Neutron cross section measurement of MA

Transcription

1 Neutron cross section measurement of MA Hideo Harada Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency 2007 Symposium on Nuclear Data Nov. 30, 2007, RICOTTI Convention Center 2007 Symposium on Nuclear Data 1

2 Neutron cross section measurement of MA Activities in the World Activities in Japan for thermal neutrons Activities in Japan for kev neutrons Possibilities in Japan for MeV neutrons Summary: Toward improvement in the MA data 2007 Symposium on Nuclear Data 2

3 1 Activities in the World LANL (USA) DANCE Ref Symposium on Nuclear Data 3 研究者数 化学部門との連携 人材育成 大形予算

4 1 Activities in the World IRMM (EU) Van de Graff, Electron L. A.: Fission, Capture, Total, (n,2n) TOF: Ge, C 6 D 6 n-tof (CERN, EU) TOF: 4πBaF 2, C 6 D 6 Karlsruhe (Germany) kev neutron capture (FP) kev neutrons TOF: 4πBaF 2 ILL (CEA, France) High flux reactor thermal neutrons Pulse height weighting technique: C 6 D 6, NaI etc low neutron sensitivity TOF method Total absorption detector: 4πNaI, BGO, BaF 2 etc high efficiency Gamma-spectroscopic method: Ge high energy resolution 2007 Symposium on Nuclear Data 4

5 IRMM (EU) 1 Activities in the World Gamma-spectroscopic method: Ge PR C56, 1266 (1996) 1200h beam time 694g U-238 F.P.=12.85 m 70% Ge 2007 Symposium on Nuclear Data 5

6 Activities in Japan Tohoku: Fission JAEA: Capture, Decay heat Kyoto: Capture & Fission TIT: Capture, γ-spectra Fundamental R&D on Neutron Cross Sections for Innovative Reactors Using Advanced Radiation Measurement Technology Project Leader: M. Igashira (T.I.T.) 80 Voltage [ch] JRR-3M 20MW 信号波形ノイズの代表波形 Time [ch] En=1-100 kev! 4πGe spectrometer KUR 5MW KURRI lead slowing down spectrometer KURRI electron linac YAYOI 2kW 2007 Symposium on Nuclear Data 6

7 2 No.1 Activities in Japan for thermal neutrons When there are resonance peaks below 0.5 ev, can we measure σ 0 and resonance integral correctly? JENDL-3.3, T = K ENDF/B-VI, T = K 237 Np Capture cross section (barn) b b Cd cut-off ev Neutron Energy (ev) 2007 Symposium on Nuclear Data 7

8 2 Activities in Japan for thermal neutrons Reaction Present JENDL-3 ENDF/B- VII Mughabghab Atlas 5 th ed. 237 Np(n, γ) 238 Np σ 0 =169±4 b b b 175.9±2.9 b 243 Am(n, γ) 244 Am σ =174.5±5.3 b (150 b) (150 b) 241 Am(n, γ) 242g Am σ 0g =628±22 b σ b b σ 0g 533±13 b σ 0 587±12 b References: Harada et al. JNST 43 (2006) Ohta et al. JNST 43 (2006) Nakamura et al. JNST 44 (2007) Dec Symposium on Nuclear Data 8

9 2 Activities in Japan for thermal neutrons Ohta et al. JNST 43 (2006) Symposium on Nuclear Data 9

10 3 KURRI Linac Activities in Japan for kev neutrons JAEA, TIT, Kyoto + n 10m Neutron flux! 237 Np 93 T 1/2 = yr 22m 10-1 H 2 O moderator e - -Ta reaction Relative neutron flux(/mev) > 1 ev Neutron Energy (MeV) 2007 Symposium on Nuclear Data 10

11 3Activities in Japan for kev neutrons: Capture JAEA, Tokyo Tech., Kyoto Electron beam Water moderator Linac shielding wall BF 3 -counter neutron monitor Evacuated flight tubes 4πGe spectrometer Lead shadow bar Neutron producing target 10.0 m Neutron beam filters Lead H 2 BO 3 Np-237 Am-241 MA sample Concrete 2007 Symposium on Nuclear Data 11 Am-243

12 Experiments for Capture KUR Electron Linear Accelerator Facility Electron beam:energy 30 MeV, Ave. Current 4πGe spectrometer Cluster 2 (14 Ge crystals) Clover 4 (16 Ge crystals) BGO anti-coincidence shields 31μA Rep. Rate 100 Hz, Pulse Width 100 ns 2007 Symposium on Nuclear Data 12

13 3 Activities in Japan for kev neutrons Nucl. Instru. Meth. A 562, 767 (2006) J. Nucl. Sci. Technol. 42, 135 (2005) 水本等 原子力学会 2007 年秋の大会 The data were successfully obtained, but needs more statistics for high energy region Symposium on Nuclear Data 13

14 Deduced capture cross section of 237 Np (5MBq sample) 2007 Symposium on Nuclear Data 14

15 Comparisons of data for kev neutrons Needs more statistics for En>100eV Energy [ev] 2007 Symposium on Nuclear Data 15

16 3 Activities in Japan for kev neutrons Tohoku, Kyoto Fission 237 Np, 241 Am, 242m Am, 243 Am En=1-100 kev Kyoto University Lead Slowing Down Spectrometer (KULS)* driven by a 46 MeV electron linear accelerator *Kobayashi et al; measurements for minor actinide, En< 20 kev In the present study Back-to-back fission chamber (BTB, Ratio measurement) 235 U 99.9 %, as a standard For extension of energy range to high energy side, - Digital signal processing (DSP) technique to eliminate γ-flash - Heavy electrical shielding of BTB, cable, PA Quantitative assay of samples: low geometry α-counting 2007 Symposium on Nuclear Data 16

17 Fission Sample deposit (U-235) Sample deposit (MA) Ar + CO 2 Connector 49 mm Electrode (anode) Chamber (aluminum) Ar + CO 2 43 mm Voltage [ch] Noise Signal DSP 信号波形ノイズの代表波形 Time [ch] Wave form analysis for each slowing down time Subtraction of γ-flash noise from raw signal (noise + signal) 2007 Symposium on Nuclear Data 17

18 4 Problems in measurement for MeV neutrons The data is very limited especially for MeV neutrons. 237 Np capture Cross Section (b) D.C.Stupegia+ ('67) M.Lindner+ ('76) L.W.Weston+ ('81) Ju.N.Trofimov+ ('83) N.N.Buleeva+ ('88) N.N.Buleeva+ ('88) N.N.Buleeva+ ('88) Katsuhei Kobayashi+ ('02) Katsuhei Kobayashi+ ('02) E.I.Esch+ ('05) Neutron Energy (ev) present (=CCONE) JENDL-3.3 ENDF/B-VII.0 Nakagawa Symposium on Nuclear Data 18

19 4 Possibilities in Japan for MeV neutrons Activation by fast neutrons at Yayoi 2007 Symposium on Nuclear Data 19

20 4 Possibilities in Japan for MeV neutrons 放射線標準施設 TOF by fast neutrons at JAEA Tokai 2007 Symposium on Nuclear Data 20

21 5 Toward improvement in the MA data Integral differential CEA ILL KUR JRR3 LANL, IRMM, n-tof KURRI linac J-PARC T.I.T. Yayoi 放射線標準施設 Abroad Japan JAEA thermal ev kev MeV Neutron Energy Several facilities covering a wide energy range are or will be soon available for the measurements of MA cross section in Japan. High flux field will contribute to deduce statistical uncertainties. Efforts to deduce the experimental uncertainties including systematic uncertainties are important. The comparisons of independent measurements will help to notice the unexpected systematic uncertainties Symposium on Nuclear Data 21