Sub-task 4: Spallation and fragmentation reactions M. Valentina Ricciardi (GSI) in place of José Benlliure (USC) Sub-task leader: Universidad de Santiago de Compostela, Spain Other participant: GSI, Darmstadt, Germany Contributor:VINČA-INS, Belgrade, Serbia TASK 11: BEAM INTENSITY CALCULATION - kick-off meeting

General idea behind sub-task 4 Spallation and fragmentation reactions are a versatile tool for the production of both neutron-rich and neutron-deficient nuclides By an appropriate combination of projectile, target and energy the production of a specific exotic nuclide can be enhanced A deep knowledge on these reaction mechanisms is essential for the planning and design of a RIB facility A deep knowledge on spallation and fragmentation reactions can be achieved by: measuring the production yields in some "key" reactions developing prediction codes benchmark of the models planning "key" experiments

Measurement of the production yields: the inverse-kinematics method at relativistic energies Identification off-line with chemistry or  spectroscopy:  only cumulative yields of long- lived isotopes  no knowledge on the kinematics of the reaction Identification on-line with recoil separator:  identification of every reaction product in-flight prior to  decay  velocity spectrum for every produced isotope

Resolution: -  (  )/   5·  Z / Z  5   A / A  2.5  The Fragment Separator at GSI Full identification of every product - Precise velocity measurement for every nuclide - Disentangling different reaction mechanisms

Example: production cross sections for 1 A GeV 238 U on p fission M. Bernas M. V. Ricciardi evaporation residues J. Taïeb Data available at:

The reaction mechanisms 238 U Abrasion sequential evaporation fission excited compound nucleus

What we learn from the experimental data FRAGMENTATION CORRIDOR E* of CN  from Coulomb excit. to central coll. Max E*  length of corridor Fragments: higher mass  CN: low E* lower mass  CN: high E* E*: low  evapor. of n (horizontal path) high  evapor. of n, p, , IMF (transv. path) FISSION AREA Fission barrier ~ Z 2 /A  e.g. Au, Pb prefer to evap. n, p (A/Z) FFs ≈ (A/Z) CN  position of the CN High E*  FFs close to stability Low E*  FFs neutron-rich COLD FRAGMENTATION EVAPORATION RESIDUES FISSION FRAGMENTS EVAPORATION RESIDUES

From experimental data to models Statistical model for the description of spallation and fragmentation 238 U Abrasion sequential evaporation fission excited compound nucleus

The statistical model From the INC stage: A CN, Z CN, E* (exit. en.), J 2 (mean sq. ang. mom.) Random sample among: n, p, light-particles evaporation and fission Probability of one or the other channel given by the decay widths If evaporation occurs:  En. consumed = bind. en. (+ Coul. barr.) + kin. en.  Mass of fragment = CN after the evaporation chain evaporation goes on until the energy is consumed or a fission event occurs If fission occurs:  En. threshold = fission barrier  Fission fragments: ≈ CN, Y = Y(E*, N) If fission fragments are enough excited they can follow an evaporation chain

From model to experimental data: the case of cold fragmentation

List of deliverables  Provide data and benchmarking of models for the reactions: 1 A GeV 238 U + p, d - evaporation residues, fission fragments (GSI, USC – month 12) 1 A GeV 238 U + Pb – fission fragments (especially low-energy fission) (GSI, USC – month 12) 1 A GeV 136 Xe + p, Be, Pb - neutron-rich nuclides (cold fragmentation) (GSI, USC – month 18) 1 A GeV 238 U, 208 Pb + Be - neutron-rich nuclides (cold fragmentation) (USC)  Systematic calculations of nuclide production cross-sections (GSI, USC, VINCA)

Implementation plan for the first 12 months Provide final data for the production cross sections of extremely neutron-rich residues in the reactions:  136 Xe(1 A GeV) + 1 H,Be,Pb  238 U(1 A GeV) + Be  208 Pb(1 A GeV) + Be Provide data and benchmarking of models for the reactions: 1 A GeV 238 U + p, d - evaporation residues, fission fragments 1 A GeV 238 U + Pb – fission fragments (especially low-energy fission) Up to 18 months:

Present status of the work Data evaluation on the production of extremely neutron-rich residues in the reactions 1 A GeV 136 Xe + p, Be, Pb and 1 A GeV 238 U, 208 Pb + Be is in progress. This work will be done with USC own resources  Experimental data: 1 A GeV 238 U + p, d - evaporation residues, fission fragments 1 A GeV 238 U + Pb – fission fragments (especially low-energy fission) are almost fully analyzed  The predictive power of the model is being improved (dynamics of fission and a proper description of collective excitations, IMF emission) 12 months 18 months

TASK 11: BEAM INTENSITY CALCULATION - kick-off meeting Thank you