Joint Research Centre (JRC)

Transcription

1 WPEC, May 2011, Issy-les-Moulineaux 1 Joint Research Centre (JRC) Report on experimental activities in Europe Arjan Plompen European Commission, Joint Research Centre, Institute for Reference Materials and Measurements

2 Measurements at IRMM GELINA 2 FP3/200m, GAINS 23 Na(n,n ), results finalized nat Zr(n,n ), data taken 76 Ge(n,n ), lower-limit 2039 kev (2 weeks) nat Mo(n,n ), data taking started FP16/30m CNRS-Strasbourg 232 Th(n,n ) and 235 U(n,n ) 238 U(n,n ), (data taking ongoing) 186,184,183 W (data taken, samples ORNL) FP3/300m 2 H(n,n) 2 H CENBG/TPC (AIFIRA): 2 H(n,d)n FP5/10m, FP15/30m, FP4/60m: Capture FP4/50m, FP2/25m: Transmission Cd (JSI, IAEA) Hf isotopes (w. SERCO, U. Birmingham, U. Manchester) W isotopes (w. ORNL, JSI, BNL, IAEA) Zr isotopes (w. INFN) Cu isotopes (w. ORNL) Rh (w. CEA) 241 Am(n, g), 241 Am(n,tot) (CEA, ANDES) 197 Au(n, g), analysis ongoing 238 U(n,g) planned (ANDES) FP17/10m, FP12/30m U. Gent, SCK 245 Cm(n,f)

3 Measurements at IRMM 3 Van de Graaff 7 Li(p,n) 7 Be with SOREQ, Hebrew University TOF measurements 1 kev and 15 kev DE p 197 Au(n,g) 198 Au/ 7 Li(n,p) 7 Be, 28 kev spectrum Follow-up of Ratynski & Käppeler PRC 1988 AMS Irradiations, w. ANSTO, VERA, KIT (EUFRAT) 232 Th(n,2n and/or 3n), 238 U(n,2n and/or 3n) 232 Th(n,g) and 238 U(n,g) 50 Cr(n,t) 48 V, 58 Ni(n,t) 56 Co, 54 Fe, 6 Li(n,t) 4 He 1d-TPC 234 U(n,f) Fission fragment yields and angular distributions 235 U(n,f) and 239 Pu(n,f) fission neutron spectrum 240,242 Pu(n,f) cs measurements planned (ANDES) VERDI+LaBr setup development, based on 252 Cf Scintia development: array of organic scintillators at GELINA new fission neutron spectrum and multiplicity measurements

4 Other laboratories 4 HZDR (Dresden-Rossendorf) 56 Fe(n,n ) and 23 Na(n,n ) by double TOF CENBG, IPNO Surrogate-n: actinide fission and capture Case study 174 Yb( 3 He,pg) 176 Lu vs 175 Lu(n, g) 176 Lu IPSC,ILL, CEA-DEN, CEN-DSM, CENBG, IPNO, Ruddersfield: U-233(n th,f) yields (Lohengrin) N_TOF 237 Np(n,f) by PPAC, paper sent 245 Cm(n,f) by FIC, under analysis (ANDES) 240,242 Pu(n,f) by FIC, planned (ANDES) 241 Am(n,g) phase-2, data taken, (ANDES) 238 U(n,g) phase-2, planned (ANDES) All Fe, Ni isotopes planned, preliminary 62 Ni (KIT, VERA, ANSTO) GANIL Fission induced in nucleon transfer using inverse kinematics GANIL, GSI, USC, CENBG, IPNL, IPNO (ANDES)

5 5 IGISOL, Jyväskylä (JYU, CIEMAT) Total absorption gamma ray spectroscopy of 88 Br, 94 Rb, 95 Rb and 137 I β-delayed neutron emission probabilities of 88 Br, 94 Rb, 95 Rb and 137 I

6 Inelastic scattering 6 filters shielding dep U90Mo10 neutron beam E l e c t r o n p i c k o f f collimation Fission chamber Detectors Sample l i n a c external trigger Digitizer Acqiris DC440 signal Neutron time-of-flight with digital processing

7 s (barn) 56 Fe(n,n g) 56 Fe 7 Improved data were sent to CEA for benchmark testing in the PERLE experiment. First feedback was received. Recommendation is to consider the data only up to 3.5 MeV Feedback indicates data above 3.5 MeV are too low, in agreement with the principle of the measurement Data were sent to ORNL to help extend the resolved resonance range analysis Collaboration between Negret, Plompen, Vaglio-Gaudard, Noguere, de Saint-Jean, et al. E n (barn)

8 23 Na(n,n g) 23 Na final results 8 Status until last meeting: (partial analysis)

9 Observed transitions Upper limit of energy 3.84 MeV Total inelastic and level inelastic (relies on decay data) 9 All statistics analysed Careful efficiency check gamma-ray detectors Final data delivered to CEA for benchmark testing Report EUR EN. Group cross section < 2.5 %!

10 Total inelastic versus other data and evaluations 10

11 Level cross sections 11

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15 Residuals Transmission 113 Cd Resonance Parameters 15 IAEA CRP: Improve consistency between integral and microscopic cross section data Measurements at GELINA Improved resonance parameters + covariance matrix exp. data REFIT Impact of new parameters on k eff using Resonance Parameters from case ENDF-VI.4 ENDF-VII this work Energy [ev] k eff Significant improvement, but calculations and experiments not in full agreement yet

16 Tungsten project w. ORNL 16 Courtesy Klaus Guber

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22 Transmission Counts / (1/ns) 241 Am measurements at GELINA 22 Solve discrepancy of σ γ th value between integral ( 700 b ) and microscopic ( 620 b ) data Collaboration : CEA ( Material, Data Analysis) JRC- ITU (Sample production & Characterization) JRC-IRMM (Experiments, Data Analysis) Unique sample : very few Am available and very hard to handle 241 Am infiltrated in Y 2 O 3 -matrix Transmission 10 Beam No - Beam Capture exp. data EBDF/B-7.0 JEFF3.1 JENDL3.3 1 energy [ev] Electron Energie / ev

23 TOF - experiments 241 Am at GELINA 23 IRMM P. Schillebeeckx, C. Lampoudis, S. Kopecky, C. Sage, P. Siegler, A. Plompen ITU J. Somers, F. Wastin, A. Fernandez, C. Nästren, H. Ottmar CEA F. Gunsing, C. Sage, G. Noguere, O. Bouland

24 TOF - experiments 241 Am at GELINA Sample (JRC-ITU Karlsruhe) AmO 2 homogeneously diluted in a Y 2 O 3 matrix (solgel method) Ø = 22.1 mm Homogeneity verified by X-ray radiography Impurities : mass spectrometry 325 mg 241 Am (40 GBq) by g - spectroscopy (calorimetry planned) Transmission at 25 m 6 Li-glass scintilllators Capture at 12.5 m Total energy detection C 6 D 6 detectors + WF (validated by exp.) Flux : 10 B(n, ) IC Normalization Internal : n from transmission External : 4.9 ev of 197 Au+n (saturated) 24

25 Transmission data and (REFIT, 241 Am) Resonance analysis to obtain resonance parameters from which cross section may be reproduced under any required circumstances Crystal lattice 25

26 Capture measurements at 12.5 m 26 Total energy detection principle C6D6 liquid scintillators 125 o PHWT R(E d,eg ) WF(Ed Flux measurements (IC) 10 B(n, ) < 150 kev ) de d ke g WF : from MC simulations C w (T n ) C c (T n,e d ) WF(E d ) de d Borella et al., NIMA 577(2007) 626

27 Residuals Yield Capture yield based on counts with E d > 650 kev is fully consistent with transmission data Exp. REFIT ( RP from transmission) Neutron energy / ev

28 Extended energy range 28 Will allow extraction of a thermal cross section consistent with the analysis by G. Noguere. Aiming for consistent analysis of internal normalization using transmission data and a normalization using Au. Calculation is based on transmission data. There is no negative resonance included yet.

29 Fission XS [b] Fission: 245 Cm(n,f) fission 29 n-beam 5 Collimator: 12mm 4 U f / / B Vacuum chamber Fit from 2 to 20 ev: U / B = 1.24 ± 0.02 SB -Detector 235-U or 245-Cm 10-B Measurement JEFF3.1 0 SB -Detector 200 Cd overlap filter m FP GELINA Energy [ev] Energy [ev] Comparison between measured 235 U(n,f) cross section and the reference JEFF3.1 evaluation.

30 Counts Yield Counts Yield Yield Fission: 245 Cm(n,f) fission (a) (b) (c) cm(n,f) N= cm(n,f) N= Background measurement: Generator at 500 Hz Pulse Generator Fit Channel Number Energy [ev] Energy [ev] (a) Pulse height spectrum; (b) fission yield spectrum; (c) Contribution of the (sf) decays measured with the beam closed and a pulse generator.

31 Fission Cross Section [b] Fission Cross Section [b] Fission: 245 Cm(n,f) fission Present Work Browne (1978) 400 Present Work Browne (1978) Moore (1971) Energy [ev] Energy [ev] Fission cross sections of 245 Cm obtained in the present work and compared with the measurements of Browne and Moore.

32 Tritium production 32

33 33 Fission fragment properties of the reaction 234 U(n,f) A. Al-Adili, F.-J. Hambsch, S. Oberstedt, S. Pomp* *Uppsala University, Uppsala, Sweden

34 Unwanted pulse height pile-ups: Alpha pile-up: Activity in 234 U sample 150,000α/sec Neutron-proton elastic scattering. Alpha pile-up correction possible in digital processing pulse-by-pulse. Pile-up correction 34 Drift-time method: False triggering due to alpha pile up

35 Strong Anisotropy 35 E n = 500 kev Strong negative and positive anisotropic distributions Before and after resonance E n = 835 kev Vs U235 thermal (isotropic)

36 Angular anisotropy 36

37 B Yield B Yield TKE June TKE dig Mass and TKE-distributions kev 1.5 MeV 500 kev 900 kev E n 835 kev 1.5 MeV 500 kev 900 kev A Mass A Mass

38 Cross section (b) Cross section (b) nelbe research program: n,n' ENDFBVI JENDL33 BROND Mo n,g n,2n Investigation of fast neutron induced reactions of relevance for nuclear transmutation and the development of Gen IV reactor systems 1. Inelastic neutron scattering (n,n g) 56 Fe, Mo, Pb, 23 Na and total neutron cross sections s tot (Ta, Au, Al, C, H) 2. Investigation of minor actinides (radioactive targets) Collaboration with n-tof at CERN Joint research project Nuclear physics data of relevance for transmutation (German Federal Ministry for Science and Technology funded, 02NUK13) Kapchigashev 64 Musgrove Neutron energy (MeV) A. V. Ignatyuk, priv.com FP7 support action, transnational access, ww

39 nelbe at ELBE : something special 39 superconducting electron accelerator cw operation with variable micropulse repetition rate micropulse charge 80 pc (thermionic Injector) micropulse length Dt < 10 ps precise definition of time of flight For time of flight measurements the repetition rate is adjustable 13 MHz / 2 n, n = 0,,10 Very high repetition rate (200 khz), low instantaneous neutron-flux background of photon flash from bremsstrahlung is reduced since Januar 2010 : SRF Laser-Injector development bunch charge up to 1 nc (not yet reached) fligh path m neutron flux on target sample cm -2 s -1 neutron energy range 100 kev < E n < 10 MeV (Liquid lead target, without moderator ) energy resolution DE/E < 1 % with 6.0 m flight path

40 nelbe double ToF detector setup 40 BaF 2 array for gamma detection (42 crystals, 20 cm, Ø 5.3 cm) neutron beam flight paths: source - sample: 600 cm sample - BaF 2 : 30 cm sample - plastics: 100 cm PTB 235 U fission chamber for neutron flux determination sample: nat Fe (99.8%) % 56 Fe mass: g g 56 Fe 4 plastic scintillators for neutron detection (1 m, 11 x 42 mm 2 ) Background from elastic scattering to BaF 2 and subsequent inelastic scattering Improve shielding and geometry of BaF 2 detectors

41 Improved double time of flight geometry and shielding 41 borated polyethylene block between BaF 2 and plastics combination of two single sided readout 20 cm long crystals to one double sided readout 40 cm long detector number of random events reduced by one order of magnitude Plastics BaF 2 -Setup angular coverage: - q n = q g = j = +/- ( )

42 Experimental methods and results Inelastic scattering Fe(n,n' g ) 56 Fe 56 Fe n * Fe n' * Fe 56 Fe γ with sample (78 h live time)

43 The 56 Fe(n,n g) cross section, 1 st excited state 43 2 MeV Fission chamber efficiency 2.1 % Fission chamber counts 0.7 % Fission chamber background 1.8 % Loss due to ADC range 0.1 % Scaling factor FC<->Target 0.3 % Attenuation factor 0.9 % Neutron flux 2.4 % Sample in counts 2.3 % Sample out counts 12.8 % Normalization factor 1.7 % BaF 2 efficiency 1.9 % Plastic efficiency (2.3 %) Reaction rate 3.8 % Cross section 4.5 % absolute normalization still not correct

44 Inelastic neutron scattering on 23 Na 44 Very preliminary: absolute normalization still not correct

45 FF distributions U

46 Results 46

47 47 N_TOF phase-2: new target 47 New pressure vessel Moderator (4 cm) Existing retention vessel protonis Pb Ø = 60 cm L = 40 cm Cooling water (1 cm) Existing Pool It is now possible to use different moderators (to optimize neutron spectrum or minimize background)

48 48 The new experimental area 48 Work Sector Type A Experimental area In the past, radioactive isotopes measured inside ISO2919 capsules, which induce a large background) Another possibility is sealed experimental area (hot lab). Dressing room Experimental area recently transformed to a Work Sector Type A (almost no restriction for radioactive samples). Various modifications: sealed area, controlled ventilation, underpressure, fire-proof doors, fire detection systems, radioactivity monitor, etc Access: dressing room, hand/foot contamination monitor, decontamination area, etc

49 The 245 Cm(n,f) reaction at n_tof 49 Very large background (0.4 GBq activity) 244 Cm contamination (6.6 %) Thr. Spontaneous fission background from 244 Cm subtracted with no-beam runs. High thresholds necessary to reduce the -background. Original raw data Backgroundsubtracted data Background Residual and SF background estimated with no beam runs 49

50 The 245 Cm(n,f) reaction: data at low energy 50 Below 200 mev, n_tof results are between White and Browne. Neither ENDF nor JENDL are ok (they don t reproduce neither of previous data). Above 1 ev, n_tof results generally agree better with White. Still differences between n_tof and evaluations, with JENDL-AC generally better. At low energy, libraries need to be revised. 50

51 The 245 Cm(n,f) reaction: data at low energy 51 JENDL-AC (based on White) agrees better with n_tof than ENDF (based on Browne), but both need revision. At higher energy, good agreement between n_tof and Moore (only data available). Resolved resonances available in evaluations only up to 100 ev, although resonance structures still present in n_tof data up to 1 kev. 51

52 The 245 Cm(n,f) reaction: data at high energy 52 Neutron energy n_tof (barn) JENDL/ AC-2008 ENDF/ B-VII n_tof cross-section higher than ENDF (JEFF and JENDL) between 10 kev and 1 MeV. In agreement with Moore up to 100 kev. Some differences with Fursov, on which evaluation is based. Analysis above 1 MeV needs refinement. First time with full range (from thermal to 20 MeV) covered in a single experiment. Browne (1978) White (1979) ev ev Moore (1971) ev kev kev-1 MeV ev-1 MeV

53 N_TOF, Am-241 capture 53

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56 Fission induced in multi-nucleon transfer using inverse kinematics at GANIL M. Caamaño, X. Derkx, F. Rejmund et al. 56 GANIL ; GSI, Germany ;USC, Spain ; CENBG, IPNL, IPNO, France Transfer reaction: access to heavy neutron-rich actinides Inverse kinematics: Identification of the complete element production Spectrometer: Isotopic distribution (detection) 238 U 6.1 AMeV recoil 12 C SPIDER DE-E FF1 FF2 VAMOS spectrometer Be Li C B Am U Np Pu

57 Update X. Derckx test