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RadiativeRadiative nucleon nucleon

capture cross section capture cross section

calculationscalculations

in in MeVMeV regionregion

E. E. BBěěttáákk

Institute of PhInstitute of Physicsysics SAS, Bratislava, SlovakiaSAS, Bratislava, Slovakia

andand

Silesian University, Silesian University, OpavaOpava, Czech Rep, Czech Rep..

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Gamma emission in pre-equilibrium reactions:

Single-particle radiative mechanism

(Běták & Dobeš, Akkermans & Gruppelaar)

Probability of γ emission (E1 transitions)

),(/),(),()(2,

2EnEmmb

nnm

GDRωεωεεσελ γγγγγ −∝ ∑

−=

2,0 −=∆n

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Spin variables (Obložinský & Chadwick)

J J

j

j

j1

S

j j

1

11

3

2

2

S

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0.001

0.01

0.1

1

10

0 5 10 15 20 25

En

erg

y s

pe

ctr

um

(m

b/M

eV

)

Gamma energy (MeV)

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Computer codes with pre-equilibrium γγγγ emission and released to public

PEQGM (1983) (spin-independent version, obsolete already)

GNASH (1992, 1995) (also spin variables and discrete levels)

(recent versions strongly improved and enlarged,

but not available anymore)

PEQAG (1989) (update of PEQGM)

PEGAS (1993) (includes spin) & DEGAS (plus discrete levels)

“Do-all” nuclear reactions codes with pre-eq. γγγγEMPIRE-II version 2.18 Mondovi (2002) version 2.19 Lodi (2005)

TALYS (2005)

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EAFEAF--2007 Workshop, Prague, 2 2007 Workshop, Prague, 2 -- 4 October 20064 October 2006 2020

CONCLUSIONS

Pre-eq. γγγγ emission useful to describe cross

sections and γγγγ spectra, if one is not just in double-magic region. Therein, DSD (or CDSD)

model is more reliable. Physically both

describe the same situation with emphasis on

different aspects of the reality.

Two released “do-all” nuclear codes TALYS

and EMPIRE give similar results away of

closed shells. In their vicinity, there is no clear

preference of either of the codes which might

be universally valid.

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Thank you