.S«miinn, and HcmyW.Mofaaa 119 Abstract of chapter to be pubhsfrtd in boofc Proceedings of the Third International Conference on Rmmm Spectroscopy, to bepubfabed by Heyden and Son, Ltd., London, 1973.
PHOTOELECTRON CHEMKAL SMFTS irt INORGANK: COMPOUNDS Gary Elder McGtnre 119 Abstract of ORNL-TM-3820.
USE OF X-RAY PHOTOELECTRON SPECTROSCOPY TO STUDY BONDING IN CHROMIUM, MANGANESE, IRON, AND COBALT COMPOUNDS J. C. Carver, G. K. Schweitzer, and Thomas A. Carbon 120 Abstract of published paper: / Chem. Phys. 57,973 (1972). XVI
STUDY OF THE X-RAY PlfOTOELECTRON SPECTRUM OF TUNGSTEN-TUNGSTEN OXIDE AS A FUNCTION OF THKXNESS OF THE SURFACE OXIDE LAYER Thomas A. Carbon and G- E. McGwire 120
Abstract C4 published paper: / Electron Spevtrosc. 1,161 < 197/2- PRESENT AND FUTURE APPLICATIONS OF AUGER SPECTROSCOPY A.Carbon 121 Abstract of paper to be pubbsbed in tuner Shell ionization Phenomena and Future Applications, vol. IV. R. V Fink. S. T. Hanson. J. M. Pabns. and P. V. Rao. «b„ Technical laformataoa Center. USAEC. Oak Ridge. Tennessee.
ANGULAR DISTRIBUTION OF THE PltOTOELECTRON SPECTRUM OF CO*, COS. CS2, NJO.HIOANOHJS A. Carbon SJH) G. E. McGuhe 121 Abstract of paUidied paper / Fleet™- Spearose. !. 209 .
STUDY OF THE ANGULAR DISTRIBUTION FOR THE PHOTOELECTRON SPECTRA OF HALOGEN^IMSTiTUTED METHANE MOLECU1ES A. Carbon and R.M. White 121 Abstract of paper to be published by the Chemical Society as part of dtt General Discussion on the Photoefcctron Spectroscopy of Molecules. Uuiumaly of Sussex, 12-14 September 1972. sponsored by the Faraday Society.
X-RAY PHOTOELECTRON SPECTRA OF ETHYUFIEDLAMBIETETRAACETK: AQD AND ITS METAL COMPLEXES ^LOamLJC-Cara.andllKmmA-Carbou 122 Abstract of paper to be published mhtotgum. Otentntfrr.
ON THE Z2 DEPENDENCE OF THE X-RAY PRODUCTION CROSS SECTION BY 5-MrV/anm HEAVY IONS A.sanderWouut.M-J-SdTmuih.C A.I.udmum. R_L. Haha,and E.Tirhtfi 122 Abstract of paper pnHhhrd in Inner SheM kmamaon Phenomena and Fnmre AfmUcatkms, ed. by R. W. Fink. S. T. J. M. Pahns, and P. V Rao. pubhshed by USAEC Teclssn^ lafonuabon Center. Oak Ridet. 1973. p 1SS8.
ENERGY SHuFIS AND RELATIVE INTENSITIES OF K X RAYS PRODUCED BY SWBFT HEAVY IONS nLJSatanafnXA-TanaerWoude.MwIC ALaaimina 122 Abstract of pubiihrd paper: knys. Raw. Lett. 29(u), 329 (1972).
METASTABLE STATES OF HBGHL Y EXCITED HEAVY KINS P.J.f*tfcP.hlC*nTiM.A.S«uuvW.W.Sun^ • ,23 Abstract of paper to be published in Ataaaat Phytaa, I
ON METASTABLE AUTOIONIZING STATES OF HrGHLY EXCITED HEAVY IONS I. A- Scum, D. J. Pegg, P. M. Griffin, and W. W. Smith .. 123 Abstract of putmshed paper: fhys. Re*. Lett. 28,1229 (1972).
METASTABIf AUTOIONIZING STATES I. A. Scum 124 Abstract of paper presented at the Third Into national Conference on Beam-Foi Spectroscopy, Tucson. Arizona, October 1972, and to be published in the proceedings, mkxAmmbepnblnhcdmNuriem Inss? menismnd Imelhodi.
ELECTRON SPECTROSCOPY OF IWL-EXCITED CHLORINE BEAMS D.J.Pea.P. M.Griffin,I. A.SeBJn,and W.W.Smith 124 Abstract of paper presented at the Third Inter national Conference on Beam-1-oil Spectroscopy. Tucson, Arizona, October 1972, and to be pnbhshed in the proceedings, which wnl be pubusbed in Nudern Instruments and Methods.
PROJECTILE STRUCTURE EFFECTS ON NEON K X-RAY PRODUCTION BY FAST, HIGHLY IONIZFD ARGON BEAMS J. R. Mowat, D. J. Pegg, R. S. Peterson, P. M. Griffin, and I. A. Seam 124 Abstract of pubfished paper: Thys. Rev. Lett. 29,1577 (1972). rvu
BEAM FRACTIONS IN "THE LOWEST QUARTET METASTABLE AUTOtONlZING STATE FOR O5* AND F* BEAMS AFTUt PASSAGE THROUGH FOILS W. W. South. B. DonoBy. D. J. Kg*. M. D. Brow, sad 1. A. Sefcn 124 Abstract of paper to be pabfahrd m the Pkyskai Review.
TIME-DEPENDENT THEORY OF STARK QUENCHING OF 2r STATES IN HYDROGEN AND HELIUM H. X. Hokaad I. A- SeBai \iS Abstract of pabMsfcjed paper: P*j* rtrr. A*. SOB (1972).
PROJECTILE STRUCTURE EFFECTS IN X-RAY PRODUCTION BY FAST, UKXJY STRJPPED HEAVY IONS I. A. ScBa. D. J. Pes, P. M. Griffin, J. R. Howat. WW San.aadR.S.Petenoa 125 caxtroa ejectm cross mlioMt • hc%t stoats stntck by aaj)dy naned heavy
AUTOI0PRZAT10N OF FAST HEAVY IONS: SPECTRA AND LIFETIMES I. A. SeBm, D. J. I^K P. M. GrtfTm, J. R. Mowat, W. W. SMith, M. P. Brow, J. R. MydnaaM. mi R. S. Petersoa 12. New •ioranbqa oooceraaw prodoctioa of fa*«wa^ aafcaow aM*astable aatokMKrac states of < alTMfORBMIDEN TRANSITION PROBABILITIES IN METASTABLE STATES OF HELIUM-IJKE HEAVY RONS L A. Sea**, D. J. Pegf, *- M- GriBia, J. R. alowt, W. W. Saath, M. P. Brow, J. K. Mn diwaH, aad R. S. Pcwrooa 12* •ocacaaeat spaMorvaaaea soft x-ny
HYPERCHANNEUNG: AN AXIAL CHANNELING PHENOMENON B R. Aapfclea,C P. Moak,T.S, Niaj|Jr,—d J. H. Barrett 12* tof|i iiilii paper: /Byxjfcr. Lett. 2*20), 1307-11 (1972L
OOUJOONAL X-RAY EXCITATION IN SOLID AND GASEOUS TARGETS BY HEAVY-ION
ILO.Life.J.Steals.Date,a»iCD.Moak 127 : of pabfaecd paper: fkjn. Rew. Lett. 2*1). t-10 (1972).
METASTABLE AUIVMOPBZWG STATES IN SODIUM4JKE CHLORBME P. J. PcffK. L A. Seam. P. M. Griffm, aad W. W. Saaith 127 Abstract of pabbsbed paper: thjs. Rep. Lett. 2S, IMS (1972). 7. INSTRUMENTATION AND EXPHUMENTAL TECHNIQUES
MEASUREMENT OF SURFACE CONTAMINATION USING OXYGErWON-WWCED X RAY S ILJSaltiaaisl^TaaaerWoade.aadCAIiJranM 12S Abstract of pabfcsbed paper: >4pat thy*. Lett. 21(2), 64 (1972L
HYDROGEN CONTAMINATION OH THE SURFACE OF THW METAL POOS M.J.Saftaka^G r^l***B«,a«dAWoKcadca 12S
of:
llALF-YALUETrllCIJIESSOFORUNARYOONCRFTEPM H. M. Batter, K. M. WaBace. aad C B. Faaajer 129 Abstract of a paper to be pabfisbed ia AWtk fkytkx
RADIATION LEAKAGE THROUGH THIN CYCLOTRON SMELD WALLS C B. Fabacr, H. M. Batter, aad X. M. WaBaec 129 Abstract of pabirbed paper: fmtide AcceL 4,63-61(1972). XV111
NEUTRON YIELD FROM A SMALL HIGH-PURITY "'PaO* SOURCE J. K. 8ak and H. M. Butler 130 Abstract of paper submitted for publication in Nuclear Technology, Technical Note.
DELAYED GAMMA RADIATIONS FROM THE ORELA TARGET CH. Johnson and N.W.Hnl 130 Delayed gamma nys of 0J and 2.2 MeV are observed from the ORELA source.
A SIMPLE METHOD FOR ACCURATE MEASUREMENTS OF TOTAL INTERNA! CONVERSION COEFFICIENTS S. Raman 132 Abstract of pobashed paper: NucL Instrum. Methods 103,407 (1972).
HGH-RESOLUTION ELECTRON MICROSCOPY PROGRAM R tWonkun, J E.Mann, E.G. Rjckanlsoo, and N. F Ziegfter 132 Development of the field emission gun and the supercomfarting objective km column for the high-coherence election microscope continued.
TRACK DETECTOR CALIBRATION H. R.Hart,Jr.,M.J.Saftiiianh,aad AvaaderWoude 133 Beams of 182-MeV Ar** and 130-MeV Fe*" have been used to calibrate the response of materials employed as track
A SkWLE W* DETECTORFOR ENERGIES OF 10 TO 70 MeV hi J. Sattora^B.hL freedom, R.D. Edge, and C.W.Da^ 133 Abstract of pvbtkhed paper: Nud. Imurttm. Methods 105,311 (1972).
** DETECTOR DEVELOPMENT M.J.Saftata^E.E.Gion^CA.I^e9u^andB-Pieedo«B 133 A lesolution of 1-MeV (FWHM) for 67-MeV protons hat been achieved in one of the plastic srintinator segments of a
DETERIORATION OF LARGE GtOO DIODES CAUSED BY FAST NEUTRONS
PIL Stetson J. K.Dkkeas>S.Rama^ai^R.C.T(amnu3 134 Abstract of published paper: NucL ItKtrum. Methods 9B, **\ -84 (1972).
TIC MEASUREMENT OF THE ABSOLUTE TRANSPORT EI11CSENCY FOR RiKOILS FROM SAVY40N REACTIONS WITH HELIUM JET SYSTEMS W.-P. ?rami(H-Ott, R. L. Mttkodai, and C R. Mnfham 13S Abstract of paper to be puhiihf d ia Macaw hatmmatts *ml Method*.
PROPOSAL FOR A NATIONAL HEAVY-ION LABORATORY ML Stetson 135
APRX)IX)8EDNATK)NALHEAVY40NAOCEURATORATOAKRirXX J. A. Martin, E. D. Hudson, R. S. Lord, Si. L. MaBory, W.T.Ifibm.S. W. hViako.aadP.lt Stcboa 136 Abstract of puouraiJ paper: Qrdotromt - 1972. ATP Conference Proceedings No. 9 (Vancouver, Canada, 18-21 July 1972), pp. 54-62, ed. by J. J. iusgerion and A. StiatlaaVe, An«rkan Institute of Physics, New York, 1972.
ALTERNATES TO THE CYCXOTRON FOR HEAVY40N ACCELERATION J.A.Martin '36 Abstract of ouMahed paper: Cyclotrons - 1972. AIP Conference Pioceedingi No. 9 (Vancouver, Canada, 18-21 July 1971), pp. 33-S3. ed, by J. J. atotjoa and A. Stnthdee, American Institute of Physics, New York, 1972. XIX
THE ORJC AS A HEAVY-ION INJECTOR FOR A SEPARATEDSECTOR CYCLOTRON E. D. Hudson. R. S. Lord, M. L. Mallory. and P. H. Stetson 136 Abstract of published paper: Cyclotrons - 1972. AIP Conference Proceedings No. 9 (Vancouver, Canada. 18-21 July 1972), pp. i '4-82. ed. by J. J. Burgerjon and A. Strathdee. American Institute of Physics. New York. 1972.
A MULTIACCELERATOR SYSTEM FOR HEAVY IONS £. D. Hudson, R. S. Lord, C. A. Ludemann, M. L. Mallory. J. A. Martin. W. T. Mflner, S. W. Mosko, P. H. Stetson, and A. Zucker 136 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco. California. March 5-7,1973).
ION STRIPPING CONSIDERATIONS FOR TANDEM-CYCLOTRON HEAVY-ION ACCELERATOR DESIGN J. A. Martin and P. H. Stetson 137 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973).
ENERGY MULTIPLICATION BY BEAM RECYCLING IN AN ISOCHRONOUS CYCLOTRON E.D. Hudson, M. L. Mallory, R. S. Lord, A. Zucker, H. G. Biosser, and D. A. Johnson 137 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973).
APPENDIX A: CYCLOTRONS - 1972. AVF AND FM F.T. Howard 137 Abstract of published paper: Cyclotrons - 1972, AIP Conference Proceedings No. 9 (Vancouver, Canada, 18-21 July 1972), pp. 689-829, ed. by J. J. Burgerjon and A. Strathdee, American Institute of Physics, New York, 1972.
COMPUTER CONTROL OF THE OAK RIDGE ISOCHRONOUS CYCLOTRON C. A. U«fc3r«n,J. M. Domaschko.S W-Mosko.andK. Slagemaiin 138 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973).
COMPUTER CONTROL SYSTEM FOR THE ORIC C. A. IuKleTnarin, J. M. Domaschko, and S. W. Mosko 138 Abstract of published paper: Cyclotrons - 1972, AIP Conference Proceedings No. 9 (Vancouver, Canada, 18-21 July 1972), pp. 500-509, ed. by J. J. Burgerjon and A. Strathdee, American Institute of Physics, New York, 1972.
LIST OR SORT? - SOME EXPERIENCE WITH THE ORIC MULTIPARAMETER DATA ACQUISITION SYSTEM D. C. HensJey 138 Abstract of paper to be published in the February 1973 IEEE Transactions on Nuclear Science.
A NEW RF SYSTEM FOR THE ORIC S. W. Mosko 139 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973). CYCLOTRON LABORATORY ACCELERATOR DEVELOPMENT PROGRAM E. D. Hudson, R. S. Lord, C A. Ludemann, M. L. Mallory, M. B. Marshall, J. A. Martin, S. W. Mosko, W. R. Smith. J. M. Domaschko, and K. Hagemann 139 Progress in computer control, rf improvement, and the ion extraction is summarized.
CYCLOTRON INTERNAL ION SOURCE WITH DC EXTRACTION M. L. MaHor/, E. D. Hudson, and R. S. Lord 140 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973).
FEASIWUTY AND COST OF A SUPERCONDUCTING HEAVY-ION LINEAR ACCELERATOR C. M. Jones 140 Abstract of paper to be published in Particle Accelerators. XX
SUPERCONDUCTING RESONANT CAVITIES I P. Judish, C. M. Jones, F. K. McGowan. and P. 2. Peebles, Jr 140 Design and construction of a second superconducting helically loaded cavity and measurement system are reported.
RESONANT FREQUENCY CONTROL OF SUPERCONDUCTING RF CAVITIES P Z Peebles, Jr 141 Abstract of paper accepted for publication in the proceedings of the 1973 Particle Accelerator Conference, March 1973.
MEASUREMENT SYSTEM FOR SUPERCONDUCTING RF RESONANT CAVITIES P. Z. Peebles, Jr., C. M. Jones, R. F. King, and J. P. Judish 141 Abstract of paper presented at IEEE Region 3 Conference, April 1972.
DESIGN AND EVALUATION OF A HIGH-POWER VOLTAGE-VARIABLE REACTANCE S. F. Smith and P. Z. Peebles. Jr 141 A voltage-variable reactance for frequency control of superconducting cavity resonant frequency has been developed through a subcontract with the Electrical Engineering Dept., University of Tennessee, Knoxville.
A SLOW TUNER FOR SUPERCONDUCTING HELICALLY LOADED RESONANT CAVITIES C. M. Jones, J. L. Fricke, B. Piosczyk, and J. E. Vetter 142 Abstract of published paper: Proceedings of the 1972 Proton Linear Accelerator Conference, LA-5115, pp. 1611-67.
STATUS OF THE UNISOR PROJECT H. K. Carter, R. L. Mfckodaj, W.-D. Schmidt-Ott, and E. H. Spejevski 142 Development of the UNISOR on-line isotope separator facility is described.
STATUS REPORT ON TH~ 3-MV VAN DE GRAAFF ACCELERATOR J. P. Judish 146 Activities associated with use of the 3-MV Van de Graaff are discussed.
STATUS REPORT OF THE 6-MV VAN DE GRAAFF ACCELERATOR J. A. Biggerstaff and W. T. Newton 146 Activities associated with use of the 6-MV Van de Gra iff are discussed.
STATUS REPORT OF THE TANDEM VAN DE GRAAFF ACCELERATOR G. F. WeUs and R. L. Robinson 146 Activities performed on the Tandem Van de Graaff during the year 1972 are summarized.
STATUS REPORT ON THE OAK RIDGE ELECTRON LINEAR > XELERATOR (ORELA) J. A. Harvey, T. A. Lewis, F. C. Maienschein, and H. A. Todd 148 The performance of the electron linear accelerator and the data handling equipment are summarized.
OAK RIDGE ISOCHRONOUS CYCLOTRON OPERATIONS R. S. Lord, A. W. Rfakola, H. L. Dickerson, C. L. Viar, M. B. Marshall, S. W. Mosko, K. M. Wallace, E. Newman, H. D. Hackler, J. W. Hale. fc. W. Sparks, C. L. Haley, G. A. Palmer, and L. A. Slover 150 The opetation of the ORIC is summarized.
8. OMNIANA
PUBLICATIONS 154 Book and Journal Articles 154 Theses 162 Annual Report 162 Topical Reports 163
PAPERS PRESENTED AT SCIENTIFIC AND TECHNICAL MEETINGS 163 XXI
ANNOUNCEMENTS 169
PERSONNEL ASSIGNMENTS '69 Guest Assignees from Abroad 169 Guest Assignees from the (Jnrted States 170 ctaft Assignments 171 Staff Appointments 171 Staff Termination 171 Staff Appointees - Intralaboratory Loans 172
MISCELLANEOUS PROFESSIONAL ACTIVITIES OF DIVISIONAL PERSONNEL 172
COLLOQUIA AND SEMINARS PRESENTED BY THE PHYSICS DIVISION STAFF 174
PHYSICS DIVISION SEMINARS 176
Ph.D. THESIS RESEARCH 177
MS. THESIS RESEARCH 178
STUDENT GUESTS 179
COOPERATIVE EDUCATION PROGRAM FOR UNDERGRADUATE STUDENTS 179
GUEST ASSIGNEES-STUDENTS NOT ENGAGED IN THESIS RESEARCH AT ORNL 180
CONSULTANTS UNDER SUBCONTRACT WITH UNION CARBIDE CORPORATION NUCLEAR DIVISION - ORNL 180
CONSULTANTS UNDER CONTRACT ARRANGEMENT WITH OAK RIDGE ASSOCIATED UNIVERSITIES 181
ANNUAL INFORMATION MEETING OF THE PHYSICS DIVISION 182
RADIATION CONTROL AND SAFETY IN THE PHYSICS DIVISION 182
UNISOR PROGRAM 182
PARTICIPATION IN VARIED INSTITUTES AND SYMPOSIA 183
ORIENTATION MEETING AT THE ORNL NUCLEAR DATA PROJECT FOR NSF-SPONSORED NUCLEAR INFORMATION RESEARCH ASSOCIATES (N1RA) 183
ORNL HEAVY-ION SUMMER STUDY 184
AUTHOR INDEX 185 Foreword
This annual progress report of the Physics Division Each month the Division Director submits a report covers the calendar year 1972. As in previous years the which summarizes some research activity within the report contains the abstracts of papers published since Division. These reports follow immediately and will give the last annual report and those prepared for publica the reader an overview of the research efforts in tion. Reprints and preprints of these articles are progress. available upon request. Preliminary results of research Looking to the future, in June 1972 the Oak Ridge work in progress »re reported in more detail. Since this National Laboratory sponsored a summer study on work is of a preliminary nature, reference to or heavy-ion research. A short report of this meeting may inclusion of these results in any other publications be found near the end of Sect. 8, and reports on should be done with the express consent of the author. heavy-ion acceleration are given in Sect. 7.
xxiii Monthly Reports of the Physics Division
The Divisional monthly reports, which consist of the Division for calendar year 1972, with references to about 200 words, summarize at least one activity of the the literature updated as of the time of submission of Division for each month of the year. These reports for this annual report, are as follows:
Pretarimry Measurements on a Low-ffhaae-Velocity Smpmmtoctmg Resonant Cavity - January Since the Oak Ridge National Laboratory has had for effectively at the "top of the resonance curve where the some time now a proposal before the Atomic Energy rf and mechanical systems ate decoupled, so that Commission for a heavy-ion accelerator, it must keep mechanica! vibrations introduced essentially no prob abreast of developments in heavy-ion accelerator tech lems for the measurements- They obtained the fofiow nology, such as the superconducting linear accelerator. ing approximate fields at a power consumption of 320 '?;:. quentry, a small experimental group in the mW/m: maximum magnetic field, 187 G; maximum Physics Division has investigated one type of supercon electric field, 4.7S MV/m; axial accelerating field, 0.7 ducting cavity possible for a heavy-ion accelerator. An MV/m. Although formidable problems retain to be important problem for the design is the low velocity of solved, C. M. Jones et al., in their preliminary investiga the ions being accelerated, which requires cavities of tion, discovered no insurmountable obstacles to the use low phase velocities. Since a helically loaded cavity has of helically loaded structures n an accelerator. this property, Jones et al.1 have constructed such a lead-plated cavity with a lead-plated helix and have measured its electrical characteristics in a supercenduct- 1. C M. Joac*. J. P. J****. R. F. King, F. K. MeGowaa, ing state at relatively low frequencies (-136 MHz). W. T. Miner, a* P. Z. PcbUet, Jr., Article AcceL 3,103-13 They operated the cavity as a self-excited oscillator (1972).
The TwoCeater Model and Fission Barriers for Light Elements {A • 180-212) - February For properties of deformed nuclei near their ground preformation of fragment shells to a system of two states, such as quadrupole moments and collective completely separated fragment nucbi. In practice, restoring forces, the Nilsson deformed shell model gives detailed two-center-modd calculations for the nuclear a good theoretical description of the experimental potential energy surface as a function of the shape information. For larger deformations, such as those parameters follow the procedure developed by encountered in the fission process, however, the Nilsson Strutinsky. In this procedure the total potential energy model has proven to be inadequate, probably because it of a nucleus is divided into two parts, a smoothly does not permit a efficient parameterization of the behaving liquid-drop energy and a strongly deforma nuclear shapes. The two-center model,1 a model con tion-dependent shell correction. For nuclei in the range sisting of a two-center oscillator potential, allows a A * 180 to 212, Motel and Schmitt2 have calculated smooth transition from the ground state via the fission barriers on the basis of the two-center model. 2
Their theoretical work gives an overall satisfactory 1. P. Holzer, U. Moset, awl W. Greiner.Mud. toys. AIM, 24 description of The fission barriers for these relatively (1969); U. Mosel and H- W. Schmiu. Xuci toys. A165, 73 light fissionable nuclei within the accuracy of the (1971). known experimental values, which is about 1 MeV. 2. U. Mosd and H. W. Schmitt./ftvs Lett. 37B. 355 < 1971).
A Position-Sensitive Proportional Detector for the Eage Magnetic Spectrograph - March
The Enge split-pole magnetic spectrograph associated pulses from the two ends of a high-resistance wire with the ORNL tandem Van de Graaff has a sufficiently anode. With 15- to 45-MeV alpha particles through the large acceptance angle that it is competitive in effi magnet, a 20-cm-long detector and also a 60-cm one ciency with good-resolution semiconductor detectors. gave resolution in position of 0.7 mm. The deviation But photographic-plate particle detectors usually used from spatial linearity was less than 3%. and the detector with such magnets have well-known disadvantages. Not could handle counting rates up to several tens of only is the reading of the plates tedious and time thousands of counts per second. Ford et al.3 have used consuming, but one also loses the *oility to monitor this detector for a systematic study of alpha-particle and modify an experiment on line. Furthermore, with scattering from transuranic elements. plates there is a limitation in precision because of the huge number of events which must be recorded to obtain statistical accuracy. Ford, Stelson, and Robin 1. J. L. C. Ford, Jr., P. H. Stelson, and R. L. Robinson, NucL son1 have gotten around these difficulties by using a instrum. Methods 98,199 (1972). position-sensitive detector in the focal plane of the 2. C. J. Borkowski and M. K. Kopp, Rev. Set Imtrum. 39, Enge magnet. The Borkowski-Kopp type of detector2 is 1515(1968). 3. J. L. C. Ford, Jr., P. H. St*lson, C. E. Bonis, Jr., F. K. a single-wire, gas proportional counter, which derives McGowan, R. L. Robinson, and W. T. Miiner, Phys. Rev. Lett. the position information from the rise time of the 27,1232(1971).
X-Ray Production by Fast Heavy Ions - April When an ion passes through matter it can excitei the fluorescence yield, that is, the fraction of inner-shell inner-shell electrons of the target atoms into the; vacancies that decay by cn^'en of an x ray, does not continuun- by direct Coulomb excitation, and some off depend on Z. Using the ORIC, van der Woude et al.1 2 6 2 these resulting inner-shell vacancies will decay byr have measured ox for 5 MeV/amu °Ne,' 0,' C, and emission of x rays. Recently there has been an increasedI 4He ions on Ti, Fe, Co, Zr, Sn, and Nd targets. They 2 interest in studying the characteristics of x-ray produc found large deviations in ax from the expected Z tion by fast ions, not only because this could be ,iI dependence and conclude, at least in the case of the K x attractive way of detecting trace elements, but also) rays from Zr, Sn, and Nd, that there is very likely a because of its intrinsic interest as a new tool in thei need for a Z3 term in the expression for the ionization study of atomic structure. As long as polarizationi cross section. effects can be neglected, the cross section 0\ for the production of vacancies in the K shell for projectiles of 2 1. A. van der Woude, M. J. Saltmarsh, C. A. Ludemann, R. L. the same velocity should be proportional to Z , where Hahn, and E. Eichler, submitted for publication in Proceedings Z is the projectile charge. The same should hold for the International Conference on Inner Shell Ionization Phenomena T x-ray production cross section ox if one assumes that (Atlanta, Georgia, April 19 *).
Improved Upper Limit for the Electric Dipole Moment of the Neutron - May
Dress, Miller, and Ramsey1 have concluded their evidence for instability in the spectrometer. In par experimental search for the electric dipole moment of ticular, they removed the principal limitation of their the neutron at the Oak Ridge Research Reactor. After previous experiment2 arising from the nonparallelism of measuring all known systematic effects, they find no the E and B fields, which gives a spurious effect throu^ 3
2$ a term B£ = -(v X F)jc. They placed the spectrometer anticipated improved sensitivity of a few times 10 " and the magnetic shields on a modified, surplus gun cm gives no electric dtpole moment, the experiment will mount so that the direction of the neutron beam provide overwhelming evidence for the superweak through the applied fieldscoul d be easily reversed, thus theory of CP violation; if the result shows an electric reversing the sign o( v ip BF . The final result of the dipole moment, then the superweak theory is not experimental search is u/e = 3 ± 6 X 10~24 cm, which responsible and there mast be a small CP violation in Dress et al. interpret as meaning u/e < 1 X 10~23 cm the weak or strong interactions. with a probability of 75%. They are moving the spectrometer to the High Flux Reactor in Grenoble, I W. B. Dress. P. D. Mitter. and N. F. Ramsey, submitted for where the liquid deuterium secondary moderator and publication in the Physical Review. D. the high flux should provide a factor of 2000 in the 2. i. K Baud, P. D. Miller, W. B. Dress, and N. F. Ramsey. intensity of the very slow neutrons required. If the Phys. Ret. 179,1285 (1969).
Excitation of Giant Qnadrapofe State m Nodei - Jane Lewis and Bert rand1 have analyzed data on inelastic the indastically s attered protons are consistent with scattering of 62-MeV protons from targets cf 27A1, the interpretation of the peaks as quadnipole reso S4Fe, 120Sn, aid 209Bi, where the protons were nances, although other interpretations are not rigor accelerated with the Oak Ridge Isochronous Cyclotron. ously ruled out.1 Data at 182 MeV definitely indicate The inelastic proton spectra, which covered the 1.5- to a quadnipole transition. Satchler2 has applied the 62.0-MeV range, showea peaks in the continuum struc deformed optical potential to calculations of dipole ture near the energy region of the giant dipole and quadnipole transitions in nuclei. He shows that the resonance - that is, the resonance arising from the strengths of the observed resonances are consistent with protons and the neutrons vibrating against each other. the quadnipole interpretation, whereas the giant dipole But the observed inelastic protons peaked at an is insufficient to explain the data. He also points out excitation energy consistently lower by ~2 MeV than that virtual excitation of the collective quadnipole the dipole resonant energy. On the basis of the energy resonance would explain the effective charge for quad- of this proton peak as well as the strength of the rupole transitions needed in shell-model calculations. resonances, Lewis and Bertrand suggest that the; have excited another giant collective state of the quadnipole 1. M. B. Lewis and F. E. Bertrand, submitted for publication type, an example of which is a collective motion in in Nuclear Physics; original data from F. E. Bertrand and R- W. which the nucleus vibrates between a prolate and an Peelle, ORNL4455, -4469, -4471, and -4638. oblate shape. At 62 MeV the angular distributions of 2. G. R. Satchler, Nucl. Phys. A195,1-25 (1972).
Hyperchanneling, an Axial Channeling Phenomenon - July The channeling of collimated heavy ions of bromine channeling hyperchanneling. In planar channeling an or iodine by adjacent atomic planes of thin crystals of ion travels in a single channel between adjacent atomic silver or gold has allowed a mapping of interatomic planes, whereas in axial channeling the majority of the potentials in crystals and has, as well, yielded insights channeled ions wander from one axial channel to into the electron capture and loss processes in the hravy another. In hyptrchanneiing, however, the transverse ions themselves.1 »2 With very tightly collimated 21.6- energy of the ions is less than the potential barrier MeV iodine ions, Appleton et al.9 have recently studied between the rows, and thus the ions are constrained to the channeling of a distinct group of ions in single gold travel through a single axial channel. The energy crystals which show, over a very small range of spectrum of hyperchanneled 21.6-MeV iodine ions incidence angles with respect to the [Oil] direction, an transmitted within ±0.012° of the incident beam unusually low energy loss. They identify this group as direction shows a rate of energy loss of 3.15 MeV/j/m, ions which remain within a single axial channel through compared with a rate of 3.9 MeV/pim for planar chan out the passage through the crystal, and call this type of neled ions. Analysis of the results indicates that hyper- *
channeled ions provide a new means for studying 2. H. O. Lurz. S- Datz. C. D. Moak. and T. S. Noggfe. Pkrs. multiple scattering, radiation damage, and ion-atom Lett. 33A.309U970)- potentials in solids. 3. B. R Appteton. C D. Moak. T. S Noggie. and J. H. Barrett. Phvs Ret. Lett. 2*. 1307 11972).
1. H. 0. Lutz. S. Datz. C D. Moak. 2nd T- S. Noggle. Phvs. Re*. Lett. 17,285(1966).
J?-Matrix Analysis with a Diffuse Edge Potential for ' *0 + n Data - August
The /^-matrix analysis, introduced by Wigner and radius inside the tail of the resulting potential at 3.86 2 Eisenbud some 25 years ago, is today the most useful fm. so that the \d3{2 reduced width is equal to frV/Jr . and physically significant way of describing resonances gives an excellent fit to the total and (n.a) cross section in nuclear reactions arm scattering. The selection of the up to 5J8 MeV neutron energy.1 Besides making the boundary radius on which reduced resonance widths reduced widths of the five %* resonances equal to the depend rather critically, however, has been something single-particle reduced width, this procedure shows that of a problem. In an /{-matrix analysis of ' *CXn,n) and the sum of the reduced widths of the V »«d the %' "0(n.a) cross sections,1 Johnson2 has found a self- states is very small and that the summed reduced widths and consistent method of selecting this boundary radius. He of thep3/2.Pi/2-/7/2' /s/2 states are, respectively, fits the off-resonance cross sections by calculated 12, 5, 14, and 1% of single-particle values as predicted scattering from a real Saxon-Woods potential with a qualitatively by the shell model. Thomas-type spin orbit term. For s and d waves he chooses the well parameters to bind correctly the 2ii/2 1. C H. Johnson, J. L. Fowler, and R. M. Feezel, pp. 2-3 in and the W3/2 states, to give the observed s-wave cross Contributions - Conference on Nuclear Structure Study with sections at thermal energy, and to place the \d state Neutrons (Budapest, Hungary, July-August 1972), Central 3/2 Research Institute for Physics, Budapest, 1972. at the centroid of the five %* states observed as 2. C. H. Johnson, submitted for publication in the Physical neutron resonances. Placing the /{-matrix boundary Review.
New Isotopes of Osmium - ' 7,Os,' 70Os,and "90s - September
The highly ionized neon beams, ?0Ne*\ from the energy 20Ne beam to reinvestigate the possible Oak Ridge Isochronous Cyclotron allow sufficient ,56Dy(20Ne,7fi) reaction which leads to '*9Os. They energies (~150 MeV) to produce new isotopes by found that the yield of the 556 ± 0.02 MeV alpha bombarding targets in the rare-earth region.1'2 With group of 3.0 ± 0.5 sec half-life increases with energy in ,s'Dy targets, Toth et al.1 discovered two new the range 146.6 to 153.4 MeV, consistent with the yield isotopes of osmium with alpha energies and half-lives as expected from the ,S6Dy(i0Ne,7n),690s reaction, 70 follows: (1) ' Os,Ea = 540 ± 0.01 MeV, Tl/2 = 7.1 which has a threshold at 117 MeV and a predicted 7, ± 0.5 sec;(2) ' Os,£a = 5.24± 0.01 MeV, r,/2 = 8.2 maximum yield at 160 MeV. They eliminated other i 0.8 sec. They made the isotopic assignments on the possible reactions on the basis of the yield data. basis of the alpha energies, half-lives, and the reaction Furthermore, the ' 690s assignment is confirmed by the energy systematics. They also observed a weak alpha fact that the alpha energy, 5.56 ± 0.02 MeV, falls group with energy consistent with that expected from almost exactly on that expected for' *9Os. 1690s decay, but the beam energy limitation at the time prevented an identification from yield vs energy 1. K. S. Toth, R. L. Hahn, M A. Ijaz, and R. F. Walker, Phys. Rev. OS, 2060 (1972). data. More recently, Toth, Hahn, Bingham, Ijaz, and 2. K. S. Toth, R. L. Hahn, C. R. Bingham, M. A. Ijaz, and Walker have taken advantage of a 1.7-MeV higher R. F. Walker, to be published in the Physical Review.
Neutron Capture in "Sr, 87Sr, and "Sr and Nucleosynthesis - October
According to cosmologists, nucleosynthesis in the capture of neutrons on a time scale which is slow interior of red giant stars takes place by multiple compared with beta-decay half-lives. Under these condi- 5 lions the product of the neutron capture cross section 30-keV capture cross section changes abruptly at the for an effective 30-keV temperature and the tsotopic nucleus, decreasing from 38 mb for **Sr and 54 rob for abundance is expected to be a slowly varying function S7Sr :o 5.6 mb for "'Sr. Nevertheless, the product of of atomic weight- Vanpraet. Mackiin. Alien, and the tsotopic abundance, corrected for a small effect Winters' have measured the capture cross section of the arising from fast neutron capture, and the 30-keV separated isotopes **Sr. *7Sr, and **Sr in the energy capture cross section is remarkably constant, in agree range 3 to 100 keV at the 40-m time-of-ftight station ef ment with the cosmoiogical predictions- This product is the ORELA. Using a pair of total gamma-ray energy 216, 204. and 259 for the isotopes **Sr, *7Sr, and detectors with suitable pube-height weighting so that **Sr respectively. the detecting efficiency was insensitive to the shape of the capture gamma-ray spectrum, they measured the I. G. J. Vanrraet. R. L Macklia. B. J. Allen, and R. R. total capture cross section relative to that of the Winters, pp. 208-9 to Contributions - Conference on Nude* Structure Study mrtk Neutrons (Budapest. Huacary. J«hr- *li(n,s} reaction in a C-5-nun-thkk glass sciiiiulaior- Angost 1972). Central Research institute for Physics, Budapest, Since the 50-neutron shell closure occurs for **Sr, the 1972.
Giant Quadrnpole or Giant Monopole Resonances? — November One of the recent major accomplishments of the excited states as well as with the quadrupole interpreta Physics Division is the discovery that inelastic proton tion which is somewhat favored by the data. Since, as scattering strongly excites nuclear states just below the he points out, scattering of polarized protons will giant dipole resonances. Lewis and Bertram!1 together distinguish between the giant monopole and the giant with Satchler2 have interpreted these states as being quadrupole excitations, experimenters are setting up consistent with the excitation of collective giant quad- apparatus to measure the scattering by appropriate rupole resonances whose strength exhausts the energy- nuclei of polarized protons which will be produced by weighted sum rule. Additional measurements3 of in- the cyclotron's polarized ion source. elastically scattered 67-MeV protons from the Oak Ridge Isochronous Cyclotron with *he high-resolution 1. M. B. Lewis and F. £. Bertrand, Bull Amer. Phyz. Soc 17, broad-range magnetic spectrograph have confirmed the 462 {\9n);NucL Phys. (in press); M. B. Lewis,Phys Rer Lett. earlier counter results' and have yielded more precise 29,1257(1972). resonant energies. In the meantime, Satchler4 has 2. G. R. Satchler, M«* Phys A195,1 (1972). 3. F. E. Bertrand, G. R. Satchler, M. B. Lewis, and D. J. shown, using a breathing-mode reaction mechanism, Horen, Butt. Amer. Phyx. Soc. (New York Meeting, January that the available proton inelastic scattering data ar<* 29-February 1,1973). consistent with a giant monopole interpretation of the 4. G. R. Satchler, Particles and Nuclei (to be published).
The 208Pb<12C,' 3C)207Pb and ""PI*12C,'' B)209Bi Reactions at High Bombarding Energies - December
Use of the position-sensitive proportional detector in 209Bi product nuclei. They find that the angular the focal plane of the broad-range magnetic spectro distributions of the liC and '5 B light-product nuclei graph of the Oak Ridge Isochronous Cyclotron has are smooth and singn; peaked and that the peak shifts allowed precise investigations of heavy-ion reactions to forward angles with increasing ' 2C incident energy. produced by bombarding 20*Pb with high-energy ' 2C They interpret these observations in terms of semi- ions. Larsen et al.1 have measured the differencial cross classical concepts. Small detector angles correspond to sections of the neutron pickup reaction, large separation distances; consequently, the probability 208Pb(12C,,3C)207Pb (Q = -2.42 MeV), and ibe for nucleon transfer shou'J be low. As the angle proton stripping reaction, 208PbO 2C,'' B)209Bi (Q = increases, the transfer probabilities should increase up -12.15 MeV), with ,2C energies of 77, 98, and 116 to the point where nuclear absorption sets in and MeV. With the detector system resolution of 250 keV, compound nuclear leactions begin to predominate. The they see groups of' 3C and '' B nuclei corresponding to peak angles in the differential cross sections are thus population of five states in each of the 207Pb and related to the optimum distance for nucleon transfer to 6 occur. A more detailed analysis allows Larsen et ai * to suggests a description dependent on the final Z07Pb * conclude that the proton stripping reaction is corc- 1 iC system. patibk with a mechanism which depmds on the initial 1. J. S. Linen. J L. C Fowl. Jr.. R. M- Gacdfce. K. S- Toth. 2, 2 *Pb • ' C system, where s the neutron pickup case J- B. Baft, and R L. Hah*, ssbcntted to ffcyorj Lttien. XX
SI PERCONDUCTING RESONANT CAVITIES I ?. Judish, C. M Jones. I. K. McGowan. and P. Z. Peebles. Jr 140 Design and construction of a second superconducting helically loaded cavity and measurement system are reported.
UESONAST FREQUENCY CONTROL OF SUPERCONDUCTING RF CAVITIES P Z. Peebles. Jr 141 Abstract of paper accepted for publication in the proceedings of the 1973 Particle Accelerator Conference, March 1973.
MEASUREMENT SYSTEM FOR SUPERCONDUCTING RF RESONANT CAVITIES P. Z. Peebles, Jr., C. M. Jones, R. F. King, and J. P. Judish 141 Abstract of paper presented at IEEE Region 3 Conference, April 1972.
DESIGN AND EVALUATION OF A HIGH-POWER VOLTAGE-VARIABLE REACTANCE S. F Smith and P. Z. Peebles, Jr 141 A voltage-variable reactance for frequency control of superconducting cavity resonant fluency has been developed through a subcontract with the Electrical Engineering Dept., University of Tennessee, KnoxvUle.
A SLOW TUNER FOR SUPERCONDUCTING HELICALLY LOADED RESONANT CAVITIES C. M. Jones, J. L. Fricke, B. Piosczyk, and J. E. Vetter 142 Abstract of published paper: Proceedings of the 1972 Proton Linear Accelerator Conference, LA-5115, pp. 163-67.
STATUS OF THE UNISOR PROJECT H. K. Carter, R. L. MJekodaj, W.-D. Schmidt-Ott, and E. H. Spejewski 142 Development of the UNISOR on-line isotope separator facility is described.
STATUS REPORT ON TH~ 3-MV VAN DE GRAAFF ACCELERATOR J. P. Judish 146 Activities associated with use of the 3-MV Van de Graaff are discussed.
STATUS REPORT OF THE 6-MV VAN DE GRAAFF ACCELERATOR J. A. BiggerstafT and W. T. Newton 146 Activities associated with use of the 6-MV Van de Gra iff are discussed.
STATUS REPORT OF THE TANDEM VAN DE GRAAFF ACCELERATOR G. F. Wells and R. L. Robinson 146 Activities performed on the Tandem Van de Graaff during the year 1972 are summarized.
STATUS REPORT ON THE OAK RIDGE ELECTRON LINEAR > XELERATOR (ORELA) J. A. Harvey, T. A. Lewis, F. C. Matenschein, and H. A. Todd 148 The performance of the electron linear accelerator and the data handling equipment are summarized.
OAK RIDGE ISOCHRONOUS CYCLOTRON OPERATIONS R. S. Lord, A. W. Rnkola, H. L. Dickerson, C. L. Viar, M. B. Marshall, S. W. Mosko, K. M. Wallace, E. Newman, H. D. Hackler, J. W. Hale K. W. Sparks, C. L. Haley, G. A. Palmer, and L. A. Slover 150 The opei4tion of the ORIC is summarized.
8. OMNIANA
PUBLICATIONS 154 Book and Journal Articles 154 Theses 162 Annual Report 162 Topical Reports ', 163
PAPERS PRESENTED AT SCIENTIRC AND TECHNICAL MEETINGS 163 XXI
ANNOUNCEMENTS 169
PERSONNEL ASSIGNMENTS '69 Guest Assignees from Abroad 169 Guest Assignees from the United States 170 ctafl Assignment* 171 Staff Appointments 171 Staff Termination 171 Staff Appointees - Intralaboratory Loans 172
MISCELLANEOUS PROFESSIONAL ACTIVITIES OF DIVISIONAL PERSONNEL 172
COLLOQUIA AND SEMINARS PRESENTED BY THE PHYSICS DIVISION STAFF 174
PHYSICS DIVISION SEMINARS 176
Ph.D. THESIS RESEARCH 177
M.S. THESIS RESEARCH 178
STUDENTGUESTS 179
COOPERATIVE EDUCATION PROGRAM FOR UNDERGRADUATE STUDENTS 179
GUEST ASSIGNEES -STUDENTS NOT ENGAGED IN THESIS RESEARCH AT ORNL 180
CONSULTANTS UNDER SUBCONTRACT WITH UNION CARBIDE CORPORATION NUCLEAR DIVISION - ORNL 180
CONSULTANTS UNDER CONTRACT ARRANGEMENT WITH OAK RIDGE ASSOCIATED UNIVERSITIES 181
ANNUAL INFORMATION MEETING OF THE PHYSICS DIVISION 182
RADIATION CONTROL AND SAFETY IN THE PHYSICS DIVISION 182
UNISOR PROGRAM 182
PARTICIPATION IN VARIED INSTITUTES AND SYMPOSIA 183
ORIENTATION MEETING AT THE ORNL NUCLEAR DATA PROJECT FOR NSF-SPONSORED NUCLEAR INFORMATION RESEARCH ASSOCIATES (NIRA) 183
ORNL HEAVY-ION SUMMER STUDY 184
AUTHOR INDEX 185 Foreword
This annual progress report of ths Physics Division Each month the Division Director submits a report covers the calendar year 1972. As in previous years the which summarizes some research activity within the report contains the abstracts of papers published since Division. These reports follow immediately and will give the last annual report and those prepared for publica the reader an overview of the research efforts in tion. Reprints and preprints of these articles are progress. available upon request. Preliminary results of research Looking to the future, in June 1972 the Osk Ridge work in progress «re reported in more detafl. Since this National Laboratory sponsored a summer study on work is of a preliminary nature, reference to or heavy-ion research. A short report of this meeting may inclusion of these results in any other publications be found near the end of Sect. 8, and reports on should be done with the express consent of the author. heavy-ion acceleration are given in Sect. 7.
xxiii -»
channeled ions provide a new means for studying 2. H. O- Lutz. S. Datz. C D. Moak. and T. S. Sogg*e, Pkrs. multiple scattering, radiation damage, and ton-atom Leu. 33A.309ii970>. potentials in solids. 3. B. R Appkrtoo. C. 0. Moak. T. S Noggk. and J. H Barrett, toys. Ret. Lett. 28.1307 (1972)
I. H. 0. Lutz. S- Datt. C. D. Moak. znd T. S. Noggle. Phvs Ret. Lett. 17,285 (1966).
A-Matrix Analysis with a Diffuse Edge Potential for "O+zi Data - August
The /{-matrix analysis, introduced by Wigner and radius inside the tail of the resulting potential at 3.86 2 2 Eisenbud some 25 years ago, is today the most useful fm. so that the \d3f2 reduced width is equal to h litr . and physically significant way of describing resonances gives an excellent fit to the total and (n,a) cross section in nuclear reactions and scattering. The selection of the up to 5.8 MeV neutron energy.'1 Besides making the boundary radius on which reduced resonance widths reduced widths of the five \* resonances equal to the depend rather critically, however, has been something single-particle reduced width, this procedure shows that of a problem. In an /{-matrix analysis of "Of/i.n) and the sum of the reduced widths of the V and the %~ l'Ofaa) cross sections,1 Johnson2 has found a self- states is very small and that the summed reduced widths ai consistent method of selecting this boundary radius. He of thep3/2.Pi/2'/7/2' 'd/s/2 states are, respectively, fits the off-resonance cross sections by calculated 12, 5, 14, and 1% of single-particle values as predicted scattering from a real Saxon-Woods potential with a qualitatively by the shell model. Thomas-type spin orbit term. For s and d waves he chooses the well parameters to bind correctly the 2sl/2 1. C. H. Johnson, J. L. Fowler, and R. M. Feezel, pp. 2-3 in and the U/3/2 states, to give the observed s-wave cross Contributions - Conference on Nuclear Structure Study with sections at thermal energy, and to place the ld state Neutrons (Budapest, Hungary, July-August 1972), Central 3/2 Research Institute for Physics, Budapest, 1972. at the centroid of the five %* states observed as 2. C. H. Johnson, submitted for publication in the Physical neutron resonances. Placing the /{-matrix boundary Review.
New Isotopes of Osmium - ' 7,Os,' 70Os,and ,69Os - September
The highly ionized neon beams, 20Ne*\ from the energy 20Ne beam to reinvestigate the possible Oak Ridge Isochronous Cyclotron allow sufficient IS6Dy(70Ne,7n) reaction which leads to ,<9Os. They energies (~150 MeV) to produce new isotopes by found that the yield of the 5.56 ± 0.02 MeV alpha bombarding targets in the rare-earth region.1'2 With group of 3.0 ± 0.5 sec half-life increases with energy in ls*Dy targets, Toth et al.1 discovered two new the range 146.6 to 153.4 MeV, consistent with the yield isotopes of osmium with alpha energies and half-lives as expected from the ,$6Dy(i0Ne»I69Os reaction, 70 follows: (1) ' Os, Ea = 540 ± 0.01 MeV, 7",/2 = 7.1 which has a threshold at 117 MeV and a predicted 7I ± 0.5 sec;(2) ' Os,£a * 5.24 ± 0.01 MeV, Tlf2 *8.2 maximum yield at 160 MeV. They eliminated other ± 0.8 sec. They made the isotopic assignments on the possible reactions on the basis of the yield data. basis of the alpha energies, half-lives, and the reaction Furthermore, the ' 69Os assignment is confirmed by the energy systematics. They also observed a weak alpha fact that the alpha energy, 5.56 ± 0.02 MeV, falls group with energy consistent with that expected from almost exactly on that expected for' 690s. >6*Os decay, but the beam energy limitation at the time prevented an identification from yield vs energy 1. K. S. Toth, R. L. Hahn, M. A. Ijaz, and R. F. Walker, Phys. Rev.C5,2060 (1972). data. More recently, Toth, Hahn, Bingham, Ijaz, and 2. K. S. Toth, R. L. Hahn, C. R. Bingham, M. A. Ijaz, and Walker have taken advantage of a 1.7-MeV higher R. F. Walker, to be published in the Physical Review.
Neutron Capture in 86Sr, 87Sr, and **Sr and Nucleosynthesis - October
According to cosmologists, nucleosynthesis in the capture of neutrons on a time scale which is slow interior of red giant stars takes place by multiple compared with beta-decay half-lives. Under these condi- 6 occur. A more detailed analysis allows Larsenet ll ' to suggests a description dependent on the final 207Pb + conclude that the proton stripping reaction is core- l3C system. patible with a mechanism which depends on the initial i. j_ s. la««. J. L. C Font. Jr.. R. M Gxrfk*. K. S Toth, 20 2 *Pb • ' C system, where s the neutron pickup case j. B. Rafl. and R. L. Hah*, ssbtaittcd toPhysic* Letters. 1. Theory
NUCLEON TRANSFER FORM FACTORS CALCULATED WITH REALISTIC INTERACTIONS1 Y. K. So2 W. T. frnkston2 K. T. R. Davies
The microscopic approach to calculating single- a = 0.6S fm). Form factors calculated with the nudeon transfer form factors is applied to reactions in Hartree-Fock potential tend to be larger in the surface the region near Ca, for example, 42Ca(p.rf)4,Ca and and smaler in the interior, compared with those 4#Ca(<**,p)*,Ca. The interaction of the transferred calculated with the Woods-Saxon. A Woods-Saxon well nudeon with the 4*Ca core is taken to be the equivalent to Hartree-Fock gives almost identical results single-particle Hartree-Fock potential of Tarbutton and in some, but not all, cases, but die parameters of this Davies, based on a two-body potential developed by well are quite different from the standard geometry and Nestor. Realistic effective interactions, including core- are highly state dependent. The form factors are found polarization renormakzation, are used for die inter to be much less sensitive to die effective two-body action of the transferred nudeon with valence nudeons interaction of the transferred nudeon with die valence and holes. The results are compared with form factors particles and holes. calculated with Woods-Saxon core interactions and phenomenologKal residual interactions. It is found that the use of the Hartree-Fock potential yields results that 1. Abstract of papa to be paMbfced in Pwtida mud Nut&tL are significantly different from most obtained from 2- Department of Phy**, VamtaWt University, Nasfcvaat,
Woods-Saxon weDs of standard geometry (r0 = 1.25 fm, Teaa.
H1GHERX)RDER CORRECTIONS TO BRUFXKNER-HARTREE^OCIC BINDING ENERGIES AND RADII1 K.T.R. Davies R. J. McCarthy2 P.U.Sauer3
Some higher-order corrections to renormalized The errors involved in estimating die corrections are Brueckner-Hartree-Fock calcubticns are estimated for discussed. "Off-diagonal occupation probabilities" are 4, 208 the nudei "0, Ca, and Pb. The diagrams of also calculated and found to be small, thereby justifying interest are the potential insertions in particle lines and ignoring such diagrams as is usually done in renormal- the two-body correlation corrections to the rms radii. ized Brueckner calculations. Studies are made of the sensitivity of these corrections to the shift in the intermediate spectrum used to calculate the G matrix. The correlation corrections to the radn ire small and seem to increase somewhat as the 1. Abstract of paper tob e pwbfahed m Physical Rrnem. 2. Deparuacat of Physcs, Indiana Uarvenrty, Mooaangton. intermediate spectrum is lowered, but there is no 3. fTtyfifraatrhrt Imtitst d*r UaiveniUtt, lie i nunp-ljcidei- appreciate change in the overall saturation properties. StrasK 3,7800 Freibwg an bYeiajav. Germany s
RENORMALIZED BRUECKNER-HARTREE-FOCK CALCULATION'S USING DIFFERENT PRESCRIPTIONS FOR THE LVTERMEDIATE^TATE SPECTRUM1
K. T. R. Dav»es R_ J McCarthy2 P. U. Sau*rJ
Calculations of dw spherica: nuclei "O, *°Ca. and between the QTQ results and some results obtained by 20*Pb are presented for G trainees ihit differ in the Segele. A study is ,*lso made 01 the importance 01 the definition c( the particle spectrum Detailed compari relative partial waves not defined in the Reid soft-core sons are ma4e using pu*e harmonic oscillator, shifted potential. oscillator, and QTO intermediate-state spectra. Atten tion is particularly focused on the saturation properties of the various G matrices. The *jTQ prescription seem* i. Abstract of published ~z?a: F.-ys. Re* C6, 1461 (1972). 2. Department of Physics, Indiana University. Btooirangton. to give somewhat better saturation prooerties tnau the 3. fiiy'skimst-hes Imiiiui der Unh'ersUi. Hermann-Herder- oscillator prescriptions. A comparison «s made in *°Ca Strasse 3. 7400 Freiburg »an Preisgau, Germany.
HARTREE-FOCK CALCULATIONS OF BUBBLE NUCLEI1
K. T. R. Divies C. Y. Wong S. J. Krieger2
Hartree-Fock calculations of 3*Ar and of 20°Hg in bubble nudeL spherical configurations exhibit densities that are very 1. Abstract of published paper: Pkys. Un. 4IB. 455 (1972) much depleted in the interior region. The depletion 2. Department oi Physics. University of Iflinois at Chicago agrees wefl with, previous theoretical predictions of Circle. Chicago.
THE RENORMAUZED BRUECKNER-HARTREE-FOCK APPROXIMATION1 Richard L. Becker
The renofrnabzation of many-body perturbation for the second-order rearrangement energy, die main theory by factorization of insertions in single-particle contribution to the shift away from the centroid of die (SP) lines having the significance of "true" occupation eigenstate of greatest SP strength. For deep holes the probabilities is reviewed. The renormalized Brueckner- strength function broadens as 2ft-lp states, etc., become Hartree-Fock (RBHF) approximation is defined, and its qu3si-degenerate with \h states; as an example, the analogue of Koopmans' theorem on the near equality of (Qj)~! strength function in ' 60 is shown. Correlation separation energy centrotds and SP energies is demon corrections to die RBHF charge density are discussed. strated. The plane wave and harmonic oscillator bases Results of RBHF calculations for nuclei with a neutron of SP states and the energy spectrum of die virtual excess are cited, and prospects of future improvements excited SP states are discussed. Binding energies, charge in calculations employing the RBHF approximation are densities, and SP energies of light spherical nuclei contemplated. obtained with RBHF calculations in the oscillator basis are presented. Corrections to the RBHF approximation, 1. Abstract of paper to be published in the proceedings of associated with correlations and rearrangement, are Symposium on Present Status and Novel Developments in the considered. Configuration mixing leads to a distribution Many-Body Probiem, Rome, Italy, Sept 19-23, 1972. (Pro of SP strength over many eigenstates Values are given ceedings to be published in II Nuovo Gmento.)
DEFORMED BRUECKNER HARTREF^FOCK CALCULATIONS1
W.F.Ford* R.C. Braky3 R.L.Becker M. R. Patterson3
The renormalized Bnieckner-Hartree-Fock (RBHF) ized to permit calculations for intrinsic states having theory for many-body nuclear systems has been general- permanent deformation. Both Hartree-Fock and 9
Brueckner self-consistencies are satisfied, and details of with predictions of ordinary and density-dependent the numerical techniques are discussed. The Hamada- Hartree-Fock theory. Johnston interaction is used in a study of deformations, binding, size, and separation energies for several nuclei. 1. Abstract of paper to be published in the proceedings of Electromagnetic transition rates, moments, and electron Symposium on Present Status and Novel Development* in the Many-Body Problem, Rome. Italy, Sept. 19-23. 1972. (Pro scattering form factors are calculated using nuclear ceedings to be published in 11 Suovo Cimento.) wave functions obtained by angular momentum pro 2. NASA, Lewis Research Center. Cleveland, Ohio. jection. Comparison is made with experiment as well as 3. Mathematics Division.
RENORMALIZED FOLDED DIAGRAM EXPANSION FOR THE NUCLEAR GROUND STATE Richard L. Becker Robert W. Jones1 Franz Mohling2
The Brueckner-Goldstone expansion for the inter For nuclear theory it is essential to convert ex action energy in the ground state of a many-fermion pansions in v into expansions in a renormalized inter system involves effective interactions (Brueckner re action such as the Brueckner reaction operator. We have action matrices) that are off the energy shell when they found that the energy-dependent single-particle propa occur in virtual intermediate states. The prime dis gator formalism is best suited to this "Brueckneri- advantage of this expansion is that difficulties associ zation" of the "field theoretic" or "folded" expansion, ated with the off-shell propagation appear in an and we have obtained the formal expansion. extreme form. Through a series of investigations culmi If the renormalized propagators are expanded in bare nating in those of Brandow, a rearrangement of the ones and then the corresponding global expansion is Goldstone expansion by summing terms related by worked out, it may be compared with the unrenor- generalized time ordering, which we shall call the malized global expansion obtained from the Brandow Brandow series, has been obtained. Brandow's series series. The lowest two terms in our single-particle involves a very satisfactory definition of the single- potential are compared with Brandow's in Fig. 1. The particle potential for hole states and for "panicle"-holc "cost" of the increased factorizability in our unrenor- creation or annihilation but, as with the Brueckner- malized expansion is the presence of new folded Goldstone expansion, does not yield a factorized skeleton diagrams. For this and other reasons we believe self-energy generalizing the Hartree-Fock potential en it is far preferable not to expand die renormalized ergy for "particle" states. propagators. If one truncates the renormalized propa By adding and subtracting folded diagrams, those in gator at second order and then truncates the sum over which normally empty states are included in the sum irreducible skeletons at first order, one obtains a over states for hole lines and normally occupied states renormalized Brueckner-Hartree-Fock (RBHF) approxi for "particle" lines, one may obtain an extension of mation which is very similar to that of a similar generalized time ordering that permits factorization of an on-shell 3rueckner-Hartree-Fock potential tor "parti ORNl-OWG 72-10165 cle" states. This was achieved earlier3 for an expansion in the bare interaction, v. The expansion with folds is a "global" expansion, meaning that it is a sum of NORMALLY OCCUPIED NORMALLY UNOCCUPIED diagrams in which the propagators refer to all the "particles" and holes present in the entire system. The Goldstone and Brandow series are also global ex BRANDOW K> pansions. Global expansions are complicated to work >€D with, however. For formal work it is more convenient to use single-particle-propagator formalisms. The folded PRESENT *7) diagram expansion can be related to expansions ob THEORY tained by applying "field dieoretic" (Feynman propa 1 K>*XED gator) methods. Jones and Mohling4 had used time- dependent propagators, and Klein5 had used frequency Fj»> 1. A comparison of the tingle-particle potential energfe* (energy)-dependent propagators in this way. proposed by Brtndow and by the present theory. 10 truncation of the BrPREDICTED INTERMEDIATE STRUCTURE IN HIGH-RESOLUTION DEEP-HOLE SPECTRA Richard L. Becker
A potentially interesting, but so far relatively un- approximation2,^3 is that the centroid rearrangement explored, region of nuclear spectroscopy is .iial of high energy nearly vanishes. Eigenrearrangement energies excitations (£hoo) of a nucleus A - 1 produced by remain large for deep-lying hole states in the RBHF nucleon-rcmoval processes such as (p,2p) or (e,e'p) theory, for example, 13 and 19.5 MeV for 0s holes in ("knockout") or (tf,3He) ("pickup"). With sufficiently ,60 and 40Ca, respectively.2,5 The identification of high incident energies, hundreds of million electron the eigenstate to which this eigenrearrangement refers volts, the dominant reaction mechanism is the relatively will be discussed below. The rearrangement energy simple one of quasi-free scattering, so the experiments calculated is the real part of the diagram shown in Fig. can be analyzed in terms of the impulse approximation. 1. The interest in the experiments stems from the presence In analyzing data from quasi-free reactions, a good of gross structures in the cross sections as functions of deal of theoretical attention has been paid to the the momentum and energy given to the target nucleus. distortion of the waves of the ingoing and outgoing These broad resonances have been interpreted in terms particles; for (p,2p) some consideration has been given of shell structure: the energies of the peaks are assumed to the off-energy-shell properties of the nucleon- to correspond to the separation energies of nucleons in nucleon scattering amplitude. On the other hand, for low-lying1 shells and their widths to the lifetimes of the the "deep-hole" spectra only the simplest model, the single-hole states. single-particle shell model, has been employed for the Experimental knowledge of separation energies is of structure of the target and residual nuclei. The residual great interest to nuclear many-body theorists. A nec essary ingredient of calculations of nuclear saturation propei ties (binding energies and sizes) is the self-con 0RNL-DWG 70-14225 sistent determination of the energies and wave func tions of single-particle states. The "single-particle en ergies" e(k) depend on the formulation employed and are not necessarily measurable. They can be defined so as to yield good approximations to various kinds of centroids of experimental distributions. But, in general, single-particle energies differ from theoretical separa tion energies. This difference is called a rearrangement energy. Thus, a theoretical separation energy is calcu lated from
£$ep(*) = *(*) + £rear(*) (1)
Depending on whether the experimental separation erergy under consideration is thaf of an eigenstate or a ce;n»oid, one needs to calculate an eigenrearrangement energy or a centroid-rearrangemeht energy.3 A virtue of the renormalized Brueckner-Hartree-Fock (RBHF) Fig. 1. Renormalized second-order rearrangement energy. 11
0HHC-IW6TC-W22T ;t) WEAK MIXING FOR HOLES AT THE FERMI LEVEL BECAUSE ALL VIRTUAL EXCITATION ENERGIES at <-RE
(3) STRONG MIXING OF Ih STATES TWO OR MORE '///&{{'£. SHELLS BELOW THE FERMI LEVLL WITH 2li-«p if T ! M AND Jh-2p STATES. EXAMPLE: '//////// Y#Wt '////////
AE-0 AE-21>» AE-2tw AEo^fe. -O- 1 (2) STRONG MIXING OF Ih STATES ONE SHELL BELOW THE FERMI LEVEL WITH Zh-1p STATES BECAUSE OF OEGENERACY. EXAMPLES to*)-' IN '*0. (op)*' IN «°Co.
''///{//A '//////A '////////. '//////// AE-0 AE-0 AE-O i t u. ill
AE»0 AE-0 &E«2«M &E>2W
Fig. 2. Mixing of Ih with 2h-lp and 3h-2p states in dreed shell nuclei in the harmonic (equal spacing) model. nucleus is then in a pure single-hole configuration. degenerate with it. The degeneracies are made approxi Kohler's estimate6 of the width of the hole state goes mate by the £ and / splittings of the subshells and by one step beyond this; he evaluated in lowest order of residual interactions among die holes and particles. perturbation theory the imaginary part of the self- The role of configuration mixing of die states of the energy of virtual transitions to (degenerate) two-hole residual nucleus in interpreting the deep-hole spectra one-particle states, the imaginary part of Fig. 1 without can be seen as follows. If \A) is the ground state of the the renormalization. Widths of 14 and 22 MeV for the target, then o(q)l4> is the nonstationary state of the Qs holes in I60 and 40Ca were obtained; these are of A — 1 nuclecn system obtained by removing a nudeen the same order of magnitude as those seen experi of momentum q. In a good-resolution experiment it is mentally. This level of description is about as far as one known that energy W (<0) a* well as momentum q have can go in the context of conventionai nuclear matter been removed. The residual nucleus will be in any of theory, either with the perturbation theoretic the states <*\ of energy WA_l=WA - Wwith
Brueckner-Goldstone expansion or the Landau-Migdal amplitude < WA _, ,a la(q)|.4>. In die plane-wave im quasi-particle approximation of the Green's function pulse approximation the cross section for (0,2/;) or formulation. One may anticipate that such information (e, e'p), is crude from the well-known fact that the quasi- particle approximation is accurate only for single- d*o particle states near the Fermi level. In particular, these dEx dSli dEi dQ.^ descriptions do not involve the concept of splitting of single-hole strength2,5 which has been of great interest where 1 and 2 label the outgoing particles, is propor for high-lying holes. For this, one needs explicit tional to the strength function (structure factor, form corporation mixing. factor) We believe that the increasing width of "hole states'1 with excitation energy is associated with the availability 2 S(q,W) = Z\WA_lMla* u/C „.o «„»v2) uppermost one, there are 2h-\p (two holes and one d WA -1 *WA ~ w particle) states which in the harmonic oscillator shell model are exactly degenerate with it. If the hole is two where (in the notation of ref. 7) b and c label bound major shells down there are, in addition, 3h-2p states (particle stable) and continuum (particle unstable) 12 states and d distinguishes among degenerate states. The tinuum part of S(/i; W) is converted into the form Dirac delta function will be smoothed when one appropriate for particle-stable states l^_! 4>, and restores the "natural" width from neglected electro consequently the spectrum consists of discrete peaks. magnetic and weak interactions. For the "deep-hole" These would be broadened by inclusion of the widths part of the spectrum under consideration, only the of the single-particle resonances. One obtains the continuum term contributes. In 15N, for example, the prediction of an intermediate structure in the single- states of in ten . are at an excitation energy of >20 hole giant resonance. The single-hole strength is split MeV. among various approximate eigenstates of the residual The momentum eigenstate |q> may be decomposed nucleus. The subpeaks are weighted according to the into contributions from the various shell-model states single-hole strength in each eigenstate and have widths \k), including both those normally occupied in A, h determined by the single-particle resonance widths of (holes), or normally empty, p ("particles"). Thus, the unbound "particles" in the approximate eigenstates. The shape of the gross "single-hole" resonance may be asymmetrical; it depends on the locations of the «t(-E «(q)aj ^^aj|0> (3) + unperturbed 2h-\p, etc., states and on the matrix h-1 p elements of the residual interaction. More generally, and one obtains a strength function of the form
5(q;H0 = l 0;.(q)**(q) $(**';*') , (4) 2 x % Wqi^lMq)! I WA_lyd\h- )\ ^- where the expression S(kk'\W) involves the amplitudes ^A-i^k^- One sees that the removal process contains interferences between removals from different shells. If one neglects uiese because the momentum 2 distributions in different shells tend to be different (this (w-wA_l)^[^(wA_l1d)] may be a poor approximation for certain values of q), one obtains the diagonal approximation where Tr is the decay width of the approximate eigenstate. h We have carried out for "0 Brueckner theoretic calcuh lions in the Bloch-Horowitz formulation of *p degen^iV.e perturbation theory to obtain eigenstates
consisting of mixtures of the Q$1/2 hole state and the with S{k,W) given by Eq. (2) with q replaced by the 17 2/i-l/7 states quasi-degenerate with it. For simplicity, shell-model-state label k. neutron removal was considered. Figures 3 and 4 show If configuration mixing in the target is neglected, then the spectra and the single-hole strengths obtained with only hole states k = h remain in Eq. (5), and only those two sets of single-particle energies. For virtual particles states |H^_ %,d) which have an appreciable single-hole with e = 8.4, 10.9, and 15.8 MeV for 0rf5/2, lsI/2, and l strength contribute strongly. The states 0d3j2, respectively, the Vi-\p states lay above the state \WA_V d) are mixtures of configurations of type \h, (0*1/2)"' and (F*8- 3) shoved it downward by an 7h-\p, 3h-2p, etc. The states | fc^_,, are particle amount ~13 MeV in good agreement with that calcu unstable by virtue of components with one or more lated3 from Fig. 1, when couplings among the 2h-\p "particles" with e(p) > 0. The lower part of the states are neglected. An additional 4.4-MeV rearrange continuum of single-particle states may be replaced, to ment energy is produced by these couplings in the full good approximation, by discrete localized states with 18-state basis. With separation energies of the s-d shell the energies of single-particle resonances. Alternatively, states in l70 used for the i(p)'s, the 2h-\p states lay one may use the discrete virtual "particle" states of an below the Os hole and shoved the dominant eigenstate oscillator-basis RBHF calculation; the single-particle upward (Fig. 4). Comparison of Figs. 3 and 4 shows a energies of these states are calculated off the energy strong sensitivity to the single-particle energies, the shell and consequently lie somewhat higher than the eigenstate of greatest single-hole strength being at 25 resonance energies. In either approximation the con MeV in Fig. 3 and at 54 MeV in Fig. 4. 13
OMN.-0M 70-MOI2 70
-23.2% — 1.94%
0.07%
-O.M% CO 9% • t2.«T% 224 •1.5»% •(21 -1.3% •2.4% 2.13% 2» (4! •0.1% 0.*% 224 4.49% 121 -!.«% 90 U» • 11.54% 23S — (21 0.2% 234 I -«2> >• 339 -(2)
40 Urn)' j S \ 8 -a*«% \ 17.41 9.TVMV 1ENCRSY FROM I OUASI-OECEMEftATE NT ENtRbV) \ ^2k-1» LEVELS •0.4% SO — N -w- .«7.4% MHTICLC EHE^GCS.* STATE « — •» I tart-' 3»-5 »-•% .2 (•»%)-' 2«.i \ 3 (•»%>'' ,7-0 4*3* *.4 5 »'/i *>» C atf^ «9.» 20 CALCULATED NEO.ECTMS UNPERTURSED MTCRACTKMS OF DIFFERENT «• STATE SAStt c».2#> E*rr SPECTRUM 2fc-tp STATES WITH EACH TYREN**/. OTNEIt. 7 STATE BASS I I O IO 20 • 20 30 40 SQUARED AMPLITUDE OF te*r* (%l SQUARED AMPLITUDE OF (•»)"* (%l
Faj.3. is O; of (Or)"' with qwati degenerate (Op)'2 {s-d)1. Calculations in whid tite s-d shell energies are those of virtual particles in 16 O, for comparison with rearrav^ment energy calculations. Spuriosities not renvved. 14
ORNL-OWG 70-U0«3 60
/
50 / ~11.4M«V—E
226 (2).'/
* (osr1 /.. («) CENTRO*0
*40 S 296 >-
235 m z o ,234„.(2) #- 4 or 335 •(2) — ?
— ?
STATE c i (OS)"1 42.9 2 (oo^r' 21.8 3 topW"1 15.7 20 -4 od% -4.1 5 isVfc -3.3 6 od% 1.7
UNPERTUR6E0 PERTURBED K) 10 20 30 SQUARED AMPLITUDE (o»)_1 (%) %
Fig. *,. ' 50; mixif of (0*)"' with quasi-degenerate (Op)"2 (s-d)1 SHI shell singfe-particle energies are centroids of separation eneigies of states in ' 70. S puriosities not elinuna ted. 15
The calculations of Figs. 3 and 4 ignore a small shifted upward from -€(0s1/2) to about 49 MeV; the technical point, namely, hat the states of the basis amount of the shift is in agreement with the center-of- contain "spurious" components corresponding to ex mass correction9 to the analogue of Koopmans' citation of the center of mass. For example, the Qs hole theorem.4 There is still a striking difference between state is 20% spurious.* By repeating the calculations in the two strength functions. The one obtained by using a 16-dimensional purified basis furnished by J. B. experimental separation energies gives a concentration McGrory, we obtained the spectra shown in Figs. 5 and of strength in a state at 54 MeV (Fig. 5), whereas the 6. These are shown to differ strikingly from those of virtual "particle" energies lead to a more symmetrical Figs. 3 and 4, the strength below 30 MeV being distribution about the centroid. The latter appears to be removed. Unlike the earlier results, the centroid is in good agreement with the best available data of Tyren
OftML-OVG 70-W702*
60
50 -CENTROO OF (os)~' STRENGTH
226 (2)
I (•si"' (fl
340 z 236 ov K Wz z o O 20 40 dV/«2 dfi2 (^b/MdV2 «r2) 0-3«.7» °- 30
STATE « I 10%)-* 42.9 2 (<»%)"' 2 <-8 3 (0pWf «5.7 20 ~4 «J% -4.1 5I»% "3.3 6 o4% 1.7
UNPERTURBED PERTURBED SPECTRUM CALCULATED M 16 (p. 2p) EXPT SPECTRUM DIMENSIONAL NOW-SPURIOUS STATE BASIS TYREN 0t #/. TOTAL (©*)*' STRENGTH-SO % 10 I I I 10 20 30 40 SQUARED AMPLITUDE OF (©*)"' (%)
.Ffc^ . 5_. >s0_;, mixing. o.f. (to),„, -1 with , . (Op)'2 <«0' Spuriosities have been ehminatetL s-d shell single-particle energies are centroids of separation energies of states in ' O. 16
ORNL-OWG 70-14703R 70 r—
(p. 2p) EXPT TYREN »t a/.
60 226 (2)
236 — (4) "55T -(2)
50 -336 (i) 2ir-(2) CENTRO-+-C OF (os)~' STRENGTH I ! 234 ! •(2) 335 -(2) z o 40 — Mod'1 1 2
0 20 40 dV*2 «u2 (p»/McV2 wr2) »-38.7- SO ASSUMED SMGLE- MRTICLE ENETOES.* STATE « 1lo*)"1 39.5 JuM^r1 2«.t 3 top^r1 17.0 4 od% 8.4 5 H«/2 K>-9 5 <*% «5-8 20
UNPERTURBED PERTURPCB SPECTRUM CALCULATED IN 16 SPECTRUM DIMENSIONAL NON-SPURKXJS STATE BASIS TOTAL las)"' STRENGTH-80%
10 15 20 SOUAREO AMPLITUDE OF (OS)"' (%)
*\.6. "O15, ; of (Or) -i with (Op)-2 (**/)' states. The two spurious states have been enmuunVd. r-J shell
single-partide energies are those of virtual particles in O; 0p3,2 and Op,/2 energies are RBHF iSOC) energies; and 'he Os energy is RBHF (SOC) phis the second-order rearrangement energy from faraway configurations. et al.,1 ° for which the energy resolution of the proton narrower peaks have yielded additional spectroscopic informa detectors is unfortunately not less than several MeV. tion, namely, occupation probabilities for partially occupied subsbeUs. In conclusicn, we believe that nucleon-removal ex- 2. R. L, Becker, "The Renormalizeu Brueckner-Hartree-Fock periinents with energy resolution capable of separating Approximation," Suovo Cimento (to be published). (Invited the intermediatt structure peaks could provide valuable paper presented at the Symposium on "Present Status and information regarding deep holes in nuclei. Novel Developments in the Nuclear Many-Body Problem," Rome, September 1972.) I. The same reactions have been used also to study nucfcon removal from the levels of the uppermost major shel, where the 3. R. L, Becker. Phys. Rev. Lett. 24,400 (1970). 17
4. R. L. Becker and ML R. Patterson, Nud. Phys. A178, 88 (1970) U. Wile and V Lipperheide. NucL Phyx. A1S9, 113 (1971). (1972). 5. R. L. Becker and M. R. Patterson. Bull. Amer. Phys. Soc. 8. E. C. Halbert. Ph.3. thesis. University of Rochester, 1956. 15,1315 (1970). 9. K T. R. Davies and R. L liecker. Hud. Phys. A176, 1 6. H. S. Kohler, NucL Phys. 88,529 (1966). (1971). 7. D. H. E. Gross and R. Lipperheide. NucL Phys. A150,449 10. H. Tyren et il.Nud. Pkyt 79,321 (1966).
BRUECKNERIZATION OF THE BRANDOW SERIES WITH A NEW PROFAGATOR-RENORMAUZED REACTION MATRIX Richard L. Becker
Brandow has *»aftiaDy summed GokSstoae's linked mation, the renormalized Brueckssr*Hsrtrs£~Fcck cluster expansion for the interaction energy in the (RBHF) approximation.2 Unfortunately, diis form of ground state of many-ferrnion systems by generalized Brueckner-Brandow series does not possess dK station time ordering.1 The Br&ndow series is an improvemee* ary properties of Eq. (2). For example, die dominant because it allows the factorization of certain kinds of term in Brandow's potential U for "particle" states, insertions in suigte-puiide ones. The factorized in which is of second order in Bt leckner's reaction matrix, sertions are of two kinds, which lead, lespectivety, to a does not emerge, from Eq. (2) applied to any skeleton self-conastent smgle-partide potential and to renormali- Vi- zatioc (line-weighting) factors for the lines of the We have found that die stationary properties are diagrams that represent the terms of the expansion, in recovered by remxmaMzing first and then summing this propagator-renorraahzed expansion the binding ladders. Our renormabzed Bruedraer reaction matrix3 energy of an infinite Fermi system is !\* its "true" occupation probability, £/* and 7* its potential and kinetic energy, e* = 7* + Uk its single-partide energy, and V - 2,-P ,-, Mr' the sum of afl irreducible dosed Gokbtone diagiams with each line renormalized with die weighting factor Urn) Mm) "•& (1 - Nk) + (TJVjt - 1W The expansion s^fisfies the variational principles
dp dp (2)
These may be used in defining stationary truncations of the series. One chooses a subset Pr of P and then T defines U and P by Eq. (2) with V replaced by V - KXi k k r.(D _« f' 1» '» For application to nuclei it is essential to convert the 9 expansion to one in a rencrmalized interaction such as rU-^' Brueckner's reaction matrix. In all the work done so fr - the "Bruecknerization" (summation of ladder dkgmns) has been done first (giving die Broeckner-Goldstoae •f \\^o series), and then for die lowest terms occupation probability line weighting factors have been factorized F* 1. Nt» UHF by generalized time ordering. This has really been discussed in detail only for die lowest-order approxi antnyiMRetrixatioii. 18 new expansion. The on-energy-shell matrix elements of to the Fermi level, as in the case of nuclei with partially B are shown by dashed jagged interaction lines, and open «-.ajor shells. In ,2C, for example, "spherical" 4 renormalized "particle" and hole lines are also dashed. calculations based on the (G») ((fc>3/2)* configuration 4 One sees that Eq. (2) yields the RBHF potential for have yielded /*op1/2 = 10%. The inclusion of the holes and a renormalked form of Brandow's second- emptiness factor, 0.9 ii. this case, can be handled as a order potential for "particles." The "true" occupation part of the "Pauli correction," which is now routinely probabilities also are given correctly. made for our reaction matrix elements. The new renormalized reaction matrix is expected to be of use chiefly for formal work. However, its 1. B. H. Brandow. Pkys. Rev. 152, 863 (\966): Ann Phys. elements may differ significantly from those of the 57,214(1970). unrenormalized matrix whenever a "particle" state has 2. R. L Becker./*»i Rer. Lett. 24,400 (1970). 3. R. L Becker. £u£ 4mer. Phys. Soc. 17,608 (1972). a nonnegUgible true occupation probability. This will 4. R. L. Becker. R. C. Braky. W. F. Ford, and M. R. occur only if an unoccupied "particle" state ties close Patterson, ORNL report ORNL-TH-3951 (1972).
TARGET EXCITATIONS AND THE OPTICAL POTENTIAL FOR PROTONS SCATTERING FROM NUCLEI1 C. L Rao2 M. Reeves 1113 G. R. Satchkr
We calculate the contributions to the optical potential potentials that gave the same scattering because of the for 30-MeV protons due to inelastic excitations of the strong A-dependence of the absorption. The con target nucleus. The scattering due to this nonlocal structed potentials concentrate die absorption at too potential is calculated exactly, and some of the resulcs small radii. It is suggested that rearrangement (pickup) are subjected to conventional optical-model analysis. processes contribute a substantial amount of absorption When only one excited state is included, a resonant at larger radii, wfane compound formation wil give rise dependence on the excitation energy is observed. Even to a volume term in the imaginary potential. with tea excited states, the position of a single one can strongly influence the scattering. It is possible to account for aoout duee-fourths of the observed absorp 1. Abstract of papa fbiwttgd for pabfccarioii m Nudem tion • 4,Ca and 2**Pb, but only by postulating fkyvn. 2. Foraedy rnandtiaf and gradsnte stedeal boa the unobserved states which exhaust the remainder of the MrasXy of Tcaacawe; preseat address: Dcpartaacat of energy-wejghted sum rules at somewhat unreasonably Physics, Laval UMvcrstv, Qacbcc, Canada. low energies. It was not posrbie to find nmple local 3. Matho—fir* Dmaxm.
EXCHANGE EFFECTS ON THE EXCITATION OF "Ne BY PROTONS1 G. R. Satcfaler
The importance of knock-on exchange is studied for potential is studied. Results are also presented for the the microscopic description of the excitation of col dependence on the sheU-modd orbits involved and the lective states by inelastic scattering. Much of the effects of imaginary, Coulomb, spin-dependent, and dbcrepaBcy found earlier between dieory and experi odd-state components in the interaction. ment may be removed by the inclusion of exchange. The usefulness of an equivalent zero-range pseudo- 1. Abstract of paper to be pubfciaed ia Policies mnd Nuclei.
INTERFERENCE NEAR THE COULOMB BARRIER AND COIftHXX INTERACTIONS FOR INELASTIC SCATTERING1 G. R. Satchler The interference between nuclear and Coulomb ex the phase of the nuclear interaction. The ' ,4Cd(A, h') citation amplitudes for inelastic scattering at energies reaction is used as an example. near the top of the Coulomb barrier is very sensitive to 1. Abstract of pubfefaed paper: Fhys. Lett. 39», 492 (1972). 19
THE FOLDING AMD DEFORMED POTENTIAL MODELS FOR INELASTIC SCATTERING1
G. R. Satchler
It is important to indude exchange effects when ties and transition potentials are sensitive to the form of generating transition potentials for inelastic scattering deformation assumed. from a folding model. The relation between potential and density deformations is discussed. Transition densi- 1- Abstract of published papa. Fhys. Lett. 391, 495 (1972).
RADIAL MOMENTS OF FOLDING INTEGRALS FOR NONSFHERICAL DISTRIBUTIONS1
G. R Saichkr
Simple relations are exhibited between die radial ization to nonscalar functions is indicated. momen s of two nonspherical distributions when one is obtained by folding a scalar function into die other. 1- Abstract of ybished paper: / Math. Pkys. 13, HIS Some ippMcations are mentioned, and the general- (1972).
THE OPTICAL MODEL1
G.R. Satchler F.G.Perey3
The use of die optical model to neutron Stnactavc Stady interactions with nuclei is reviewed. U Jwfr 31-Awjnt 5.1972. 2. Nestroa Physcs DMML 1. Abstract of to be
EXCITATION OF GIANT MONOPOLE RESONANCES IYIVOTON SCATTERING1
G.R. Satchler
Data from proton inelastic scattering to die giant preferred. Asymmetry measurements on the excitation resonance region are examined for evidence of die by polarized protons co«4d easily dfclmguiih between excitation of an isoscabr monopok breathing mode. diese two poadbimes. The asymmetries predicted for Two sfcghtiy different models for the interaction are monopok excitation are sensitive to the deformation of constructed and studied. The currently avsttble data the: are compatibtr with such a roonopok excitation whose strength exhausts me energy-weighted sum rule, al 1. Abstract of paper to be ' /VHCKL though die quadrupofc interpietation is somewhat to be
NUCLEAR GIANT RESONANCES, SIM RULES, EFa^ECTTvT CHARGES, AND SOCH-LKE1
G.R. Satchler
Recent results on die excitation of giant multipole x Abstract of paper iliwiii resonances are reviewed. on Afofear md Fmkk Phywo. 20
EXCITATION OF GIANT DIPOLE AND GIANT QUADRUPOLE STATES IN NUCLEI1 G. R. Satchler
Calculations are presented for the excitation by The isovector coupling potential is determined by protons of giant dipofe (T = 1) and quadrupoie (T= 0) analysis of {p. n) transitions to analog states. Compari states in nuclei. Two simple models are used for the son with data for 61- and 182-MeV protons shows diat transition densities and potentials in the dipole excita die dipole excitation is too weak, but inclusion of the tion. The usual deformed optical potential is applied to quadrupote state gives good agreement with die mea the quadnipcte transitions. The strengths are deter surements. mined by exhausting the linear energy-weighted sum rules. The relationship to the effective charges needed for transitions between low excited states is discussed. 1. Abstract of published paper: SucL Phys. A195, 1 (1972).
EFFECTIVE HAMILTONIANS FOR TRUNCATED SHELL MODELS B. R. Barrett1 E. C. Halbert J. B. McGrory
We continue our study2 of die construction and success, we guessed that we would only improve things properties of renormalized Hamiltonians. In this project by adding in the missing term of second-order Htff. we concentrate on die nude; A = 17-20, and we try to However, we now find that this addition does not yield construct s>3ie (rfs/2'$i/2X*-16 models that will general improvement. Instead, we find very serious 16 19 20 20 simulate the results of a given (d$f2, ^1/2^3/2)^ ~ deterioration for F, F,and Ne. Thus, the simple modeL Hereat'er we refer to the larger vector space as second-order scheme seems to be qualitatively correct dsd. and die truncated space as ds. for the two-body part of the effective Hamiltonian but In all our work we assume for die dsd model a misleading for the three-body part. Hermiaan (1 + 2Vbody Hamiltonian H. We investigate In our study of the projection method, the three- three distinct methods to find renormalized ds body-operator part of rfeff has been used so far only
Hamiltonians iie{f One mediod is a simple second- for A - 19. In this case we are interested in the order perturbation scheme. The second mediod is importance of non-Hermiticity. (Non-Herrraticity arises least-sq>iares search 10 fit selected dsd eigenvalues. The in rfeff because the ds projections of the dsd eigen third is a "projection method." by which we construct vectors are not mutually orthogonal.) In our previous a ds Hamiltonian whose eigenvalues exacdy match work we learned that die non-Hermiticity of the
selected dsd eigenvalues, and whose eigenvectors ex projection-method ,lcff is unimportant for A = 18. actly match die corresponding projections of dsd Now we find that for A = 19, non-Hermiticity is slighdy eigenvectors on the ds space. more important, but still almost inconsequential for Several variations of each method are examined. In most levels. One exception is the lowest 7/2+ in 19F,
the study of perturbation and projection methods, our where symmetrization of the non-Hermitian rfeff leads recent efforts are to extend diese methods so as to take to a 2-MeV error in the energy eigenvalue. account of three-body-operator terms induced in the The airr. of our least-squares-search study is to effective Hamiltonian, as well as die (1 + 2>-body terms. determine whether there exists a Hermitian (1 +
For the least-squares method, our recent efforts are to 2>body operator ,/eff which somehow incorporates the refine our criteria for selecting the dsd levels to be advantages gained in die other methods by reso.ting to fitted by least squares. ds Hamiltonians which are non-Hermitian (I + 2 + For the simple truncation dsd -*• ds, a complete 3>body operators. It is advisable to take considerable second-order perturbation scheme gives an effective care in selecting the set of dsd levels to be fitted by Harraltonian having (1 + 2 + 3>body terms (but no least squares, because the emergent least-squares terms of higher particle rank). In our previous work2 Hamiltonian wil be unnecessarily distorted if die we found that the (1 + 2>body terms of second-order least-squares-fitted subset includes too many states widi
Keff were surprisingly successful in reproducing die dsd considerable "intruder" character. Two separate least- results for A = 18, 19, and 20. Given this moderate squares searches are studied. Case A concentrates on 21 fitting low-lying dsd levels and also any others that squares. Still, each of A and B yields fits which are, seem to be members of ground-state bands. Case B overall, obviously better than those produced by the (1 concentrates on fitting dsd levels that we hopefully + 2>body parts of //cff (second order) and Meff identify as "nonintruders," because their wave func (projection). This superiority does not extend to the tions have large projections on the ds space and because eigenvectors of tfeff. For low-lying states, all our these projections are almost orthogonal to each other. renonnalized Hamiltonians Keff have ds eigenvectors Unfortunately, our results from these searches are not that look very much like ds projections of the dsd so clear-cut. In particular, we find no clear confirmation eigenvectors; the exceptions are no fewer or milder for of the hope that our criteria in case B are useful for fieff (least squares) than for the (1 + 2)-body parts of defining ind identifying "nonintruder" states. The f/eff (second order) and rYeff (projection). optimized fits from cases A and B each include some disappointingly large deviations from dsd eigenvalues - 1. Department of Physics, University of Arizona, Tucson. even for levels that were explicitly fitted by least 2. Phys. Div. Amu. Frogr. Rep. Dec. 3i. 197i, ORNL-4743.
A PROGRAM FOR EXTENDED WEAK-COUPLING CALCULATIONS L. B. Hubbard1 J. B. McGrory
It is now established that large shell-model calcu approach would be to diagonalize Ht and Hu in the lations are extremely useful in the study of nuclear large inequivalent spaces, choose only a small set of structure. It is also well known that the region of low-lying eigenstates of Ht and//7/ to form a truncated applicability of such calculations is severely limited by coupled basis, and diagonalize HJ_II in this truncated the dimension explosion problem; that is, as the space. We have developed a program to carry out this number of active particles or the number of single- procedure. One type of calculation that might be particle orbits in the model space is increased, the carried out with the program is for nuclei where there is dimensions of the matrices to be diagonalized rapidly a significant neutron excess, so that the valence neutron increase until the problem is intractable in practice. It is orbits are quite different from the valence proton thus very desirable to find a truncation scheme that orbits. One might then expect the neutron-proton leads tc results in a small-dimensional space that are in interaction to be relatively weak. The prescription is good agreement with calculations in a larger more then to diagonalize the proton-proton and the neutron- complete space. We have developed a program that neutron interaction separately, use a truncated set of should be useful in investigations of some types of neutron states and a truncated set of proton states, and truncation schemes. We assume that the model space is diagonalize the neutron-proton interaction in the space divided into two completely inequivalent spaces (so generated by coupling these inequivalent states. that antisymmetrization between the two spaces can be The program has been checked out by repeating ignored). The model interaction can be written in the complete s-d shell-model calculations in a neutron- form proton formalism, that is, treat 20Ne as 180 states coupled to 18Ne states, and making no truncation in
H = HI + HII+HI_I/, the two spaces. These results have then been compared with calculations made of the same nuclei with the Oak where / and // label the two inequivalent spaces. One Ridge—Rochester shell-model program. can always work in a basis of states of the form Applications of the program will include studies of transitions from spherical to deformed structure- in nuclei with neutron excesses and studies of the coupling of multiparticle multihole states in nuclei near closed shells. where j0/> and |#7/> are eigenstates of Hr and Hu. If there is some reason that the interaction between states in the two inequivalent spaces is weak, then one 1. Consultant from Furman University, Greenville, S.C. 22
SHELL-MODEL CALCULATIONS OF NUCLEI IN THE 20t Pb REGION J. B. McGrory C. M. Ko1 T. T. S. Kuo1
The properties of the following nuclei have been omitted from the modil space. For the case of 210Pb, calculated in terms of a conventional shell model: these orbits can be included in the model space, and it
204,205,206,2IO,21l.2l2pb 2l0po 21 lAt md is found that although they comprise only 4% of the 2l2Rn. The lead isotopes *°«.*°*.™«pb were treated 2' °Pb ground-state wav* function, this 4% accounts for as nuclei with four, three, and two neutron holes in almost 50% of the ground-state transition strength for 208 208 210 Pb. The isotopes 210.211.212^ Vltn ^3^ & the Pb(f. p) Pb reaction The observed relative nuclei with two, three, and four neutron particles strengths for transitions o states of the same /value in outside 208Pb. The remaining three nuclei were treated the 208Pb(/>, /)206Pb and ™Tb(p. t)20APb reactions as two, three, and four protons outside 208Pb. The are accurately reproduced by the calculations. model space for the neutron-hole states calculations A "pairing-vibration" phonon model for 212Pb and included the lowest six single-neutron-hole orbits in 204 Pb has been investigated. The phonons consist of 208Pb. The model space for the proton-particle nuclei the lowest few eigenstates in 210Pb and 206Pb. The included the lowest six single-proton particle orbits spectrum of low-lying states is found to be very outside 208Pb. The model space for the neutron accurately reproduced in a space formed by coupling particle states included the lowest five single-neutron the five lowest "phonons" of v' °Pb, that is, particle orbits outside 208Pb. Experimental single- 2 2 2 ?p 2 particle energies were used, and for the two-body part U ' Pb) - E cif U ' b) X *,< »°Pb), of the model Hamiltonian, we useu the "realistic" interaction of Kuo and Herling.2 The properties calcu lated include binding energies, excitation energies, where #, is an eigenstate in 2l0Pb. Similar results are magnetic dipole and electric quadrupole moments, found for 204Pb, when treated as the coupling of B(Miys and B(E2)\ and strengths for one- and low-lying "phonons" of 206Pb. two-particle transfer reactions. With a few exceptions, the calculated values for these observables are in good 1. Department of Physics, State University of New York at agreement with measured values. The main discrep Stony Brook, Stony Brook, Long Island, N.Y. ancies involve the two-nucleon transfer strengths. For 2. T. T. S- K.'O and G. H. Herling, N.R.L. memorandum the lead particle states, the !2 orbits were report 2258 <;97«,
COULOMB ENERGY DIFFERENCES IN s-d SHELL NUCLEI IN THE CONVENTIONAL SHELL MODEL J. B. McGrory
A subject of long interest in nuclear physics is the lations. For the two-body part of the effective nuclear Coulomb energy difference between members of iso- Hamiltonian, I used the "realistic" interaction of Kuo. baric multiplets. I have calculated these Coulomb For the two-body Coulomb interaction, the bare energy differences in nuclei with masses A = 19, 20, and Coulomb interaction and harmonic oscillator wave 21 in terms of a conventional shell model. An inert' 60 functions were used, with the oscillator parameter core is assumed, and particles are distributed in the evaluated from the relationship **o = 41.4"l/3 MeV. In ^s/2> si/2» and P3/2 orbits. All possible states of all Table 1, I have tabulates the difference in binding Pauli-allowed configurations of active particles dis energies, measured with respect to ,60, of the ground tributed among these orbits are included in the model state and its isobaric multipiet partner for 11 different space. The calculations are done in a neutron-proton nuclei. For the 11 cases shown, the typical energy (n, p) formalism. For neutron states, the singie-particle difference is about 4.00 MeV, and the average absolute energies are taken from the experimental spectrum of deviation between theory and observation is 0.05 keV. 1 70; for proton states, the single-particle energies are The calculations have been repeated with only the taken from the experimental spectrum of 17F. The one-body Coulomb interaction included, and with only same single particle energies are used for all the calcu- the tw^-body Coulomb interaction included. The pre- 23 ponderance of the Coulomb energy difference comes the good agreement. In the calculation of both the from the one-body part, which probably accounts for nuclear and Coulomb two-body matrix elements, the single-particle wave functions are approximated by Table 1. Energy differences of lowest member of isobanc charge-independent harmonic-oscillator wave functions. multiplets in light j-4-shell nuclei This should be especially bad for the case of the relatively long-ranged Coulomb interaction. The isospin Experiment** Nuclei T Calculation mixed wave functions generated with the full 1-body + ,9I-,9Nc 1/ 4.02 3.94 2-body charge-dependent interaction have been ana •2 19 ,9 lyzed for the degree of isospin impurity. In a majority 0- F \ 3.53 3.50 I9 19 of cases, the mixing is very small, less than 2%, but in F- Ne % 3.98 3.93 several isolated cases, the mixing is as much a" 20%. 20 20 N.- F 1 4.C3 3.93 This is due to accidental degeneracy of states with the 20N.20F 1 442 4.40 same J and different T values in the calculated 20I l00 2 3.48 3.47 20 _20 spectrum, and not because of any strong Coulomb N F 2 3.<>7 3.91 matrix elements. This type of shell-model calculation is 2l 21 N;- Na 4.33 4.36 % not nearly accurate enough to predict when such 2,Ne-21F 3.95 3.95 % mixing will occur, bui it clearly points to the possibility 2lNa-21Ne 4.44 4.36 \ of such strong mixing due- to similar degeneracies in 21Mg-21Na 4.95 4.78 \ nature.
ai. Janecke, Isospin in Nuclear Physics, p. 376, ed. by D. H. Wilkinson, North-Holland, 1969.
ALPHA-PARTICLE SPECTROSCOPIC AMPLITUDES AND THE SU(3) MODEL1 Munet.':ekhimura2 Akito Anma3 E. C. Halbert Tokuo Terasawa4
Formulas for calculating spectroscopic amplitudes for reduced widths for states which are mainly 4p-4h than emission or transfer of alpha particles are developed in for states which are mainly Oo-Oh or 2p-2h. Spec the framework of the harmonic-oscillator she.'l model troscopic amplitudes are also calculated for some ! 60 with SU(3) classification. These formulas are applied to and l2C states described as linear chains of alpha some interesting states of 20Ne, for example, low-lying particles. (set)4 shell-model states, members of the lowest K = 0" band with SU(3) label (90), ana ^.iw-excited states with 1. Abstract of paper submitted for publication in Nuclear SU(3) label (10,0). Spurious center-of-mass motion is Physics. removed. The formulas are also applied to the ground 2. Department of Physics, State University of New York at and some excited states of ,60. The ,60 wave Stony Brook, Stony Brook, Long Island, N.Y.; on leave from functions of Brown and Green are used in an investi Institute of Physics, College of General Education, University of gation of how the mixing among 0p-0h, 2p-2h, and Tokyo. 3. Department of Physics, State University of New York at 4p-4h states affects the wave function for relative Stony Brook, Stony Brook, Long Island, .>.'.. motion between the alpha cluster and the mass 12 4. Institute of Physics, College of General Education, Univer nucleus. These calculations indicate much larger alpha sity of Tokyo, Komaba, Meguru-ku, Tokyo, Japan.
AN ANALYSIS OF SHELL-MODEL WAVE FUNCTIONS FOR s-d AND f-p SHELL NUCLEI IN TERMS OF SU(3) REPRESENTATIONS J. B. McGrory
It was suggested1 by J. P. Elliott that states which shell nuclei. Shell-model wave functions for s-d shell carry representations of the group SU(3) would make nuclei with A = 18-22 and A = 34-38 have been up a "good" representation for nuclei in the light s-d determined by diagonalizing so-called "realistic"' inter- 24
actions in the complete space of s-d shell wave Table 1. Avenge probability amputate foe indicated SU(3) functions in a /-/ coupled representation. States which representation ia the member of the ground-state carry representations of the group SU(3) have been potential band in some light s-4 shell nuclei determined by diagonalizing the one-body plus two- body Casimir operator for this group in die complete Nucleus SU(3) label (X, u) Average probability (%) space of/-/ coupled s-d shell states for A = 18-22 and ,9F (6.0) 75 A = 34-38 nuclei. It is then possible to express the 20F (6,1) 70 "realistic" eigenstates for these nuclei in terms of 20 SU(3Mabeled states by computing overlaps between the Ne (8,0) 78 "realistic" eigen;tates and the SU(3) eigensiates as 21 Ne (8,1) 74 expressed in the /*-/' representation. The member* of the 22 Ne (8,2) 57 l9 20 20 21 22 ground-state bands of F, F, Ne, Ne, Ne, 22 Na (8,2) 71 and 32Na are ail dominated by one SU(3) state, as expected. In Table 1 we list the dominant component made here might be useful in the calculation of for each band and the average value of the probability alpha-transfer processes. For A = 34—38 nuclei die that this component exists in each member of the SU(3) representation is no longer "good." For these ground-state band for diese nuclei. Some members of nuclei the largest SU(3) component typically is excited bands in these nuclei also have lirge admixtures 15—20% of the total wave function. Similar calculations of one or two SU(3) states. Arguments have been made for f-p shell nuclei with A = 44 also show that SU(3) is to show that the spectroscopic factor for use in the no longer a "good" representation in these nuclei. This calculation of alpha-transfer cross sections and alpha- breakdown can be traced to strong spin-orbit effects. decay widths is proportional to how "good" the SU(3) is for the involved states, so that the type of analysis 1. J. P. Elliott, Proc. Roy. Soc. A245, 128 and 562 (1958).
SHELL-MODEL CALCULATION FOR MASSES 27,28, AND 29: GENERAL METHODS AND SPECIFIC APPLICATIONS TO 27 Al, 28Si, AND "Si1 B. H. Wildenthal2 J. B. McGrory
A shell-model calculation for A = 27, 28, and 29 that a unified and quantitative explanation of nuclear nuclei has been carried out in a truncated structure around A = 28 can be obtained via shell-model 0^5/2-1*1/2*0^3/2 Da^s space with an MSDi Hamil techniques. ton ian. A comparison of the calculated results for level energies, sirigje-nucleon spectroscopic factors, and £2 1. Abstract of paper to be published in Physical Review. and M\ transition strengths in 27A1; 28Si, and 29Si 2. Cyclotron Laboratory, Department of Physics, Michigan with the corresponding experimental values indicates State University, East Lansing.
SHELL-MODEL CALCULATIONS FOR ,4 = 18,19, AND 20 NUCLEI WITH CORE EXCITATION INCLUDED EXPUCITLY1 J. B. McGrory B. H. Wildenthal2 Eigenvalues and eigenvectors for all low-lying positive and the corresponding shell-model eigenvalues. The and negative parity nuclear states of A - 18,19, and 20 energy-level spectra and single-nucleon spectroscopic are calculated in a shell-model basis of all Pauli-allowed factors from these calculations are compared with the 13 0pi/2-0rf$/2-l*i/2 configurations outside an inert C available experimental data in this region. The calcu core. Two different effective Harniltonians are used. lations are also examined for the existence and charac One is based on a reaction matrix treatment of die teristics of sequences of levels which might be called Hamada-Johnston potential. The second o»e is obtained "rotational bands." by varying the 33 effective Hamilton:*?, matrix ele 1. Abstract of paper to be published in Physical Review. ments to reach a least-squares fit between 133 experi 2. Cyclotron Laboratory, Department of Physics, Michigan mental level energies in nuclei in the/I = 13-21* :e<-*ot~ State Univerity, East Lansing. 25
ANALOG AND CONFIGURATION STATES IN 49Sc (J* = 3/2" AND 1/2") AND THE LOW-LYING LEVEL STRUCTURE IN 48Sc1 S. D. Bloom2 J. B. McGrory S. A. Moszkowski3
J* = 3/2" and 1/2" states in 49Sc generated by the observed experimentally. The £2 decays of all the configurations Kl/7/2)8 (2P3/2.1/2)] are discussed. predicted 3/2" states to the 7/2" ground state were also Excitation energies, MX transitions, and El transitions calculated. In the case of the E2 decay of the 4(3/2") among the seven 3/2" and five 1/2" levels, including the state, comparison with experiment is hampered by the
3/2" analog state at Ex = 11.56 MeV and putative role of fine structure: experiment is weaker than theory excited analog 1/2" state at ^13.6 MeV, were calcu by afectorof^SOX. lated and compared with experiment where possible. The (1/7/2)' group of levels in 48Sc were alsu The beta decay of 49Ca to the 3/2 level at 3.08 MeV calculated (J* = 0* •* 7*). The PMM iorce gave and to the (presumably) 1/2" level at 4.49 MeV (the excellent agreement with recent experimental results, lowest-lying 3/2" and 1/2" levels) were also calculated. while the KB force gave relatively poor agreement, as Two interactions were used, the well-known Kuo- might be expected from the severe truncation of the Brown (KB) force and a new interaction that we call shell-model basis. The suggestion is that the phenome- the PMM force, the latter being derived mainly from nological basis of the PMM force corresponds physically direct-reaction cross sections of nucleons on various 8 48 to the (l/7/2) . space of Sc as well as the nuclei. Both KB and PMM interactions lead to cancella 8 49 (l/7/2) (2p3/2 or 2p1/2) space of Sc. tions which cut down both the beta decay of 49Ca and the Ml decay of the A state to the lowest-lying 3/2" and 1/2" states, as observed experimentally. In addi 1. Abstract of paper to be published in Nuclear Physics. tion, strong Ml decays to several 3/2" and 1/2" levels 2. Lawrence Livermore Laboratory, Lrvermore, Calif. with excitations of 7 to 11 MeV are predicted, as is 3. Department of Physics, UCLA, Los Angeles, Calif.
ON THE TRANSITION FROM SHELL STRUCTURE TO COLLECTIVE BEHAVIOR: A SIMPLIFIED SHELL-MODEL STUDY1 K. T. Hecht2 J. B. McGrory J. P. Oraayer2
To study the feasibility of carrying out shell-model for example, only three of the 94 shell-model states calculations in nuclei with active protons and neutrons with /„ = 2 are retained in the truncation scheme. In in different major shells, the following simple idealized this highly truncated basis both the energies and the model has been studied: (1) Proton and neutron strong BKk values for the transitions from these states configurations are chosen to be (fsiiPsiiPxj'tfP and to similar favored states with other /values are within a (^7/2^'/2^3/2Ji/2)n'1. s0 mat results for the separate few percent (or better) of the results of exact shell- proton and neutron basis states to be used in any model calculations. A truncation of the shell-model approximation scheme can be compared with the space based on such superpositions of favored pair results for exact shell-model calculations. (2) The states leads to a manageable shell-model basis (dimen proton and neutron single-particle energies for these sions <200). (1) The number of states in the separate active shells are separately taken to be degenerate. (3) proton and neutron parts of the basis are small enough The two-body interaction is approximated by the (8 to 13 for the proton space, 15 to 30 for the neutron simple surface delta interaction (SDI). space). They are also the key states in the following To effect the severe truncation of the full shell-model sense. (2) They include the low-lying energy eigenstates space needed to make such a shell-model study possible, of the separate p-p and n-n parts of the interaction. (3) the separate proton and neutron parts of the shell- They contain most of the collective coherence of the model basis are built from a superposition of the separate proton and neutron configurations. (4) The favored pair slates of the SDI (with / # 0, as well as/ = matrix elements of the n-p part of the interaction 0). In the neutron configuration between the favored states is in general very large compared with the matrix elements between a favored (#7/2^5/2<*3/2*l Itf" 4, and an excluded state. The latter effect is studied from 26 several aspects, in particular in terms of sum lu'cs tor spectrum The presence and exact nature of a 0* the matrix elements of the surface multipole operators member of the 0*, 2\ 4* "two-phonon triplet" is from which the n-p part of the SD1 is built. For most of dependent on the inclusion of the key favored states the low-lying favored states the sum over all favored with seniorities of 6. states gives more than 90% of the total sum rule for the squares of matrix elements of the surface multipole 1. Abstract of published paper: Nucl. Phys. A197, 369 operators. The results of shell-model calculations in this (1972). truncation scheme, with np = 4 or 6 and nn - 4, show 2. Department of Physics, University of Michigan, Arm many of the features of a quadrupole vibrational Aibor.
WHERE LIES THE INTERACTION BARRIER?1 C. Y. Wong
Simple expressions are obtained for the total reaction cross section in terms of the interaction barrier for the s 1. Abstract of paper submitted for publication in Physical wave. These expressions allow the interaction barrier to Review Letters.. be determined experimentally.
ON SUPERHEAVY NUCLEI SYNTHESIS BY THERMONUCLEAR EXPLOSIONS1 C. Y. Wcng
Simple estimate shows that with presently available superheavy atoms with thermonuclear explosions is not technology the yield of superheavy nuclei obtained in well substantiated. thermonuclear explosions is very small. A recent claim 1. Abstract of paper submitted for publication in Physical of a possible production of macroscopic quantities of Review "Comments and Addenda."
STABILITY OF A ROTATING TOROIDAL MASS1 C. Y. Wong
Idealizing a rotating toroidal star as uniform and considered proved for such a case only. The case of incompressible, Kowalewsky, Poincare, and Dyson in small and moderate aspect ratios, for which a high the last century showed that a toroidal mass has a degree of accuracy is required, was never discussed. minimum in its energy vs breathing deformations and Attention is therefore fixed on a toroidal mass with an therefore can be stable against expansion and contrac arbitrary aspect ratio which need not be large. The mass tion of the major radius because of the balance between is likewise idealized for simplicity to be a uniform and the gravitational and the centripetal forces. Dyson also incompressible mass distribution rotating about the investigated other distortions and found that such a central symmetry axis with a uniform angular velocity. breathing deformation minimum is stable against all A high degree of accuracy in the evaluation of the distortions except "sausage" deformations, in which the gravitational potential is achieved by expanding the torus is thicker in some sections but thinner in others. potential as an infinite series of functions of toroidal Sausage deformations are therefore the only large-scale harmonics. Our result indicates that for a given angular distortions leading to instability. It should be realized momentum, one obtains a definite breathing deforma that Dyson's proofs made use of approximate expres tion minimum characterized by an aspect ratio of major sions for the gravitational potential and the moment of to minor axis. The aspect ratio increases monotomcally inertia appropriate for large aspect ratios of major to as a function of the angular momentum, being nearly minor radius R/d. The conclusion on instability of the unity for no rotation. However, not all the toroidal toroidal mass against sausage deformations should be masses at their respective breathing deformation min- 27 ma are unstable against sausage deformations. Al Thus, the possibility is opened up for a rotating toroidal though a toroidal mass with a large aspect ratio (Rjd S mass to have its independent existence, and it need not 6.7) is indeed unstable against sausage deformation - as necessarily be the companion of a certral nucleus, as a was already pointed out by Dyson a toroidal mass ring structure has. up to now. always been iield to be. with an aspect ratio Rjd in the range 1.05 $ Rjd S6.7 is stable against sausage deformations of all orders. Some of these stablt toroidal masses may conceivably 1. Abstract of paper submitted for publication in Astro- be stable also against all other large-scale deformations. physical Journal.
FUSION THRESHOLD ENERGY IN HEAVY-ION REACTIONSl
C Y Wono
We examine the dependence of the fusion threshold increases. The value of re is larger when either the energy for various combinations of projectile and target projectile or the target nucleus is endowed with a nuclei. It is found that when the threshold energy is permanent positive quadrupole moment. 2 ! 3 parameterized in the form ZlZ2e j [re(A i ' + A
TOROIDAL NUCLEI1 C. Y. Wong
There are shells in the single-particle spectrum of a 70 and 4 $ 250 along the beta-stability line. icrcidal nucleus. The shell-corrected deformation ener gies, calculated with Strutinsky's theory of renormaliza- 1. Abstract of published paper: Phys. Lett. 41B, 446 (1972). tion, show breathing deformation minima for 40 $ A ^
BUBBLE NUCLEI1 C. Y. Wong
There are shells in the single-particle spectrum of a with a small hole in the interior, while ! 74Yb and bubble nucleus. The shell-corrected deformation ener 250104 have secondary minima in the bubble degree of gies, calculated with Strutinsky's theory of renormaliza- freedom. tion, show that 36Ar, 84Se, ' 38Ce, and 200Hg in their ground or low-lying excited states are bubble nuclei 1. Abstract of published paper: Phys. Lett. 41B, 451 (1972).
TOROIDAL LIQUID STARS' C. Y. Wong The toroidal liquid stars of Poincare, Dyson, and other perturbations and render themselves observable in Kowalewsky are found to be stable against sausage nature. deformations if the aspect ratio is not too large. It is conceivable that these stars may also be stable against 1. Abstract of paper submitted for publication in Nature. 28
A PEDESTRIAN APPROACH TO THE INTERMEDIATE STRUCTURE IN PHOTONUCLE AR REACTIONS IN UGH1 NUCLEIl F B. Malik2 M G. Mustafa3
The intermediate st^-cture in photonuclear reactions ««d a transition via a series of closely lying intermediate is discussed within the context of a general theory states. based on a many-body Hamiltonian. The results are shown for !2C, I60, and 28Si. The comparison with 1. Abstract of paper to be published in Proceedings of the V Symposium on the Structure of Low-Medium Mass Nuclei experiment indicates two competing processes for 2. Department of Physics, Indiana University, Bloomington. photonucleon emission in light nuclei: a direct emission 3. On leave from Atomic Energy Centre, Dacca. Bangladesh.
A THEORY OF INTERMEDIATE STRUCTURE, OVERLAPPING RESONANCES, AND PHOTONUCLEAR REACTIONS IN LIGHT NUCLEI < M. G. Mustafa2 F. Bary Malik3
Starting from a many-body Hamiltonian, a general explicit equations for this case have beer obtained. This theory involving intermediate structures and overlap microscopic theory also provides a justification of the ping resonances in nuclear reactions has been worked model of Duke, Malik, and Firk in explaining the out. This treatment, based on Trefftz's work on intermediate structure in giant dipole resonance region dielectronic recombination in atomic physics, avoids of l60 and 28Si. However, the formalism is a general explicit use of projection operators, aid all relevant one and is suitable for the study of intermediate quantities like decay widths and energy shifts are structure involving isolated and overlapping resonances explicitly expressed in terms of two-body matrix for many types of reactions. elements. In particular, attention has been focused on the interaction of bound states among themselves and then on the coupling of the continuum with these 1. Abstract of paper submitted for publication in Helvetica interacting bound states. For the case of overlapping Physica Acta. resonances, it is shown that in general one cannot take a 2. On leave from Atomic Energy Centre, Dacca, Bangladesh. simple energy average of the resonant amplitudes, and 3. Department of Physics, Indiana University, Bloomington.
THE GAMMA-RAY ABSORBED FRACTION FOR SMALL OBJECTS Lincoln B. Hubbard1 At the limit of extremely small size the absorbed l*if££L(l_e-M/e)j fraction for internal gamma emitters varies as th? cube root of the mass. As the mass increases, the effects of
attenuation and multiple scatter become proportion where \ien is the energy absorption coefficient and \i is ately larger and larger; eventually this causes significant the attenuation coefficient. If this is expanded in deviation from this simple dependence. These effect: powers of/?, the absorbed fraction appears as become significant at relatively small sizes; with a
1-MeV source in a mass of about 10 g the attenuation l \**\ienR-\wenX* ••• • correction is 10% of the absorbed fraction. However, the attenuation and multiple scatter effects enter with The first term, proportional to the cube root of ihe algebraically opposite signs and approximately equal mass, is the no-attenuation, no-scatter-buildup approxi magnitudes. For example, if multiple scatter is ne mation. glected (i.e., only the first collision of each gamma ray If the multiple scatter contribution is also expressed is included) in a uniform sphere ot radius/? containing in powers of/?, the lead frm can be calculated2 for/? a central point source, the absorbed fraction is: < Mil as 29
ORNl-OWG 72-11865 +0.770i + M,.,>*i,„*/?2 .
where *Vi* is the energy absorption coefficient for gamma r^ys having the average scattered energy If we take the ratio of these orrection terms we find:
\i2Wen*1 [0.770Z-M,,,)^„**2]
~ 0.7 at 0.1 MeV, 1.4 at 3.0 MeV .
Thus, there is an approximate cancellation of the leading attenuation correction term and the leading multiple scatter term. The approximation
is fairly good to radii of the order of a mean free path. An example for an 0.l6~MeV source is shown in Fig. I. The Monte Carlo result is from the results of Brownell et al.3
0 0.0 1.0 1.5 2.0 1. Consultant from Furman University, Greenville, S-C. pR, MEAN FREE PATHS 2. L. B. Hubbard and F. S. Williamson, Phys Med. Biol. 16, 35(1971). Fig. 1. The absorbed fraction as a function of size for a 3. G. L. B.owndl, W. H. Ellet, and A. R. Reddy, /. Nucl muscle sphere containing a central 0.16-MeV point source. The Med. MIRD Suppl 1, 27 (1968). line labeled Men/? is the small mass (no-attenuation, no-scatter- buildup) approximation. 0] is the result assuming no scatter buildup but assuming attenuation. The Monte Carlo result is from Brownell et al., / Nucl. Med. MIRD Suprf. \, 27 (1968). 2. High-Energy Physics
EVIDENCE FOR A NEUTRON HALO IN HEAVY NUCLEI FROM ANTIPROTON ABSORPTIONS W.M.Bugg1 HO. Conn G.T.Condo1 EL. Mart1 R. D. McCuIIoch2 In recent years, considerable interest has been at annihilations produce events with a net charge of 0 and tached to the question of whether heavy nuclei have a -1 respectively. It is presumed thai the nuclear capture neutron excess in their periphery. The most recent process, as in the K~ case, occurs in the nuclear experimental results3 utilizing high-energy scattering periphery.7 imply near equality for the neutron and proton radii in A summary of our data is presented in Table 1, in the heavy nuclei. The strongest evidence supporting the which we give the numbers of events with the observed existence of a neutron halo has been presented by Davis net charges in the mesonic prongs. Strict scanning et al.4 from a study o(K~ absorptions in the heavy and criteria were imposed to exclude from our sample all light nuclei of nuclear emulsion. They observed that K~ events for which the exact origin of each mesonic prong capture by a neutron in (Ag,Br) was 5.0* J ;f times as could not bo determined. This is clearly desirable, since likely as was K~ absorption by a neutron in (C,N,0). A the annihilation star was not visible when it occurred in subsequent analysis of these data by Burhop5 has one of the plates. The data in Table 1 have not been reduced this number to 4.2 ± 0.8. Since the nuclear corrected for hydrogen events that occurred in the absorption of slow, heavy, strongly interacting particles darkened regions about the plates and that were is expected to occur from atomic states of large angular indistinguishable from events occurring ui the plates. momentum (/ ~ 6 in Ag), this implies that the capture This hydrogen contamination amounts to 12.3% forC, occurs in the nuclear surface where the nucleon density 9.1% for Ti, 13.3% for Ta, and 11.7% for Pb. Thus, for is <20% of its central density.6 The obvious conclusion, example, for each 1000 events which appear to stop in therefore, is that a considerable neutron halo exists in tantalum, 133 are actually hydrogen captures occurring heavy nuclei; however, a precise analysis of the extent in darkened regions about the plates. of this halo is difficult5 because of the £ conversion Although few antiproton annihilation experiments in process and the presence of the Y% (1405), which media other than hydrogen or deuterium have been drastically alters the K'p and K~n absorption ampli reported, it is clear from the early experiment of Agnew tudes. In the present paper we will report on an experiment utilizing p absorptions that confirms the existence of a neutron halo in heavy nuclei. Table 1. Net observed chaiye distribution of p annihilations after geometric correction The data were obtained from an exposure of the 30-in. BNL hydrogen bubble chamber to a beam of Boso'iic C Ti Ta Pb slow antiprotons. The chamber contained four rectang charge ular plates of carbon, titanium, tantalum, and lead that +3 10 6 5 1 were mounted so that the optic axis of two of the +2 141 54 75 45 stereo cameras was approximately parallel to the faces +! 1166 391 400 265 of the plates. The thicknesses of the plates were: C, 0 3491 927 940 767 0.85 cm; Ti, 0 56 cm; Ta, 0.22 cm; Pb, 0.35 cm. These -1 2246 784 856 659 were selected so that about 25% of the low-momentum -2 512 209 236 215 -3 43 23 33 30 p beam at BNL would stop in the plates. The physics of -4 2 2 0 0 the experiment derives from the fact that pp and pn
30 31
Table 2. Summary of results
Number TouH Observed No. of excess. of Proton "Halo Element N/Z No. of .*/ = «<**> + »<* > charged pn pp \pn pp)c events neutron captures factor" events multiplicity captures
C 1.00 7611 6675 19.023 2.500 1929 2469 4206 0.587 1.00 1.00 Ti 1.18 2396 2178 5.600 2.337 762 1043 1135 0.919 157 1.33 s 0.22 Ta 1.48 2S45 2207 5.772 2.26S 862 1216 991 1.227 2.09 141 ±0.24 Pb 1.54 1982 1750 4.4" 1 2.236 821 1175 575 2.043 3.48 2.26 ± 0.50
'Including events in hydrogen. et al.8 that secondary interactions of the annihilation elements normalized to the carbon data always exceeds products are an important facet of any annihilation the ratio of neutrons to protons in the capturing experiment in nuclear matter. The data in Table 1 also nucleus. Thus an antiproton is about 3 % times as likely support this conclusion. Rather than attempt to predict to be absorbed by a neutron in lead as it is in carbon. the charge distributions in Table 1 from a theoretical One would expect this ratio to be 1.54 merely because model, we resort to a purely empirical interpretation, of the neutron excess of heavy nuclei. Over and abv*ve which is outlined in Table 2. This analysis relies on the this expected neutron enhancement, neutron captures fact that each neutron annihilation will produce a are 2.26 times as likely as proton captures in Pb. The meson ic system with a net charge of -1. Thus, to corresponding enhancements in Ti and Ta are 1.33 and determine the number of neutron annihilations in any 1.41 respectively. It is interesting that tantalum appears particular plate, we must find the total excer of to be more like titanium than lead, even though it is negative charge in the mesonic prongs. This is not much nearer lead in the periodic table. While this must difficult to effect, since we need only multiply the remain a mystery, it is interesting to observe mat observed n~ excess by the ratio of the multiplicity of nearby elements exhibit anomalous behavior in the A" charged pions at the annihilation to the observed mesic x-ray studies of Wiegand et al.1' In these x-ray charged pion and multiplicity: experiments, the x-ray intensities observed near the termination of the atomic cascade are far less for Number of pn annihilations elements similar to Ta than to those observed for most _/ true multiplicity \ other elements. It is also possible that the large = xNot . orf excess n ( — ; , . .. .— ) \ observed multiplicity7, quadrupole moment of Ta could affect either the atomic cascade or the subsequent nuclear annihilation This assumes that secondary interactions and our process. geometric limitations affect the number of n* and *~ It is to be noted that pn/pp for carbon is 0.587, losses equally. The charged pion multiplicity has been whereas it has been reported to be 0.69 and 0.75 in two measured in deuterium9 to be 3.11 (or pp annihUations prior deuterium experiments.9*12 Since N/Z is the same and 3.15 for pn captures. The extant data for carbon8 for both elements and since there exist no known and the light nuclei of emulsion10 are consistent with boson'c resonances with a mass near pp threshold, it those figures if there is a pion absorption probability in might be expected that the carbon and deuterium the parent nucleus of about 8%. Therefore, we tak»* die result* would be similar. The differences in this result true multiplicity of charged pions ij be 3.13. Once the could have several origins. First, Agnew et al.8 present number of neutron annihilations is known, the number evidence which suggests that, in carbon, about 15% of of proton annihilations is just the difference between the pp absorptions charge-exchange to an nn final state. the total number of captures in the element and Nipri). The resulting annihilation is that of an n in carbon, The last three columns of Table 2 list the ratio pn/pp which will lead to a substantial number of mesonic final for each element, pn/pp normalized to the carbon states with a net positre charge [q(h~p) = +IJ. If p result, and the "halo factor," which we define as the charge exchange also occurs in deuterium, pipn) -*• normalized (pn/pp)c ratio divided by NjZ. h\nn), only neutral mesonic systems can result This The most striking feature of Table 2 is that the would cause our reported pn/pp ratio for carbon to be neutron-to-pioton annihilation ratio for the various smaller than the deuterium determination. Second, any 32 observation of ai.ibiguity between protons and positive !. University of Tennessee, Knoxville. pions in our experimental procedure which resulted in 2. Mathematics Division. the inclusion of protons in our v* sample would also 3. B. W. AI lardy ce, C. J. Batty, D. J Baugh. E. Friedman. distort our pn/pp ratio toward a smaller value. We G. Heymann. J. L. Weil, M. E. Cage. G. J. Py!e. G. T. A. observe, however, that both of these effects would be Squtcr. A. S. Clough. J. Cox. D. F. Jackson, S. Murugesu. and applicable to all four of our plates, and while they V. Rajaratnam. preprint; C. J. Batty and E. Friedman, NucL Phys. A179, 701 (1972). affect the absolute pn/pp ratio for any individual plate, 4. D. H. Davis. S. P. Lovell. M. Csejthey-Barth, J. Sacton, comparisons between plates arc relatively independent G. Schorochoff. and M. O'Reilly, Nucl Phys. Bl, 434 (1967). of these effects. Thus a 27c pion-proton ambiguity and a 5. E. H. S. Burhop, tfuc/. Phys. B44, 445 (1972). 10% pp +nn rate results in the normalized pn/pp ratios 6 A. D. Martin, Nuovo Cim. 27, 1359 (1963). of 1.48 for Ti. 1.97 for Ta, and 3.17 Tor Pb, and an 7. E. H. S. Burhop. p. 2280 in High Energy Physics, vol. Ill, ed. by E. H. S. Burhop, Academic, New York, 1969. absolute ratio for carbon, pn/pp = 0.74. g I C \„.,~,, i, -r ct:~l4 is valid; namely, that while the mean 10. A. J. Apostolakis, G. A. Briggs, N. A. Khan, and J. V. Major, Nuovo Cim. 37. 1364 (1965). square radii of neutrons and protons in heavier nuclei 11. C. E. Wiegand. Phys. Rev. Lett. 22, 1235 (1969); C. E. are quite similar, nevertheless, there exists in their Wiegand and R. Kunsehvin, Proc. Int. Conf. Hypemudear tenuous outer reaches an ethereal neutron halo. Physics, Argonne National Laboratory, Argonne, 111. (1969), p. 669. We are grateful to the many people at Brookhaven 12. A. Bettini, M. Cresti, S. Limentani, L. Peruzzo, R. San- National Laboratory, especially A. G. Prodell, who gave tangelo, S. Sartoni, L. Bertanza, A. Bigi, R. Carrara, R. Casali, us their complete cooperation during the course of this and P. Lariccia,M«H*o Cim. 47A 642 (1967). experiment. We also wish to thank our scanners, Mrs. 13. J. P. Schiffer, Proc. Int. Conf. Hypemuclear Physics, Argonne National Laboratory, Argonne, 111. (1969), p. 693. I. S. Han and Mrs. M. K. Burton, for their painstaking 14. E. H. S. Burhop, D. H. Davis, J. Sacton, and G. Schoro efforts on our behalf. choff. Nucl. Phys. A132, 625 (1969).
THE FOUR-PION DECAY OF THE f° MESON1
W.M.Bugg2 G.T.Condo2 E.L.Hart2 H.O.Cohn R. D. McCulloch3 R. J. Endorf4 C. P. Home4-* M. M. Nussbaum4
A search for the n*it*it~n~ decay of,the/°(1260) has 2. University of Tennessee, Knoxville. been made in 7.87-GeV/c ir*d interactions. We find no 3. Mathematics Division. evidence for this decay. The ratio of this decay mode 4. University of Cincinnati, Cincinnati, Ohio. 0 5. Present address: Department of Physics, Florida State relative to the dipion decay mode of the/ is consistent University, Tallahassee. with zero and less than 3.1% with 90% confidence.
1. Abstract of paper submitted for publication in the Physical Review.
MULTIPION DATA ON THE T REGION1
W.M.Bugg* G.T.Condo2 E.L.Hart2 H.O.Cohn R.D.McCulloch3 M. M. Nussbaum4 C. P. Home45 R. J. Endorf4
From 8-GeV/c n*D interactions we have found that 2 University of Tennessee, Knoxville. one of the two resonances reported HIGHER-MASS BOSONS FROM 7.87-GeV/c rr*d INTERACTIONS' W.M. Bugg2 G. T. Condo2 E.L.Hart2 H. 0. Cohn R. D. McCuiloch3 M. M. Nussbaum4 R. Endorf4 C. P. Home4-5
By employing the 83-in. BNL deuterium bubble 2. University of Tennessee. Knuxville. chamber as a missing mass spectrrmeter, evidence for 3. Mathematics Division. an odd G parity state with a mass in the T region (2.1 4. University of Cincinnati. Cincinnati, Ohio. to 2.4 GeV/c2) is presented. Indications from the 5. Present address: Department of Physics, Florida State University. Tallahassee. individual channels suggest that it has at most a marginal amplitude for decay into ppit.
1- Abstract of published paper. Phys. Rev. 6D, 3047-50 (1972). 3. Nuclear Structure, Reactions, and Radioactivity
3a. Systematics
ORELA NEUTRON CAPTURE AND STELLAR NUCLEOSYNTHESIS1 B..?. Allen2 R. L. Macklin
A NUCLEAR REACTIONS: X(n.y). E = 2.5 1000 keV; measured o„ r Deduced parameters, averages. Enriched targets.
The Electron Linear Accelerator (ORELA) at Oak ment of fast-neutron capture cross sections and the Ridge. Tennessee, is an outstanding facil'ty for neutron application cf these data to reactor physics and physics research. Well planned aid equipped, this nucleosynthesis. *he creation of elen.:nts in stars. accelerator is making a strong impact on the neutron data situation, particularly in the important ki'ovolt 1. Abstract of paper submitted tor publication in Australian journal A tomic Energy. energy region. This article reviews briefly the ORELA 2. Present address: Australian Atomic Energy Commission. research program, and considers in detail tho measure Lucas Heights, Australia.
STATUS REPORT OF THE NUCLEAR DATA PROJECT D J. Horen R. L. Auble F. E. Bertrand Y A. E'lis W. B. Ewbank H. Harmatz M B. Lewis M. J Martin S. Raman M. R. Schmorak D. C. V.est During the calendar year 1972. the Nuclear Data A = 108. F. E. Bertrand Project continued its efforts to update the .4-chain 4 = 112. S. Rarrun and H. J. Kim compilations, improve communications between the .4 = 122. F.E. Bertrand A = 123. R. L. Aubie Project and researchers in the field as well as other A = 125. R. L. Auble compilers of nuclear data, pursue the utilization of A = 127. R. L. Auble computer aids in the compilation process, and pursue A - 129. D. J. Horen intera ions with applied users of nuclear data. These .4 = 163. A. Buyrn1 topics are more thoroughly discussed in the following. A = 1°3. MB. Lewis A - 194, R. L. Auble A = 595..M. J. Martin Nuclear Data Sheets A = 196. M.R. Schmorak A = 197. M.B.Lewis Revised A chains A = 206, K. K. Seth2 A = 212. S. C. Pancholi2 and M. J. Martin A = 70, K. R. .ilvar' and S. Raman 2 A - 91. H. Veiheul and W. B. Kwbank Survey of Nuclear Structure Systematics for A > 229, A - 92. D. C. iCocher1 and D. J. Horen A = 93. D. C Kocher1 Y. A. Ellis and M ft. Schmorak. A = 95. L. R. Medsker1 and D. J. Horen A = 96, L. R. Medsker' 1. Nuclear Information Research Associate (Nir.A). A = 107. F. E. Bertrand and D. J. Horen 2. Consultant.
34 35
Recent Re jrences A. Artna-Cohen (U.S.A.) is presently compiling A = 183. The response to a questionnaire indicated excellent H. Verheul (Netherlands) is presently compilinp A = reception of "Recent References" by the basic nuclear 62. structure community. In view of this, publication three L. K. Peker and B. S. Dzhelepov (U.S.S.R.) are times per year as issues of Nuclear Data Sheets will be presently compiling/4 - 140. continued. The first issue for 1973 will include a listing of nuclear reaction papers tabulated according to specific reactions to demonstrate more clearly the National Science Foundation-Nuclear Information potentialities of the key-word system. Research Associate (N1RA) Program During 1972. the Council of the Division of Nuclear The N1RA Program entered its second year in Physics of the American Physical Society, based upon October 1972 with me addition of 1) postdoctoral the results of a poii of the membership, recommended appointments. This makes a total of 22 NIRA's that nuclear key words be included in Physical Review presently engaged :n mass-chain compilations. The Data C. This has been accepted by the editors of the journal Project is participating in this program in four ways: and will commence in 1973. We have sent letters requesting similar action to the editors of the other 1. Providing reference lists to all NIRA's (and magnetic major nuclear physics journals. tapes containing tables and pret/ams useful in preparing compilations). "Recent References (September 1971-December 2. consultation and/or coauthorship. 19^;>." D. C. West. F. W. Hurley, S. H. Dockery, and S. J. Ball 3. review, 'Recent References (January 1972-April 1972)." D.C. 4. publication. West. F. W. Hurley, S. H. Dockery, and S. J. Ball As of January 1 '> "73, the status was: "Recent References (May 1972-August 1972)." D. C. Mass chains publshed - A = 70, 92, 93, 95,96. 163. West. W. B. Ewbank. F. W. Hurley, and M R. McGinnis Mass chains received and at various stages of review - A = 71. 77. 101. 153. 157, 159, 165, 174, 225. Research Papers, Verbal Presentations, Etc. Services Provided Most members of the Project are actively engaged in experimental or theoretical research, ana writeups of The Data Project routinely provides reference list* to the works are included in this annual report. These the following: amount to 12 published papers and 10 abstracts Table of Isotopes (J. M. Hollander and C.M.I crderer, presented at American Physic£i Society meetings. U.S.A.). magnetic tapes Atomic Mass Adjustment (A. H. Wapstra, Netherlands; Computerization N. B. Gove USA.) Efforts are proceeding to improve the utilization of Nuclear Moments (G. H. Fuller and V. Shirley, USA.) computer techniques in three areas, {a) reference Photonuclear Cross Section Center (E. G. Fuller, U.S.A.) systems, (b) calculational and analysis programs used by National Neutron Cross Section Center (BNL, U.S.A.) compilers, and (c) establishment of a data Pie. A b?sic data format has been adopted. Work is progressing to NIRA's (22 compilers) develop and modify cperational programs which can Non-Project Compilers (4) utilize data prepared in the basic format to perform routine calculations, etc.. as well as produce new data In addition, more than 30 recorded requests for cards for graphics and use for a data file. information from a variety of establishments, including other divisions at ORNL, private industry, U.S. govern Non-Project Mass Chain Compilers ment laboratoiies and agencies, university researchers, foreign scientists, etc., were answered in 1972. Informa S. C. Pancholi (India) spent three months at ORNL to tion requested included selected reference lists as well begin work on compilation of 4 = 138. as specific data. 36
In late 1972. the Data Project offered to proviJe on both U.S. and foreign scientists, This is being done with magnetic tape the Atomic Mass Adjustment by Wap;tra the assistance of N. B. Gove of the Mathematics and Gove to those persons supplying a tape. Fourteen Division. such mass tapes have been sent to requesters, including
EVIDENCE FROM INELASTIC PRDTON SCATTERING FOR A GIANT QUADRUPOLE VIBRATION IN SPHERICAL NUCLEI1 M.B.Lewis F.E.Bertrand
27 54 ,20 209 NUCLEAR REACTIONS. Al. re, Sn. Bi ip.p'), Ex = 6-40 MeV, Ep = 61.7 MeV;
ced giant quadrupo'ic excitation from systematic; of a(Ex, 0).
A systematic study of inelastic proton continuum continuum with properties of a giant quadrupole spectra produced at small angles by bombardment of vibration.
27 S4 ,20 209 A1, Fe, Sn, and Bi v/ith 62-MeV protons 1. Abstract of published paper: NucL Phys. A196, 337 suggests the existence of a collective region in the (1972).
REACTION LIST FOR CHARGED-FARTICLE-INDUCED NUCLEAR REACTIONS. Z = 1 TO Z = 99 (H TO Es), JULY I97I-JUNE 19721 F. K. McGowan W. T. Milner
This reaction list for chargM-particle induced nucle2« involving mesons in the outgoing channel are not reactions has been prepnicd from tb journal literature included. Theoretical papers which treat directly with for the period Ju.y 197! through June 1972. Each the analysis oi nuclear reaction data and results «.r- published experimental paper is listed under the target included in the reaction list. nucleus in the nuclear reaction with a brief statement of the type of data in the paper. The nuclear reaction is 1. Abstract of puSlished paper- SucL Data Table* A'l,
denoted by A{a,'u)B, where Ma > (one nacleon mass). 1-126(1972). There is no restriction on energy. Nuclear reactions
REACTION LIST FOR CHARGED-PARTICLE4NDUCED NUCLEAR REACTIONS. Z = 1 AND 2 (H AND He), MAY 1969-JUNE 1971; Z = 3 TO 99 (Li TO Es), I948-JUNE 1971; COULOMB EXCITATION, 1956-JUNE 1971
F. K. McGowan W. T. Miiner
This reaction list for charged-particle-induced nuclear mesons in the outgoing channel are not included reactions has been prepared from the journal literature Beginning with July 1970, theoretical papers which for the period 1948 through June 1971. Each published treat directly with the analysis of nuclear reaction data experimental paper is listed under the target nucleus in and results are included in the reaction list. the nuclear reaction with a brief statement of the type of data in the paper. The nuclear reaction is denoted by 1. Abstract of paper to be published in Atomic and Nuclear
A(a,b)B, where Ma > (one nucleon mass). There is no Data Reprints, vol. 1 (Academic Press). restriction on energy. Nuclear reactions involving 37
3b. A < 2?
IMPROVED UPPER LIMIT FOR THE ELECTRIC DIPOLE MOMENT OF THE NEUTRON'
W. B. Press P. D. Miller N. F. Ramsey2
The previously desc ibed neutron resonance spec trometer has been modified to improve the determina 1. Ahst-act of paper submitted for publication in the Physical tion of the effect of E X v/c. An improved upper limit Review. 2. Harvard University,Cambridge, Mass. has been obtained for the neutron electric dipole 23 moment i^e/ei < ! .0 X !0~ crn with 80% confidence.
PROGRESS REPORT ON THE EXPERIMENT TO DETECT AN ELECTRICAL DIPOLE MOMENT OF THE NEUTRON
P. D Miller1 W. B. Dress1 P.Perrin2 R. Bouchez2 N. F. Ramsey3 R.Mossbauer4
During the last half of 1972. most of the apparatus programming of the system is commencing with the for the '.'xperiment to detect an electrical dipole new year. moment of the neutron has been assembled. The The measurement of the neutron intensity confirms mechanical assembly of the magnetic resonance spec our earlier estimates that about 60 days of data trometer on its turntable and the assembly of those on acquisition should produce a sensitivity of a smaB the platform furbished by the Institut Laue-Langevin number times 10~2S cm. This compares with the has been completed. present upper limit of 1.0 X I0"i3 cm. This estimate The intensity has been measured to be 6 X I06 assumes that the apparatus is mechanically and mag neutrons/sec The detector uses a 6 Li-loaded glass netically stable enough to take full advantage of the scintillator with fairly standard photomultiplier and fast intensity available. electronic equipment. A PDP-11 computer furnished by the ILL has been 1. On assignment: Institut Laue-Langi-vin, Grenoble. France. 2. Centre D*Etudes Nudeaires de Grenoble. Grenoble. interfaced to a CAM AC crate containing the necessary France. standard and special modules for the data acquisition 3. Harvard University, Cambridge, Mass. system, the latter being furnished by CENG. The 4. Institut Laue-Langevin, Grenoble, France
THE p-p FINAL-STATE INTERACTION IN THE 3HeR. W. Rutkowski2 E. E. Gross
The final-state interaction peak for the reaction 3HtHd,t)2p at 5° lab. 23.5 MeV cm. is analyzed with 1. Abstract of published paper: Pkys. Lett. 356, 151 (1971). the Corn approximation. Using an effective-range wave 2. Oak Ridge Graduate Fellow from the University of Tennessee under appointment from Oak Ridge Associated function for the diproton system, we extract y = 0.360 Universities; present address: VS. Atomic Energy Commission, ± 0.015 fm~' for the Gaussian range parameter Oak Ridge, Tenn. describing the charge distribution in 3He.
CHARGE-ASYMMETRY EFFECTS IN THE REACTION 2H(4 He,3He)3H'
E. E. Gross E.Newman M.B.Greenfield2 R. W. Rutkowski3 W.J. Roberts4 A. Zucker
Differential cross sections for the process 82.1, 64.3, and 49.9 MeV. The measurements were 2H(4He,3He)3H are r*relented for4He beam energies of made to test the Barshay-Temmer theorem, which 38 requires %V and 3He yields to be independently account for the observed deviatiens. symmetric about 90° cm. We find a pronounced deviation from 90° cm. symmetry which is angle- and energy-dependent. A distorted-wave Born-approx- 1. Abstract of published paper: Phys. Rev. CS. 602 (1972). 2. Florida State University. Tallahassee. imatiop analysis assuming the reaction mechanism to be 3. USAEC. Oak Ridge. Tenn. a simple / = 0 nucleon-pickup process can qualitatively 4. Tenr.ecomp. Oak Ridge.Tenn.
SEARCH FOR A 3 He + J He RESONANCE IN 6 Be: ASTROPHYSICAL IMPUCATIONS ML. Halbert D.C.Hensley H.G.Bingham
6 3 3 3 NUCLEAR REACTIONS: Lk He./>. E = 46.3 MeV: measured a(Er d = 5°). Deiuced: no He He resonance in6Be.
Recent measurements of the terrestrial flux of high- used in the focal plane to distinguish tritons from energy neutrinos1 give an uppe- limit approximately deut ons. nine times smaller han the flux expected from the The focal-plane position expected for tritons corre proton-proton cycle in the sun/ One explanation, sponding to the resonance was determined by increasing proposed independently by two groups.3,4 postulates the magnetic field slightly to record the ground-state that in the solar interior the reaction 3He(3He4He)2p and first-excited-state deuterons from the removes most of the 3He ind thereby reduces tiie 6Li(3He^/)"'Be reaction. The resolution of these two amount of 7Be formed from the capture of 3He by peaks was about 30 to 35 keV FWHM for a target of 4 He. This in tum decreases the production of high- about 60 ug/cm2 6Li<98.7% enrichment) on a backing energy neutrinos, since such neutrinos are produced of ~3 Mg/cm2 Formvar. With a targe! having about ten mainly in the 0* i>ecay of 8B formed from the radiative times as much Li. the observed resolution was about 42 capture of protons by 7Be. keV; the resolution for tritons should have been similar. For this explanation to be quantitatively successful, An additional position check was obtained by substi the 3He + 3He reaction must be re.-onant very near tuting a carbon taiget, reducing the magnetic field, and 2 3 2 threshold, with a width of no more than about 20 keV. recording ground-state tritons frr-n the ' C( Hej)' N If the resonance were further above threshold or were reaction. broader, its effects would have been already observed in Figure ' shows the measured triton spectrum from 6 3 A 3 2 two experiment* that measured the reaction down to the L< He/) Be* reacuon .or 5.1 X 10"* C of He * within 80 keV of threshold. Moreover, because of the on the thicker target. The solid angle of the spectro- strong energy dependence of both the cross section graph-deiector combination was 0.93 X \0~* sr. The 6 (due to the Coulomb barrier) a .id the Maxwcllian range of Be excitation energies covered here is about 2 2 2 velocity distribution of the solar 3He, there would be a 0 *o MeV. Tritons from ' C( He./V N are off scale at negligible reduction in the amount of 7Be formed this Held setting. unless the supposed resonance were about 20 keV The expected position of the resonance, near channel above threshold and had a width <10 keV.3-4 2800. is shown by the arrow, and the horizontal bar Such a resonance woiMd correspond to an excited indicates the expected FWHM. No peak is evident in slate in * Be at about 11.5 MeV. The reaction this vicinity. By means of a least-squares peak-fitting 6Li(3He/) 6Be* was selected to search for a state in program, the ^*k area was found to be consistent with this region of excitation. A beam energy of 46.3 MeV zero, with a standard deviation of about 40 counts. This was chosen to avoid possible interference from deu- result did not change if the centroid was allowed to He teron groups originating in target impurities. The beam anywhere in the range 2500 to 3250. The corre was produced by the ORIC. The tritons were observed sponding limit on the cross section is with the Elbek broad-range spectrograph6 at a labora tory angle of 5° in order to obtain adequate energy- (^)c.m<1J^/Sr f°r^.m.=8.4°. resolution. A silicon position-sensitive detector was 39
(*NL-D*C 73-694 •40
• t20 • - • - s> • • • — I, • .r • • '-.is- £ • • • c » • • •>• • • • 1> • • 2 • •-> 80 • in • CVJ • • R 60 c 8 40
20 *
! • i i 2000 2500 3000 3500 4000 4500 5000 CHAMCL NUMBER
Fig. 1. Spectrum of tritons at 5° from bombardment of 6Li with 46-VMeV 3He.
To express this limit in terms of the structure of 6Be, 1. R. Davis. Jr., Bull. Amer. Phys. Soc. 17,527 (!972). we have carried out simplified DWBA calculations very 7 2. J. N. Bahcall and R. K. Uhich. Astrophys. J. 170, 593 similar to those described by Parker et al.. who-studied (1971); Z. Abraham and I. Iben, Jr., Astrophys. J. 170, 157 the same reaction at 25.5 MeV. Parker's calculations are (19711. based on the zero-range approximation reported by Oh 3. W. A. Fowler. Nature 238,24 (1972). et al.* for (3He,6Li) reactions on a number of light 4. V. N. Fetisov and Yu. S. Kopysov. Phys. Lett. 40B, 602 nuclei. In our calculations it was assumed that 75% of (1972). 6 3 9 J0 5. M. R. Dwarafc?nath and H. Winkler,/"*)*. Rev. C4, 1532 the time the Li consists of He + t clusters. The (1971); A. D. Bacher and T. A. Tombiello. unpublished work 6 'esutting spectroscopic factor for the Be* being quoted in the same reference. composed of two 3 He particles is 6. J. B. Ball,/££F Trans. SucL Sci NS-13. 340 (1966). 7. P. D Parker, D. J. Pi^.io M. L. Cobern, and (i. H. Marks. 5(6 Be*) < 0.00036. Yale preprint 3074-283 (1972). 8. 8. K. Oh. C. S. Zaidins. C. D. Zafiratos. and S. I. Hayakawi. Nud. Phys. A178,497 (1972). which is 17 times smaller than the result f-om ref. 7. 9. A. M Young, S. L. Blatt. and R. C. Seyter. Phys. Rer. A 3He + 3He resonance this -*eak V, inadequate to Let:. 25,1764(1970). a.count for the apparent absence of hig>-energy neu- 10. F. VtntLra. C. C*. Chang, and W. H. Meyerhof. Nucl. Phys. trir>o» from the sun.4 "7 A173, I (1971).
ISOSPIN CONSERVATION IN COMPLICATED REACTIONS C. D. Goodman D. C. Hensley A. van der Woude S. Raman
NUCLFAR REACTIONS: ' W*He)7Bc. MB(
a(9). oj(0)/<72(0> compared with isospin prediction.
As a continuation of our study of the excitation of small that we were unable to make useful measure isospin multiplets in nuclear reactions, we turned our ments. attention to reactions that appeared to have reasonable We have studied the reactions '' B(J.6He)7Be and cross sections, in contrast to the reactions that we 1' B(J,ft Li*)7 Li (where *Li* stands for the 3.59-MeV T reported last year, for which the cross sections were so = 1 state in 6Li). We have also studied the comple- 40 mentary pair of reactions: '' B(J.7Lii6Li* and difference in final energies. This correction would alter 1' B(
ORNL-WK 72-»23C8
T0 STRETCHER GATES »ULSE ! STITCHER ! J . L GATE STHOB2 EVENT ! A0C FORWARD —T T **• CONTROLLER DETECTOR j STROBES j
TC SCAL.R TTTT "FORWARD" • 234 TO PULSE STRETCHERS
•JLSE 4 LpSTRETCHE R ! Mii]—r CRCM C!G-TA_ GATE STROBE 2 D SCRIM- LATCH iMATCRS GATE PROM A0C TO L ATCH SIT 2 ^CONTROLLER
TO SCA'-ER CCINCJENCES" RCCOH DETECTOR
TO LATCH 8IT4 AT SCATTERING IN COUNTING CHAMBER ROOM
Fig-1. Electronics arrangement for data acquisition in the '' B(
oo
i en 8
CB Si o
o> «» OB i- ^ks •c J t- -J «T X «
e .2 s c e « S * e 5
1•"• ' o >• *
s-Jf-r * <1 # g-i c I i ri ;0M M& m 42
For each coincidence we recorded E and A£" for both -•**- Mr*, i '•* counters in a list mode. V. 1 The l!B(d,6He)7Be and ' 'B(t/,7Be)6He reactions 1 could be identified in the singles array, but the ~ 0.6 7 6
*_ o> •-- - "Bit/. Li) Li* and, to some extent, the X 1 6 7 to » ' B(rf, Li*) Li reactions could not be observed clearly ' I 1 < » in singles due to a continuum background from particle 1 0.5 l . breakup of unbound 6Li and 7Li states. Thus we i studied both singles and coincidence data. b 0-4 For each ai.gle of the forward counter, it was necessary to collect data for several settings of the A 1 1 1 1 .. . 1 recoil angle because the reactions do not have identical 0 10 20 30 40 50 kinematics; in particular the recoil angle for mass 7 LAB. ANGLE (DEGREES) forward differs significantly from the recoil angle for mass 6 forward. To save time, it was necessary to run at compromise recoil angles for some runs, at one setting Fit,. 3. The observed ratio of cross sections corrected for coincidence efficiency. to pick up the mass 6 recoils and at another *o pick up the mass 7 recoils. We measured the coincidence efficiency curve for making corrections to the runs for the angular acceptance of the recoil counter, so no which the recoil angle was set at a compromise value correction was required within the accuracy of the An additional complication occurs because the 6Li* experiment. deexcites by gamma emission in flight. This produces a The measured ratios are shown in Fig. 3. They are in very small uncertainty in the forward angle cone and good agreement with the predicted ratio. produces a significant spread in the recoil angle cone. In our case the maximum spread in angle was smaller than I. Robert K. Adair,toys. Rev. 87. 1041 (1952).
NAT ! ABSOLUTE NEUTRON YIELDS FROM THICK-TARGET C(a,n) J. K. Bair
Recent measurements of the neutron yield resulting neutrons for alpha-particle energies between 2 and 9 from the alpha-particle bombardment of carbon have MeV. disclosed an error in the data reported in the literature. 1. Abstract of paper submitted for publication in Nuclear New values are given for the thick-target yield of Science and Engineering, Technical Note.
TOTAL NEUTRON YIELD FROM THE REACTIONS ' 3C(a,nf 60 AND '7J 80(a,w)20' ' Ne1 J. K. Bair F. X. Haas2
Compound states of high excitation in ,70 and for ' 80 •» a. For astrophysical purposes these strength 2,'22Ne have been observe!, with good resolution, in functions are used to extrapolate the average cross the total neutron yield from the reactions ,3C(or,n)160 sections to lower energies. and ,7',80(a,/i)20-2,Ne. Bombarding alpha-particle energies were approximately from 1 to 5 MeV. Analysis of the area under the excitation curves gives alpha- 1. Abstract of paper submitted for publication in the Physical
particle strength functions of Sa = 0.029 ± 0.030 for Review. 13C + a, 0.030 ± 0.023 for * 70 + a, and 0.022 ± 0.010 2. Mound Laboratory, Miamlsburg, Ohio. 43
THE LEVEL STRUCTURE OF ' 70 FROM NEUTRON TOTAL CROSS SECTIONS J. L. Fowler C H. Johnson R. M. Fee/el2
The neutron total cross section of oxygen is measured 5.215 and 7.573 MeV; rhese levels have rr<0.l keV. in the energy regions from 0.6 to 0.9. 1.12 to 1.16, and The previously report.^ narrow 3/2* le\cl at 7.6^4 i.39 to 4.33 MeV. More than half of this region is MeV does noi exist. Many of the resists are based >n a surveyed with energy resolution and energy steps of multilevel /^-matrix analysis: this is also extended to the about 2.5 keV. On the basis of these data and published I60(«,«) and ,3C(a,w) cross sections for supplementary published data on the (n.») angular energies corresponding to ' 70 excitation up to 9.5 distributions and the 13C(a,n* re.-u.uon. the l70 level MeV. This extension shows that there are two levels energies in million electron vi lt« and in parentheses. Jn rather than only one near 8.47 MeV and that the
values and center-of-mass to'ai widths. Tr = Tn + Ta in 9.42-MeV level has J"= 3/2" Other assignments are thousand election volts, ^re 5.696 (7/2~. 3.4). 5.731 confirmed. The most accurate excitation energies below (not l/2\ <1.0). 5.86 7 (3/2*. 6.6). 5.9: J (1/2". 32). 9.5 MeV are reviewed from the literature, and the 6.354 (l/2\ 124), 6.860 (rot 1/2*. K-MATR1X ANALYSIS WITH A DIFFUSE-EDGE POTENTIAL FOR ' 60 + // DA f A: C. H. Johnso I J. L. Fowler R. M. Feezel2
An K-matrix analysis of the leO(n,n) and l60(n,a) are about as expected from the shell model. cross sections below 5.8 MeV shows that the off- resonance cross sections are described by scattering in a i. Abstract of published paper: pp. 2-3 in Contributions - potential, that the boundary radius must be inside the Conference on Nuclear Structure Study with Neutrons (Buda tail of this potential, that the total of the spectroscopic pest, Hungary, July-August 1972), Central Research institute for Physics, Budapest, 1972. factors for five observed d3/2 fragments is unity, and 2. Urdergraduate student from Auburn University in ORNL that the spectroscopic factors for other partial waves Cooperative Educational Program.
A UNIFIED K-MATRIX-PLUS POTENTIAL ANALYSIS FOR * 60 + n CROSS SECTIONS' C. H.Johnson
A multilevel two-channel /{-matrix analysis is made must be chosen carefully inside the tail of the potential for both the neutron total and angle-integrated (n,a) in order to subtract the ld3/2 state and in order to cross sections of l60 for 0- to 5.8-MeV neutrons. place the unbound 2p and 1/ states at energies Off-resonant phase shifts are described by scattering in consistent with the observed p- and /-wave fragments. a real Saxon-Woods local potential with a spin-orbit Spectroscopic factors are deduced for 26 levels in ' 70 term and a parity dependence for the well depths The between 4.5 and 9.5 MeV, and the sums of these factors well parameters are chosen to bind the \dsj2 and 2s,/2 are 1% for/* = 1/2*; 5% for 1/2"; 12% for 3/2';99% levels at the energies of the lowest two states in ,70 tor 3/2*: 0.1% for 5/2*; 1% for 5/2": and 147 for and the quasi-bound l
NEUTRON CAPTURE IN FLUORINE BELOW 1503 keV R. L. Macklin R. R. Winters2 I ' " i l9 | NUCLEAR REACTION: H/i.7). £ = 2.5 5000 keV; mea>ired 7„ Deduced levels. I\ sriy j
Neutron time-of-flight radiative capture data taken at anlat 173.5 keV, gVn = 0.35 ±0.10 eV. The increase the Oak Ridge Electron Linear Accelerator have been of nearly an order of magnitude in radiative width with analyzed for single-level resonance parameters. Ten increasing energy up to 600 keV is notable. Twelve resonances were found, with parameters as indicated, large resonances between 1600 and 5000 keV were m»» listing E0 (keV), J value assumed, and p^ (ev) ir. ordri. analyzed for capture because of detector sensitivity to 27.07 (2) i .4 ± 0.3, 48.7 (1) i .7 ± 0.4,97.0 (1) ^6.0 ± the inelastic scattering channels which oper in that 1.8, 269 (2) 3.5 ± 0.8, 270 (1) <4.4, 386 (1) >7 ± 2, energy region. 490.5 (0) >10 ± 3, 59i(2> >1 ± 2, 1460(l)>i i ±3. Vi!>»ps of total width were also found for these resources. 1 -HO resons'-»*ec are very narrow, and their 1. Abstract of paper submitted for publication in Physical capture yields estimates of gVn. At 43.5 keV, gVn = Review C. 0.086 ± 0.02 eV if J> 1 or r„ = 0.42 ± 0.1 eV if/ = 0: 2. Present address: Der'son University, Granville, Ohio.
TOTAL NEUTRON YIELDS FROM THE PROTON BOMBARDMENT OF ' 7l 80' J. K. faair
The ,70(p,/i)I7F reaction has been observed for the neutron cross sections are also given for the reaction first time in the energy region from threshold to 5 MeV. 18 Oip.n)18 F from threshold to 4 MeV. Total neutron production cross sections measured with good resolution are given. The reaction threshold is 1. Abstract of paper submitted for publication in the Physical determined to be 3743 ± 6 keV. High-resolution iota1 Review.
THE ENERGY LEVELS OF 2' Na1 F. X. Haas2 C. H. Johnson J. K. Bair
20 21 NUCLEAR REACTIONS: Ne(p,-y) Na, E = 0.98 to 2.2 MeV; measured Ey I T. enriched targets: deduced 2I Na levels, Q value. 20Ne(J,n)21 Na, £ = 3.6 to 6 MeV. Measured absolute differential cross sections, enriched targets; deduced levels and spectroscopic factors.
The energy levels of 2' Na are investigated with the 4453 ± 12 keV and 5009 ± 12 keV for incident 20Ne(>vy)21Na and 20Ne(tf,w)2! Na reactions. From deuteron energies of 3.60, 4.88. 5.57, and 5.94 MeV. the gamma-ray energy measuiements the excitation The unbound 4.12-MeV state has a stripping pattern energies in 2,Na are found to be 331 ± 3, 1717 ± 3, consistent with / = 1. Its laboratory width from the 2426 ± 2, 2800 ± 4, 3545 ± 3, 3679 ± 4, 3867 ± 4, gamma-ray work is 125 kcV. The combined evidence of 4117 ± 11, and 4297 ± 4 KeV. A 20Ne(/?.7)2,Na Q the branching ratios, reduced widths, and stripping value of 2434 ± 2 keV is deduced. Branching ratios are patterns shows that the 4.12-keV level is the mirror of determined for the upper five levels. Direct nonresonant the 4.73-MeV level in 2,Ne. capture is observed to the 0.33- and 2.43-MeV states. 20 2, Angular distributions for the Ne(tf,«) Na reaction 1. Abstract of published paper: Nucl. Phys. A193.65 (1972). are presented for all of these levels, and for levels at 2. Mound Laboratory, M:snisburg, Ohio. 45
HEAVY-ION NEUTRON YIELDS J. K. Bair W. B. br-ss C.H.Johnson P. H. Stclson
1 j NAT l6 ,l, , l l6 ,r - 15 to 55 Mev:
j Nl'CLFAR Rl ACTIONS: Cl - Ojr/i). *- *: K ,8 63 65 ,IS S8 60 6l 62S) ,ls 64,66 #>7 6 70 6 (U«). h=35 U 55 j - Cu(" 0 vw) - - - Ni(" O v«) - "- 2n)' . MeV. Measured total neutron yields. i _ —.
Previously reported ' total neutron yields resulting the yield Is plotted as o'v, where a is the usual cross from the it:50 bonibaiunien; of thin targets have section and ^ ib the average number of neutrons been completed. Final results are now available for produced .jer neution-producing event, bnergies are the NATC, 16 I80, and 63'65Cu. Figures 1-4 show these data. Since at sufficiently high energies more than one OHNL-DWC 72-13927 neutron can be produced per neutron-producing event.
: i i
I • | f
10' 10 12 16 20 24 28 32 36 40 44 48 52 56 12 16 20 24 28 i2 36 40 44 48 52
fL4B 'MeV) £LAb (MeV)
Fig. 1. These data were obtained by bombarding a layer of Fig. 2. These data were obtained by bombarding tantalum carbon evaporated onto a platinum blank. Target thickness was blanks which had been anodtzed in either natural water or wate approximately 160 kcV at 30 McV. enriched to 97.2% l80. Target thickness was approximately ISO keV at 50 MeV. 46
64.66.67.08.70 !6,18 bombarding 'aboratory energies corrected for target Zn( 0x/l)data thickness effects. In addition to the error bars shown, we estimate an uncertainty of ±4, 17, and ±4% (one standard devia tion) for the carbon, oxygen and copper targets 1. W. B. Dress, J. K. 3air, C. H. Johnson, and P. H. Stetson. Bull. Amer. Phys. Sot. 17, 530 (1972). Also J. K. Bajr. W. B. respectively. Dress, C. H. Johnson, C. M. Jones, and P. H. Stelson. Program Final corrections have >ci to be made to and Abstracts, Physics Division Information Meeting (1971), the S 8,6 0,6 l.6 2,6 4^10,1^,^ data am, {0 me abstract 16(c).
ORNL-OWG 7.-14005 ORNL-DWG Tc- 14006 4 1 1 » c T • i Q3 4- u **0 Rf AM ! • ~f *0 BEAM • X 1- » 5 _ 0 * 1 • o M i o "Cu «, — i 1 Cu o 2
10 • > •? Kl
5 5 E
1 b J 1 i * 2 T 10'
K)'
tr •j 1
2 10 34 38 42 46 50 54 i > *-LAB(MeV)
0 •n Fig. 4. These data were taken using the same targets as used 34 38 42 46 50 54 to obtain the data of Fig. 3. *WMeV)
Fig. 3. These data were obtained by bombarding a thin layer of enriched metallic copper evaporated on platinum blanks. Target thickness was approximately 350 keV at 50 MeV. 47
TOTAL NEUTRON YIELD FROM THE (aji) REACTION ON :' :: Ne» F. X. Haas- J. K. Bair
Compound states of high excitation in 2s,2f,Mghave astrophysical purposes, these strength functions are been observed, with good resolution, in the total used to extrapolate the averaged cross sections to lower neutron yield from alpha-particle bombardment of energies. 21 -22Ne. Bombarding energies were from I to 5 MeV. Analysis of the areas under the yield vurves ^ives f 1. Abstract of paper submitted for publication in the Physical alpha-particle strength functions o Sa = 0.031 ± 0.02 i Review. 2 22 for ' Ne + a and SQ = 0.026 ±0.012 for Ne + a. For 2. Mound Laboratory. Miamisburg. Ohio.
(3Heji) REACTION AT 25 MeV' M. B. Greenfield2 C. R. Bingham3 E. Newman M. J. Saltmarsh
The (3He/i) reaction has been studied on targets of cases, generally reproduced by the calculations. ForO* I2 27 28 8 n C, A1, Si. ind s -«>o.62Ni at an incident energy targets the J of many final states coald be assigned. of 25 MeV. The observed resolution of the neutron Comparison of experimental with theoretical relative time-of-flight spectrometer used in this work was about magnitudes permitted assignment of dominant shell- 1%. Differential cross sections were obtained for the model configurations. To first approximation the rela resolvable final states over the angular range of 0 to 40° tive transition strengths to final states in 140,30S, and (L). The angular distributions were compared with the 60Zn were consistent with the assumption of two predictions of a simple one-step two-nucleon-transfer pai tides coupled to an effectively "closed core." model. In this formalism the diprotcn stripped from 3He is transferred to the target, retaining its lS 0 1. Abstract of published paper: Phys. Rev. C6, 1756 (1972). relative motion. The shapes of the angular distributions 2. Present address: Florida State University. Tallahassee. were unique for a given / transfer and were, in most 3. University of Tennessee, Knoxvilie.
3c. 22NEUTRON TOTAL CROSS SECTIONS FOR KILOVOLT NEUTRON ENERGIES W. M. Good J. A. Harvey
3 6 NUCLEAR REACTIONS: 21 nuclides:measured onT,En = 10 -10 eV;enriched targets.
Neutron transmission studies have continued of nu Very little information is generally available on total clides whose neutron resonant spacings are of the order cross sections 29,30Si, 33>34S.' Hence the resonant of a kilovolt. The erergy range of study generally is energies observed for these nuclides in the present about 1 to 400 keV, and separated isotopes are measurements are listed in Table I. An explicit repre employed. sentation of the results as obtained for 34S is given in Continuing as of one year ago,29-30Si,4042-43-44Ca, Fig. I. 47,49 54.57 204 .206,20 7,208p ^ j _ Tj Fei af)d b p yar On account of ORELA's high resolution, many levels ious stages of study, and to these have been added are expected to be observed in present transmission
33 34 measurements which were unobservable before, except 90,91 .92.94,96£r ' S 48
OtdL-OWG 73-186* 40
12.99 bcrn/atom
"^kVpMMMn, **iArtn*i4M0*A*(
106 NEUTRON ENERGY (eV)
Fig.1. Thetotal cro a section of 34
Table 1. Listing of resonances observed possibly for the earlier capture measurements (capture in the target nuclides 2v,30Si, 3334s. 54S7Fe can be a bi more sensitive to narrow resonances than transmission). In Table 1 are listed the resonances In5451 Fe. * indicata new. ** in kitodectron volts previously S4S7 observed but different energy assignments observed in Fe in the present measuremei'.ts. The most recent data for comparison are Hockenbury et al.2 "s. 30Si 3JS ,4S $4Fe "Fe and Rohr and Muller.3 15.29 2.235 13.44 30.37 7.813 1.628 No listing is provided of the resonance levels observed 38.79 498 17.63 118.5 9.476 3.973 90 s 4 90 159.6 63.43 23.93 231.3 11.169* 4.746 in - * Zr. However, a scan of the raw Zr transmis »84.5 1858 30.37 301.3 14.455 6.276 sion data indicates many small resonances not resolved 336.7 235.1 52.17 317.6 30.628* 7.215 5 385.4 3027 53.54 357.2 39053* 7.934 in the previous measurements. In the energy interval 553.2 413.5 59.06 362.5 51.533* 12.847 from 3 to 70 keV. on which only 13 resonances were 650.3 644.4 77.84 396.6 52.1 13.286* 747.6 81.46 435.7 55 341* 13.966 then reported, there now appear ai least 35. 849.9 87.50 4640 72.089 18.224 101.2 470.8 98.820 21.049* Study and analysis of these nuclides are continuing. 151.6 510.2 2! 284 168.7 642.5 28.624 178.3 800.6 29.6»C 197.3 814.5 37.078" 1. CINDA72,vol. 1, IAEA. Vienna (1972). 221.7 839.5 39.361* 228.8 851.0 41643 2- R. W. Hockenbury. Z. M. Bartolome, J. R. Tatarczuk, 238.4 893.7 41.958* W. R. Moyer, and R. C. Block, Phys. Rev. 178, 1746 (1969). 935.8 47.164 3. G. Rohr and K.-N. Muller, Z. Phys. 227, I (1969). 1019 49 917* 4. Measurements on 90,9' Zr were made in collaboration with 1089 52.644* 1125 56-539 Mr. Richard E. Tooh^y, Physics Division. Argonne National 1193 61.786 Laboratory. Samples were courtesy of Dr. A. H. Smith, 1313 65.416* Argonne National Laboratoy. 1352 74.331* 5. V.'. M. Good and H. Kim, Jftys. Rev. 165, 1329 (1968). 1391 77.528 1450 83-812* 88.089* 89.816* 91.672* 93912* 101.695** 109.866** 118.832**
keV NEUTRON TOTAL CROSS SECTION MEASUREMENTS AT ORELA • J. A. Harvey
54 57 NUCLEAR REACTIONS: Fe, Fe, Fe onT;En = 10-1000 keV; Fe filters for minima. Enriched targets.
Neutron total cross sections are measured at ORELA samples of iron 4, 6, 12, and 20 in. thick to obtain using samples as small as a few square millimeters and accurate values of the cross-section minima. Enriched flight paths from 18 to 200 m, with energy resolutions 54Fe and 57Fe samples have been measured to deter (AE/E) from 1/300 for measurements below —10 keV mine their contributions to the windows in natural iron. to ~ 1/2500 up to 200 keV and y/E (in MeV)/1000 above 1 MeV. A new efficient neutron detector using NE 110 has been developed for keV measurements 1. Abstract of invited paper published in Proceedings of ANS Topical Meeting on New Developments in Reactor Physics and whose efficiency is ~30% for 10-keV neutrons, rising to Shielding Calculations. Kiamesha Lake. New York, September 90% for 50-keV neutrons. Transmission measurements 12 15. 1972, USAEC CONF-720901. Book 2, pp. 1075-86 using iron-filtered neutron beams have been made upon (1972). 50
THE *°B(l60//).l°B(' *0,a), AND ' 2C(' *OA) REACTIONS J. L. C. Ford, Jr. J. Gomez del Campo1 S. T. Thornton2 R. L. Robinson P H. Stelson
NUCLEAR REACTIONS: ,0B(16O^/), ,0B(160.Q). l2G*0.a):£ = 40-46 MeV, measured o<£> at 7°. 22Na. 24Mg dediced levels. Enriched target.
The observation of sharp states at high excitation the fact that light-ion work has indicated that there are energies in 24Mg by means of the ' 2C(! 6Oxr) reaction3 at least 50 states between 13 and 14 MeV in excitation has created a great deal of interest in such reactions. energy. At this energy and angle the most prominent The use of position-sensitive proportional detectors cr. features cf the spectrum are the *erv sircr.g states near the focal plane of the Enge spiii-poie spectrograph 12 MeV. The extensive excitation functions of the which is located at the tandem accelerator provides a MIT-Brookhaven group show that there is a strong technique for observing states over a wide energy range maximum in the yield curve near this energy for these with good resolution and is, therefore, well suited for states.8 such studies. Our counter is a 60-cm-long single-wire gas The energy resolution for this spectrum is about 50 proportional detector of the Borkowski-Kopp de 4-6 keV. and the doublet at 16.55 and 16.59 MeV is not sign which derives the position in!"om:ation from separated. However, if the magnetic field is changed in the rise time of the pulses from the two ends of a order to shift the spectrum along the focal plane so that high-resistance wire anode. The construction of the the radii of curvature of the particles within the field detector is shown in Fig. 1. are increased, then the resolution improves sufficiently The alpha-particle soectrum measured with this to separate these states, as is shown in Fig. 3. In counter from the I2C(,60A) reaction at an incident addition, other peaks, such as that corresponding to the energy of 46 MeV and a laboratory angle of 7° is 15.15-MeV state, also appear to have a complex displayed in Fig. 2. The target was an approximately structure. 7-^g/cm2-thick ' 2C foil. The states observed at 14.14, 16.3, 16.55, and 16.8 MeV are those which were most Most of the strong states observed in the ' 2C(' 60,a) strongly excited in the work of Middle ton et al.3 Those reaction were also seen by means cf the 10B(,6O//) states at 4.12, 8.12, and 13.2 MeV are the 4+, 6*, and reaction, which also leads to 24Mg as the final nucleus. 8* members of the ground-state rotational band.7 The However, the yield for the majority of the levels was selectivity of 'his heavy-ion reaction can be noted by down by a factor of about 100.
OHNL-OWG 72-9247 ^O.005-in.-diom NICHROME , ' GRID WIRES
INCHES
Fig. 1. Assembly drawings of the 60-cm-long proportional df lector. Reports previously issued in this section are as follows: ORNL-2718 Period Ending March 10. 1959 ORNL-2910 Period Ending February 10. 1960 ORNL-3085 Period Ending February 10, 1961 ORNL-3268 Period Ending February 10. 1962 ORNL-3425 Period Ending January 31, 1963 ORNL-35S2 Period Ending January 31. 1964 ORNL-3778 Period Ending December 31. 1964 ORNL-3924 Period Ending Decem-^er 31, 1965 ORNL-4082 Period Ending December 31, 1966 ORNL4230 Period Ending December 31, 1967 ORNL-4395 Period Ending December 31, 1968 ORNL-4513 Period Ending December 31, 1969 ORNL-4659 Period Ending December 31, 1970 ORNL-4743 Period Ending December 31, 1971 EXCITATION ENERGY (MEV) OtNL-DVMC 72-549/
12C(1 SO. «4HE)24MC
LM. MM1' MVI « s to K>
% 5.2 3 o /I
^ IL -• - " ' Jo1 ' ' 'icV ' ' 'titi "'366'" &' ' ' '306' ' ' Hfc' ' ' V Mlfla BO B ttf—lioroif CHANNEL NUMBER
Fig. 2. The alpha-particle spectrum from the 'I *C(2/VI' °0/>6 ) reaction with the magnetic field set to cover the energy region from the doublet at 4.12 to 4.23 MeV up to 17 MeV in excitation energy in 2'"Mg4 . The laboratory angle and bombarding energy were 7° and 46 MeV respectively. 52
£ £
I
> »
I
! c i
9
o
Cb
13NNUH0 U3d S1N003 MW99 < RNLOWQ, 72 12092*
lOB(!60.UHn:>?NR
IM. PCMt MVI • m.tO im. war wn;.' . »•
1 1 •••&•• -tfe • • •,& •• &' •'&'•" sfo" * *to" ' MOB'" \F%. 4. TIHS alpha-particle spectrum from the B(' 0/x) reaction. The laboratory angle and bombarding energy were 7° and 44 MeV respectively. 54
The competing ' ° B(' °Oxi) reaction has a larger yield and icads to 22Na. an odd-odd nucleus with a rota tional-like level structure. The levels observed in this nucleus at an incident energy of 44 MeV and an angle of 7° are shown in Fig. 4. The target was a self-support ing enriched ' °B foil with a thickness of approximately 17 jig/cm2, resulting in an energy resolution of about 120 keV. Among the states populated are the 3*. 4*. 5*, and 6* members of the ground-state rotational band at 0, 0.89, 1.54, and 3.72 MeV respectively. An investigation of 22Na by means of the 12C(,4N,a) reaction has suggested that the 7* member of the band may be the state at 4.520 MeV.9 If the 7* state is the one observed here near 4.5 MeV, then the intensities of the first five members of the band are in reasonable agreement with the 2/+ 1 intensity rule. The members of the lowest lying 7* = 1 band have been identified at 0.66, 1.95, and 4.07 MeV. These peaks should occur at approximately channels 865,785,and670 respectively. The possible appearance of the 1.95- and 4.07-MeV states in the ,0B(l60,a) reaction is in contrast to the I2C(l4N,ft) reaction, in which these states were not populated. States in 22Na have been reported in the literature up to about 10 MeV in excitation energy. However, in the present reaction we continue to see 40 41 42 43 44 45
strong structure in the energy spectrum that corre *XAB WeV) sponds to excited states up to at least 18 MeV and that tracks with angle as it should to be in 22Na. Fig. 5. Excitation functions measured at 7° foe the members of ti"ie ground-state rotational band, and the strongly popuhted The excitation functions for members of the ground- levels at 7.4S and 9.9 MeV. state rotational band, as well as the strong states at 7.45 and 9.9 MeV, are plotted in Fig. 5. In the energy interval from 40 to 46 MeV there appear to be no dramatic changes in the cross sections. In contrast, the 5. C. J. Borkowski and M. K. Kopp, IEEE Trans. Nucl. Set excitatOPTICAL-MODEL FAMILY AMBIGUITY RESOLVED FOR HELION ELASTIC SCATTERING FROM ""Ni1 C. B.Fulmer J.C.Hafele2
NUCLEAR REACTIONS: 6°"NH/;./r>0 . E = 296. 35-1.49.7.59.8. 71.1 MeV: optical-model analysis, deduced potentials. Enriched target.
3 Optical-model fits with successive fixed values of real 130 MeV is JR - 330 MeV fm for each data set. and 3 well depth V to five angular distributions for JR changes by ~ 100 MeV fm for successive families. 60 60 3 Ni(A./j) Ni which include data to angles >110° for The unambiguous value of JR ~ 330 MeV fm for the projectile energies between 29.6 and 7i.i MeV yield x2 higher energy data sets and the near independence of vs V plots with a deep nvnimum at V ~ 130 MeV for JR on energy implies a similar unique value and each data set. For the lower energy data sets, other corresponding unique family for the lower energy data minima (parameter families) are observed at intervals sets. This value of 330 MeV fm3 is somewhat lower above and below this vaiue. but the higher energy data than values of J^ > 400 MeV fm3 suggested by earlier sets (59.8 and 71.1 MeV) show only one unique family studies. near V = 130 MeV. The absence of the family ambiguity for the higher energy data sets demonstrates the importance of both large-angle and high-energy data 1. Abstract of paper to be published in Physical Review C. for the removal of optical-potential ambiguities. The 2. Research Department, Caterpillar Tractor Co.. Peoria, III. normalized volume integral of the real potential at V ~ 61602.
ENERGY DEPENDENCE OF THE OPTICAL MODEL FOR HELION SCATTERING FROM 60Ni* C. B.Fulmer J.C.Hafele2 C.C.Foster3
NUCLEAR REACTIONS: 60Ni(A,/i). E = 29.6. 35.1, 49.7, 59.8, 71.1 MeV; optical-model analysis, deduced potentials and energy dependence. Enriched target.
An optical-model analysis of measured angular dis tory data were found to be in better agreement with the tributions for 6ONi(7i,/060Ni with five different helion predictions of the above-listed family with V = 126 energies (29.6, 35.1, 49.7, 59.8, and 71.1 MeV) MeV. Slightly improved fits to the five data sets were produced satisfactory fits to ail five of the data sets obtained in a sea.ch with the real and imaginary well with an optical potential having all parameters com depths dependent on helion energy and with Die rest of 2 f mon. This energy-independent potential gave a x the parameter? common. In this case, V and V. D were minimum with V= \26 MeV.r^ =rs= 1.12 fm. a^ =as found to have a weak but approximately linear depend
= 0.84 fm, WD = 20.4 MeV, r, = 1.26 fm, at = 0.84 fm, ence on helioii energy E, with V = 133.9 - 0.1 AE MeV and Vs - 2.85 MeV. Another parameter family with V- and WD = 22 A - 0.04E MeV. 170 MeV also gave an equally good minimum in x2- These two parameter families were used to predict 1. Abstract of paper to be published in Physical Review C. 2. Research Department. Caterpillar Tractor Co., Peoria, 111. scattering cross sections at 180° over the helion energy 61602. range from 21 to 32 MeV, and corresponding labora 3. University of Missouri. St. Louis 63130.
SPIN-ORBIT AND TARGET-SPIN EFFECTS IN HELION ELASTIC SCATTERING1 C. B.Fulmer J.C.Hafele2
The well depth of the spin-orbit term for the by performing parameter searches for elastic scattering r helion-nucteus optical-model potential was determined data at successive fixed values o Vs. Resulting plots of Vll
EVIDENCE FROM INELASTIC PROTON SCATTERING FOR A GIANT QLADRL POLE VIBRATION IN SPHERICAL NUCLEI M. B U»t> and I . I. Bertram! 36 Abstract of published paper: Xuit Ptm. AI96. 337 < 197"!>.
REACTION LIST FOR CHARGED-PART1CLE-1NDUCED M CLEAR REACTIONS. 7 = I TO 7 = 99 (H TO Es>. JULY 1971 -JUNE 1972 I. K. Mctiowan an«? W. T. Milner 36 Abstract of published paper: \udcar Data TaNes A11.1 126 M 972 >.
REACTION LIST FOR CHARGED-PARTICLE-INDCCED NUCLEAR REACTIONS. Z = I AND 2 (H AND He). MAY 1969-JUNE I97I:Z = 3 TO 99 (Li TO Es). 1948-JUNE 1971; COULOMB EXCITATION. 1956-JUNE 1971 f. K. McGowan and W. T. Milner 36 Abstract of paper to be published in Atomic and Muclear Data Reprints. Vol. I < Academic Press). ib. A<22
IMPROVED UPPER LIMIT FOR THE ELECTRO DIPOLE MOMENT OF THE NEUTRON W. B. Dress. P. D. Miller, and N. F. Ramsey 37 Abstract of paper submitted for publication in the Physical Review.
PROGRESS REPORT ON THE EXPERIMENT TO DETECT AN ELECTRICAL DIPOLE MOMENT OF THE NEUTRON P. D. Miller. W. B. Dress, P. Perrin. R. Bouchez, N. F. Ramsey, and R. Mossbauer 37 The neutron intensity from the reactor at Institut Laue-Langevin will allow a sensitivity of 10" 5 cm as compared with the present upper limit of 1.0 X I0~23 cm.
THEp-p FINAL-STATE INTERACTION IN THE 3He(
CHARGE-ASYMMETRY EFFECTS IN THE REACTION 2H(4He,3He)3H E. E. Gross, E. Newman, M. B. Greenfield, R. W. Rutkowski, W. J. Roberts, and A. Zucker 37 Abstract of published paper: Phys. Rev. C5,602 (1972).
SEARCH FOR A 3He + 3He RESONANCE IN 6Be; ASTROPHYS1CAL IMPLICATIONS M. L. Halbert, D. C. Hensley, and H. G. Bingham 38 The reaction Li( He,/)6 Be* shows no evidence for a He + He resonance just above threshold. Therefore, some other solution to the solar neutrino problem must be sought.
ISOSPIN CONSERVATION IN COMPLICATED REACTIONS C. D. Goodman, D. C. Hensley, A. van der Woude, and S. Raman 39
6 7 6 7 The reactions '' B + d -* He + Be or Li* + Li have been studied and the ratio o6(0)(o^0) has been compared with a prediction based on isospin symmetry.
ABSOLUTE NEUTRON YIELDS FROM THICK-TARGET NATC(«,#r) J. K. Bair 42 Abstract of paper submitted for publication in Nuclear Science and Engineering, Technical Note.
TOTAL NEUTRON YIELD FROM THE REACTIONS ' 3C(a,»i)160 AND '7'' 8O(a,#i)20'2INe J. K. Bair and F. X. Haas 42 Abstract of paper submitted for publication in the Physical Review.
THE LEVEL STRUCTURE OF ' 70 FROM NEUTRON TOTAL CROSS SECTIONS J. L. Fowler, C. H, Johnson, and R. M. Feezel 43 Abstract of paper submitted for publication in the Physical Review. 56
X* V vs y^ snow consistent minima for the 13 data sets MeV greater (3.0 to 4.0 MeV). This difference in the 60 used. Eia^tic angular distributions studied were for Nt best-fit values of Vs is consistent over a wide range of at four energies bevween 35 ;«nd 71 MeV and for three target mass and o\ scattering energy .nd suggests the fioups of neighboring ?ven- and odd-mass targets at presence of a detectable target-spin interaction in helion
2 t 1r\ betweep 2.0 and 3.0 MeV. while the plots 2. Research Department. Caterpillar Tractor Co.. Peoria. 111. ioi ali the odd-mass (/ * 0) targets have minima about 1 61602.
6 3.65 Cu(n.w'7) REACTIONS
G. G. SLughter G. L. Morgarsiirrj - J. K. Dickens*
63 65 63 6S I NUCLEAR REACTIONS: - Cuut./i-,); E = 0.5 MeV-10 MeV; measured En. EyJy: ' Cu deduced energv levels. Enriched and natural samples.
Gamma-ray spectra have been obtained due to neu however, the small sample sizes (~50g each) precluded tron interactions with natural copper at the 10-m obtaining definite data in a reasonable period of station of the ORELA for 0.5 < En < 10 MeV using a machine time. However, for both of these small isotopic Gel Li) detector system.2 Speura were also obtained for samples, gamma-ray spectra were obtained using a small enriched isotopic samples of 63Cu and 6SCu; Ge(Li) detector and 4.9-MeV neutrons produced using a Van de Graaff accelerator system.3 There two sets of ORIK.-0WG 72-12303 data are being studied to obtain spectroscopic informa 2406.0 JTKS.0 tion for the two copper isotopes. Figure 1 shows the Z276.0 level structure and gamma decay scheme determined ZMJB-0 thus far for 6SCu. 20M.0 ?unJ • ORNL-OWG 73-1462
65 Cu(/J,/7'y)
fr=!HSkeV ;->».o t««.0 'J
5 UJ
< 5 5 < ~ IIIS.I- Y z a o z 2: o t- u 771.1! • UJ IQO ° PRESENT Nol DATA in • PRESENT GelLi! DATA '. o ac 8NL-325 u 5- «*,; o A.8. SMITH \n,n'\ z uJ 1 W
, -i 111 00- 0 1.0 12 1.4 1.6 1.8 20 22 2.4 2.6 (55-CU LEVEL DifiuRfWI NEUTRON ENERGY IMtVl
Fig. 1. 6SCu level structure determined from this experiment. Fig. 2. Excitation function for the 1115-keV transition in These data represent new information on the decay modes for 65Cu. The differential cross sections are in millibarns per steradian with respect to the natural sample and not corrected levels having Ex > 2 MeV. for isotopic abundance. 57
The CjeiLi) data are also being supplemented by whic!, should aid in spin-parity assignments. gamma-ray production cross-section data obtained with the natural copper sample at the 50-m station of the ORE LA.4 We have begun to extract excitation func tions from these data for individual transitions; that for 1. Neutron Physics Division. 6S 2. O. A. Wasson and G. G. Slaughter. "Valency Neutron the t'y - 1115 keV transition in Cu is shown in Fig. 92 93 Capture in Mo(n.>) Mo." to be published in Physical 2. In this figure the data are shown for the natural Review C. element and not corrected for isotopic abundance. The 3 J. K Dickens and F. G Perev. Nucl. Sci. Eng. 36, 280 Nal data are determined absolutely; the Gel Li) data are (1969). determined relatively and normalized to the Nal data. 4. J. K. Dickens. T. A. Love, and G- L. Morgan. ORNL^»846 The solid curve and the dashed extrapolation were '1972). 5. J. R. Stehn. M. D. Goldberg. B. A. Magumo. and taken from BNL-3Z5 jef. 5). Neutron scattering R. Weiner-Chasman. BNL-325 (1964). 6 measurements by Smith et a!. are also shown. These 6. A. B- Smith. C. A. Engelbrecht. and D. Reitmann. Phys. data should be amenable to theoretical interpretation Rev. 135, B76 (1964).
NEUTRON CAPTURE CROSS-SECTION MEASUREMENTS FOR 86Sr 8 7Sr, AND 88Sr' G.J.Vanpraet2 R. L- Macklin B.J. Allen3 R.R. Winters4
86 87 NUCLEAR REACTIONS: Sr(n.86 87 Neutron capture cross sections for Sr, Sr, and 1. Abstract of paper to be published in proceedings of IAEA 88Sr have been measured from 3 keV up to 600 keV Conference on Nuclear Structure Stud> with Neutrons, July with total-energy detectors. Maxwellian averaged cross 29- August 4, 1972. Budapest. Hungary. sections are calculated as a function of energy. The 2. Present address: State University Center of Antwerp, correlation between these values and the solar system Antwerp. Belgium. 3. Present address: Australian Atomic Energy Commission, isotopic abundances is discussed in terms of stellar Lucas Heights. Australia. nucleosynthesis by slow capture. 4. Present address: Denison University, Granville, Ohio.
NEUTRON RESONANCE PARAMETERS OF 92Mo» O.A.Wasson2 B.J.Allen3 R.R. Winters4 R. L. Macklin J.A.Harvey . >
T 'p—J 92 NUCLEAR REACTIONS: Mo(n,-y), E < 32 keV; measured anT, any. Deduced 42 levels, r„, rr J, j jr. /, 5°. S1. Enriched target.
Neutron transmission and total neutron capture yields respectively. The s-wave neutron strength function is were measured using the time-of-flight technique at the (0.65 ± 0.26) X 10"4, while the p-wave strength Oak Ridge Electron Linear Accelerator facility using function is (3.3 ± 1.1 )X 10"4. enriched samples of 92Mo. A total of 42 resonances were observed for neutron energies less than 32 keV. Twelve are assigned to s-wave interactions, while 23 are 1. Abstract o." paper submitted for publication in Physical assigned to p-wave interactions. The resonant energies, Review C. 2. Present address: Brookhave.i National Laboratory. neutron widths, radiation widths, and spins are de 3. Present addiess: Australian Atomic Energy Commission, duced. The average 5- and p-wave radiation widths are Lucas Heights, Australia. equal to 0.178 ± 0.015 eV and 0.24 ± 0.03 eV 4. Present address: Denison University, Granville, Ohio. IX
ENERGY DEPENDENCE OF THE OPTICAL MODEL FOR HELION SCATTERING FROM °°Ni C. B. l-'ulmer. J. C. Hafele. and C. C. l-'oster 55 Abstract of paper to be published in Fliysica! Review C.
SPIN-ORBIT AND TARGET-SPIN EFFECTS IN HELION ELASTIC SCATTERING C. B. Fulmer and J. C. Hafek 55 Abstract of a paper to be published in Physical Review C
636SCu(n.ny) REACTIONS G. G. Slaughter. G. L. Morgan, ard J. K. Dickens 56 Gamma-ray spectra from the ;«./?'->) reaction on ' *Cu were used to deduce energy levels in ~ Cu. Excitation functions obtained relatively were normalized to absolute data obtained with a Nal crystal, with excellent agreement.
NEUTRON CAPTURE CROSS-SECTION MEASUREMENTS FOR R6Sr. 87Sr. AND 88Sr G. J. Vanpraet. R. L. Macklh. B. J. Allen, and R. R. Winters ... 57 Abstract of paper to be pubiished in proceedings of IAEA Conference on Nude?r Structure Study with Neutrons, July 29-August 4, 1972, Budapest. Hungary.
NEUTRON RESONANCE PARAMETERS OF 92Mo O. A. Wasson, B. J. Alien, R. R. Winters, R. L. Macklin, and J. A. Harvey 57 Abstract of paper submitted for publication in Physical Review C.
92 93 VALENCY NEUTRON CAPTURE IN Mo
VALIDITY OF THE VALENCE-NEUTRON MODEL FOR 98Mo G. W. Cole, R. E. Chrien, R. C. Byrd, S. F. Mughabghab, J. A. Harvey, and G. G. Slaughter 58 The validity of the valence neutron model for predicting partial radiation widths in the 98Mo(«.7)99Mo reaction bgood for resonances with large reduced neutron widths, and seems to be less good for smaller resonances where statistical effects would be more important.
THE 91 Zripj) REACTION AND THE LEVEL STRUCTURE OF 89Zr J. B. Ball 59 Abstract of published paper: Phys. Rev. C6, 2139 (1972).
SYSTFMATICS OF L = 0 TRANSITIONS OBSERVED IN THE ,/) REACTION OF NUCLEI NEAR N = 50 J. B. Ball and J. S. Larsen 59 Abstract of pubfched paper: Phys. Rev. Lett. 29,1014 (1972).
A REMARK ON THE LEVEL STRUCTURE OF 93 Mo AND THE FAILURE OF / DETERMINATION BY SPECTROSCOPIC FACTOR RATIOS NEAR CLOSED SHELLS J. B. Ball 59 Abstract of published paper: Phys. Lett. 41B, 55 (1972).
ENERGY LEVELS OF 94Ru OBSERVED WITH THE 96RuTHE LEVEL STRUCTURE OF 92Mo AND 94MO STUDIED WITH THE (p.t) REACTION J. S. Larsen, J. B. Ball, and C. B. Fulmer 60 Abstract of paper to be published in Physical Review C.
CALCULATED ENERGY LEVELS FOR 89Y,90Zr,9,Nb,,2Mo,93Tc, AND94Ru J. B. Ball, J. B. McGrory, and J. S. Larsen 60 Abstract of published paper: Phys. Utt. 4IB, 581 (1972). 58
VALENCY NEUTRON CAPTURE IN ^MO^^MO1 O. A Wasson2 G. G. Slaughter
92 93 NUCLEAR REACTIONS: Mo(n.7>: E = 5 eV-100 keV; measured En. £7, /r 0rrr; Mo measured binding energy, deduced /, *, /. Enriched target.
Capture gamma-ray spectra from the 92Mo(n'y)93Mo 10 3 and k(A1l) = (11.5 ± 23) X 10"3. For the reaction were measured for neutron energies below 100 7129-keV transition to the s = 1/2 first excited state the keV using the 10-m flight path at the Oak Ridge average reduced strength is enhanced by a factor of 5 Electron Linear Accelerator. For neutron energies less and 2 for the £1 and Af 1 transitions respectively. Nearly than 25 keV a total cf 23 different s- and p-wave 30% of this enhancement for the E\ multipoles is resonances were resolved. The neutron binding energy is attributed to the valency-model contribution, while the 8067.4 ± 1.5 keV. The partial radiation widths for the remainder is assigned to other processes, such as the 12 highest energy gamma rays which populate positive giant dipole resonance and doorway state components. parity states below 2.5 MeV excitation were deduced The average El width for the 8067-keV ground-state and compared with the valency model predictions of gamma rays is approximately 10% of the average E\ Lane and Lynn. For gamma-ray energies less than 6.5 ground-state width. MeV, the average A/1 partial rsdiation width is approxi mately equal to the average El partial radiation width. 1. Abstract of paper submitted for publication in Physical The reduced transition strengths as defined by Barthol Review C. omew for these transitions *re k(El) = (12 ± 0.2) X 2. Present address: Brookhaven National Laboratory.
VALIDITY OF THE VALENCE-NEUTRON MODEL FOR 98Mo G.W.Cole1 R.E.Chrien1 R.C. Byrd1 S.F.Mughabghab1 J.A.Harvey G. G. Slaughter
98 9 NUCLEAR REACTIONS: Mo(n,7); E = 5 eV-6 keV; measured En, Ey, fy; *Mo deduced levels. Enriched sample. j
Recent resonance neutron capture measurements near section measurements were made on separated 98Mo the 3p maximum in the p-wave strength function have samples in order to obtain partial radiative widths and shown a considerable degree of validity for the valence- resonance parameters at higher neutron energies. The neutron model. The model describes radiative capture radiative capture measurements were made at a nominal in terms of a transition of a valence neutron outside the time-of-flight resolution of 2.5 nsec/m. Twenty-three core to a low-lying state of the final nucleus; the core resolved resonances, up to 5600 keV, have been does not participate in the trai «on. This leads to the analyzed. The resonance parameters were obtained prediction that Hy,, the partial radiative width to state from total cross-section measurements on a thick i, is proportional both to the reduced neu'ron width of sample of 0.0434 atom/b, taken with a nominal the resonance and to the spectroscopic factor of the resolution of 0.06 nsec/m. final state. Such valence contributions should be most The success of ihe model for resonances below 1 keV important where the neutron widths are large, since is related to the large reduced widths of these reso they compete with the random compound-nucleus nances. Spectra obtained for these resonances are in contributions. substantial agreement with the earlier work. Above 1 In the case of 98Mo, the success of the model for keV, the reduced neutron widths are significantly several large p-wave resonances below 1 keV prompted smaller, and statistical processes can be expected to further study at ORELA in order to extend the energy dominate the valence capture process. This expectation range over which the model could be tested. Both is confirmed by the present results, in which measured capture gamma-ray measurements and total cross- partial radiative widths do not in general agree with 59 those calculated using the valence model and the scopic factor of the six low-lying s and d states of measured resonance parameters. It is of interest, how interest \S{d.p) = 0.67). ever, to note that the ground-state transition is the strongest in 11 out of 18 p-wave resonances up to 5600 keV; the ground state of *9Mo has the largest spectro- 1. Brookhaven National Laboratory.
THE 9' Zi(p.r) REACTION AND THE LEVEL STRUCTURE OF 8,Zr» J. B. Ball
9i 9 i Nl CLEAR REACTION*: Zrip.D. £ = 3! MeV; me^uicd ai£rd). * Zr deduced levels, L2n.J.n, enhancement factors.
The 9' Z\{p,t) reaction has been studied at a proton transfers allowed from a nonzero-spin target. Two types energy of 31 MeV. Tritons were detected in a magnetic of neutron configurations are observed to be populated spectrograph yielding a resolution of 18 keV. Angular in 89Zr by this reaction: single-hole states and one- distributions for levels up to 2.75 MeV of excitation in particle, two-hole states. 89Zr are compared with two-nucleon-transfer DWBA calculations and analyzed in terms of the mixed L 1. Abstract of published paper: Phys. Rev. C 6,2139 (1972).
SYSTEMATICA OF L = 0 TRANSITIONS OBSERVED IN THE (p,t) REACTION OF NUCLEI NEAR N = 50' J. B. Ball J. S. Larsen2
88 90 2 92 94 96 NUCLEAR REACTIONS: Sr. '* Zr, ' Mo. Ru (p.t),E- 31 MeV; measured We present excitation energies and transition intensi increasing proton number. ties observed for 0* states populated by the ip,t) 1. Abstract of published paper: Phys. Rev. Lett. 29, 1014 reaction on nuclei near N = 50. Comparison of results (1972). on selected isotopes of ST. Zr, Mo, and Ru shows an 2. Visiting scientist from Nid< Bohr Institute. Copenhagen, unexpected loss of neutron L = 0 transfer strength with Denmark.
A REMARK ON THE LEVEL STRUCTURE OF9 3 Mo AND THE FAILURE OF / DETERMINATION BY SPECTROSCOPIC FACTOR RATIOS NEAR CLOSED SHELLS' J. B. Ball
95 93 NUCLEAR REACTIONS: Mo(p,r).£ = 31 MeV; measured a{Et, e). Mo deduced levels,Lln,J,». / for 1.495- and 1.695-MeV levels.
The 95Mo(/>,:)93Mo reaction is used to establish the ison of spectroscopic factor ratios is presented. 1 69-MeV level in 93Mo as 5/2* rather than 3/2* as assigned in recent (d,p) and (d,t) studies. An explana tion for this failure of/-value determination by compar- 1. Abstract of published paper: Phys. Lett. 41B, 55 (1972). 60
ENERGY LEVELS OF 94Ru OBSERVED WITH THE 96Ru(p,f) REACTIONl J. B. Bail C.S. Fulmer J. S. Larsen2 G.Sletten2
96 9 NUCLEAR REACTIONS Ru(p.r), £ = 31.1 M.V;measured <*£,, «)- *Ru deduced levels, L2n.J. •K. Enriched target.
The level structure of the neutron-magic nucleus 3.615, and 3.770 MeV and the 3" octopole vibration at *4Ru, up to an excitation energy of 4 MeV, has been 2.965 MeV. studied by means of the (p,t) reaction. Particular 1. Abstract of paper submitted for publication to Nuclear emphasis was placed on a search for excited 0* levels, Physics. none of which have been reported previously. Among 2. The Niels Bohr institute. University of Copenhagen. new ieveis observed in this rtudy are 0* levels at 2.995, Denmark.
THE LEVEL STRUCTURE OF 92Mo AND 94Mo STUDIED WITH THE (p.t) REACTION1 J. S. Larsen2 J. B. Ball C. B. Fulmer
NUCLEAR REACTIONS: 94'9*Ho{p,t), £ = 3i MeV,measured ad„0). 92'94l«odeduced levels, The 94Mof>,f)92Mo and 9'Uc(p.t)94Uo reactions enhancement factors. Particular emphasis is placed on have been studied at an incident proton energy of 31 the study of the L ~ 0 transitions near the closed shell MeV. The triton spectra were obtained with a magnetic at 50 neutrons. spectrograph with overall resolution of about 20 keV. Experimental angular distributions are compared with 1. Abstract of paper to be published in Physkal Review C. two-nucleon-transfer distorted-wave Born-approxima 2. Visiting scientist from Nids Bohr Institute, Copenhagen, tion calculations to extract spin-parity assignments and Denmark.
CALCULATED ENERGY LEVELS FOR *9 Y, 90Zr,9' Nb, 92Mo, 93Tc, AND 94R«! J. B. Ball J. B. McGrory J. S. Larsen2
Recent experimental data for the heaver N = 50 fitting 44 experimental level energies. nuclei are examined in terms of a model based on an 1. Abstract of published paper: Phys. Lett. 4IB, 581 (1972). 8 inert *Sr core. The 11 interaction parameters required 2. Visiting scientist from Niels Bohr Institute, Copenhagen, to define the shell-model space are determined by Denmark.
EXCITATION FUNCTIONS FOR HEUON-INDUCED REACTIONS IN IRON1 C. B. Fulmer I.R.Williams2 W.C. Palmer3 G. Kindred4
56 5 SS.S6.$->.S8 S2.S3 52,54.56^ ^ » NUCLEAR REACTIONS. Fe(A,x) ' 'Si, COf Fe< CXfE< 7Q MeV;measured o(£); deduced reaction mechanism Natural targets.
Target foil stacks of iron were bombarded with beams to obtain excitation functions for production of of he'.ions at incident energies <70 MeV. Gamma S6$7Ni, 5$'56,$7',8Co, 52,53Fe, s2$4$6Mn, and spectra of individual foils were measured and analyzed $' Cr; for $ 3 Fe and 5 2 Mn, data were obtained for both 61 lUounc ;• id isomeric slates. The yields of S6Co and nant contributor to the yields of 5,Cr. S2$4Mn, 5 7Co are much larger than those of the respective Ni 51-53Fe.55Co.and$6$7Ni. isobars. Recoil measurements (to determine momentum transfer to the target nucleus) were made ai Eh =41 1. Abstract of published paper: Phys. Rev. C6, 1720 30 and 51 MeV. These data show 57Co to result princi (1972). pally from direct reactions. There is also evidence of a 2. Consultant from Knoxville College. Kaoxville. Tenn. large contribution 'jy direct reactions to the 56Co yield. 37921. 3. Great Lakes Colleges Association-ORNL trainee from The excitation function data are compared with predic Earlham Colkge. Richmond, lnd. 47374. tions of compound-nucleus evaporation theory, these 4. Undergraduate Summer Science and Engineering Program indicate compound-nucleus reactions to be the uomi- trainee ..om Knoxville College. Knoxville, Tenn. 37921.
ELASTIC SCATTERING OF HELIONS AND ALPHA PARTICLES AT AND NEAR 180° W.W.Eidson1 C.C. Foster2 C. B. Fulmer J. C. Hafele3 DCHensley N.M.O'Fallon2
Recently reported analyses4,s have demonstra*«»d the Particles scattered through large angles traverse 'he importance of large-angle heiior. and alpha elastic magnetic fieki again and are deflected away from the scattering for removal of ambiguities in the optical- incident beam into a detector. The detector is mounted model potentials involved. Measurements6-8 of alpha on a movable arm which pivots about an axis through scattering at angles approaching 180° show apparently the target position and can be moved into position to anomalous behavior, suggesting that a careful theoreti detect particles scattered in the angular range 155 to cal analysis could yield important nuclear reaction 188°. information. Such data, which have usually been For alpha particles a silicon surface-barrier detector is obtained for targets with A < 50 and at energies below used; for helions, where particle identification is neces 30 MeV. indicate pronounced maxima at 180°. These sary, a AE-E detector telescope is used. When the maxima have been analyzed in terms of nuclear glory apparatus was moved to ORIC, we decided to use a scattering.9 angular momentum mismatch between the position-sensitive detector to permit simultaneous data elastic channel and the reaction channels,10 and alpha accumulation over a range of angles. This increased cluster structure in the target nuclei.8 Data from a efficiency is needed because the particles are scattered wider range of target nuclei and at higher energy are in a reflection mode from the target, which necessitates obviously needed for a better understanding of extreme the use of thin (< 1 mg/cm2) target foils, and because back-angle scattering of composite particles. We report the cross sections being measured are small, especially here preliminary results of such a systematic study. for helion*. The position-sensitive detector is a transmis A magnetic deflection system for obtaining large- sion detector and can serve as a LE counter when angle (including 180°) measurements was developed by particle identification is required. The detector pulses Hafele at Washington University. This system was used are processed by the Tennelec ADC system at ORIC to at the Washington University cyclotron to obtain helion yield energy spectra for seven angles at intervals of 1°. and alpha scattering data from a number of targets at A collimator is used to ensure that only scattered energies extending up to ""30 MeV. the maximum particles with the proper rays in the magnetic field tnergy available at that accelerator. The magnet facility enter the detector, but since proper rays are a function is capable, however, of being used for alpha particles of both incident particle energy and target mass, there with energies up to *~45 MeV and helions up to ~60 is an angle adjustment for the skew of the collimator. MeV. During 1972. with the support of a National Calibration of the angle adjustment of the collimator Science Foundation grant to the University of Missouri for the position-sensitive detector was a time-consuming at St. Louis, the apparatus was moved to Oak Ridge and but necessary part of the early data runs at ORIC. installed on a beam line at ORIC. Calibration runs have Angular distributions taken with this system are been made, and preliminary data have been obtained shown in Figs. 1-4 for a range of incident particle with the system in the ne.v installation. energies for both helions and alpha particles elastically In the system the incident beam of particles passes scattered from 27AI and 18Si. Excitation functions for through a magnetic field, imo a target chamber at the 180° scattering are plotted in Fig. 5. Figure 6 shows exit side of the magnet, thro igh the target foil at the angular distributions of 28 J-MeV alpha particles elas center of the chamber, and thence into a Faraday cup. tically scattered from targets of a wide range of mass. 62
The data shown in Figs. 1-5 were obtained ai large-angle alpha elastic scattering cross sections are Washington University, and the data shown in Fig. 6 orders of magnitude larger than helion elastic scattering were obtained at ORIC. Some preliminary 40-MeV cross sections. There are large differences between alpha scattering data have also been obtained at ORIC. neighboring targets for elastic scattering of either At 40 MeV the 180° alpha scatORNL-0WG 73-614 27Al(a.a)
0 J I I L 1 1 L 190 160 !7D 180 190 150 160 170 16C 190
Ffc.1. dMrib«tioMror27AL xi\
POTENTIAL ENERGY FOR THE FISSION OF A SUPERHEAVY NUCLEUS M. O Mustafa. U. Mosel. and H. W. Schmitt 102 The potential energy surface for the fission of the superheavy nucleus 114X i g4 has been calculated.
DEPENDENCE OF FISSION MASS ASYMMETRY ON THE INTERNAL EXCITATION ENERGY OF THE FISSIONING NUCLEUS M. G. Mustafa and H. W. Schmitt 103 Preliminary calculations based en th^ asymmetric two-center model have begun in an effort to study changes in the effective potential energy surface for fission with increasing compound-nucleus excitation energy.
REALISTIC SINGLE-PARTICLE K MATRIX FOR DEFORMED AND FISSIONING NUCLEI R. Y. Cusson. D. Kolb. and H. W. Schmitt 106 Reahstk calculations uased on the Brueckner-GoUman density-dependent and momentum-dependent single-partici'? Hssihcsaa have been performed foi ii&ii nuclei from He 10 ~ Ca and are m progress for heavy nuclei.
SYSTEMATICS OF FRAGMENT MASS AND ENERGY DISTRIBUTIONS FOR PROTON-INDUCED FISSION OF 233U, "5U, AND 238U Robert L. Ferguson. Franz PbtaL Frances Pleasonton. S. C. Burnett, and H. W. Schrnitt 106 Abstract of paper submitted f 1 publication in Physical Review C
FISSION OF 20'M BY 3*.l-MeV PROTONS: SEARCH FOR AN ASYMMETRIC COMPONENT IN THE MASS DISTRIBUTION, AND NEUTRON EMISSION RESULTS Franz Pbsn, Robert L Ferguson, Frances Pkasontou. and H. W. Sdunitt 106 Abstract of paper submitted for publication in Physical Renew C.
MASS AND TOTAL KINETIC ENERGY DISTRIBUTIONS FROM THE SPONTANEOUS FISSION OF 24*Gn Frances rVasoaton, Robert L. Ferguson. Franz Pbs8, and C L. Bemis, Jr 107 Fragment mass and total kmctic energy distributions have been detemtiatJ in an energy-energy correlation experiment on fawn of "'Cm.
NEUTRON MULTIPLICITY DISTRIBUTIONS W THE SPONTANEOUS FISSION OF 24*Ou, 24,Gn, AND 2S2Cf R. W. Stougbton, J. Halperin, C. E. Benus. Jr.. aad H. W. SdunMt 109 Abstract of paper accepted for publication in Nuclear Science and Engineering.
PROMPT GAMMA RAYS EMITTED IN THE THERMAL-NEUTRON'I.NDUCED FISSION OF 233U, 23SU. AND 23'Pu AND THE SPONTANEOUS FISSION OF 2S2Cf Frances Pkasonton, Robert L. Ferguson, and H. W. Schmitt 109 iesutts are given for the average energy and average number of gamma rays emitted within ~5 nsec after fission as functions of fragmentmass . Sunibriries are noted in the mass dependence of gamma-ray and neutron emission.
LOOTS OF ANGULAR MOMENTUM IN HEAVY-ION COMP0UNT>NUCLEUS REACTIONS M. Bfann and Franz Pbsi 112 Abstract of pubhshed paper: Pfiys Rev. Lett. 29. 303 (1972).
PREDICTIONS FOR HEAVY-fON REACTIONS BASED ON THE ROTATING LIQUID DROP MODEL Franz Pbsil 113 Abstract of paper published in proceedings of Europear. Conference on Nuclear Physics, Aix-en-Prov.snce, June-Juty 1972, vol. II. p. 51./ toys.. Paris, France f'972).
EQUILIBRIUM CONFIGURATIONS OF ROTATING CHARGED OR GRAVITATING LIQUID MASSES WITH SURFACE TENSION. PART II S. Cohen, Franz Pbsil, and W. J. Swiatecki 113 Abstract of paper submi'ted for publication to Annals of Physics. 63
When optical-model potentials obtained from analysis The angular distribution* in Fig. 6 show a maximum of angular distribution data that do not include extreme between 160 and \10J in addition to the larger back-angle data are used, the optical model predicts maximum at 180°. We have performed preliminary 180° helion elastic scattering cross sections that are in optical-model calculations that show a strong depend 11 reasonable agreement with measured values. Using ence of r0. the radius paumeter of the real welt depth, potentials that correspond to alpha scattering data of a on the extreme back-angie alpha elastic cross section, similar range, however. !he optical model predicts 180° both the magnitude of the 180° maximum and the cross sections that are too small by an order of relative size of the two observed maxima. The calcu magnitude or more.12 lated cross sections, however, are more than an order of
0RNL-OWG 73-613 ^S^a.a) i—!—i—i—»—r
150 160 170 180 190 150 160 170 180 190
Fig. 2. Large-angle alpha elastic scattrring angular distributions for 28Si. 64
ORNL-OWG 73-6M 27AI!A,A) 180
160 -
140
120 -
100 -
80 -
60
-40 - b° 50
30,
35
25
15
30
20
10
Ffe.3. Uffe^ii|fehciioiiel»stkKattcriii|aivriaratk>Mfar27/7A, L 65
ORNL- 0*6 73-612 28Si(A,/» 180 1 r—r r £h(MeV) i—I—r 40 - 22.0 14.2 100^- H*+ll 320 h 20 - 40 - 23.9 I
H 20
80
60
40
20 80
60 70
H 50
30' ' I ' ' J L 30 J I L J L 160 170 180 190 160 170 180 190
Ffc.4- iMft+ajthdkmtautic tetrilMiikw for 2* Si- magnitude smaller than the measured ones. The shapes 27A1 angular distribution measured at 40 MeV is of these large-angle alpha elastic angubr distributions inconsistent with the predictions of this theory, but are in good qualitative agreement also with the nuclear more data at 40 MeV on alpha-clusteHilx nuclei will be glory scattering model presented in ref. 9, especially for needed before any definite conclusion can be drawn. the / = 0 targets. This model, however, does not Eberhard1 ° has used a model suggested by Robson to attempt to explain the absolute magnitude of the explain the "anomalous" backward enhancement of scattering. 24-MeV elastic alpha scattering from targets nearvf = The model of alpha-particle clustering in the target 40. The model treats the angular momentum "mis nucleus8-13 suggests that the consistent difference match" between the elastic channel and the reaction between the 27AI and 2sSi angular distributions could channels, principally the (a/i) reaction channels. Since *e attributable to alpha-particle clustering in 28Si, but the neutrons generally can carry off less angular it gives little insight into the observed difference momentum than alpha particles, there are many high- between the $*Ni and 60Ni angular distributions. In angular-momentum partial waves in the incoming chan addition, it would appear that the magnitude of the nel that the ia/i) reaction channels cannot match, and 66
2 ORML-wre rs-zjo I ELASTIC SCATTERING 105 t iw- \ : 9= 180* 5?" -*-*
Fjj. 5. ExcttatkM ftuctaow for 130° dasfk scattering of ttom<7AIaad2SSL
Fa>6. Latfumjic 2S3-MeV alpha ekatic acattataag ifli dirtribrtiom for acwral targets. 67 there is. hence, an /-value cutoff for the effect of the relevance to heavy-ion induced reactions, in vhich large (ajt) channels. It turns out that these higher partial amounts of angular momentum are present in the waves most strongly contribute to the cross section near incoming channel. 1 o this end. we are extending our 0 and 180° and may account for the enhancement of systematic study o! large-angle scattering re neighboring alpha-particle elastic scattering at back angles. The targets over a wide range of target masses and to higher order of enhancement involved appears, qualitatively, energies for both hehons and alpha particles. to be sufficient to bring the predictions of the optical model into agreement with our data, but detailed calculations have not yet been attempted. Furtnerrnore. i. Drexel University. this "mismatch" model predicts that the S8Ni elastic 2. University of Missouri. St. Louis. alpha cross section should be bigger than that for fc 'Ni, 3. Washington University, St. Louis. Mo.; present address: since 60Ni has a lower (cut) threshold, wh;ch, because Research Department, Caterpillar Tractor Co.. Peoria. 111. 4. C. B. rulrr.er and J. C. Hafele. rhys. Rev. C 5, 1969 of the additional energy and number of enamels (1972). available, implies a high /-value cutoff and. conse 5. D. A. O'.nberg and S. M. Smith. Phys. Rev. Lett. 29, 500 quently, less enhancement for the elastic scattering on (1972). 60Ni this is in good agreement with our data. 6. A. Budzanowski. K. Grotowski. L. Jarczyk, B. Micek, H. Nievodniczanski, A. Stralkowski. and Z. Wrobel. Phys. The 180° excitation functions shown in Fig. 5 Lett. 16,135(1965) indicate that the magnitude of the elastic scattering of 7. A. Bobrowska. A. Budzanowski. K. Grotowski. L. Jarczyk 28 Si relative to 27A1 is roughly the same for helions as S. Micek. H. Niewodniczanski. A. Strzalkowski, and Z. Wrobel, for alpha particles. Consequently, the target-alpha- Nucl. Phys. A126, 361 (1968). cluster model does not seem either necessary or 8. B. I. Kuznetsov. R. £. Ousannikova, and I. P. Chernov. Yad. Fiz. 15, 673 (1972). transl. Sov J. Nucl. Phys 15, 377 adequate to explain this feature of our data. On the (1972). 28 other hand, the greater binding of Si with respect io 9. H. C. Bry.wt and N. htmie, Ann. Phys. 47, 127 (1968). 27A1 suggests that the angular momentum mismatch 10. K. A. EbcThnd.Phys. Lett. 33B, 343 (1970). theory would predict greater back-angle enhancement 11. C. B. Fuhner, J. C. Hafele, and C. C. Foster,/%>-£ Rev. C for the scattering from 28Si. We plan to examine this (to be published). 12. P. T. Sewell, J. C. Hafele. C. C. Foster, N. M. O'Fallon, possibility in the near future. and C. B. Fulmer, Phys. Rev. C (to be published). We are especially interested in testing the angular 13. D. Agassi and N. S. Wall, University of Maryland momentum mismatch theory because of its "bvious Department of Physics Technical Report No. 72-120.
INTERFERENCE BETWEEN COULOMB AND NUCLEAR EXCITATION IN INELASTIC SCATTERING OF ' "0 IONS1 F. Videbaek2 I.Chernov3 P. R. Christensen2 E. E. Gross
The excitation function for the process 58Ni(l60, which is localized over a distance of ~1 F and appears l60')58Ni* has been measured at 60, 75, and 90° lab to be correlated with a r;se in elastic scattering (relative over the energy range 34 to 58 MeV. At low energy the to Rutherford scattering). cross section rises as expected from Coulomb excitation of an electric quadrupole with a B(E2) vriue of (0.066 1. Abstract of published paper: Phys. Rev. Lett. 28, 1072 2 2 (1972). ± 0.004) e b . As the energy is increased further, the 2. Niels Bohr Institute. University of Copenhagen, Copen 2* excitation function exhibits a deep valley, due to an hagen, Denmark. interference between Coulomb and nuclear excitations, 3. Tomsk Polyiechnical Institute. Tomsk, U.S.S.R.
TOTAL CROSS SECTION OF CALCIUM C. H. Johnson J. L. Fowler N. W. Hill1
NUCLEAR REACTION: Ca;£'n = 60 to 1000 keV. measured onliE).
We have made a preliminary measurement of the total energy resolution ranging from 0.1 to 1.0 keV. We used cross section of calcium from 60 to 1000 keV with the plastic scintillator NE ilO2 for the neutron XIX
THE ORIC AS A HEAVY-ION INJECTOR FOR A SEPARATE D-SECTOR CYCLOTRON E. D. Hudson. R. S. Lord. M. L. MaUovy. and P. H. Stelson 1 3n Abstract of published paper: Cyclotrons 1972. AlP Conference Proceedings No. 9 (Vancouver. Canadj. 18-21 J:J!V 1972). pp. ; '4 82. ed. by J. J. Burgerjon and A. Stra'hdee, American h^tituie of Physics. New York. 1972.
A MULT1ACCELERATOR SYSTEM FOR HEAVY IONS E. D. Hudson, R. S. Lord, C. A. Ludemann, M. L. Mallor>. J. A. Martin. W. T. Miner. S. W. Mosko. P. H. S'elson, and A. Zucker 136 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San I rancisco. California, March 5 7, 1973).
ION STRIPPING CONSIDERATIONS FOR TANDEM-CYCLOTRON HEAVY-ION ACCELERATOR DESIGN J. A. Martin and P. K. Stelson 137 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7,1973).
ENERGY MULTIPLICATION BY BEAM RECYCLING IN AN ISOCHRONOUS CYCLOTRON E. D. Hudson, M. L. Mailory. R. S. Lord, A. Zucker, H G. Biosser, and D. A. Johnson 137 Abstract of paper to be published in proceedings of the 1973 Particle Acr?!r-»tor Conference (San Francisco. California, March 5-7.1973).
APPENDIX A: CYCLOTRONS - 1972. AVF AND FM FT. Howard 137 Abstract of published paper: Cyclotrons - 1972, AlP Conference Proceeding.. No. 9 (Vancouver, Canada. 18-21 July 1972), pp. 689-829, ed. by J. J. Burgerjo*; am. A. Strathdee. American Institute of Physics, New York, 1972.
COMPUTER CONTROL OF TOE OAK RIDGE ISOCHRONOUS CYCLOTRON C. A. Ludemann, J. M. Domaschko, S. W. Mosko. and K. Hagemann 138 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, CalifoTiia, March 5-7,1973).
COMPUTER CONTROL SYSTEM FOR THE ORIC C A. Ludemann, J. M. Domaschko, and S. W. Mosko 138 Abstract of published paper: Cyclotrons - 1972, AIP Conference Proceedings No. 9 (Vancouver, Canada, 18-21 July 1972), pp. 500-509, ed. by J. J. Surgcrjon and A. Strathdee, American Institute of Physics. New York, 1972.
LIST OR SORT? - SOME EXPERIENCE WITH THE ORIC MULTIPARAMETER DATA ACQUISITION SYSTEM D. C. Hensley 138 Abstract of paper to be published in the February 1973 IEEE Transactions or. Nuclear Science.
A NEW RF SYSTEM FOR THF. ORIC S. W. Mosko 139 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5-7.1973).
CYCLOTRON LABORATORY ACCELERATOR DEVELOPMENT PROGRAM E. D. Hudson, R. S. Lord. C. A. Ludemann. M. L. Mallory. M. B. Marshall. J. A. Martin. S. W. Mosko, W. R. Smitn. J. M. Domaschko. and K. Hagemann 139 Progress in computer control, rf improvement, and the ion extraction is summarized.
CYCLOTRON INTERNAL JON SOURCE WITH DC EXTRACTION M. I. Mallory. E. D. Hudson, and R. S. Lord 140 Abstract of paper to be published in proceedings of the 1973 Particle Accelerator Conference (San Francisco, California, March 5 7. 1973).
FEASIBILITY AND COST OF A SUPERCONDUCTING HEAVY-ION LINEAR ACCELERATOR C. M. Jones !40 Abstract of paper to be published in Particle Accelerator-;. 68 detectoi at the 200-m time-of-flight station of the Oak A£/£ = 0.0004[ 1 + 3.5£(MeV)]l'2 . Ridge Electron Linear Accelerator. Figures 1 and 2 show the total cross section of calcium (96.96% 40Ca) :n the range 200 to 600 keV. From the widths of which gives A£ = 0.1 keV at 200 keV. narrow unresolved resonances, we determined the neu In the range of our measurenents up to 1000 keV we tron energy resolution as a function of neutron energy see approximat?ly 100 resonances, about one-sixth of as follows: which we identify as s-wave resonances from their
ORNL-DWG 72-1234! 20
16 CALCIUM
M t- v*v I •• 11 .. I1 i- V. V
4 8 ~~A \sy j ^*Kfi' w
3CO 324 348 372 396 ENCR6Y ;KSW)
Fif 1. Total cioai section of calcium from 200 to 400 keV. Vertical lines give counting statistics.
0RNL-0WG 72-13433 12
• CALCIUM i A,
4 -
~~ Xx... •-—j—-^V---|«—.'"-•— 1 1 i i i * 400 424 448 472 496 o » «2 —
8 —- 1 i 1
, ' •'_ 1
1 1 ..'*•••"'•'•"'• '1 .-.'• . ,', A 1 I ! "T" '" 1 I i i 500 524 572 596 EI4ERGY (l«V)
Fig. 2. Total atom tection of calcium from 400 io 6o0 kaV. 69 heights and shapes. The cross sections at the interfer cross-section measurements ;n the energy range below ence Uips before the s resonances seem to be unex 1000 keV. pectedly large. We are investigating background effects, 1. Instrumentation and Controls Division. particularly background arising from gamma rays, 2. J. A. Harvey. N. W. Hi!!, and W. E. Kinney. Bull Amer. which could have an appreciable effect on total Phys.Soc. 17,901 (1972).
NEUTRON SHELL STRUCTURE IN 98Zr, 9SZr, AND 97Zr BY (d.p) AND (a.3 He) REACTIONS1 C. R. Bingham2 G. T. Fabian1
9294 96 92 94 96 3 NUCLEAR REACTIONS: ' Zr(). ' ' ZrDifferential cross sections for9 2,94'96Zi(/;*,p) at 33.3 sented for levels assigned to
42.5° lab. The resolution was about 25 keV full width hXXj2 states, these sums are in good agreement with at half maximum. Many levels were characterized which sum-rule predictions. Only ~50% of the expected hx t/2 were not reported cr were improperly identified in strength was observed; the remainder appears to be previous neutron-transfer studies, (a,3He) spectra with highly fragmented and at excitation energies above S 55 keV resolution were obtained at 15 and 20° for each MeV. target with 65.7-MeV alpha particles. The data were compared with distorted-wave calculations. With a few 1. Abstract of paper accepted for publication in Physical exceptions, consistent spectroscopic factors were ob Review C. 3 2. University of Tennessee, Knoxville. tained from the (d,p) and (a, He) reactions. Sums of 3. Graduate student from U.T.; present address: Rutland spectroscopic factors and centers of gravity are pre- AFB. Albuquerque, N.M. 87117.
GIANT RESONANCES IN THE HIGH-ENERGY INELASTIC SCATTERING CONTINUUM1 M. B. Lewis
The details cf the structure previously observed in the pole strengths exhaust most of their corresponding sum high-energy proton scattering continuum are inspected rules, the octopole component does not. The possible for collective multipole contributions. Evidence is nature of the less structured component at this con shown that in the E* * 10-25 MeV excitation region tinuum region is discussed. of the 40Ca continuum, at least dipole, quadrupole, and octopole excitations contribute to the structure of the 1. Abstract of published paper: Phys. Rev. Lett. 29, 1257 cross sectio.i \o(d, £*)]. While the dipole and quadru- (1972).
RULES FOR SPIN AND PARITY ASSIGNMENTS BASED ON LOG ft VALUES1 S. Raman N. B. Gove2
RADIOACTIVITY: 65Ni {from 64Ni(n,r)|; 90mY (fr«m 89Y(n/y)l; ,44Pm (from ,45NdA survey was made of log ft values for forbidden beta for making spin and p?jity assignments from log ft transitions. Three cases, 90mY, 6SNi, and M4Pm values are proposed. decays, were examined experimentally. A number of low log // values reported in the literature were 1. Abstract of paper to be published in the Physical R mew. superseded by more recent larger values. Empirical rules 2. Mathematics Division. xxi
ANNOUNCEMENTS 169
PERSONNEL ASSIGNMENTS '69 Guest Assignees from Abroad 169 Guest Assignees from the United States 170 Staff Assignments 171 Staff Appointments 171 Staff Termination 171 Staff Appointees - Intralaboratory Loans 172
MISCELLANEOUS PROFESSIONAL ACTIVITIES OF DIVISIONAL PERSONNEL 172
COLLOQUIA AND SEMINARS PRESENTED BY THE PHYSICS DIVISION STAFF 174
PHYSICS DIVISION SEMINARS 176
Ph.D. THESIS RESEARCH 177
M.S. THESIS RESEARCH 178
STUDENT GUESTS 179
COOPERATIVE EDUCATION PROGRAM FOi? UNDERGRADUATE STUDENTS 179
GUEST ASSIGNEES-STUDENTS NOT ENGAGED IN THESIS RESEARCH AT ORNL 180
CONSULTANTS UNDER SUBCONTRACT WITH UNION CARBIDE CORPORATION NUCLEAR DIVISION - ORNL 180
CONSULTANTS UNDER CONTRACT ARRANGEMENT WITH OAK RIDGE ASSOCIATED UNIVERSITIES 181
ANNUAL INFORMATION MEETING OF THE Pi!YSKS DIVISION 182
RADIATION CONTROL AND SAFETY IN THE PHYSICS DIVISION 182
UNISOR PROGRAM 182
PARTICIPATION IN VARIED INSTITUTES AND SYMPOSIA 183
ORIENTATION MEETING AT THE ORNL NUCLEAR DATA PROJECT FOR NSF-SPONSORED NUCLEAR INFORMATION RESEARCH ASSOCIATES (NIRA) 183
ORNL HEAVY-ION SUMMER STUDY . . 184
AUTHOR INDEX 185 70
LOG/r VALUES FOR SECOND-FORBIDDEN BETA TRANSITIONS AND THE DECAY OF 24Na» S.Raman N.B.Gove2 J.K.Dickens3 T. A. Waikiewicz4
24 23 24 RADIOACTIVITY: Na [from Na(n,-y)|; measured t'y. /7; deduced log //. Mg deduced levels.
24 The 4* -»• 22* beta transition in Na decay is based on log/f is appropriate. important because it has been considered to have the lowest log ft (10.7) for a second-forbidden beta 1. Abstract of published paper: Phys. Lett. 40B, 89 (1972). transition. We find that this beta transition is possible, 2. Mathematics Division. 3. Neutron Physics Division. but only a lower limit on the log/f (>11.2) is really 4. Summer research participant from Edinboro State College, established. Therefore, a revision of/* assignment rules Edinboro, Pa., supported by Oak Ridge Associated Universities.
CROSS SECTIONS FOR THE * * Ni,6 3Cu ('60Xi REACTIONS R.L. Robinson J.C.Wells, Jr.1 H.J.Kim J. L. C. Ford, Jr.
NUCLEAR REACTIONS: MNi,63Cu (l*O.X),E = 38.5-48.5 MeV; measured a{E). Enriched taifits.
This is a continuation of a program to ascertain tions for some of the exit channels from the reactions quantitatively what nuclei can be produced via heavy- "Ni^Cu^O.JT) for£l6 =38.5,41,43.5,46, and ion-induced reactions. Here we present the cross sec 48 5 MeV. °
7J-1244
«l «r*o, x) 2*»
r-^ •^ _. K* ^ s *«"_ y «•• / / ^^ Y+- \ ' T5" / r / s r / - ' ( / / L, / / ^ r f / U^^ / / *"* *- -^*=t f—— "J "H^/ t*"— / X / / / / / -i + f / 7" 1 1 / r 96 40 42 44 411 £^(KhW) £ «0l*M
D161 i,1lo6 Fh> 1. Cro* sections for the Ni(M 0,X) reactions wh«t» the tmitfi partkta X mm dmotttf hi thi Agar*. "O eaetgiet ar. given in the laboratory system. 71
OHNL-I MK 73-1245 VJD ' ' ! T
1 6 3 6 ^uC* !? XI i i Fig. 2. Cross sections for the Cu(' O.JO reactions. l , ?oo
The gamma rays from the resulting radioactivities and too i it 3-—* j T^t^ * in-beam gamma rays were measured. Cross sections •^ i if. *tO -T^ j ^ t i/^ were extracted from the resulting yields. Some discus ^T f * ?|W sion of the details is given :J ref. 2. JT ± H^t^«*-
The present results are summarized in Figs. 1 and 2. 20 Jf'• Zaff For the radioactivity studies, the 6' Ni target was 0.99 2 63 _ JrJ* mg/cm thick, and the two Cu targets were 0.895 10 2 &k^A and 1.20 rag/cm thick. An approximate correction of 7^\ 71it\£z the target thickness is obtained by plotting the experi 5 i -T f 1• 16 J S ! mental points in Figs. 1 and 2 at the average 0 ^£-—V"jr 69.3-keV gamma ray in Kr was used for the 0.2 ?"*' cross-section determination. ' I For the in-beam studies of "Ni, the target was thick 0.1 4 u enough to stop the beam. Cross sections obtained from AM the thick-target yields are given as dashed curves in Fig. 1, and errors are illustrated by the flags. The hvbeam 3 data for * Cu have not yet been analyzed. flfl»
1. TcimeMee Technological UaHrtrmy. Cookcv3le. OIM 2. R. L. Robinmi. H. J. Kira. and J. L. C Ford, Jr../ Phys.. 3« 40 42 44 4t 41 soppl. to No. 11 -12.32,265 (1971). £>_ (IMVl
INTCIWIETATKWOFTHE"^'^^©.^ REACTIONS R. L. Robinson H. J. Kim
One of the most promising uses of heavy-ion projec- stability. But again because of lack of experimental ties is in inducing reactions whjch produce nuclei far data, there has been little testing of these calculations. from stability. However, there is stall very limited To provide quantitative information, we initiated a knowledge about the degree to which this process is program for determining absolute cross sections for the successful. More specifically, there is little de ailed various exit channels resulting from heavy-ion-induced experimental information about the competition be reactions. Thus far, we have obtained the cross sections tween pure neutron emission, which n the mechanism for products due to bombardment of * ,,*°Ni with 38-, required to produce nuclei farthest fiom stability, and 42-, and 46-MeV ' *0 ions. The technique is discussed charged-particle emission. There has been an excellent in ref. 2; the results are summarized by Figs. 1 and 2. effort by Blann1 to predict what products will result in The flags indicate the size of the relative errors. These such reactions. By assuming statistical decay of a curves were derived from gamma-ray yield curves after compound-nuclear system, he calculated exceedingly correcting for the thickness of the target (1.00 mg/cm3 small cross sections for production of nuclei far from for "Ni and 1.64 mg/cm2 for *°Ni). There has been 72
ORNL-OW6 72-3707R ORNL-OWG 72-3706R
40 42 44 48
F»j. 2. Expcriawatal cron aectioas for icactkm pcoducte ™0 boa »'0 KMH iacideat oa 60NL
F%. 1. ExporiR^stal foe reactkm prodacts bom "Okm M s8NLThe ' 60 energies are in the reaction. The real and imaginary potentials have a bbontoiy system. l 3 Woods-Saxon form with r0 = 1.25 fm [R = r0(AT l + V /3>] and a - 0.6 fm. For V = 27 MeV and W = 11.4 another measurement of some of these cross sections by MeV, the parameters of Obst et al. for energies well Bair et al.3 which provides an independent check of oui above the Coulomb barrier, the predicted total reaction absolute cross sections. They measured with high cross sections for S8'*°Ni at 46 MeV are 415 and 457 precision die total number of neutrons emitted in these mb, as compared with the experimental values of 390 ± reactions as a function of projectfle energy by means of 40 and 405 ± 40 mb. We exar.uned the dependence of
a large graphite sphere with embedded BF3 counters. the magnitude of the crctr section on the various Their results are given in Figs. 3 and 4. Then by taking optical-model paramtters and found it insensitive to V our cross sections in which neutrons are emitted, with and W (a 5% change in V or V gi.es ~1% change in a)
appropriate weight for the number of neutrons, we but very sensitive to r0 (a 1% change in r0 gives "7% obtain the solid curves given in Figs. 3 and 4. The error change in a). bars give representative uncertainties in our data. To explain the shape of the cross section at the In this report, we compare the total experimental Coulomb barrier requires a drastic change in one or cross section with the total reaction cross section more parameters. Obst et al. in their fit of the calculated with an optical model and compare the *«Fe(I*0,,60)56Fe data varied W, the imaginary relative population of the exit channels with those given potential, as a function of the projectile energy. We for statistical decay of a compound nucleus in which have done a similar thing after first forcing the angular momentum is ignored. Initial values for the calculations at 46 MeV to equal our data by varying
optical-model parameters were taken from those ob only r0; r0 was somewhat arbitrarily adjusted because tained by Obst et al.4 for the 56Fe(,60,,60)5*Fe this required the smallest percentage change of any 73
n-yrom ORNL-DWG 73-1229 ! 1 10- •°ni f*o.r#)
-^— CAaVmt* - HAW SPECTROSCOPY j I » ^Ni^O.I*) ! 1 • (5RAPHIT E SPHERE <5AMMA-RA Y SPECTROS•COP Y 1 i if r/~£ f 10' 4 ' m > • / / > /. / r / t «o' b 1.. / 1 / J/ • § • 101 if • i • < » 10° • 36 42 90
£m (WV) •o
don enunsion. Points give the values obtained by means of the graphite -^here. The solid curve is a fit to die cross sections deduced from the gamma-fay studies.
10° 34 38 42 46 50 O)WL-0««73-122a 20 c",6 (MeV) f60 1 O 08ST tf d. Fjg. 3. Comparison of experimental cross sections for «% tron rminrioo. Points give the values obtained by means of the 15 •— graphite sphere. The solid curve is a fit to the cross sections *•• ^*m • deduced from the gamma-ray studies. • i > i / r ^> s K> 1 t \ ' S / H^^^M^MW m *S parameter. The values r0 - 1.24 and 1.23 fm were 1 1 58 60 f obtained for - Ni. We then forced the calculated jj values to fit our experimental curves below 46 MeV by / i S varying only W. The resulting curves of W for $8,60Ni • with error bars representing the experimental uncertain ties are given in Fig. 5. Values derived by Obst et al. 36 38 40 42 44 46 from their elastic scattering ofl * O from $ 6 Fe are given £_(!**) by the points in this figure. Note that W as obtained by the two types of measurement goes to zero at about the ¥%. 5. Vataes of the imaginary potential required for the same projectile energy. optical-model predictions to fit the experimental results. The points are obtained by Obst et al. \fhyt. Rev. C 6, 1814 For the decay we have used a modified version of a (1972)) for fitting the elastic scattering of 160 from "Fe. program developed by Blann.1 Briefly, it considers the The curves are from fitting the reaction crosvsection results of S8,60 statistical probability for decay of the compound Nl 74
OflNL-MG 73-1226 OKNL-OWG 73-1227 K» 100 r—— -f r 1 £ ^Nil^a Jr) EXPERIMENTAL
..^P"- 1 , | ZP_, ! i : ! 20 I *£, £ .o _*2A
> ^..^ p 1 *=T»l 4 ^» _l jSE Ul as
0L2
(