1. Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx1 peter.schillebeeckx@ec.europa.eu Joint Research Centre (JRC) IRMM - Institute for Reference Materials and Measurements Geel - Belgium http://irmm.jrc.ec.europa.eu/ http://www.jrc.ec.europa.eu/ Neutron Induced Cross Section Measurements Workshop on Nuclear Reaction Data for Advanced Reactor Technologies Trieste, Italy, 19 – 30 May 2008

2. 2Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Importance of neutron induced reactions for reactor operation Nuclear fuel U, Pu, Th (n,f), (n,  ), … Fission products (“neutron poisoning”) 103 Rh, 135 Xe, 135 Cs, 149 Sm (n,  ) Structural materials Fe, Cr, Ni n,xn n,3n            233 Th 232 Th 231 Th 230 Th 230 Pa 231 Pa 232 Pa 233 Pa 234 Pa 234 U 233 U 232 U  n,f n,2n n,  e.g. Th-U cycle Safety + Economics

3. 3Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Cross section data Integral data Theory Evaluation Evaluated Data File Industry Microscopic data Research Laboratories Regulatory Bodies Benchmark measurements

4. 4Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Neutron induced reactions n + X  Y + r Various reaction channels n + X  X + n(n,n)elastic scattering  n  Y +  (n,  )capture    Y 1 + Y 2 (n, f)fission  f  Y + p(n,p)  p ... Probability for a reaction (n,r) to occur: Partial cross section:  r Total cross section  tot =  r =  n +   +  f +  p + …

5. 5Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Cross section A cross section  has the dimension of an area. The unit of a cross section is taken as: 1 barn, 1 b = 10 -24 cm 2. Reaction rate for a neutron beam on a target (thin layer) :  n : neutron flux N A : Avogadro constant N X : number of nuclei M X : molar mass of nucleus X m(X): mass of X in most cases the number of nuclei per unit area are required (these will be denoted by n)

6. 6Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resonance structure A cross section as a function of E n shows a resonant structure, which can be described by a Breit-Wigner shape : with  natural line width (FWHM) E R resonance energy o  tot  tot / barn

7. 7Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Cross sections : energy dependent 238 U(n,tot) = 238 U(n,n)+ 238 U(n,  )  tot =  n +   Resonance Region : D >  Resolved Resonance Region :  R < D Unresolved Resonance Region :  R > D High Energy Region : D <   tot ERER

8. 8Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Parameterisation of neutron cross sections by nuclear reaction theory Ensures consistency between partial and total cross sections Ensures consistency between cross section data in different energy regions Prevents the use and recommendation of unphysical data Reliable calculations of Doppler broadened reaction cross sections Permits inter - and extrapolation into regions were no experimental data are available Permits prediction of reaction cross sections for isotopes not directly accessible to experiments

9. 9Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Parameterisation of neutron cross sections by nuclear reaction theory Thermal:R - Matrix RRR:R - Matrix (SLBW, Reich-Moore) URR:Statistical Models (Hauser – Feshbach + WF) High:Optical Model, precompound, direct reactions, …

10. 10Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Parameterisation of neutron cross sections by nuclear reaction theory URR Statistical Models Res. Par. E Rj,  n,j,  ,j, J j, R High Energy Optical Models Thermal RRR R-Matrix Level Statistics + R D 0, S o, Average Par. D o,1, S o,1,, R Exp. Data

11. 11Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Neutron energy spectrum Reactor ADS : E p = 600 MeV

12. 12Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Importance of resonance structure Transmission (d Fe = 40 cm) nat Fe + n GELINA

13. 13Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resonances : compound nucleus reactions n + X  C *  Y + r Entrance channel Compound nucleus Exit channel

14. 14Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Two step process (1) Formation of compound nucleus  C* (2) Decay of compound nucleus P r Partial cross section Bohr’s hypothesis : compound nucleus reaction Resonance part of cross section AXAX -S n EnEn A+1 X  c*  E* A X +n

15. 15Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx E R = 134 eV  n = 0.093 eV   = 0.106 eV J  = 1 -  = 0 g J = 3/4 e.g. 109 Ag s-wave at E R = 134 eV (E R,  n,  , J (  ), )  tot  tot / barn ERER ERER ERER

16. 16Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Compound nucleus reactions No capture without scattering Relative contribution of  n and   to  tot may be different Boundaries of the resonance region differ Not only resonances (see 58 Fe + n)  tot

17. 17Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx SLBW for low energy s-wave (n,n) and (n,  ) (n,  ) (n,n) Total  (E R,  n,  , J(  ), )

18. 18Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Interference term s-wave p-wave ( > 0)  (E R,  n,  , J(  ), )

19. 19Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Ideal experiment In ideal conditions, without any instrumental resolution broadening, we can determine  o   /  and  from one experiment.    and  n  o = f(g J,  n,  ) However, Due to instrumental limitations and Doppler effect it is in most cases impossible to determine  and  o   /  Due to the instrumental limitations the effective experimental observable is : the area of a resonance ERER

20. 20Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Experimental observables Transmission Capture n is the number of nuclei per unit area Neutron energy / eV Rae et al., Nucl. Phys. 5 (1958) 89 F. Fröhner et al., ND1966, p. 55

21. 21Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Capture + Transmission  Ideally : combine thin capture measurements with transmission measurements on samples with different thicknesses Capture Transmission Rae et al., Nucl. Phys. 5 (1958) 89 F. Fröhner et al., ND1966, p. 55 more sensitive to small resonances

22. 22Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Example: 109 Ag s-wave at 5.2 eV I = 1/2 -, i = 1/2, and = 0  J = 0 - or J = 1 -  g J = 1/4 or g J = 3/4 Thin Sample Transmission n = 1.39 10-5 at/b A t,thin = 0.106 eV Thick Sample Transmission n = 4.74 10-4 at/b A t,thick = 1.039 eV g J = 3/4 g J = 1/4 Rae et al., Nucl. Phys. 5 (1958) 89  (g J  n  9.5 meV,   150 meV, =0)

23. 23Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resonance Area Analysis e.g. 109 Ag 5.2 eV E R = 5.2 eV,  n = 12.7 (0.23) meV,  = 149.0 (7.8) meV, g J = 3/4 g J = 3/4 g J = 1/4 g J = 3/4 Rae et al., Nucl. Phys. 5 (1958) 89  (E R,  n,  , J(  ), )

24. 24Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Neutron width s-wave p-wave ( > 0)  n depends on E n : due to the centrifugal- barrier penetrability, which depends on the angular momentum quantum number of the incoming neutron and E n (penetration probability depends on ) s-wave ( = 0) p-wave ( = 1)  cross section at 0.025 eV (Thermal)

25. 25Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx  th and contribution of s-wave resonances Additional contribution from bound states (negative resonances) AXAX -S n A+1 X  c*  E* A X +n

26. 26Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Determination of resonance parameters SLBW and Resonance Area Analysis –Instructive –Principles remain valid ! Resonance Shape Analysis (RSA) (R- Matrix : theory) –Extension of RRR –Direct treatment of broadening effects (Resolution & Doppler) –Direct treatment of multiple scattering effects (capture data) –Reduction of uncertainties –SAMMY ( N. Larson)  S. Marrone –REFIT ( M. Moxon) Summer School on Neutron Resonance Analysis 2- 6 June 2008, IRMM Geel

27. 27Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx TOF - measurements Introduction TOF - measurements –TOF-principle –Neutron production –Resolution –Experimental observables Transmission experiments Examples

28. 28Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Cross section measurements Thermal –Reactor –TOF-facilities Resolved Resonance Region –TOF-facilities (photonuclear reactions, spallation sources) Unresolved Resonance Region –TOF-facilities –VdG + TOF –Filtered beams (+ TOF) –Activation High Energy Region –TOF-facilities (spallation sources) –Activation –VdG (< 20 MeV) –Cyclotron  N. Colonna

29. 29Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx TOF - measurements Photonuclear reactions –GELINA(n,tot)+(n,  ), (n,f), (n,p), (n,  ) –ORELA(n,tot)+(n,  ), (n,f), (n,p), (n,  ) –RPI (+ filtered)(n,tot)+(n,  ), (n,f), (n,n) –POHANG (KAERI)(n,tot) –KURRI(n,tot)+(n,  ) Spallation sources(N. Colonna) –n_TOF(n,  ), (n,f) –LANSCE(n,tot)+(n,  ), (n,f)

30. 30Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Velocity from TOF Resolution  L Neutron flux  L TOF - measurements 150 MeV LINAC Sample Flight path U depl.    f    n’   tot tntn L vnvn 

31. 31Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx TOF-facility : GELINA Time-of-flight facility Pulsed white neutron source (5 meV < E n < 20 MeV) Multi-user facility with 10 flight paths (10 m - 400 m) The measurement stations have special equipment to perform: –Total cross section measurements –Partial cross section measurements Pulse Width:1ns Frequency:50–800 Hz Average Current:4.7–75  A Neutron intensity:1.6 10 12 –2.5 10 13 n/s

32. 32Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx GELINA : neutron production e - accelerated to E e-,max ≈ 140 MeV (e -,  ) Bremsstrahlung in U-target (rotating & cooled with liquied Hg) ( , n), ( , f ) in U-target Low energy neutrons by water moderator in Be-canning

33. 33Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Compression Magnet  compressed pulse length ~ 1 ns  E = 60 MeV  = 10 ns

34. 34Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx GELINA : neutron production SHIELDING for MODERATED SPECTRUM SHIELDING for FAST SPECTRUM Flaska et al.,NIM A, 531, 394 (2004)

35. 35Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx ORELA : neutron production

36. 36Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resolution  T –Initial burst width –Time jitter of detector –Electronics  L –Neutron transport in target and moderator –Neutron transport in the detector or sample Detector L0L0 Resolution L = L 0 + L’ m EnEn e - beam

37. 37Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resolution: Monte Carlo simulations Flaska et al.,NIM A, 531, 394 (2004)

38. 38Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resolution : experimental verification

39. 39Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Direct spectrum Moderated spectrum (n,  )NIM, A577 (2007) 626 (n,tot)NP A 773, 173 (2006) (n,f) and (n,cp)NSE 156, 211 (2007) (n,n’  )NP A 786, 1 (2007) Measurement Stations

40. 40Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Experimental observables Reaction Measurements Transmission Detector

41. 41Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission Incoming flux cancels Detection efficiency cancels Good geometry  Direct relation between T and  tot Reaction  r Neutron fluence rate  r Detection efficiency A r Effective area Y r Reaction Yield Beam fraction undergoing (n,r)  Complex relation between C r and Y r Y r related to  r Experimental observables

42. 42Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Reaction yield : thin Sample Thin sample, no scattering only self-shielding  Y r = f(  r,  tot ) Infinitely thin sample  Direct Relation : Y r  r nn  x  n (x)

43. 43Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Correction for self-shielding and multiple scattering requires   tot &  n Reaction yield : thick sample

44. 44Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission experiments Introduction TOF – measurements Transmission experiments –Principle –Experimental set-up –Facilities –Data reduction Applications

45. 45Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission : principle –All detected neutrons have traversed the material –Neutrons scattered in the target do not reach the detector  Homogeneous sample  Importance of collimation (good geometry!) sampledetector

46. 46Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Neutron Detector Lithium-glas scintillator Neutrons interact with lithium via 6 Li(n,  )t The charged particles create fluorescence in the scintillator material The light is reflected to the entrance window of the photomultiplier The light is transformed into electrons in a photocathode The electron signal is amplified in the photo-multiplier tube 6 Li(n,t)  Scintillator + Photomultiplier

47. 47Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission detector Time Resolution 6 Li(n,t)  Scintillator + Photomultiplier

48. 48Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission: experimental set-up Sample & Background FiltersDetector Kopecky and Brusegan, Nucl. Phys. A 773 (2006) 173 Borella et al., Phys. Rev. C 76 (2007) 014605 Low energy : 6 Li(n,t)  Li-glass High energy :H(n,n)HPlastic scintillator Detector stations at GELINA Moderated : at 30 m, 50 m, (100 m, 200 m) Fast : at 400 m

49. 49Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission

50. 50Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Transmission Sample out (1) Dead time correction (2) Background subtraction Sample in (1) Dead time correction (2) Background subtraction RRR Resonance shape analysis URR Correction for resonance structure

51. 51Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Resonance analysis : 241 Am

52. 52Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx ORELA : transmission + capture Guber et al., Phys. Rev C 65 (2002) 058801 35,37 Cl + n Transmission - at 20, 80 and 200 m - 6 Li-glass scintillator Capture - at 40 m - C 6 D 6 -detectors Measurements on over 180 nuclides: ORELA measurements have contributed to ~80% of U.S. Evaluated Nuclear Data File (ENDF/B) evaluations

53. 53Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx RPI : transmission + capture Transmission - at 15, 25 and 100 m - 6 Li-glass scintillator Capture - at 30 m - 16 segment NaI(Tl)-scintillator Drindak et al., Nucl. Sci. Eng. 154 (2006) 294 Leinweber et al., Nucl. Sci. Eng. 134 (2000) 50 Nb

54. 54Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx POHANG : transmission Transmission - at 10 m - 6 Li-glass scintillator (1.5 cm thick) Lee et al., Radiat. Meas. 35 (2002) 321

55. 55Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx LANSCE : transmission in high energy region Transmission - at 38 m - plastic scintillator (1.27 cm thick) Abfalterer et al., Phys. Rev. 63 C (2001) 044608

56. 56Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Applications Introduction TOF – measurements Transmission experiments Applications –Doppler –Thermal region –RRR & URR –High energy region

57. 57Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Doppler measurements Temperatures from 10 K - 300 K

58. 58Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Optimise the U - Pu fuel cycle More accurate nuclear data are needed for: 1)Tendency to operate conventional nuclear power plants at increased fuel burn-up 2)Fuel cycles based on reprocessed fuel (closed fuel cycle) 3)Spent fuel storages (ORNL – RADWASTE) M. Salvatores, ND2002, J. Sci. & Techn. 2 (2002) p. 4 F. Storrer et al., ND2002, J. Sci. & Techn. 2 (2002) p. 1357 NEA High Priority List, March 2001   < 2-3% 1 & 2: Collaboration with CEA Saclay (F) 3: Collaboration with ORNL (US)

59. 59Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx 103 Rh: Thermal region  (n,  ) at 25.3 meV WF: 142.0 (1.5) b 1.0 % normalization 0.5 % uncorrelated Counts: 143.3 b Transmission: 50 m 100 Hz Capture : 15 m 40 Hz n = 3.35 10 -4 at/b n = 1.87 10 -3 at/b E R =1.260 eV  n = 0.464 meV   =156.0 meV g J =3/4  D  35 meV  R < 5 meV

60. 60Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx 55 Mn Transmission measurements at 50 m

61. 61Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx IAEA CRP: Thorium – Uranium Fuel Cycle Resonance parameters (RRR & URR) for 232 Th + n

62. 62Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx 232 Th Resolved Resonance Region Simultaneous analysis of transmission and capture DetermineR Determine   Determine  n Verifyg J  Examples

63. 63Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Scattering radius : transmission with thick sample R’ = 8.9 fmR’ = 9.5 fm Neutron Energy / eV Transmission Interference  pot  res 232 Th + n

64. 64Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Statistical factor : simultaneous analysis of capture and transmission data Neutron Energy / eV Capture Yield Transmission g J = 2 g J = 1 200.0 199.0 200.0 199.0 232 Th + n

65. 65Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Average radiation width from capture data with REFIT ORELA (Transmission): = 25.10 (0.40) meV IRMM (Capture) : = 25.12 (0.06) meV 232 Th(n,  )

66. 66Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Evaluation in URR and high energy region Sirakov et al., Annals of Nuclear Energy, accepted 2008 Capote et al., Phys. Rev. C 72 (2005) 064610 Soukhovitskii et al., Phys. Rev. C 72 (2005) 024604

67. 67Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx 206 Pb + n : new evaluation in RRR Thermal neutron energy BNC RRR GELINA

68. 68Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Scattering radius from transmission of s-wave at 66 keV R = 9.55 (0.02) fm R = 9.46 (0.15) fm (Mughabghab) Interference  pot  res Borella et al., Phys. Rev. C 76 (2007) 014605 206 Pb+n

69. 69Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Determination of statistical factor g J thin thick transmission 206 Pb+n

70. 70Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Final RSA results: 206 Pb+n 304 resonances observed 221 resonances in evaluated files R = 9.54 (0.02) fm E n,  n from transmission < 80 keV : IRMM data (Borella et al.) > 80 keV : ORELA data (Horen et al.) E 0,   up to 620 keV (Borella et al.) (before up to 200 keV ) f E1 and f M1 from unfolding of C 6 D 6 spectra Horen et al., Phys. Rev. C 24 (1981) 1961, C20 (1979) 478 Borella et al., Phys. Rev. C 76 (2007) 014605 Rochman and Koning, Nucl. Instr. Meth. A (2008), doi:10.1016/j.nima.2008.02.003

71. 71Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx High energy region + Optical Model LANSCE Finlay et al., Phys. Rev. C 47 (1993) 237 Abfalterer et al., Phys. Rev. C 63 (2001) 044608

72. 72Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Total cross section + Optical model Deb et al., Phys. Rev. Lett. 86 (2001) 3248

73. 73Workshop on Nuclear Reaction Data for Advanced Reactor Technologies – Trieste, 19 – 30 May, 2008, P. Schillebeeckx Importance of transmission data Easiest and most accurate measurement No need for a standard cross section ! Resonance region –parity assignment –thick & thin measurements result in (g J,  n ) and R (scattering radius) –partial cross section data complementary to transmission for   <<  n –normalization of capture data (  n <<   )  tot data are a prerequisite to good partial cross section analysis (Fröhner, JEF Report 18) –self-shielding and multiple scattering corrections –neutron sensitivity of the detectors Total cross section + optical model (predictive power) High resolution transmission data for shielding calculations