1. Comprehensive investigation of nuclide production cross sections in 238U(1AGeV)+d
J.Pereira1, P.Armbruster2, J.Benlliure1, M.Bernas3 ,A.Boudard4, E.Casarejos1, S.Czajkowski5, T.Enqvist2, R.Legrain4, S.Leray4, B.Mustapha3, M.Pravikoff5, F.Rejmund3, M.V.Ricciardi2, K.-H.Schmidt2, C.Stéphan3, J.Taieb3, L.Tassan-Got3,C.Volant4, W.Wlazlo4
1USC, E Santiago de Compostela, Spain
2GSI, Planckstrabe 1, D Darmstadt, Germany
3IPN Orsay, IN2P3, F Orsay, France
4DAPNIA/SPhN CEA/Saclay, F Gif sur Yvette, France
5CENBG, IN2P3, F Gradignan, France

2. Residue production of 238U(1A GeV)+d measured with the FRS at GSI
Around 1500 residues have been measured and identified
Production cross sections have been measured with precission of 5-15%
Kinematical properties were determined for each nucleus
Fission and fragmentation residues were separated

3. Underlying physics in the 238U+d system
Fissility
Excitation energy
Shell effects
M.Bernas et al J. Taieb T. Enqvist et al.

4. Spallation reactions:Two-step model
First stage: production of a thermalized prefragment
Interaction of projectile and target: Intranuclear cascade
(Isabel, INCL)
Emission of preequilibrium particles
Excitation energy, mass and angular momentum of prefragment
Second stage: deexcitation of prefragment
Two decay modes: evaporation of particles and fission (Abla)
Evaporation of particles: statistical model (Ewing-Weisskopf)
Fission: Transition-state model (Bohr-Wheeler)

5. More details: talk of B.Jurado in this conference
The fission reaction mechanism at high excitation energies: 208Pb(1AGeV)+p
Statistical description of fission: Transition-state model (Bohr-Wheeler)
Dynamical description of fission:
Coupling between collective (deformation) and intrinsic degrees of freedom: dissipation coefficient b
T.Enqvist et al.
Fission is well described with both cascades and with a dissipation coefficient b=2x10-21 s-1
More details: talk of B.Jurado in this conference

6. The onset of a break-up stage at high excitation energies
The reaction mechanisms at higher excitation energies: 208Pb (1 A GeV)+d
At high excitation energies:
Light fragmentation residues underestimated
Fission residues overestimated
The onset of a break-up stage at high excitation energies
High excitation energy:
Deexcitation by simultaneous decay into several fragments
(Break-up)
Low Excitation energy:
Deexcitation of compound nucleus by statistical decay
(Fission and Evaporation)
Onset of break-up stage: TBU = 5 MeV
T.Enqvist et al.
K.-H. Schmidt et al., Nucl. Phys. A710 (2002)
Data well reproduced with ISABEL + dissipation + break-up decay
Fission overestimated with INCL

7. Differencies between ISABEL and INCL
Fission cross sections overestimated with INCL
Large angular momenta J reduces fission barriers
INCL overestimates angular momentum

8. Isobaric distributions in 238U(1AGeV)+p, d
M.Bernas et al M.V.Ricciardi J.Taieb et al.
E.Casarejos J.Pereira

9. Shell effects and collective excitations on the system 238U+d
Shell effects are compensated with collective excitations

10. Summary
The reaction 238U(1AGeV)+d is a complicated system (high fissility, high excitation energies, shell effects,...)
The precision and completeness of the data demand highly accurate implementation of the physical ingredients of the models
Fission is well described with a dynamical model (dissipation)
Break-up stage must be included at high excitation energies (T>5MeV)
INCL seems to overestimate the angular momentum of the prefragment
Shell effects and collective excitation must be included in the description of the level densities