Fragmentation of very neutron-rich projectiles around 132 Sn GSI experiment S294 Universidad de Santiago de Compostela, Spain Centre d’Etudes Nucleaires Bordeaux-Gradignan, France Warsow University, Poland GSI Darmstadt, Germany VINCA-Institute Belgrade, Serbia Institute of Physics, Bratislava, Slovakia GSI Oct.‘06

Motivation  Production of extremely neutron-rich isotopes (EURISOL DS task 11.2) (two-step schemes: fission + cold fragmentation) n,p U  132 Sn + Be  X  Ground state properties of extremely neutron-rich isotopes Total interaction cross sections: rms matter distributions Proton knock-out: rms charge distributions, binding energies Proton and neutron pickup: charge versus mass distribution GSI Oct.‘06

Motivation Fission + cold fragmentation  Production of medium-mass neutron-rich isotopes n,p U  132 Sn + Be  X GSI Oct.‘06

Motivation  Production cross sections of neutron-rich residues in the fragmentation of 132 Sn 132 Sb 132 Sn 131 In 132 In 130 Cd 129 Ag 128 Pd 1-4 proton removal cross sections mb 122 Pd 123 Pd 124 Pd 125 Pd 126 Pd 127 Pd 128 Pd EPAX COFRA  neutron separation enegies (W.A. Friedman et al., PRC 67 (2003) R) GSI Oct.‘06

Motivation  Mass and charge rms radii from specific reaction channels Total interaction cross sections: rms matter distributions GSI Oct.‘06

Motivation  Mass and charge rms radii from specific reaction channels 132 Sb 132 Sn 131 In 132 In 130 Cd 129 Ag 128 Pd Total interaction cross sections: rms matter distributions Proton knock-out: rms charge distribution GSI Oct.‘06

Motivation  Mass and charge rms radii from specific reaction channels 132 Sb 132 Sn 131 In 132 In 130 Cd 129 Ag 128 Pd Total interaction cross sections: rms matter distributions Proton knock-out: rms charge distribution Proton and neutron pickup: charge versus mass distribution N+n    N+p +  - N+p    N+n +  + v(cm/ns) R. J. Lombard et al., Europhys. Lett. 6 (1988) 323 A. Kelic et al., PRC 70 (2004) Pb+p,d  208 Bi+  - GSI Oct.‘06

Proposed experiment 132 Sn + Be  131 In, 130 Cd, 129 Ag, 128 Pd 1-4 proton removal:   p,2p,3p,4p ~ mb Sn + Be  X total interaction:  int ~ 2 b Sn + Be  In 1 proton removal:  1p ~ 20 mb Sn + Be  In charge pickup:    p+  - ~ 0.5 mb Sn + Be  Sn neutron pickup:    n+  + ~ 5  b 238 U(950 A MeV)+Pb  Sn  Production of neutron-rich fission residues  Fragmentation of neutron-rich fission residues GSI Oct.‘06

Experimental details S2-S4: Sn + Be  X S0-S2: 238 U(950 A MeV)+Pb  Sn  Z/Z ~  B  /  ~  ToF ~ 150 ps L ~ 18 m  A/A ~  Z/Z ~  B  /  ~  ToF ~ 150 ps L ~ 36 m  A/A ~ GSI Oct.‘06

Experimental details 238 U(1 A GeV)+d  1XX Sn 5 different settings centered on: 124 Sn, 126 Sn, 128 Sn, 130 Sn, 132 Sn GSI Oct.‘06

Beam time request S2-S4: Sn + Be  X S0-S2: 238 U(950 A MeV)+Pb  Sn 238 U beam intensity: 10 8 ions s Pb target: 1500 mg/cm 2  total rate at S2: ~26000 ion s -1  132 Sn rate at S2: ~ 1000 ions s -1  total rate at S4: >> 1000 ions s -1 Reaction probability and acquisition time with a 2.6 g/cm 2 Be target:  total interaction: ~ 2 b  15 min. < 1% statistical accuracy  1p: ~ 25 mb  1 hour ~ 1% “  2p: ~0.3 mb  15 hours ~ 1% “  3p: ~ 5  b  3 days ~ 7% “  4p: ~ 0.1  b  1-2 per day  proton pickup: ~ 0.5 mb  10 hours ~ 6% “  Production yields and acquisition time Limiting factor DAQ unless S1 degrader!!! GSI Oct.‘06

Beam time request Projectile1 st FRS section2 nd FRS sectionBeam time 238 U(950 MeV) FRSCalibrations1 day 238 U(950 MeV) 124 Sn 124 Sn (int. + 1p) 123 Sn (pickup) 3 hours 7 hours 238 U(950 MeV) 126 Sn 126 Sn (int. + 1p) 125 Sn (pickup) 3 hours 7 hours 238 U(950 MeV) 128 Sn 128 Sn (int. + 1p) 127 Sn (pickup) 3 hours 7 hours 238 U(950 MeV) 130 Sn 130 Sn (int. + 1p) 129 Sn (pickup) 3 hours 7 hours 238 U(950 MeV) 132 Sn 132 Sn (int. + 1p) 131 Sn (pickup) 134 Sn (2p,3p,4p) 3 hours 7 hours 4 days Total requested time: main beam time ( 238 U)  7 days (21 shifts) 6 days accepted parasitic beam ( 136 Xe)  5 days accepted GSI Oct.‘06

Final detector setup ?? S1: GSI Oct.‘06 Sc1degrader S2: MW21MUSIC1TPC1TPC2SlitstargetTPC3TPC4Sc2 S4: MW41MUSIC2TPC5TPC6Sc4

Open issues Energy of primary beam Lower energy (~ 500 A MeV): closer to EURISOL conditions and higher cross sections for neutron and proton pickup Lower energy: lower transmission Detailed calculations of FRS magnetic settings Larger acceptance for fission fragments (new target position) Beam intensity GSI Oct.‘06 Setup Degrader at S1 Optimum detector positions at S2

Participants GSI Oct.‘06 NovemberDecember FRS Detector tests136Xe238U Participant H. Alvarez USC J.Benlliure USC E.Casarej USC Dragosavac M.Gascón USC A.Heinz K. Helariutta A. Kelic GSI S. Lukic GSI F. Montes GSI D. Perez USC K.-H Schmidt M. Stanoiu GSI K. Summerer J. Taieb CEA

Tasks and responsibilities GSI Oct.‘06 MUSICsS. Lukic MWsK. SummererE. Casarejos ScintillatorsE. Casarejos TPCsBratislava targetsA. Kelic DAQC. NocciforoD. Perez On-lineH. AlvarezD. Perez FRS optics FRS settingsJ. BenlliureD. Perez

J. Benlliure et al., NPA 660 (1999) 87 Production of heavy neutron-rich isotopes Analytical description of cold-fragmentation reactions Mass loss: impact parameter geometry N/Z: hypergeometrical distribution Excitation energy: particle hole excitation+final interactions 1 Prefragment formation (statistical equilibrium) Two-step process: 2 Neutron evaporation Binding energies+temperature Sensitivity of the isotopic distributions to the excitation energy induced per abraded Nucleon: 27 MeV Isospin thermometer GSI-PAC Sep‘04

Motivation  Isotopic scaling in nuclear reactions GSI-PAC Sep‘04 Reactions governed by the statistical model M.B. Tsang et al., PRL 86 (2001) 5023

Medium-mass neutron-rich isotopes Sanibel´02 Two-step schemes: fission + cold fragmentation Only for extremely neutron-rich Residues the production rates by direct fission is bellow the two-step scenario Primary beam: 1 mA Production target: 100 g/cm 2 UCx Fragmentation target: 20% of range

Medium-mass neutron-rich isotopes Sanibel´02 Two-step schemes: fission + cold fragmentation

Medium-mass neutron-rich isotopes Sanibel´02 Two-step schemes: fission + cold fragmentation

Motivation 238 U(1 A GeV) + Pb  Residue production in fission reactions 238 U(950 A MeV)+Pb (T. Enqvist et al., NPA 658 (1999) 47) 238 U(1000 A MeV)+p (M. Bernas et al., NPA 725 (2003) 213) 238 U(1000 A MeV)+d (J. Pereira et al., PhD, USC (2004)) GSI Feb.‘06

Motivation  Residue production in cold-fragmentation reactions Peripheral heavy-ion reactions at relativistic energies: large fluctuations in N/Z and excitation energy Proton-removal channel: only protons are abraded and the induced excitation energy remains bellow the particle emission threshold 197 Au(950 A MeV)+Be (J. Benlliure et al., NPA 660 (1999) 87) GSI Feb.‘06

Motivation Cold fragmentation is not well understood for neutron-rich projectiles  Fragmentation of neutron-rich projectiles EPAX ABRABLA COFRA GSI Feb.‘06

Mass loss: impact parameter +matter/charge distribution N/Z: hypergeometrical distribution Excitation energy: isotopic distributions 1 Abrasion phase (excited prefragment): (Abrasion-ablation model) Motivation  Description of the residue production in fragmentation reactions 2 Ablation (evaporation) phase Binding energies+temperature  Some of these parameters can be determined from specific reaction channels GSI Feb.‘06