Experimental determination of (n,x( n,x) cross sections on germanium (Ge( Ge), terbium (Tb) and lutetium (Lu)

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1 Dzysiuk Nataliya and Kadenko Igor Experimental determination of (n,x( n,x) cross sections on germanium (Ge( Ge), terbium (Tb) and lutetium (Lu) Workshop on Nuclear reaction Data for Advanced Reactor Technologies 19-3 May 28 Trieste

2 Reasons why cross sections are necessary Current importance and applications Incompleteness of EXFOR database NO DATA FOUND Ge( n,2 n) Ge Lu( n, α) Tm Lu( n, α) Tm Discrepancy in cross section values

3 Reasons why cross sections are necessary T. Sato, Y. Kanda, I. Kumabe (1975 ) E n =14.6 MeV σ= 2.3 (.57 ) mb

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6 Requirements of cross sections for applications Testing of nuclear reaction codes Geophysics (nuclear microanalysis of materials) Astrophysics Nuclear medicine Improvement of experimental information for data for providing reliability of neutron calculations in power engineering (advanced nuclear reactor plants) Transmutation of radioactive waste

7 Subject and purposes of investigations Purpose of the investigations: Independent measurements of neutron cross sections More precise definition of existing data for neutron cross sections at energy of 14.5 MeV Obtained new experimental values of cross section R. Forrest EURATOM/UKAEA Fusion Association, Culham Science Center, Abington,Oxon OX14 3DB, UK Fusion Engineering and Design 81 (26) Data requirements for neutron activation Part I: Nuclear data Data requirements for neutron activation Part II: Decay data

8 Neutron-activation method Neutron source is a pulse neutron generator NG-3/15 Neutrons generated in nuclear reaction Average neutron energy E = 14.5 MeV Average density of neutron flux Monitor nuclear reaction Al( n, α) F = 4 Tdn (, ) He Zr( n,2 n) Zr Nb( n,2 n) Nb m Instrumental spectrums of nuclear reaction products were measured with HPGe (coaxial) and Ge - planar detectors Na sec neutrons ond Nb( n,2 n) Nb 93 92m σ x ( 1 λ ) ( ) m tirrad λm tcooling _ m λm tmes _ m 1 ( 1 λ t ) x tcooling _ x ( x tmes _ x 1 ) x irrad λ λ Sx εm e e e Nm nγ λ m x = σ S ε e e e N n λ m x x γ x m m

9 Scheme of experiment ( n, γ ) ( n, α ) ( np, ) HPGe neutrons In Cd ( nt, ) Al Tb ( n,2n) events channels

10 Self-absorption of gamma-ray in the sample (decreasing of pecks area) Sample s dimensions Coincidence summing effect (distortion of spectrum, appearance of false peaks, alterations of full-energy peaks area) geometry of measurements detectors specifications peculiarities of decay scheme of radionuclide γ Effect of sample positioning on the detector surface Sample size ε S real ε = εexp ε μ ρ d = Sdet 1 e μρ point scope d ε = ε K K exp coinsidence self absorption

11 The model of detector GC22 (CANBERRA ) has been created by MCNP code Абсолютна ефективність,2,18,16,14,12,1,8,6,4,2 Sample located on the detector surface Point source on the distance 3.2 сm Point source on the distance 11 сm Calculations with increased dead layer Experiment,,,5 1, 1,5 Енергія гамма-квантів, МеВ Ba E γ = 8.9KeV Co E γ = 117KeV Co E = E = 132KeV γ Cs Eγ = 662KeV Am E γ = 59KeV γ Geometry settings structure fields x1=5.75 cm x2=2.45 cm x3=1.1 cm x4=3.1 cm x5=.25 cm x6=.135 cm x7=.135 cm x8=.3 cm x9=.76 cm x1=.35 cm x11=7.62 cm x12=.15 cm x13=.15 cm x14=1.27 cm x15=.15 cm x16=.32 cm

12 Peculiarity of determination 72 Ge(n,2n) 71 Ge cross section Ge( n,2 n) Ge Ge( n,2 n) Ge k α1 k α 2 k β1 = 9.252KeV = 9.225KeV = 1.264KeV

13 Peculiarity of determination 72 Ge(n,2n) 71 Ge cross section Ge(n,2n) 71 Ge cross section, mb 6 4 Talys-.64 experiment(27) Jendl-3.3 Jeff-3.1/A neutron energy, MeV

14 Lu(n,p) 175 Yb Lu(n,a) 173 Tm cross section, mb Talys(Ldmodel 1) Talys(Ldmodel 2) Our result (28) EXFOR Cross section, mb Talys(Ldmodel 2) Talys(Ldmodel 1) Our result (28) Endf.B/VI neutron energy, MeV Neutron energy, MeV Ge(n,p) 7 Ga Tb(n,a) 156 Eu 8 Cross section, mb 1 5 H.M. Hoang(1992) J.L. Casanova(1976) G.P. Vinitskaya(1967) C.S. Khurana(1965) E.B. Paul(1953) Our result(27) Talys-.64(Ldmodel1) Talys-.64(Ldmodel2) Neutron energy, MeV Cross section, mb Neutron energy, MeV Talys (Ldmodel 1) Talys (Ldmodel 2) Endf EXFOR Our result (28) 6 4 2

15 Nuclear reaction Cross section, mb Neutron energy, MeV EXFOR 7 Ge(n, p) 7 Ga 123(12) 14,53 119(8) 74 Ge(n, а) 71m Zn 3,4(,6) 14,53 3,4(,4) 72 Ge(n, 2n) 71 Ge 653(66) 13,36 72 Ge(n, 2n) 71 Ge 717(51) 13,69 72 Ge(n, 2n) 71 Ge 74(45) 14,36 72 Ge(n, 2n) 71 Ge 917(77) 14,74 76 Ge(n, 2n) 75(m+g) Ge 914(73) 14,53 116(13) 76 Ge(n, 2n) 75m Ge 7(5) 14,53 8(56) 7 Ge(n, 2n) 69 Ge 47(8) 14,53 49(8)

16 Nuclear reaction Nuclear reaction Half-life 175 Lu(n,2n) 174m Lu 142 days 175 Lu(n,2n) 174g Lu 3.31 years 175 Lu(n,p) 176 Yb 4.19 days 175 Lu(n,a) 172 Tm 63.6 hour Half-live Neutron energy, MeV Cross section, mb Cross section, mb EXFOR 159 Tb(n,p) 159 Gd 18,48 hour 4.8(.5) 6.6(.7) 159 Tb(n,a) 156 Eu 15,19 days 2.2(.3) 2.2(.5) 159 Tb(n,2n) 158 Tb 18 years 1913(6) 199(82) EXFOR (63) (59) 515(36) (6) 627(52) (25) 189(124) (219) 167(159) (19) 19(162) (.7) (.7) (.9) 18.5(2.2) 3.4(.5) (.1) (.3) (.2) 176 Lu(n,a) 173 Tm 8.24 hour (.34) 2.3(.6)

17 Conclusions Four cross sections for 72 Ge(n,2n) 71 Ge nuclear reactions and three cross sections for 175 Lu(n,a) 172 Tm have been measured experimentally at first time Cross sections for 176 Lu(n,a) 173 Tm and 175 Lu(n,p) 176 Yb nuclear reactions have been improved Effectiveness and correctness of neutron-activation method were confirmed by good agreement of obtained results with results of other research groups These results can be used to update nuclear databases Obtained results can be considered as important in the process ofo nuclear data estimation

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