—''• '- ,!• INlS-mf —14534 AREAEA/ Seminar Series No. 1 ARAB REPUBLIC OF EGYPT ATOMIC ENERGY AUTHORITY THE IRPS-AEA SEMINAR ON CURRENT TRENDS IN RADIATION PHYSICS Editors M.A. GOMAA A.Z. ELBEHAY G.M. HASSIB A.M. ELNAGGAR Printed By AEA Information Centre 1993 NUCLEAR INFORMATION CENTRE ATOMIC ENERGY POST OFFICE CAIRO, ARE Seminar Series No. 1 ATOMIC ENERGY AUTHORIT iNTERNATIONAL RADIATION PHYSIC SOCIETEY The IRPS-AEA Joint Seminar on Current Trends in Radiation Physics 21 November !992 Editors M. A. GOMAA A Z ELBEHAY G. M. HASSIB A M. EL NAGGAR i- y : - r. t • l-'j^ r >. 58 ;•'•) ' ;". -"'. (• > •)t- w^--.i,\ nor.) ArjD i' rf - • Y Forward Ourinc the second ha!f of November .99? two important functions in ••hi.M"-" physu;;. tooK place in Fgyul The fust wau during 15- 19th Novembei at -.f:f city ;.,f Oena '.vhieM hosted at the Univorstiy campus Tho conference was attended by hundred Radiation Physicists ?tom Egypt, the Arab countries. India. 5- •.)!!•:.• otvji Japan /• who'.o day four of rhe cay of' u<os was one of the touristic rn j!:i> ;M-... • /' th" ;.<..; ••?<>•• <.:'.)<.>• Dfof F H ri^fi imacj rhsiiman of the Atomic Energy : ^,,:':o!' Y .IP' r>- .!' A'.-'lei-hJdi Ai Karr;r;i V;d; President of Ass.'ut •..'r!i'.--:f,•'•:!'"•'•:.•!'..J S';v.r;'^ :;.'v:v<!oci tho c:oi:forenoj with their knowledge and r ••:••;••:,;'!•>"• '••' . - •: ..--*".--. •-- ri--. 1 = pK>..>-:-'1inQt-. .vni .if>::>.-a m rhp May I994 issue of .....)• ••:.•,; '-.t R-i.^ifi!.,-.!: f;h,',, •. ;n:a Jh^n^suy Pu^i'sh'j'j by Pergumon Press.. :. Cunr: ;h. O./H .' ,>f rh..-iritni-njiiun,?! Radiation Physics society "IRPS" •-.(.! ••..••ni'vf '.-•: '.•:••;; '-j.i -Kii-no^tir.Q. on Novembpr ?Oth 199? The meebng was >it:>.::i'.1<'(7 i \ '-'•''!•,* :,' A Gor?iyfj :vi.J Prof G.M Hass'b fiom AEA. Egypt, as o!r-.. >\ •.•:-. •"': s v.',-j-, ii-,\ny.'t--d on rjovtvn!>er 2"-A by a full day 1RPS-AEA joint :"r 'i-i.-i/n .I. me 'Ci!<i'.';it Ti».:nd'.. in Radiation phyb.iCj' Three IRPS council "•.''•<-\'j>•••• p:O-...!''-'u:: ~\uc a's-1 AEA sciontisr- Topics included subjects on r 1 "--'•• •'•'•' f.i:.-' 'r..•(.•<:. [ •;•*•-.rn^ntiii RycjidHor Phyr^iCv. Aspects of uppl!cat:on; •>:•.,;•• ••'•:<•:•:),- w.^-.i':•-r •. .'i Tumour coii kti'i.ng. and Radon Monitoring for ri. '*'"!;•.(.,-.;•.{• --ff.vi!,.•;,-.•: :,••(• -. onipifte event v/a--. 0 trumpet of success by al! 1 •• .'.•.:.'!••. *• ii: ••:.>., :•»•'•''•••! ir•:.'•: £!vf^ogod about hund-«o arid twenty scientists who •..M:;; .'\)[--.', ••<> .'.•.-., • <r ••!'•• --.Ting jt:d --'irriulatiny di'scub^ions •'• .-'• • •-' •;..' •;..'••-••: .-,.•.. -•ndtK.tec; late 16 orii > on the same days and honouied ••,• --H- •>fiir;c;i'\-.. • ' .; '.>>"<>i!ancy the cn-n.-n^T*:' of Electricity and Eneigy. The ••'•'f1-'1.: •.'/.!•• -..w-'tji..;. ci !••• :.-ay cnbiite to the oiuneeif. of radiation and nuclear : f •-•'••/ ••--.:. :"' c;vp- ,.>.^i. •• •; P'of M'-'K nt<ji. r^of F!- iarii ^rof Hadarah. Prof E!- p- ••••'•• • -;' :' ;' '•- •••' y>^',.i '"'.'"• Auirni;- Fue'yy embiern was pressented to ;'•••.• .i'' • ,•; •..:••::••;..••. ;' ':n:u ^;o^ijplivt .-jnd achiovornrnts in thoir scientific •• • .•• '> • ••: IT • '••••\-\nt-:i the co'npk-K: work ot the joint seminal on current : M.-:..r.,-i ;•',•....•:, CaiirOith ••Jov^-rn^t'. !992 We thank fnnds who •i- .1 •••:" :;•• '•••••• ' r"; r;-,.•('.• support in i..ifdc! to cairv out our future plans •:•'!..-i., (. ;/'•;•;!;",ri- • >' wJdi3tion °nysic^ Conference W^ -Vo.riii;i Prof AZEf-Behay f'i M r-iii-.. ..!-. P»of AM Ei-Naggar CCJKO Auyus! 1993 - 1 - AXIAL AND SPHERICAL SYMMETERY IN EXPERIMENTAL RADIATION PHYSICS A.M. Ghose Variable Enerqv Cyclotron Centre, Calcutta Abstract The accuracy attainable in experimental radiation physics often depeds critically on the geometry linking the source, scatterer and detector along with the spectral response of the detector. Some of the recent advances in this field will be described with special reference to: 1. Scatterer optimization problem for time of flight measurement using d-t neutrons. 2. Absolute measurement of energy absorption coefficients for gamma rays by sphere transmission technique. 3. Exact equivalence of modified cylindrical and spherical geometry and its applications. - 2 ~ SYMMETRYJNVARIANCE AND SCALING IN EXPERIMENTAL RADIATION PHYSICS A.M. GHOSE VECC, CALCUTTA.INDIA 1- SYMMETRY, INVARIAHCE, SCALING SPATIAL, TEMPORAL AND SCALE SYMMETRIES 2- BASIC SPATIAL SYMMETRIES r = const., 0 = const., 0 = const., sph. symm, S of R, pot 3- NEED FOR DETECTOR DEVELOPMENT USS.RR.SF 4- EXAMPLES (a) Production of Monoenergetic Neutrons Opmisation of TOF Geometry (b) Measurement of uen (c) Cylindrical Symm. Modified Cylindrical Geometry 5- TEMPORAL SYMMETRY. 6- SCALING SYMMETRY 7- POLARISATION - ESOTERIC EXPTS. 8- CONCLUSION. -3 - Fig (1) S =the effective centre of the source, D =the effective centre of the detector, SD=the symmetry axis of the system, T atypical point on the target2, P -fixed reference plane through SD, 0 =the angle of scattering and <p =the azimuthal' a'ngle. Angular coordinates in a typical radiation physics experiment. Spherically symmetric • geometry Phenomenon Spherr i-ansmisston technique independent S = point source of angular T = Infinltesimally thin coordinates target concentric 8 and <p with the source D n constant fraction cie'iGctor with ideal characteristics Fig. 2 Ideal spherically symmetric geometry for processes or phenomena independent of angular corj.'dinates 0 d Axlally •»• symmetric geometry Phenomenon Independent of <pbut depends on B (b) surface of revolution geometry S =. point source T = taroat, Infinitesimaily thin ring in (a), infinitesimally thin surface of revolution in (b) 8 a direct beam stopper D a dateetor of neglibly small dimensions Fig. 3 (a) Ideal ring geometry (b) Ideal surface of revolution geometry Circular arc geometry Circular arc technique Phenomenon depends on S = point source both the angular D = ideal point detector coordinates 9 and 99 B = direct beam stopper T -J Inflnltesimally thin target Ideal circular arc geometry for angle dependent Fig entities Fig (5) Ideal cyiindrically symmetrical geometry with Infinitely long line source S, infinitely long, infinites!ma!ly thin target T and infinitely long detector D. Fig (6) Fig (7) Energy E of the incident radiation —- tnergy E of the incident radiation -— Uniform spectral sensitivity counter for the measure- Proportional response counter for the measurement of ment of total absorption cross section <raby the sphere energy absorption cross section o^by the spectra transmission technique method - 7 - Fig (8) I 2. o Eo Enargy £ of the Incident radiation — Spectral response of an Ideal detector for sphere trans- mission measurement of non-elastic cross sectionone - 8 - Fig (9) A - Carbon filter B - Aluminium filter C - Copper filter D - Tin filler x 1- w 0,1 CO ^>» b? 2.0 3.0 4.0 Energy of photons (MeV) —- Paraxial efficiency of a 20 g/cm2 Nal/TI crystal fitted with optimum filters of different compositions. - 9 - Fig (10) •''" *.' •'*/*,*' •f Schematic design of the experimental arrangement used in measuring (jj.«n/p).for p.araffin-wax; S denotes the photon source, S1 & H^Q wax spherical absorbing shell and filter respectively, C the detector collimation, D the Nal detector and S1 and S2 the cylindrical Pb detector shielding and composite fluorescence shield respectively. A similar arrangement was employed for cylindrical absorbing shells for detector to source separations in the range 2.5 to 5.0m. - 10 Table 1 Detector - Source (Hen/p) Separation (m) (m2kg-i) x 10-3 2.0 3.8 + 0.02 2.5 3.6 +0.02 3.0 3.3 + 0.02 4.0 3.2 + 0.02 5.1 3.3 + 0.02 Measured values of (jien/p) as a function of source to detector separation. Fig (II) 1.50 Biswas etal Present experiment to __.- .. ideal counter u3 1.00 ^>^0r~ • mm —~ ~* mm ••• *•" ••"» «•• MI — "BBr'*^, o CD s 0.50 / Mitra eta! "53 0.1 0.5 T.o "~ 1.5" Energy E of photons \r. W&V Normalised efficiences of different proportional res- ponse systems. 1 '"' '!72 Rotation for the third reading Schematic arrangement of the ivjunoenergetic secon- dary neutron source for the measurement of activation cross sections. N.G. = d-b neutron generator for ptimary neutron S = tritium target which is the source location of the prim- ary neutrons C =• hydrogenous converter B = direct beam stopper shadow bar T = sample whose cross section for secondary neutrons under study - 13 - - 03> Scattering geometry in the time-of-rlig,ht meJhod. Surface-of-revoluiion configuration in ihc time-of-fiight rnetliod. 14 - Ring or linn cylinder 8000 3000- 4000- 3000- 2000- 1000- 0.980 0.985 0.990 0.99*; 1.00C 1.005 1.010 t' Line tliapc in the lime specira of neutrons clanically rc-aCcrctl !>y pm'oits. ' ,cj"r.;c,:;; the mean val i« of f' for the line. - 15 - Fig(15) OD-J High efficiency polarimeter system proposed for spin half partices. i ,-; - D\_ R2 n< Double interaction polgrlrneter for nucleons. Fig (16) 3 05 CD O c zr a.. Uniform > !Q> activation 8 ° ^—J at source Decay or a" a cooling of OQ O -i CD » the activities CO EL-4 CD Detector 1 o to count o activities o* I Detector 2 »» o <• 5 (0 - IS V Fig (18) Fig (20) Fig (19) a ^ Ai.'-ii~;un- foil b s Sphenca! scintillator c = Light guide (Perspex) d =: Photomultiplier e = Photocatode { -.- Silicone high viscocity fluid g x Black tape. —9 Energy of neutrons — Optical coupling of a spherical scintillator to a photomultiplier Existence of a scale factor m in the relative efficiency curves of biased recoil photon neutron detectors. Fig (21) Fig (22) (12.5, 12.0} G.iV- (12.5, ",i.Q) ,L O2.s. 11.5) 0 ."! i 0.6- E 0.4! o J2 0.4 (13.5. 11.0) I (13.5, 11.0) CO 0.2 0.2 (12.0.