Prompt γ-rays from Neutron Inelastic

Transcription

1 Prompt γ-rays from Neutron Inelastic Scattering at FaNGaS: Benchmark Spectrum Analysis T.H. Randriamalala, M. Rossbach Institute of Energy and Climate Research, Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, Germany August 23-28, 2015 MTAA 14 Delft, The Netherlands

2 Outline Introduction & Motivation Experimental Setup Sample Properties Benchmark Studies Conclusion & Outlook T.H. Randriamalala August 28, 2015 MTAA 14 2

3 Introduction & Motivation Prompt γ-rays Neutron Activation Analysis (m n, E ther. ) (m n, E > E T ) (m n, E ) Requirement for the use of fast neutrons interrogation: Knowledge of the absolute intensities or/and the partial cross section of (prompt) γ-rays Knowledge of the total (n, n γ) cross section T.H. Randriamalala August 28, 2015 MTAA 14 3

4 Introduction & Motivation FaNGaS The Fast Neutron Gamma Spectrometry aims to investigate (n, n γ) reaction using the ssion neutrons at FRM II, Garching. Scope of presentation: Confrontation of the measured intensity and count rate of γ-rays with the existing data or with the calculation results from theoretical model. T.H. Randriamalala August 28, 2015 MTAA 14 4

5 The Facility D 2 7 = 548 cm D 7 6 = 67 cm 1 Reactor core 4 Inner collimator 7 Irradiation position 2 Convertor plates (93% 235 U) 5 Outer collimator 8 Decay measurement 3 SR10 beam line 6 Shielded 50% HPGe position detector T.H. Randriamalala August 28, 2015 MTAA 14 5

6 FaNGaS Instrument Outer 2 Sample holder 3 γ 4 Detector shielding 5 collimator collimator (PE 5 n B4 C Pb ) Iron frame support W H L 126 cm 126 cm 266 cm Weight 4 tonnes Movable instrument T.H. Randriamalala August 28, 2015 MTAA 14 6

7 Beam Characteristic Neutron Beam Spectrum (Very pure) foil activation technique: Sample irrad. time 10 h Decay meas. time 1-2 h 12 threshold and 5 (n, γ) reactions Spectrum unfolding using STAYSL PNNL 1 code: Parametrized prior ux 2 : φ(e) = α t E exp( E/kT ) + α i E (1+c) exp( d/ E) + α f exp( E/a) sinh( be) 1 F.G. Perey, ORNL-TM-6062(1997). 2 H. Breitkreuz et al. NIM A 593 (2008) 466. T.H. Randriamalala August 28, 2015 MTAA 14 7

8 Beam Characteristic Neutron Beam Spectrum 10 8 E φ [MeV cm 2 s 1 ] E 2.1 MeV φde 10 8 cm 2 s 1 α f /α t > E [kev] Fast neutron beam energy spectrum at FaNGaS T.H. Randriamalala August 28, 2015 MTAA 14 8

9 FaNGaS Spectrometer n-type HPGe:GMX50-83, ORTEC Data acquisition: DSPEC-50, ORTEC + GammaVision-32 Spectrum evaluation: HYPERMET-PC Efficiency Ba Cl(n,γ) Co Cs Eu Cl 3 10 Energy [kev] 4 10 Detector eciency for prompt γ-rays (67 cm away from the detector) T.H. Randriamalala August 28, 2015 MTAA 14 9

10 Background H-D.E. N Ge 72 Ar, Ge In Ge C Al Pb 27 Pb 65 Cu 70 Ge Cu 63 Counts Pb 72 Ge 56,56Mn Ge Ge Pb 74 Ge Counts Pb Annih. B Ge 71m 75 m Ge Ge { H-S.E. X Energy [kev] Energy [kev] S.E. 55 -D.P. -S.E. -D.P.-S.E. 55 Counts D.E. 13 C -D.E. 14 N 12 C C C-S.E Counts N Pb 104 -D.P.-D.E S.E. -S.E. 2 H Energy [kev] Total count rate beam on: 4000 cps Strong lines: H(110 cps), B(36 cps), (5 cps) Fast neutron rate at the detector 10 s 1 (from Ge(n, n0 γ) Ge) 74 T.H. Randriamalala 3500 Energy [kev] August 28, 2015 MTAA 14 10

11 Sample Properties Foil Θ [mm] m [g] purity [%] Be Al Ti Co Ni Cu Zr Nb Rh Pd Cd In W Pt Pb U T.H. Randriamalala August 28, 2015 MTAA 14 11

12 Sample Properties Foil Θ [mm] m [g] purity [%] Be Al Ti Co Ni Cu Zr Nb Rh Pd Cd In W Pt Pb U T.H. Randriamalala August 28, 2015 MTAA 14 11

13 Benchmark Spectrum Found γ-rays are matched with γ-rays transition based on ENSDF a 83 γ-rays found: 54 (7), 56 (72), (4) Counts a Energy [kev] Prompt γ-rays from iron sample irradiation T.H. Randriamalala August 28, 2015 MTAA 14 12

14 Benchmark Analysis Found γ-rays Isotope Demidov 3 FaNGaS Missed by FaNGaS Co Ni Cu A.M Demidov et al., ATLAS of Gamma-Ray Spectra from Inelastic Scattering of Reactor Fast Neutrons Moscow (1978). T.H. Randriamalala August 28, 2015 MTAA 14 13

15 Benchmark Analysis I/I Dem Co Ni Cu E [kev] Relative γ-ray intensities compared to those of Demidov T.H. Randriamalala August 28, 2015 MTAA 14 13

16 Rate Comparison Measured count rate: R meas = R N = C Nεκt meas C : the counts in the peak ε: the eciency t meas : the measurement time κ: a correction factor (sample self-shielding) Calculated count rate: R calc = R N = σ p (E)φ(E)dE σ p : the γ-ray production cross section calculated from TALYS 3 φ: the determined ux 3 T.H. Randriamalala August 28, 2015 MTAA 14 14

17 Rate Comparison meas. 56 calc. 54 meas calc. R [ atom 1.s 1 ] R/R c E [kev] T.H. Randriamalala August 28, 2015 MTAA 14 15

18 Rate Comparison Co meas. 59 Co calc R [ atom 1.s 1 ] R/R c E [kev] T.H. Randriamalala August 28, 2015 MTAA 14 15

19 Rate Comparison Ni meas. 58 Ni calc R [ atom 1.s 1 ] R/R c E [kev] T.H. Randriamalala August 28, 2015 MTAA 14 15

20 Rate Comparison Cu meas. 63 Cu calc R [ atom 1.s 1 ] R/R c E [kev] T.H. Randriamalala August 28, 2015 MTAA 14 15

21 Conclusion Neutron inelastic (prompt) γ-rays were measured using 10 8 n cm 2 s 1 with Ē = 2.1 MeV at FaNGaS. FaNGaS can resolve a larger part of the γ-rays (cp. Demidov 1978) Measured intensity and count rate of γ-rays agreed with existing data. Outlook γ & n background reduction Total and partial cross sections determination Build an (n, n γ) catalog of elements T.H. Randriamalala August 28, 2015 MTAA 14 16

22 FaNGaS Collaboration: FZ-Jülich GmbH: M. Rossbach, T. Randriamalala, E.Mauerhofer MLZ, Garching: Zs. Révay, P. Kudejova, S. Söllradl, F. Wagner, C. Genreith FaNGaS is supported by BMBF. Project Nr: 02S9052A T.H. Randriamalala August 28, 2015 MTAA 14 17

23 Thanks for your attention!

24 Foils Mass [g] Reaction E thr [MeV ] R [/atom s] Al Al(n, p) 27 Mg (5.40 ± 0.14) Al(n, α) 24 Na (1.22 ± 0.04) Ti Ti(n, p) 46 Sc (1.87 ± 0.35) Ti(n, p) 47 Sc (2.19 ± 0.05) Ti(n, p) 48 Sc (5.45 ± 0.21) (n, p) 56 Mn (1.99 ± 0.07) Co Co(n, α) 56 Mn (4.00 ± 0.15) Ni Ni(n, p) 58 Co (9.67 ± 0.21) Ni(n, p) 61 Co 49 (2.45 ± 0.14) Cu Cu(n, p) 65 Ni (6.14 ± 0.37) Rh Rh(n, n ) 103m Rh (4.05 ± 0.36) In In(n, n ) 115m In (2.42 ± 0.04) (n, γ) 59 (3.22 ± 0.29) Co Co(n, γ) 60m Co (9.78 ± 0.22) In In(n, γ) 116m In (5.03 ± 0.08) W W(n, γ) 187 W (3.86 ± 0.10) Au Au(n, γ) 198 Au (9.59 ± 0.09) 10 17