(n,xn ) reaction cross section measurements for (n,xn) reaction - PowerPoint PPT Presentation

WONDER 2012 3rd International Workshop on Nuclear Data Evaluation for Reactor Applications September 25-28, 2012 Aix en Provence, France (n,xn γ ) reaction cross section measurements for (n,xn) reaction studies M. Kerveno A. Bacquias, C. Borcea, Ph. Dessagne, J.C. Drohé, N. Nankov, M. Nyman A. L. Negret, A. Plompen, C. Rouki, G. Rudolf, M. Stanoiu, J.C. Thiry 1 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Introduction : general context Gen IV reactor systems I mpo rta nt ne e ds o f ne w nuc le ar data Ne w c onc e pts of r e ac tor s o ve r a wide ra ng e o f -> fa st re a c to rs nuc le i, e ne rg y a nd re a c tio ns -> a c c e le ra to r drive n syste ms One o f the c ha lle ng e s Ne w fue l c yc le is -> 238 U / 239 Pu me asur e me nt’s ac c ur ac y -> 232 T h / 233 U NEA Nuclear Data High Priority Request List e ac tions (x ≥ 1) c o ntrib ute to I n re a c to r, (n,xn) r -> E ne rg y lo ss me c ha nism -> Ne utro n multiplic a tio n Bib lio g ra phy in da ta b a se s sho ws tha t -> Pro duc tio n o f ra dio a c tive iso to pe s ove me nt o f the knowle dge of impr (n,xn) pro c e ss is ne c e ssar y . 2 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Introduction : importance of (n,xn) cross section knowledge xample of 238 U(n,n’) E State of the ar t : OR fro m 1956 to 2009 40 me asur e me nts in E XF oss se c tion me a sure me nts 8 total c r => lar ge disc r e panc ie s b e twe e n e xpe rime nta l da ta a nd b e twe e n e va lua te d c ro ss se c tio ns => 238 U(n,n’) XS unc e r tainty = 20 % Pr e c ise r e quir e me nt fr om NE A and CE A/ Cadar ac he Salvato r e s e t al. ; A.Santamar ina e t al. Curre nt unc e r taintie s on 238 U(n,n’) impac t the ac c ur ac y o f the k e ff , o f the a nd o f the β e ff c alc ulations o f la rg e c o re re a c to rs (PWR, F R). powe r ac y o n 238 U(n,n’ ) : T ar ge t ac c ur -> PWR : ± 10 % -> SF R : ± 5 % 3 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Introduction : experimental method How to study (n,xn) r e ac tions? de te c tio n o f the γ -r ays -> Dire c t me a sure me nt o f se c o nda ry ne utro ns ste mming fro m the -> Ac tiva tio n te c hniq ue de c ay of e xc ite d state s ompt γ -r o f nuc le us c re a te d b y -> pr ay spe c tr osc opy the (n,xn) r e ac tion . Example o f 238 U(n,n’ γ ) (n,xn γ ) c r oss se c tions : D.Be r nar d e t al. - c a n a lso impac t the k e ff c a lc ula tio n, F o r sma ll re a c to r c o re : - c a n b e me a sure d using “white ” ne utr on be am k e ff -> 50 % of its se nsitivity with the T OF te c hniq ue , fr om fir st ine lastic thr e shold - pro vide e xc lusive me asur e me nts ve r y F o r la rg e re a c to r c o re : ic tive fo r te sting mo de ls. r e str adial powe r -> se nsitivity to r the fir st ine lastic le ve ls om (n,xn γ ) c ro ss se c tio n me a sure me nts to total (n,xn) c ro ss se c tio n : F r e tic al mode l … Ne e d of str uc tur e par ame te r s and the or 4 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Introduction : IPHC / IRMM / IFIN-HH experimental project (n,xn γ ) r e ac tion c r oss se c tions me asur e me nts IPHC (F r anc e ) / IR MM (Be lgium) / IF IN-HH (R omania) c ollabor ation => de ve lo pme nt o f a n e xpe r ime ntal se t-up GR APhE ME de dic a te d to the pr e c ise me asur e me nt o f the (n,xn γ ) r oss se c tions o n a c tinide s e ac tion c r @ GE L INA fac ility (IR MM-Be lgium) 2005 – 2010 : 235 U c a mpa ig n 2009 – 2010 : 232 T h c a mpa ig n 2009 – 2012 : nat,182,183,184,186 W c a mpa ig n 2011 – 2012 : GRAPhEME 238 U c a mpa ig n (GeRmanium array for Actinides PrEcises MEasurements) ation with the or e tic ians a nd e valuator s to impr ove the quality Collabor a nd the de sc r iption o f o ur me asur e d c r oss se c tions 5 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Experimental set-up @ GELINA : GRAPHEME GE L INA, IR MM, Ge e l, Be lgium Prompt γ spectroscopy White neutrons beam few eV ➔ 20 MeV Pulsed f = 800 Hz Neutron Beam Fission e - Chamber 30m HPGe Uranium planar Target detectors 150° 150° 110° 110° Sample 6 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Experimental set-up @ GELINA : GRAPHEME F P16 – 30 m F issio n Cha mb e r ( 235 U) GRAPhEME -> DAQ T NT 2 Car d @IPHC BEAM BEAM GRAPhEME GRAPhEME 4 HPGe pla na r de te c to rs M A E B Noise insulation (e le c tro ma g ne tic fie ld fro m the a c c e le ra to r) and Shie lding : Pb -Cd-Cu c a stle γ bac kgr ound r e duc tion 7 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Data Analysis and γ spe c tr T OF a R adioac tivity h(n,n’ γ ) 232 T 232 T h h(n,2n γ ) 231 T 232 T h h(n,3n γ ) 230 T 232 T h 232 T h γ -flash 8 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Data Analysis T OF spe c tr um γ flash 235 U c ase E n = 20 Me V E n = 6 Me V E n = 1 Me V E n = 0.1 Me V r adioac tivity 9 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Data Analysis 235 U c ase and γ spe c tr T OF a gy gate (n,n’) e ne r gy gate (n,2n) e ne r 10 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Data Analysis γ Cr oss se c tion c alc ulation n : number of detected det σ N : number of atoms γ ( n , xn ) d n at θ = in the sample ( ) det Ω ⋅ φ ⋅ ε ⋅ φ d N t : neutron flux n Pulsed at n ε : HPGe efficiency Neutron Beam t : measuremen t time Fission Chamber Diffe re ntia l c ro ss se c tio n c a n b e e xpre sse d b y a finite sum of L e polynomials : e ge ndr σ γ σ ∞ ( n , xn ) HPGe d ∑ θ = θ tot ( ) a P (cos ) planar Ω π i i detectors d 4 = i 0 Me a sure me nt a t the polynomial node s 150° 150° e : Gauss quadr atur 110° 110° Sample σ σ ⎡ ⎤ d d γ σ = π θ + θ ( n , xn ) * * * * 4 w ( ) w ( ) ⎢ ⎥ Ω Ω tot 1 1 2 2 ⎣ ⎦ d d w 1 = 0.3479 fo r θ 1 = 30.56° o r 149.44° and w 2 = 0.6571 fo r θ 2 = 70.12° o r 109.88° 11 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Data Analysis What about unc e r taintie s? De te c te d hits in a g ive n ra y: - pe ak ide ntific a tion (po ssib le c o nta mina tio n) Δσ/σ : 5% to 7% E n = 0.5 – 9 Me V - Good statistic s n > 9 Me V But c a n r e ac h up to 20 % E - L ow bac kground (whe re the ne utro n flux is lo w) Cr oss se c tion of a give n γ r ay tr ansition [b] σ γ Ac q uisitio n time [s] ( n , xn ) d n θ = - L ong time ( ) det me asur e me nts Ω ⋅ φ ⋅ ε ⋅ d N t (sta b ility) γ at n Numb e r o f a to ms in ta rg e t γ de te c tio n e ffic ie nc y - Sample c omposition - Me asur e me nts - Pre c ise me a sure me nts ( size , - Simulations (a tte nua tio n, we ight ) o xida tio n) I nc ide nt ne utro n flux [s -1 ·c m -2 ] F ission c hambe r c har ac te r istic s 12 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Results 235 U(n,xn γ ) Be am time : 1466 ho urs 1 γ tra nsitio n in 235 U Sample : e nric hme nt 235 U 93.2 % 3 γ tra nsitio ns in 234 U ma ss 37.43 g -> Co mpa re to T AL YS c alc ulations dia me te r 12.00 c m (P.Ro ma in, CE A/ DAM, F RANCE ) thic kne ss 0.21 mm Bibliogr aphy: y fe w me a sure me nts in E OR : Ve r XF 4 σ (n,n’) me a sure me nt (1961-1969) 1 σ (n,n’ γ ) me a s. ( 2000 Yo une s e t al. ) 2 σ (n,2n) me a sure me nt (1972-1980) 1 σ (n,2n γ ) me a s. ( 2000 Yo une s e t al. ) + σ (n,xn γ ) in A.L . Hutc he so n T he sis (2008) 13 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Results 235 U(n,xn γ )* Ground State Band e xp data % Our e xp data * disc r e panc ie s with Hutc he son da ta . * agr e e me nt with Youne s da ta fo r the 244 ke V γ tra nsitio n but disc r e panc ie s at high ne utr on e ne rgie s fo r the 2 o the r (n,2n γ ) tra nsitio ns. T AL YS % E xp data * phe no-c gmr is the be st par ame te r ization . Ground State Band Ground State Band * (n,n’ γ ): sha pe a nd a mplitude a re no t we ll re pro duc e d. * (n,2n γ ) : q uite g o o d a g re e me nt in the sha pe b ut fa c to r 1.5 to 1.9 in a mplitude . *J.C Thiry et al. paper submitted soon 14 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France

Results NEA Nuclear Data 238 U(n,xn γ ) : pr e liminar y High Priority Request List About 30 (n,xn γ) tra nsitio ns “spo tte d” Be am time : 1200 ho urs y γ tra nsitio ns in 238 U Sample : purity na t U 99.9 % 20 pr e liminar ma ss 10.62 g inc luding 5 g o ing to the gr ound state . dia me te r 7.02 c m -> Co mpa re to T AL YS c alc ulations thic kne ss 0.18 mm (P.Ro ma in, CE A/ DAM, F RANCE ) 238 U level scheme Bibliogr aphy: oss se c tion me a sure me nts in E OR b ut : lot of total c r XF 4 σ (n,n’ γ ) me a s. ( 1976 Vo ss e t al., 1979 o lse n e t al., 2004 F o tiade s e t al., 2009 Hutc he so n e t al. ) 2 σ (n,2n γ ) me a s. ( 2009 Hutc he so n e t al., 2004 F o tiade s e t al., ) 15 Maëlle Kerveno WONDER2012 - September 25-28, 2012, Aix en Provence, France