Review of European Fusion File evaluations performed at Bologna

Fusion Engineering and Design 37 (1997) 197-209 ELSEVIER

Fusion Engineering and Design

Review of European Fusion File evaluations performed at Bologna G. Reffo *, M. Herman, F. Fabbri Centro Dati Nucleari ENEA, Dipartimento Energia, Via Martiri di Monte Sole 4, 40138 Bologna, Italy

Abstract We give a short presentation of the evaluation work performed at ENEA Bologna in the frame of the network for the European Fusion File. The files produced were obtained by complementing the best files available with missing information or by replacing certain parts with improved model calculations. Here we indicate in each case the type of modification introduced. © 1997 Elsevier Science S.A. Keywords: European Fusion File; Model calculations; Information

1. The philosophy The evaluations performed in the frame of the European Fusion File include a list of high priority nuclei for which higher accuracy was required. Bologna has contributed with reviews of existing evaluated files which lead to the choice of the best among the files available and contributed with the re-evaluations of the families of aluminium, silicon, molybdenum and with the evaluation of double differential cross sections for 56Fe [1-8]. Before starting model calculations, the existing evaluated files have been considered and compared with experimental information. Available evaluated files from E N D F B - V I , JAERI-3, JEF-2 showed certain discrepancies between each other or with experimental data, which needed actions to be taken especially in the higher energy range * Corresponding author. Tel.: + 39 51 6098522; fax: + 39 51 6098785.

of interest in fusion activities. At higher energies in fact we found recoils were missing, or realistic double differential cross sections, or total g a m m a production. The good overall quality of the existing files, however, allowed us to simply adopt the best ones and complement them with the missing information, or replace those parts that we believed to be able to improve by use of our theoretical methods. In any case we introduced recoils and double differential cross sections for particles and g a m m a rays, without changing the integrated cross sections in any channel. An important point is that we intended to produce pure theoretical calculations rather than evaluations, in the sense that we did not perform any effort to force models to fit data: both, because in our models there is little leverage for it and because getting best fits of experimental data at one energy point does not ensure a similar adherence at the other energies. On the contrary,

0920-3796/97/$17.00 © 1997 Elsevier Science S.A. All rights reserved. PII S0920-3796(97)00043-4

198

G. ReJJb et al. /Fusion Engineering and Design 37 (1997) 197 209

the comparison of straight model calculations with experiment, without manipulations, gives an idea of the confidence degree on a sizeable neighbourhood around the energy point where the comparison has been made.

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2' ~0"

~c--

~ c,c.~~ o~

•

• ~.~-'~

..

z

,i

..~

2. Models adopted Compound nucleus mechanism was treated in terms of the usual Hauser-Fesbach theory as coded in Refs. [9-11]. Total level density and

2

•

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S

~0

~2

;*

~6

MAT 1237, MT 10. E= 14.200, ANGLE = 25.00 I0"

10'I

I

I

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I

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5

"0"

3

O

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! 104 7

4

6

10 2

6

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E(UeV)

-

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t

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t~

E v

10"

"0

<>.

"o

4

:0"

10

4 ~0~ 2

4

e

a

I0

12

I,~

16

16

E(MeV)

Fig. 2. Total neutron emission spectrum at 14.5 MeV in [27A1], at 15, 25 and 45 °. Circles are O K T A V I A N measurements and the full line is our calculation.

0

t

J

I

I

2

4

6

8

I

I0

12

14

Neutron Energy(MeV) Fig. 1. Total neutron emission spectrum at 14.5 MeV, in [27A1]. Triangles, O K T A V I A N data; circles, Dresden data. Our exciton model-coupled channels calculations are depicted in the histogram.

gamma ray emission channels were treated according to the Gilbert-Cameron approach and Brink-Axel approach, respectively, as discussed in Ref. [12]. Preequilibrium calculations were performed with an exciton model, as described in Refs. [1315], or with a unified microscopic Multistep-Di-

G. RefJb et al. / Fusion Engineering and Design 37 (1997) 197-209

rect Multistep-Compound formalisms according to the theories outlined in Refs. [16-19]. In all cases microscopic quasi-particle state densities were adopted based on combinatorial calculations and on BCS approach for effective

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14.200, ANGLE = 90.00

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14.300, A N G L E = 60,00 i0 ~

,

'

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2

' 8 E(MeV 0 )

4

MAT 1237, MT 10. E=

r

i

10

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~4

16

1 4 . 2 0 0 , A N G L E = 110.00

10"

x I0"

<

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~a~\~ ~.

I

E(UeV) 4

MAT 1237, MT 10. E=

14.200, ANGLE = 70.00 ~0~

,

, 2

,

, 4

/ S r(MeV)a

t

I1 lo

,

,

12

~

3 :0 °I

3

>~

'~f~~~I

~

MAT 1237, MT 10. E=

1 4 . 2 0 0 , A N G L E = 120.00

10-'

!0 "~

3 2 tO"

3 ~0~

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4

6

I0

E(~eV) 10

I12

II*.

~0

18

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,o-,

/° '

o

2

4

~

~s

4

0 E ( ~ e V a)

10

12

]4

16

Fig. 4. Total neutron e m i s s i o n spectrum at 14.5 MeV in [27A1], at 90, 110 and 120 °. Circles are O K T A V I A N m e a s u r e m e n t s and the full line is our calculation.

.6~

s

E(MeV)

1o

~2

Fig. 3. Total n e u t r o n emission spectrum at 14.5 MeV in [27A1], at 50, 70 and 80 °. Circles are O K T A V I A N m e a s u r e m e n t s and the full line is our calculation.

energies determinations, as illustrated in Refs. [20-23].

High energy capture cross sections included direct and collective contributions according to the models indicated in Ref. [24].

G. Reffo et al./Fusion Engineering and Design 37 (1997) 197 209

200

3. Results

10°~

3.1. Aluminium

~A • '

'

'

'

Here we adopted the file available in JENDL-3 and added double differential cross sections as well as gamma cascading emissions following n, 2n; n,pn; n,np; n,~n and n,n~. Preequilibrium

MAT 1237, MT 10. E= 1 4 . 2 0 0 , A N G L E = 130,00 ~0" 3 ¢

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10-e 3

<

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>

10-3

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3 ,

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2

,.

,

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e E

)8

:.

'..

~0

~2

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~5

(MeV

16' MAT 1237, MT 10. E=

E-

14.200, A N G L E = 140.00

E

4

% I

I

I

I

I

I

0

2

4

6

8

10

12

£), ( M e V ) Fig. 6. Total gamma-emission in [27A1], induced by 14 MeV neutrons. The histogram represent the results of the present calculations, the solid line is a fit of available experimental data.

4

2

4

6 E(MeV 0)

MAT 1237, MT 10. E=

10

12

14

27AI (E n = 14.5 MeV) I

103

14.200, A N G L E = 160.00

>o

3

:::L ,....,, • ;,,. 10 3

b

11~ 0

12

& 14

16 18 t(UeV)

Ilo

112

f14

I

I~

10

15

20

25

Er (MeV)

Fig. 5. Total neutron emission spectrum at 14.5 MeV in [27A1], at 130, 140 and 160 °. Circles are OKTAVIAN measurements and the full line is our calculation.

Fig. 7. Total gamma-emission in [2VAI], induced by 14 MeV neutrons. The histogram represent the results of the present calculations, e , experimental data.

G. RefJb et al./:Fusion Engineering and Des(gn 37 (1997) 197-209

MAT 1 4 2 8 , i0 °

I

MT 10, E=

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i

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10

8

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,

12

f

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,

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E(MeV)

Fig. 8. Total neutron emission spectrum at 14.5 MeV, in [2sSi], at 20 and 40 °. Open circles are OKTAVIAN data, the solid line represents our exciton model-coupled channel calculations.

emissions were calculated with the exciton model. In Fig. 1 our total neutron emission spectrum (histogram) is compared to the ~ 14 MeV experi-

mental data by the Dresden and Osaka group. In Figs. 2 - 5 the details are given of total neutron emission at 12 different angles from 15 to 160 °.

G. Reffo et al. /Fusion Engineering and Design 37 (I997) 197 209

202

MAT 1 4 2 8 , 10-'

I

MT 10,

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1

14

16

E(M~V) Fig. 9. Total gamma-emission in [27A1], induced by 14 MeV neutrons, at 90 and 120°. The histogram represents the results of the present calculations. ©, experimental data.

Here the structure observed in the hard tail above 9 MeV, is due to the direct collective inelastic scattering, while the dip around 9 MeV is due to

the lumped effect of a shell gap plus pairing gap in the final lp, lh quasi-particle state. In practice, no lp, lh states exist in 27A1 up to 5 MeV, i.e. the

G. Reffo et al./ Fusion Engineering and Design 37 (1997) 197 209

MAT 1428, MT 10, E=

I0-'

I

I

203

14. t00, ANGLE=150.O0

I

i

I

I

3

10 -=

3 10 -= (9

3 J3

1 0 -'L

3 ,

1 0 "=

0

I

,

2

I

,

4

I

,

6

[

t

8

10

t

12

I

L

14

E(MeV) Fig. 10. Total gamma-emission in [27A1], induced by 14 MeV neutrons at 150°. The histogram represent the results of the present calculations. ©, experimental data.

low lying levels are purely collective. Coupled channel calculations provide the correct description of the hard part of the spectrum, which is consistent with the picture obtained from combinatorial calculations of single particle states. It has to be noted that there is no way to systematise quasi-particle state thresholds, this is why use of William-type calculations cannot be made in this case. In Figs. 6 and 7 our calculated total gamma ray emission (histogram) is compared with experimental data (solid line and solid circles respectively).

calculations were made with the exciton model. Also in this, relatively, light materials particularly strong nuclear structure fluctuations are visible in the double differential measurements available from the O K T A V I A N experiment. Also here the correct determination of double differential cross sections needs use of microscopic level densities. Once again we have a hard tail constituted purely by direct collective inelastic scattering and a sequence of dips due to gaps in the lp, lh quasi-particle states. Our observations are illustrated at various angles in Figs. 8-10. Our total calculated gamma ray spectrum is given in Fig. 11.

3.2. Silicon 3.3. Iron

We have considered the files ENDFB-VI, B R O N D and JENDL-3. Here we adopted JENDL-3 and added double differential cross sections as well as gamma cascading emissions following n,2n; n,pn; n,np; n,Tn and n,nT. Preequilibrium

We have considered only the most important isotope [56Fe], for which we have adopted the I R K evaluation by the Vonach group, as a basis to where to include our model calculations of

G. RefJo et al. /Fusion Engineering and Design 37 (1997) 197 209

204 MAT 1428

l

O

0

~

E=

14.000

tion calculations agree well with experimental data and with E N D F B - V I , see Fig. 16. Double differential cross sections for total neutron emission where calculated both in terms of exciton model (Fig. 17) and in terms of the unified microscopic model (Fig. 18). As one can see, the latter includes collective type of fluctuations which do not appear in the frame of an exciton model. In terms of absolute values and confidence interval, the two calculations are equivalent in this case.

2

I i-'

4. Conclusions

2

2

10-'

,

0

I

~ I 2

,

4

I

,

6

I

1 8 10 E(MeV) ,

,

I t 12

I 14

,

I , I 16 18

,

20

The present model calculations have shown how the fluctuations of experimental double dif5 6 - F e ( n , x n ) MSD+MSC, mic. I.d., BCS

Fig. 11. Total gamma-emission in [2sSi], induced by 14 MeV neutrons. The histogram represent the results of present calculations, the solid line through closed circles is a fit of available experimental data.

.I--. in

14.80 MeV 8 ~29

E: io~

iJ

double differential cross sections. This isotope shows emission spectra with structure fluctuations down to 7 MeV, as seen in Figs. 12-15. As [56Fe] is far from magic numbers, these type of fluctuations are not of the type of shell model irregularities, but more collective in nature. In fact in the case of [56Fe] the exciton model could not account for experimental data even when using microscopic quasi-particles state densities. Instead the use of our unified microscopic approach for multistep compound and multistep direct process was able to give emission spectra, following experimental data at all angles closely enough both in trend and in absolute value. This success is also due to the introduction of collectivity via the R P A response function.

----~10~

%

'<'-; ),(-

~o°

3

• ^ / /

/

\, "'X ' . "->-.

~I

6

9

12

15

18

s (MeV) 5 6 - F e ( n , x n ) MSD+MSC, mic. I.d., BCS

~io ~

E:

t4.70 MeV 0-7

>~

_~. 10~

lo°

_ f\ I~

if\ 0

After a critical intercomparison of the content of the files E N D F B - V I , JEF-2 and J E N D L - 3 we adopted E N D F B - V I as a basis on which to introduce recoils, double differential cross sections and photon emissions. Our total photon produc-

,
' I ~,

i0 <

10-,

3.4. Molybdenum

r '

/~

l

"'¢S ~<'

],

3

/ \

/

~

\1I

"lro, \'. /

,

,

/ 6

9

12

15

18

s O{~v) Fig. 12. Total neutron emission spectrum at 14.5 MeV, in [56Fe], at 14.5 MeV at 29 and 45 °. O, OKTAVIAN data. The solid line is the result of our unified microscopic multistepcompound and multistep-direct approach. Dotted-dashed line gives the MSC contribution and the two dashed lines give the first two MSD contributions.

205

G. Reffo et al. ,/Fusion Engineering and Design 37 (1997) 197-209

56-Fe(n,xn) MSD+MSC, mic. I.d., BCS 56-Fe(n,xn) MSD+MSC, mic. I.d., BCS E:

14.46 MeV 4 ) = 6 5 E:

-/~.:'~%%

14.01 MeV

= 100

73

7J

1o'

10~

) -,%. i0°

/

b •

ix

10-t 0

,~ I'~'k

3

,

"

I

\,

'\

\ ,\1

I

! j,

,

\

'~

6

9

m

'

to o

., ',,-%\~,

b

12

15

•

E (MeV)

'/

•

~./ ,

i,<-7

tO-1

18

,

3

'

6

9

12

15

18

56-Fe(n,xn) MSD+MSC, mic. I.d., BCS 56-Fe(n,xn) MSD+MSC, mic. 1.d., BCS E =

.~IeV

14.25

= 80

E:

13.74 3IeV a = 120

7~

cJ

4

= 10'

10'

-X i0 ° , q t\

10-~ 0

I [,

i kl

, ~

6

9

E

tOo

~.r,\y,

,' . . . . / '

b

~, ,

,

~

12

<

' , ..

,< . .

,

15

18

ferential cross sections are m o d u l a t e d b y the fine n u c l e a r s t r u c t u r e c h a r a c t e r i s t i c s o f each i n d i v i d u a l isotope. T h e s e results p u t in e v i d e n c e the i m p o r t a n c e o f i n t r o d u c i n g the m e a n field irregularities, via a m i c r o s c o p i c a p p r o a c h to q u a s i - p a r t i c l e state density. I n p a r t i c u l a r , t h e y s u p p l y e v i d e n c e to the limits o f s y s t e m a t i c s for a n g u l a r d i s t r i b u t i o n s , w h i c h c a n a c c o u n t o n l y for the gross t r e n d o f e m i s s i o n spectra, as well as the w e a k n e s s o f W i l l i a m s types o f a p p r o a c h e s w h i c h c a n n o t acc o u n t for the m e a n field irregularities o r n u c l e a r s t r u c t u r e p r o p e r t i e s t h a t l e n d very little to systema t / s a t / o n a n d t h a t c a n n o t be f o r e s e e n a priori. A n o t h e r i m p o r t a n t i n d i c a t i o n to be stressed here is t h a t the classical e x c i t o n m o d e l , even w h e n supplemented with microscopic quasi-particle state d e n s i t y , c a n a c c o u n t o n l y for t r a n s i t i o n s

,

j

\./

,

\>

10-'

(.~[ev)

Fig. 13. Total gamma-emission in [28Si], induced by 14 MeV neutrons, at 65 and 80° . The histogram represents the results of present calculations, the solid line through closed circles is a fit of available experimental data.

,!

, 3

6

9

12

15

Fig. 14. Total gamma-emission in [28Si], induced by 14 MeV neutrons, at 100 and 120°, The histogram represents the results of present calculations, the solid line through closed circles is a fit of available experimental data. 56-Fe(n,xn) MSD+MSC, mic. I.d., BCS %

.

E=

13.35 MeV 8 = 159

~o

iO'

"

";~,t\" •

= lO°

,\~,~,,

,"

" - _ ,'/

, •

,

1 ~,

'~

, ) I

10-~ 3

6

9

t2

15

18

z (Mev) Fig. 15. Total gamma-emission in [28Si], induced by 14 MeV neutrons, at 159°. The histogram represent the results of present calculations, the solid line through closed circles is a fit of available experimental data.

G. Reffo et al./'Fusion Engineering and Design 37 (1997) 197-209

206

!

~

Mo(n, xT ] O= 125" En = 13.98 to 16.99 NeV -Evaluation ENOF/B 128?

2

m' >

5

,

__

L_ _Q C 0

1#

0

5

03 ~0 0 (_ (J

t#

,~, L o

I

,.oo

I

'2.oo

I

3.oo

I

,.oo

111

II11

5.00

O~:~mma Roy Energy

III

e.oo (

I 7.oo

III o.oQ

I

s.oo

I0.0

MeV )

Fig. 16. Total gamma-emission in molybdenum, induced by 14 17 MeV neutrons at 125°. The histogram represent the results of present calculations, the thick solid line JENDL-3 and the dashed line ENDFB-VI. Experimental data are Oak Ridge data.

between single particle state density, for transitions between single particle states and not transitions to collective levels. Coupled channel calculations describe well the direct collective inelastic scattering to low lying levels. But in many cases (e.g. [56Fe] and Mo-isotopes) considerable structure is observed experimentally through a wider energy.

These fluctuations cannot be explained using only single particle state transitions. We have shown that our unified microscopic multistep approach can also account for collective effects, when R P A response functions are used. We believe that the present calculations represent an improvement both in numerical and conceptual terms.

207

G. Reffo et al. ,,/Fusion Engineering and Design 37 (1997) 197 209

MO-NAT DDX AT 14.11dEV 30-DEG. BY PLDDX 10 °

I

~Ij-[-'IE iNOL_ JEF-2 ~ -3

'

01/,K^llASII I ,,t '88 ) !1'

I0 -i

ol

r-

t.. 0r~

I 0 -2

.o

10-3

o--

QI

O L

t I

IO-S 0.0

,

w

I

,

I

T

J

I

1~

I

5.0

,

r

If

I 15.0

I0.0

Second. Neutron Energy( MeV) MO-NAT DDX AT 14.IMEV 150-OEG. BY PLDDX I0°

t

)~a~

I

.L--'JENOL' ENOF/O-VIJ-I-' JEF-Z3:-" O[AKAIIAS[H,,t ' 88) j

"~.~. IO-I !,~ e '--L - ~ . . ,

t-

L_ 0

I 0 -2

o

I0-~

O

I0

-5

I

I

I

""

I

I

,

J

t "t¢

1,~

I

I

l

II

1 I

n

0.0

5.0

IO.O

IS.O

Second. Neutron Energy(IdeV) Fig. 17. Total neutron emission spectrum at 30 and 150° for 14 MeV neutrons. The full line is our unified exciton model calculation. Dotted circles are OKTAVIAN data.

208

G. RefJb et al. /Fusion Engineering and Design 37 (1997) 197-209

MO-NAT DDX AT 14.1MEV 150-DEG.

10 o

--JENOL-3 ~ JEF-2

>

O[^KAIIAS}t!,( '881 [

I

-

---ENOF/B-YI mE

BY PLDDX

i0 -]

t._ to ~o

c

10 -2

t_ E2

r"

o

10_31 I I

m

-i

i0-~

I I

0 t_ ¢_)

t I

! I

10 -5 0.0

,

,

,

,

I

,

,

,

5.0

Second.

~']-

I

t

l

! I

I0.0

Neutron

Energy(

l

,

I 15.0

MeV)

Fig. 18. Like Fig. 12, except the full line is the result of our unified microscopic multistep-compound and multistep-direct approach.

References [1] G. Reffo, F. Fabbri, M. Herman, Evaluation of Double Differential Cross-Sections for Aluminium, European Fusion File meeting, Saclay 2 3 December, 1991, Report EFF-DOC-53, 1991. [2] M. Herman, G. Reffo, Review of Existing Evaluations for V, Zr, Nb, Ta, European Fusion File meeting, Saclay 2-3 December 1991, Report EFF-Doc-78, 1991. [3] M. Herman, G. Reffo, Review of Existing Evaluations for 52-Cr, European Fusion File meeting, Saclay 2 3 December, 1991, Report EFF-Doc-104, 1991. [4] G. Reffo, M. Herman, Evaluation of Double Differential Cross Sections for 28Si, European Fusion File meeting, Saclay 2-3 December, 1991, Report EEF-Doc-105, 1991. [5] M. Herman and G. Reffo, Review of Existing Evaluations for the S-Family, European Fusion File meeting, Saclay 2 3 December, 199l, Report Eff-Doc-106, 1991. [6] M. Herman and G. Reffo, Review of Existing Evaluations for Rh, European Fusion File meeting, Saclay 2-3 December 1991, Report EFF-Doc-107, 1991. [7] M. Herman, G. Reffo, Evaluation Tools for the Calculation of Neutron and Gamma Emission by 14-MeV Neutrons in Mo-Isotopes, Report EFF-Doc-190, December, 1992.

[8] G. Reffo, M. Herman, Evaluation of the Double Differential Neutron Spectrum for 56-Fe, Report EFF-Doc. 235, 1993. [9] G. Reffo, F. Fabbri, M. Herman, The IDA Modular System of Codes for Nuclear Data Evaluation, Symposium on Nuclear Data Evaluation Methodology, Brookhaven National Laboratory, Upton, New York, USA, 12 16 October, 1992. [10] F. Fabbri, G. Reffo, CERBERO: A Fortran Programme for the Calculation of Nuclear Reaction Cross-Section, CNEN Rep. RT/FI 74 (1974) 36. [11] F. Fabbri, G. Fratamico, G. Reffo, CERBERO2: Improved version of the CERBERO Computer Code for the Calculation of Nuclear Reaction Cross Sections, CNEN Rep. RT/FI 77 (1977) 6. [12] G. Reffo, Parameter Systematics for Statistical Theory Calculations of Neutron Reaction Cross-sections, IAEA Winter Courses in Nuclear Physics and Reactors, Trieste, 17 January 10 March, 1978, Rep. IAEA-SMR-43, 1980, CNEN Rep. RT/Fi 78 (1978) 11. [13] J.M. Akkermans, H. Gruppelaar, G. Reffo, Angular Distributions in a Unified Model for Preequilibrium Neutron Emission, Phys. Rev. C 22 (1980) 73. [14] G. Reffo, C. Costa, F. Fabbri, Angular Momentum Conservation in Precompound Decay, ENEA Report RT/ FI (83) 10.

G. Reffo et al./Fusion Engineering and Design 37 (1997) 197-209 [15] G. Reffo, M. Herman, On Exciton and Multistep-Compound Models Differences and Similarities, Nuovo Cim. A 103 (1990) 557. [16] M. Herman, G. Reffo, H.A. Weidenmuller, Multistepcompound Contribution to Precompound Reaction Cross-section, Nucl. Phys. A 536 (1992) 124. [17] M. Herman, A. Hoering, G. Reffo, Gamma-emission in precompound reactions II. Numerical applications, Phys. Rev. C 46 (1992) 2493. [18] H.A. Hoering, H.A. Weidenmuller, F.S. Dietrich, M. Herman, G. Reffo, A study of Reaction Mechanisms for Gamma Production in Fast-Nucleon Induced Reactions, 7th International Symposium on Capture-Gamma-Ray Spectroscopy, Pacific Grove, CA, USA, 14 19 October, 1990. AlP Conference Proceedings 238 (1990) 742. [19] M. Herman, H. Lenske, G. Reffo, H.H. Wolter, Unified Microscopic Multistep Approach to Nucleon Induced

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Statistical Reactions, in press. [20] G. Reffo, M. Herman, Spin Distribution of Exciton Levels for Spherical Nuclei, Lettere al Nuovo Cimento 34 (10) (1982) 261. [21] M. Herman, G. Reffo, Realistic Few Quasi-Particle Level Densities in Spherical Nuclei, Phys. Rev. C 36 (1987) 1546. [22] M. Herman, G. Reffo, R.A. Rego, Effect of Nuclear Deformation on Few Quasi-Particle State Densities, Phys. Rev. C 37 (1988) 797. [23] M. Herman, G. Reffo, M. Rosetti, G. Giardina, A. Italiano, Eigenvalue Spacings of the Shell-Model Hamiltonian, Phys. Rev. C 40 (1989) 2870. [24] G. Longo, G. Reffo, F. Saporetti, Compound Nucleus and Direct-Semidirect Contributions to Radiative Capture of Fast Neutrons, Lettere al Nuovo Cimento 16 (7) (1976) 193.