RU0110982 The Ministry of Russian Federation for Atomic Energy The State Scientific Center of the Russian Federation — Institute for Physics & Power Engineering named after Acad. A. I. Leipunsky XIV International Workshop on Nuclear Fission Physics Proceedings Obninsk, 2000 The XlV-th International Workshop on Nuclear Fission Physics was organized at the State Scientific Center of the Russian Federation - Institute for Physics and Power Engineering, Obninsk, Russia in cooperation with Ministry of the Russian Federation for Atomic Energy and Russian Foundation for Basic Research, 12-15 October, 1998. Organizing Committee: Chairman: B.I.Fursov (IPPE) Vice-Chairman: A.A.Goverdovski (IPPE) Scientific Secretary: V.V.Ketlerov (IPPE) Members: B.D.Kuzminov (IPPE) G.A.Petrov (SPINP, Gatchina) A.V.Ignatyuk (IPPE) V.P.Eismont (RI, St.Petersburg) Yu.B.Ostapenko (IPPE) G.A.Otroshenko (RC KI, Moscow) V.E.Rudnikov (IPPE) P.V.Bogdanov (MINATOM, Moscow) V.F.Mitrofanov (IPPE) Yu.Ya.Stavisski (INR, Moscow) M.G.Itkis (JINR, Dubna) E.F.Fomushkin (FC VNIIEF, Sarov) W.I.Furman (JINR, Dubna) Published by State Scientific Center of Russian Federation — Institute for Physics & Power Engineering (SSC RF IPPE) 249020, Bondarenko sq.l, Obninsk, Kaluga Region, RUSSIA © SSC RF IPPE, 2000 PREFACE The international workshop in Obninsk was the 14-th of the series of meetings on Physics of Nuclear Fission, which started in 70-th. It took place from 12-15 October 1998 and was organized by Institute of Physics and Power Engineering named after acad. A. I. Leipunsky in cooperation with MINATOM and RFBR. More than 100 scientists participated in this workshop including more than 20 young specialists and students. The aim of the Workshop was to present and discuss main new both theoretical and experimental results obtained in the area of nuclear fission, its dynamical feature, properties of fission fragments and complementary radiations. As usual, the program of the Workshop was designed to cover a wide range of physical phenomena - from low energy and spontaneous fission to fission of hot rotating nuclei and multifragmentation at intermediate and high energies. Reaction induced by slow and fast neutrons, light and heavy ions were discussed. In addition, nuclear data associated with nuclear fission process were in focus of interest. B.Fursov A. Goverdovski V.Ketlerov m CONTENTS Interference Effects in Fragment Angular Distribution and Fission Dynamics 1 G.V.Danilyan, A.M.Gagarski, P.Getlenbort, F.Goennenwein, P.Jesinger, A.Koetzle, Ye.I.Korobkina, M.Mutterer, V.Nesvizhevsky, S.R.Neumaier, V.S.Pavlov, G.A.Petrov, V.I.Petrova, K.Schmidt, V.B.Shvachkin, S.M.Soloviev, O.Zimmer Dynamical Bimodality in Fission of Actinides 5 S.V.Bastrukov, V.S.Salamatin, O.I.Streltsova, I.V.Molodtsova, D.V.Podgainy New Calculations of Excited Nucleus Fission Characteristics within Multidimensional Langevin Approach 13 G.I.Kosenko, D.V.Vanin, G.D.Adeev Evidence of Pair Correlations in Actinide Neutron-Induced Fission 19 V.M.Maslov Nuclear Molecules in Low-Energy Fission of Actinides? 31 Yu.V.Pyatkov, V.V.Pashkevich, V.G.Tishchenko, A.V.Unzhakova Systematic of Delayed Neutron Parameters 40 S.G.lsaev, V.M.Piksaikin Simultaneous Measurement of Neutrons and Fission Fragments of Thermal Neutron Fission of U-233 ....52 I.Kimura, K.Nishio, Y.Nakagome Multimodal Analysis of Prompt Neutron Spectra for Plutonium Isotopes Type of Study: Theoretical Model Calculation Based on the Multimodal-Random-Neck-Rapture Model 62 T.Ohsawa, T.Horiguchi, M.Mitsuhashi Features of the Neutron Spectra Accompanying the Fission of Actinide Nuclei 72 G.N.Lovchikova, A.M.Trufanov, M.I.Svirin, A.V.Polyakov, V.A.Vinogradov, V.D.Dmitriev, G.S.Boykov Exotic Ternary Decay Modes in the 248Cm and 252Cf Nuclei 83 Yu.V.Pyatkov, V.V.Pashkevich, Yu.E.Penionzhkevich, V.G.Tishchenko, C.-M.Herbach Simultaneous Emission of Two light Charged Particles in Spontaneous Fission of 2WCm and 252Cf 88 M.P.Ivanov, G.V.Buklanov, I.David, V.F.Kushniruk, Yu.G.Sobolev, A.S.Fomichev Study on the Formation and Deexcitation of Superheavy Elements 94 P.D'Agostino, G.Fazio, G.Giardina, F.Hanappe, A.Lamberto, A.Nasirov, R.Paiamara, R.Ruggeri, L.Stuttge Analysis of Fusion-Fission Fragments in 48Ca + 238U Collisions' 106 G.G.Adamian, G.Giardina, A.K.Nasirov Fission Lifetimes of Heavy Nuclei as a Probe of the Shell Effects 117 O.A.Yuminov, S.Yu.Platonov, D.O.Eremenko, O.V.Fotina, Yu.L.Parfenova, E.Fuschini, F.Malaguti, G.Giardina, R.Ruggeri, R.Sturiale, A.Moroni, E.Fioretto, R.A.Ricci, L.Vannucci, G.Vannini IV Satellite Fission Processes in Heavy Nuclei 126 G.E.Solyakin, A.V.Kravtsov Nudeon-Induccd Fission Cross-Sections of Uranium up to 40 MeV 138 V.M.Maslov The 234U Neutron Induced Fission Cross-Section Near the Thermal Point 146 M.Florek, V.Yu.Konovalov, L.B.Pikelner, Yu.S.Zamyatnin, Sh.S.Zeinalov Measurements of Energy Dependencies of Hotofission Cross-Sections of Actinide Nuclei by Relative Method on Bremsstrahlung in Energy Region 5-10 MeV 149 A.S.Soldatov Proton Induced Fission Cross-Sections for Heavy Nuclei in the Energy Range 200-1000 MeV 155 V.G.Vovchenko, A.A.Kotov, L.A.Vaishnene, Yu.A.Chestnov Investigation of the CsI(Tl) Scintillator Properties for Registration Low-Energy Charged Particles 158 V.A.Khryachkov, M.V.Dunaev, V.V.Ketlerov, N.N.Semenova, M.Z.Tarasko Nonmonoenergety of Neutron Source Based on a Solid Tritium Target 164 S.P.Simakov, G.N.Lovchikova, A.M.Trufanov, V.A.Vinogradov, M.G.Kobozev Investigations of Fission Fragments Angular Anisotropy for Low Energy Neutron Induced Fission of Aligned 235U Target 176 D.I.Tambovtsev, L.K.Kozlovsky, N.N.Gonin, W.I.Furman, Yu.N.Kopach, A.B.Popov, J.Kliman Deformed Neutron Shells in the Symmetric Modal Fission of Pre-Actinides 185 S.l.Mulgin, K.-H.Schmidt, A.Grewe, S.V.Zhdanov The Emission of High Energy Gamma-Rays and Bremsstrahlung Photons in Spontaneous Fission of Heavy Nuclei 196 N.V.Eremin, G.Giardina, D.A.Smirnov, E.V.Tkalya Investigation of the Resonance Self-Shielding Effect in the a-Value of 239Pu 203 Yu.V.Grigoriev, V.Ya.Kitaev, K.V.Moiseev, Ts.Ts.Panteleev, H.Faikov-Stanchik Measurements of the Photofission Cross-Section for Cf-249 Nuclei in the Giant Dipole Resonance Range 211 N.I.Tarantin, Kim Su Men Isotopic Dependence of Fissility of Preactinide Nuclei by 200 MeV Protons 217 V.D.Dmitriev, A.T.D'yachenko, A.I.Obukhov, O.E.Shigaev Emission of Light Charged Particles from Fragments Produced on Fission of Uranium Nuclei by 153 MeV Protons and 1700 MeV Negative Pions 220 G.E.Belovitzky, O.M.Shteingrad Coupling of Mass and Charge Distributions for Low Excited Nuclear Fission 229 V.S.Salamatin Revealing of the Structure Peculiarities of the Fission Fragments Two-Dimensional Distributions 234 Yu.V.Pyatkov, V.G.Tishchenko, V.V.Pashkevich, V.A.Maslov, I.V.Kljuev Neutron Induced Fission Cross-Section of 243Am in the Energy Region from 0.8 to 50 eV 243 M.Florek, V.Yu.Konovalov, Yu.S.Zamyatnin, Sh.S.Zeinalov Correlation between Independent Yield and Total Kinetic Energy of the Fragments with A-100 and Their Partners for IP35 Thermal-Neutron-Induced Fission 248 V.I.Pelekhov Energy Dependence of Average Half-Life of Delayed Neutron Precursors in Fast Neutron Induced Fission of 23SU and Z36U 257 S.G.Isaev, V.M.Piksaikin, L.E.Kazakov, M.Z.Tarasko Fission Rate Determination in Delayed Neutron Emission Measurements with T(p,n) and D(d,n) Neutrons 265 V.M.Piksaikin, V.S.Shorin, R.G.Tertytchnyi VI RU0110983 INTERFERENCE EFFECTS IN ANGULAR DISTRIBUTIONS OF OUTGOING PARTICLES IN BINARY AND TERNARY FISSION INDUCED BY POLARIZED COLD NEUTRONS G.V. Danilyan ', A.M. Gagarski2, P. Geltenbort3, F. Goennenwein4, P. Jesinger 4 , A.Koetzle * , Ye.I.Korobkina s .M.Mutterer 4,V.Nesvizhevsky 3 , S.R.Neumaier 6 , V.SIPavlov ', G.A.Petrov 2,V.I.Petrova J, K.Schmidt *, V.B.Shvachkin ', S.M.Soloviev 7, O.Zimmsr'. 1. SSC RF ITEP, Moscow, Russia ' 2. PNPI of RAS, Galchina, Leningrad district, 188350, Russia 3. ILL , Grenoble, France 4. Physikalisches Lnstitut, Auf der Morgenstelle 14,72076 Tuebingen, Germany 2 5. RSC - KIAE, Moscow, Russia 6. Institut fur Kemphysik, TU Darmstadt, 64289, Germany 7. Khlopin Radium Institute, 2-nd Murinski Ave. 28, St.Petersburg, 194021, Russia Abstract In the beginning of 1998 three experiments, devoted to the investigation of the P-odd and P-even interference effects in the fission products angular distributions, were performed in parallel way on the cold polarized neutron beam of ILL high llux reactor. Preliminary experimental results, obtained in ihese investigations are as follows : • in the fission of237 Np, 245 Cm and M9 Cf the PNC asymmetry coefficients of the light fragment emission were found to be : (0.86+-0.42) x 10 -•, (-0.26 + - 0.06) x 10-•and (0.13+ -0.13) x 10 -1 respectively, • in the 233U fission llie fragment mass-energy dependence of PNC effect was measured with mus-s resolution aboul 2 amu . Results of the off-line calculations will be published anywhere soon, • unexpectedly large left-right asymmetry of the long range alpha-particles emission relative to the plane, formed by the vectors of the neutron spin and light fragment momentum was observed with asymmetry coefficient equal to (- 4.1 + - 0.1) x 10 -J. In this report we'll describe the latest experiment and the experimental result will be discussed in connection with possible violatiou of Time Reversal Invariance (TR1). The violation of TRI in some hypothetic interaction follows from the observed CP violated asymmetry in K° meson decay in the assumption of the validity of CPT theorem.