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

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 1

• 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
• M. Kerveno

(n,xn γ) reaction cross section measurements for (n,xn) reaction studies

WONDER 2012 3rd International Workshop on Nuclear Data Evaluation for Reactor Applications September 25-28, 2012 Aix en Provence, France

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 2

Gen IV reactor systems

Ne w c onc e pts of r e ac tor s

• > fa st re a c to rs
• > a c c e le ra to r drive n syste ms

Ne w fue l c yc le

• > 238U / 239Pu
• > 232T

h / 233U I mpo rta nt ne e ds

• f ne w nuc le ar

data

• ve r a wide ra ng e o f

nuc le i, e ne rg y a nd re a c tio ns One o f the c ha lle ng e s is

me asur e me nt’s ac c ur ac y NEA Nuclear Data High Priority Request List

I n re a c to r, (n,xn) r e ac tions (x ≥ 1) c o ntrib ute to

• > E

ne rg y lo ss me c ha nism

• > Ne utro n multiplic a tio n
• > Pro duc tio n o f ra dio a c tive iso to pe s

Bib lio g ra phy in da ta b a se s sho ws tha t

impr

• ve me nt o f the knowle dge of

(n,xn) pro c e ss is ne c e ssar y.

Introduction : general context

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 3

Introduction : importance of (n,xn) cross section knowledge

E xample of 238U(n,n’)

Pr e c ise r e quir e me nt fr

• m 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 238U(n,n’) impac t the ac c ur ac y o f the ke ff, o f the powe r a nd o f the βe ff c alc ulations o f la rg e c o re re a c to rs (PWR, F

R).

T ar ge t ac c ur ac y o n 238U(n,n’ ) :

• > PWR : ± 10 %
• > SF

R : ± 5 % State of the ar t :

40 me asur e me nts in E XF OR fro m 1956 to 2009 8 total c r

• ss se c tion me a sure me nts

=> 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 => 238U(n,n’) XS unc e r

tainty = 20 %

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 4

Introduction : experimental method

How to study (n,xn) r e ac tions?

• > Dire c t me a sure me nt o f se c o nda ry ne utro ns
• > Ac tiva tio n te c hniq ue
• > pr
• mpt γ-r

ay spe c tr

• sc opy

(n,xn γ) c r

• ss se c tions :
• c a n a lso impac t the ke ff c a lc ula tio n,
• c a n b e me a sure d using “white ” ne utr
• n be am

with the T OF te c hniq ue ,

• pro vide e xc lusive me asur

e me nts ve r y r e str ic tive fo r te sting mo de ls.

de te c tio n o f the γ-r

ays

ste mming fro m the

de c ay of e xc ite d state s

• f nuc le us c re a te d b y

the (n,xn) r

e ac tion. Example o f 238U(n,n’ γ) D.Be r nar d e t al.

F

• r sma ll re a c to r c o re :

ke ff -> 50 % of its se nsitivity fr

• m fir

st ine lastic thr e shold

F

• r la rg e re a c to r c o re :

r adial powe r-> se nsitivity to the fir st ine lastic le ve ls

F r

• m (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 :

Ne e d of str uc tur e par ame te r s and the or e tic al mode l…

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 5

Introduction : IPHC / IRMM / IFIN-HH experimental project

(n,xn γ) r e ac tion c r

• ss se c tions me asur

e me nts

GRAPhEME

(GeRmanium array for Actinides PrEcises MEasurements) IPHC (F r anc e ) / IR MM (Be lgium) / IF IN-HH (R

• mania) 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

• f the (n,xn γ) r

e ac tion c r

• ss se c tions o n a c tinide s

@ GE

L INA fac ility (IR MM-Be lgium)

2005 – 2010 :

235U c a mpa ig n

2009 – 2010 :

232T

h c a mpa ig n 2009 – 2012 :

nat,182,183,184,186W c a mpa ig n

2011 – 2012 :

238U c a mpa ig n

Collabor ation with the or e tic ians a nd e valuator s to impr

• ve the quality

a nd the de sc r

iption o f o ur me asur e d c r

• ss se c tions

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 6

30m

Uranium Target

e- f = 800 Hz

White neutrons beam few eV ➔ 20 MeV GE L INA, IR MM, Ge e l, Be lgium

Pulsed Neutron Beam Fission Chamber Sample HPGe planar detectors

150° 110° 110° 150°

Prompt γ spectroscopy

Experimental set-up @ GELINA : GRAPHEME

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 7

F P16 – 30 m

Experimental set-up @ GELINA : GRAPHEME

Noise insulation

(e le c tro ma g ne tic fie ld fro m the a c c e le ra to r)

and

γ bac kgr

• und r

e duc tion

GRAPhEME

BEAM BEAM B E A M

4 HPGe pla na r de te c to rs

GRAPhEME GRAPhEME

F issio n Cha mb e r (235U) Shie lding : Pb -Cd-Cu c a stle

• > DAQ

T NT 2 Car d @IPHC

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 8

T OF and γ spe c tr a

Data Analysis

232T

h(n,3n γ)230T h

232T

h(n,n’ γ)232T h

232T

h(n,2n γ)231T h γ-flash

R adioac tivity 232T

h

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 9

T OF spe c tr um

Data Analysis

γ flash

E n = 20 Me V E n = 6 Me V E n = 1 Me V r adioac tivity

235U c ase

E n = 0.1 Me V

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 10

T OF and γ spe c tr a

Data Analysis

235U c ase

(n,n’) e ne r gy gate (n,2n) e ne r gy gate

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 11

Cr

• ss se c tion c alc ulation

) (cos 4 ) (

) , (

θ π σ θ σ

γ i i i tot xn n

P a d d

∑

∞ =

= Ω

⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Ω + Ω = ) ( d d ) ( d d 4

* 2 * 2 * 1 * 1 ) , (

θ σ θ σ π σ

γ

w w

xn n tot

w1 = 0.3479 fo r θ1 = 30.56° o r 149.44° and w2 = 0.6571 fo r θ2 = 70.12° o r 109.88°

Pulsed Neutron Beam Fission Chamber Sample HPGe planar detectors

150° 110° 110° 150°

t N n d d

n at xn n

⋅ ⋅ ⋅ = Ω ε φ θ σ

γ det ) , (

) (

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 ge ndr e polynomials :

Me a sure me nt a t the polynomial node s

Gauss quadr atur e : t time measuremen : efficiency HPGe : flux neutron : sample in the atoms

• f

number : detected

• f

number :

det

t N n

n at

ε φ γ

Data Analysis

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 12

t N n d d

n at xn n

⋅ ⋅ ⋅ = Ω

γ γ

ε φ θ σ

det ) , (

) (

Cr

• ss se c tion
• f a give n

γ r

ay tr ansition [b]

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)

• Good statistic s
• L
• w bac kground

Numb e r o f a to ms in ta rg e t

• Sample c omposition
• Pre c ise me a sure me nts (size ,

we ight)

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

γ de te c tio n e ffic ie nc y

• Me asur

e me nts

• Simulations (a tte nua tio n,
• xida tio n)

Ac q uisitio n time [s]

• L
• ng time

me asur e me nts

(sta b ility)

What about unc e r taintie s?

Data Analysis

Δσ/σ : 5% to 7% E

n= 0.5 – 9 Me V

But c a n r

e ac h up to 20 % E

n> 9 Me V

(whe re the ne utro n flux is lo w)

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 13

235U(n,xn γ)

Results

Be am time : 1466 ho urs Sample : e nric hme nt 235U 93.2 %

ma ss 37.43 g dia me te r 12.00 c m thic kne ss 0.21 mm

Bibliogr aphy: Ve r y fe w me a sure me nts in E XF OR : 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)

1 γ tra nsitio n in 235U 3 γ tra nsitio ns in 234U

• > Co mpa re to T

AL YS c alc ulations

(P.Ro ma in, CE A/ DAM, F RANCE )

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 14

235U(n,xn γ)*

Results

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

• n 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 .

* (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

Ground State Band Ground State Band Ground State Band

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 15

238U(n,xn γ) : pr

e liminar y

Results

Be am time : 1200 ho urs Sample : purity na tU 99.9 %

ma ss 10.62 g dia me te r 7.02 c m thic kne ss 0.18 mm

Bibliogr aphy: lot of total c r

• ss se c tion me a sure me nts in E

XF ORb ut : 4 σ(n,n’ γ) me a s. (1976 Vo ss e t al., 1979 o lse n e t al., 2004

F

• 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

• tiade s e t al., )

About 30 (n,xn γ) tra nsitio ns “spo tte d” 20 pr e liminar y γ tra nsitio ns in 238U

inc luding 5 g o ing to the gr

• und state .
• > Co mpa re to T

AL YS c alc ulations

(P.Ro ma in, CE A/ DAM, F RANCE )

NEA Nuclear Data High Priority Request List

238U level scheme

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 16

238U(n,n’ γ) : pr

e liminar y

Results

N.B. we a re a b le to

me asur e the de - e xc itation o f the fir st le ve l in 238U

e xp data % Our e xp data

* F

• tia de s da ta slig htly

highe r tha n o ur da ta b ut good agr e e me nt in shape.

T AL YS % E xp data

* Sha pe is we ll r

e pr

• duc e d

e xc e pt in so me c a se whe n a dir e c t c ompone nt a ppe a rs :

the re la tive pro po rtio n o f the two c o mpo ne nts a re no t we ll c a lc ula te d. * I n amplitude, disc r

e panc ie s

de pe nd o n the γ-tra nsitio n.

Ground State Band Ground State Band Ground State Band

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 17

232T

h(n,xn γ) : ve r y pr e liminar y

Results

Be am time : 375 ho urs Sample : e nric hme nt 232T

h 99.5 % ma ss 11.99 g surfa c e 36.46 c m² thic kne ss 0.30 mm

Bibliogr aphy: Se ve r al me a sure me nts in E XF OR : 3 σ(n,n’) me a sure me nt (1962-1983) 12 σ(n,n’) le ve l pro duc tio n me a sure me nt (1962-2001) 1 σ(n,n’ γ) me a s. (1985 Dave e t al. ) 21 σ(n,2n) me a sure me nt (1956-2011) 0 σ(n,2n γ) me a s. 12 γ tra nsitio ns in 232T h 1 γ tra nsitio n in 231T h

• > Co mpa re to T

AL YS c alc ulations

(A.K

• ning , NRG, T

he Ne the rla nd)

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 18

Results

N.B. we a re a b le to

me asur e the de - e xc itation o f the fir st le ve l in 232T h

e xp data % Our e xp data

* agr

e e me nt is ve r y good up

to E

n=2 Me V (hig h limit o f the

J.H. Da ve e xp da ta ).

T AL YS % E xp data

* amplitude is we ll

r e pr

• duc e d fo r sta te s in

g ro und_sta te b a nd but

• ve r

e stimation above E

n = 7 Me V.

* fo r o the r γ-tra nsitio ns the

agr e e me nt is le ss good. 232T

h(n, n’ γ) : ve r y pr e liminar y

Ground State Band Ground State Band

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 19

186,184,183,182W(n,xn γ) : ve r

y pr e liminar y

Results

Be am time : 300 ho urs 186,184,183W

500 ho urs 182W

Sample : e nric hme nt 186,184,182W ~ 94.5 %

183W ~ 83.75 %

ma ss ~ 45 to 49 g dia me te r ~ 6.6 to 7.1 c m thic kne ss ~ 0.13 to 1.30 mm

Bibliogr aphy:

F e w me a sure me nts in E

XF OR:

182W : 2 σ(n,n’) me a sure me nt (1967 – 1999)

7 σ(n,2n) me a sure me nt(1959 – 1997)

183W : 2 σ(n,n’) me a sure me nt (1982 – 1996)

1 σ(n,2n) me a sure me nt (1980)

184W : 3 σ(n,n’) me a sure me nt (1967 – 2003)

4 σ(n,2n) me a sure me nt (1966 – 1982)

186W : 3 σ(n,n’) me a sure me nt (1967 – 1996)

14 σ(n,2n) me a sure me nt (1959 – 1999)

182W sample

27 γ tra nsitio ns in 182W 4 γ tra nsitio ns in 181W

183W sample

17 γ tra nsitio ns in 183W 5 γ tra nsitio ns in 182W

184W sample

15 γ tra nsitio ns in 184W 4 γ tra nsitio ns in 183W

186W sample

15 γ tra nsitio ns in 186W 3 γ tra nsitio ns in 185W

• > Co mpa re to T

AL YS c alc ulations

(P.Ro ma in, CE A/ DAM, F RANCE )

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 20

Results

186,184,183,182W(n,xn γ) : ve r

y pr e liminar y

184W(n,n’ γ)

Pr e liminar y c onc lusions T AL YS % E xp data

* in mo st c a se s the shape is

we ll r e pr

• duc e d but the

disc r e panc ie s fo r the amplitude a re diffe r e nt fo r e ac h γ tr ansition.

* br

anc hing r atio da ta

b a se s pla y a n impor

tant r

• le.

Ground State Band Ground State Band Ground State Band

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 21

From (n,xn γ) to (n,xn) cross sections?

T

• tal ine lastic sc atte r

ing c r

• ss se c tion is the sum o f the

c ro ss se c tio n c a rrie d b y all tr

ansitions tha t dir e c tly de c ay to the gr

• und-state

I n g e ne ra l c a se :

• R

e quir e s a good knowle dge of spe c tr

• sc opic par

ame te r s

• Pra c tic a lly, the de duc e d ine lastic c r
• ss se c tion is a lowe r

limit fo r the total ine lastic c r

• ss se c tion-> mode l pr

e dic tion

Me asur e d

(n,xn γ) c ro ss se c tio n

total

(n,xn) c ro ss se c tio n

Spectroscopic Parameters

∑

≤ =

→ → → =

E Li E i k i i k i n n

x i i

L L p s g L p L L E E

) ( 1 , ' '

) ( .) . ( ) , ( ) (

γ γ

σ σ

Theoretical model

gs Li Lki

AX

Observed γ

Lj

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 22

From (n,xn γ) to (n,xn) cross sections?

235U(n,2n) c ase

We ha ve me a sure d only ~20% o f the to ta l c ro ss se c tio n … Str

• ng mode l de pe nde nc e

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 23

E xpe r ime ntal point of vie w :

• c ontr
• l a nd minimize a ll so urc e o f e r

r

• r
• matr

ix c ovar ianc e c a lc ula tio n

• me asur

e me nt o f a maximum of γ-tr ansitions

• e ffor

ts ha ve to b e do ne to me asur e the γ- tr ansitions to the gr

• und state

From (n,xn γ) to (n,xn) cross sections? Discussion

T he or e tic ians and e valuator s point of vie w :

• fo r fissio na b le nuc le i, σ(n,f) must b e we ll de sc r

ibe d

• nuc le us str

uc tur e , br anc hing r atios a nd inte r nal c onve r sion c oe ffic ie nts pla y a n impor tant r

• le
• anothe r

appr

• ac h tha n the e xc iton mo de l (T

AL YS- 1.2) ha s to b e te ste d to mo de l the pr

e –e quilibr ium

re a c tio ns

235U(n,n’) 235U(n,2n) 235U(n,f)

What did we le ar n?

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 24

Conclusion

pr e c ise σ(n,xn γ)

235U, 238U, 232T

h,

186,184,183,182W

Covar ianc e matr ix Collabor ation with e valuator s:

q ua lity o f e xpe rime nta l da ta

the or e tic ians:

q ua lity o f mo de l pre dic tio ns

pr e c ise σ(n,xn γ) highly r adioac tive tar ge ts

233U (232T

h c yc le )

Se gme nte d HPGe

Br anc hing r atio Conve r sion e le c tron me asur e me nts

WONDER2012 - September 25-28, 2012, Aix en Provence, France Maëlle Kerveno 25

Geel, Belgium

• A. Plompen, J.C. Drohé, M. Nyman

Strasbourg, France

• A. Bacquias, Ph. Dessagne, M. Kerveno, G.Rudolf
• C. Borcea, A.L. Negret

Bucharest, Romania

T he author s thank the te am of the GE L INA fac ility for the pr e par ation

• f

the ne utr

• n

be am and for the ir str

• ng

suppor t day afte r day….

Collaboration, Financial support, Acknowledgement