i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Neutron transmission and capture measurements for 241 Am at GELINA C. Lampoudis, S. Kopecky, A. Plompen, C. Sage P. Schillebeeckx, R. Wynants, O. Bouland, G. Noguere and F. Gunsing 3 rd International Workshop on Nuclear Data Evaluation for Reactor applications September 2012, Aix-en-Provence, France 1 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Outline i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Motivation existing data GELINA facility linac experimental setup - sample Measurements analysis and results Summary 2 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Motivation i r f u i r f u i r f u Nuclear waste management: s s s a a a c c c l l l a a a y y y a major pressing and potentially costly environmental problem Main components of waste from nuclear reactors Long term radiotoxicity and high volume makes geo-disposal not an optimum solution 3 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Resonance parameters for 241 Am+n in literature i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Capture Transmission – Weston and Todd NSE 61 (1976) 356 – Derrien and Lucas � ORELA (20 m and 85 m) � Saclay, LINAC (17 m and 53 m) � 1.1 10 -4 at/b 241 Am, AmO 2 + S powder � AmO 2 (4.5 10 -4 , 1.6 10 -4 , 4.7 10 -4 at/b) � Total energy + WF (C 6 F 6 ) � 10 B(n, α 1 ), 478 keV with NaI � E d > 500 keV � Normalized at E n = 0.0253 eV th = 582 b σ γ – Kalebin et al. – Jandel et al. PRC 78 (2008) 034609 � LANSCE (20 m) � Chopper, � 1.7 10 -6 at/b 241 Am (electroplated on Ti) � AmO 2 (3.3 10 -3 and 6.3 10 -3 at/b) � Total absorption (4 π ) � Collimation ~0.8 and 0.4 mm tot < 5.4 MeV � M γ = 4 and 3.75 < E γ ε n, γ = 12.5 ± 1.0 % � BF 3 proportional counters � Normalization at 4.9 eV of 197 Au(n, γ ) th = 665 ± 33 b ⇒ σ γ 4 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Literature data i r f u i r f u i r f u σ γ (E = 0.0253 eV) 1.3 Reference Year Weston and Todd s s s a a a c c c l l l a a a y y y Kalebin et al. 1.2 Derrien and Lucas ± 33 Jandel et al. 2008 665 (2g Γ n ) X / (2g Γ n ) Jandel ± > 24 Nakamura et al. 2007 690 1.1 ± 48 Fioni et al. 2007 696 ± 10 Maidana et al. 2001 672 1.0 ± 58 Shinora et al. 1997 854 0.9 ± 19 0.8 Evaluation 1982 610 Fröhner 0.7 0.1 1 10 Neutron energy / eV ⇒ A γ ≈ g Γ n for E r = 0.306 eV, 0.574 eV and 1.272 eV ⇒ Transmission: verify normalization of capture data of Jandel et al. and Weston and Todd ⇒ Capture to verify the thermal point and extend the energy range Homogeneous well characterized sample is required 5 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
GELINA facility i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Time-Of-Flight facility GELINA: dedicated to Pulsed white neutron source ∀ σ (n,tot) (10 meV < E n < 20 MeV) ∀ σ (n,f), σ (n,p), … Multi-user facility with 10 flight paths ∀ σ (n, γ ) (10 m - 400 m) The measurement stations have equipment to perform: F L IG H T P A T H S N O R D Total cross section measurements Partial cross section measurements E L E C T R O N L IN A C N E U T R O N Pulse width : 1ns T A R G E T Frequency : 50 – 800 Hz Average current : 4.7 – 75 μ A F L IG H T P A T H S Neutron intensity : 1.6 10 12 – 2.5 10 13 n/s S O U T H 6 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
GELINA neutron source i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y NEUTRON FLIGHT PATHS e - accelerated to E e-,max ≈ 140 • MeV (e - , γ ) Bremsstrahlung in U-target • (rotating & cooled with liquid Hg) ( γ , n) , ( γ , f ) in U-target • • Low energy neutrons by water NEUTRON ELECTRON moderator in Be-canning NEUTRON TARGET BEAMLINE EXIT MODERATOR 7 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
TOF - experiments at GELINA i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y • Sample – AmO 2 in Y 2 O 3 matrix (homogeneous) – Purification to reduce 237 Np – 40 GBq of 241 Am 324.5 mg by γ - spectroscopy 324.6 mg by calorimetry – Ø = 22.14 mm • Transmisson at 25 m verified by γ - radiography – 6 Li-scintilllators combined with non-contact electronic • Capture at 12.8 m microscope – Total energy detection – C 6 D 6 detectors + WF – Normalization � Internal : Γ n from transmission � External : 4.9 eV 197 Au+n 8 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Experimental conditions i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Capture and transmission 3 10 ⇒ g Γ n FWHM / meV 2 10 Doppler broadening dominates the observed width for E r > 1 eV 1 10 Γ tot Δ Doppler (292 K) Δ L = 25 m Only for low energy Δ L = 12.5 m resonances Γ can be 0 10 0.1 1 10 100 determined from shape Neutron energy / eV analysis 9 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Experiments at GELINA i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Measurement Flight path Frequency Filters Overlap Fixed Additional background background Transmission 25 m 50 Hz Co, Bi, Na Ag, Cd 50 Hz Co, Bi, Na, Pb Ag, Cd 10 B 800 Hz Na, Pb Au, W, Co, Mn Capture 12.5 m 50 Hz Co, Bi, Na Cd, Ag, W 400 Hz Cd Bi, Na Ag, W 10 B 800 Hz Na, S, Pb Ag, W, Co Region Overlap Fixed background filters − 50 Hz < 100 eV Co, Bi, Na 400 Hz > 1 eV Cd Bi, Na 10 B 800 Hz > 20 eV Na, S 10 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Transmission setup i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y Li-glass scintillator at 25 m C in − B in E r = 6.6735 ± 0.0030 eV of 238 U+n T exp = C out − B out L = 26.444 ± 0.006 m 11 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Transmission data i r f u i r f u i r f u Fixed background filters s s s a a a c c c l l l a a a y y y 3 10 3 10 ' C ' in C out ' B 2 Response / (1/ns) 10 ' in B 2 Response / (1/ns) 10 out 1 10 1 10 0 Na 10 0 Na Bi 10 Bi -1 10 Co -1 10 W Ag Co W Ag -2 10 1.2 4 5 6 7 -2 10 10 10 10 10 4 5 6 7 10 10 10 10 Time Of Flight / ns 1.0 Time Of Flight / ns Transmission 0.8 0.6 0.4 0.2 0.0 4 5 6 7 10 10 10 10 Time Of Flight / ns 12 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Capture measurements at GELINA i r f u i r f u i r f u L = 12.8 m s s s a a a c c c l l l a a a y y y Total energy detection • C 6 D 6 liquid scintillators – 125 o – PHWT • Flux measurements (IC) 10 B(n, α ) – WF : from MC simulations ' − B w ' − B w ' ' C w C w ∫ R ( E d ,E γ ) WF ( E d ) dE d =kE γ ' σ � Y exp = N ' Y � � N ' − B � ' − B � C � C � C w ( T n )= ∫ C c ( T n ,E d ) WF ( E d ) dE d Borella et al., NIMA 577(2007) 626 13 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Pulse height spectra : threshold i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y -1 10 241 Am(n, γ ) resonances 241 Am decay Counts / (1/keV) Choose optimum threshold -2 10 conditions on detected gamma ray energy due to sample’s activity -3 10 -4 10 241 Am Standard 0 2500 5000 7500 10000 E d ≈ 160 keV 650 keV Deposited energy / keV E γ ≈ 300 keV 850 keV 14 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Capture data (counts) for E d > 650 keV i r f u i r f u i r f u 0 -1 10 10 s s s a a a c c c l l l a a a y y y ' C C' ϕ B ' ' B ϕ 1 Counts / (1/ns) -1 B ' 10 Counts / (1/ns) 2 -2 10 ' = B ' ' B 1 +B 2 -2 10 -3 10 -3 10 1.0 Na Co -4 -4 10 10 4 5 6 7 4 5 6 7 10 10 10 10 10 10 10 10 0.8 Time-of-flight / ns Time-of-flight / ns 0.6 Yield Time dependent background 0.4 dominates 0.2 0.0 4 5 6 7 10 10 10 10 Time-of-flight / ns 15 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
Capture data: impact of threshold i r f u i r f u i r f u s s s a a a c c c l l l a a a y y y 0 1.0 10 Ed > 160 keV Ed > 650 keV 0.8 -1 10 0.6 Yield Yield 0.4 -2 10 0.2 -3 0.0 10 0.1 1 10 100 0.01 0.1 1 10 Neutron energy / eV Neutron energy / eV 16 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
i r f u i r f u i r f u Capture and transmission data consistency s s s a a a c c c l l l a a a y y y Exp. REFIT ( RP from transmission ) 1.0 Yield 0.5 Residuals 4 0 -4 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Neutron energy / eV 17 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
i r f u i r f u i r f u Capture and Transmission s s s a a a c c c l l l a a a y y y 0.030 1.2 0.025 1.0 exp. data Yield [not normalized] RSA fit 0.020 transmission 0.8 0.015 0.6 0.010 0.4 exp. data RSA fit 0.005 0.2 0.000 0.0 0.1 1 10 0.1 1 10 neutron energy [eV] neutron energy [eV] 18 Christos Lampoudis, CEA/Saclay WONDER 2012, Aix – en – Provence
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