fragmentation of very neutron-rich projectiles around 132 sn gsi experiment s294
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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Fragmentation of very neutron-richprojectiles around 132Sn
GSI experiment S294
Universidad de Santiago de Compostela, SpainCentre d’Etudes Nucleaires Bordeaux-Gradignan, FranceWarsow University, PolandGSI Darmstadt, GermanyVINCA-Institute Belgrade, SerbiaInstitute of Physics, Bratislava, Slovakia
GSI Oct.‘06
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Motivation
Production of extremely neutron-rich isotopes (EURISOL DS task 11.2)
(two-step schemes: fission + cold fragmentation)
n,p + 238U 132Sn + 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
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Motivation
Fission + cold fragmentation
Production of medium-mass neutron-rich isotopes
n,p + 238U 132Sn + Be X
GSI Oct.‘06
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Motivation
Production cross sections of neutron-rich residues in the fragmentation of 132Sn
132Sb
132Sn
131In 132In
130Cd
129Ag
128Pd
1-4 proton removal cross sections
mb 122Pd 123Pd 124Pd 125Pd 126Pd 127Pd 128Pd
EPAX 0.285 0.182 0.109 5.93 10-2 2.90 10-2 1.25 10-2 4.74 10-3
COFRA 0.106 0.045 0.024 7.23 10-3 2.88 10-3 3.61 10-4 6.77 10-5
neutron separation enegies (W.A. Friedman et al., PRC 67 (2003) 051601R)
GSI Oct.‘06
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Motivation
Mass and charge rms radii from specific reaction channels
Total interaction cross sections: rms matter distributions
GSI Oct.‘06
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Motivation
Mass and charge rms radii from specific reaction channels
132Sb
132Sn
131In 132In
130Cd
129Ag
128Pd
Total interaction cross sections: rms matter distributions
Proton knock-out: rms charge distribution
GSI Oct.‘06
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Motivation
Mass and charge rms radii from specific reaction channels
132Sb
132Sn
131In 132In
130Cd
129Ag
128Pd
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) 323A. Kelic et al., PRC 70 (2004) 064608
208Pb+p,d 208Bi+-
GSI Oct.‘06
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Proposed experiment
132Sn + Be 131In,130Cd,129Ag,128Pd 1-4 proton removal: p,2p,3p,4p~ 20-1 10-
4 mb
124-132Sn + Be X total interaction: int ~ 2 b124-132Sn + Be 123-131In 1 proton removal: 1p ~ 20 mb124-132Sn + Be 124-132In charge pickup: p+- ~ 0.5 mb124-132Sn + Be 125-133Sn neutron pickup: n++ ~ 5 b
238U(950 A MeV)+Pb 124-132Sn
Production of neutron-rich fission residues
Fragmentation of neutron-rich fission residues
GSI Oct.‘06
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Experimental details
S2-S4: 124-132Sn + Be X
S0-S2: 238U(950 A MeV)+Pb 124-132Sn
Z/Z ~ 5 10-3
B/~ 3 10-4 ToF ~ 150 psL ~ 18 m
A/A ~ 2.4 10-3
Z/Z ~ 7 10-3
B/~ 3 10-4 ToF ~ 150 psL ~ 36 m
A/A ~ 4.5 10-3
GSI Oct.‘06
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Experimental details
238U(1 A GeV)+d 1XXSn
5 different settings centered on: 124Sn, 126Sn, 128Sn, 130Sn, 132Sn
GSI Oct.‘06
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Beam time request
S2-S4: 124-132Sn + Be X
S0-S2: 238U(950 A MeV)+Pb 124-132Sn238U beam intensity: 108 ions s-1 208Pb target: 1500 mg/cm2
total rate at S2: ~26000 ion s-1 132Sn 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/cm2 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
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Beam time request
Projectile 1st FRS section 2nd FRS section Beam time238U(950 MeV) FRS Calibrations 1 day238U(950 MeV) 124Sn 124Sn (int. + 1p)
123Sn (pickup)
3 hours
7 hours238U(950 MeV) 126Sn 126Sn (int. + 1p)
125Sn (pickup)
3 hours
7 hours238U(950 MeV) 128Sn 128Sn (int. + 1p)
127Sn (pickup)
3 hours
7 hours238U(950 MeV) 130Sn 130Sn (int. + 1p)
129Sn (pickup)
3 hours
7 hours238U(950 MeV) 132Sn 132Sn (int. + 1p)
131Sn (pickup)134Sn (2p,3p,4p)
3 hours
7 hours
4 days
Total requested time: main beam time (238U) 7 days (21 shifts) 6 days accepted parasitic beam (136Xe) 5 days accepted
GSI Oct.‘06
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Final detector setup ??
S1:
GSI Oct.‘06
Sc1 degrader
S2:MW21 MUSIC1TPC1 TPC2 Slits target TPC3 TPC4 Sc2
S4:MW41 MUSIC2TPC5 TPC6 Sc4
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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
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Participants
GSI Oct.‘06
November December
FRS Detector tests 136Xe 238U
Participant 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 2829
30 1 2 3 4 5 6 7 8
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
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Tasks and responsibilities
GSI Oct.‘06
MUSICs S. Lukic
MWs K. Summerer E. Casarejos
Scintillators E. Casarejos
TPCs Bratislava
targets A. Kelic
DAQ C. Nocciforo D. Perez
On-line H. Alvarez D. Perez
FRS optics
FRS settings J. Benlliure D. Perez
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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 isotopicdistributions to the excitationenergy induced per abraded Nucleon: 27 MeV
Isospin thermometer
GSI-PAC Sep‘04
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Motivation
Isotopic scaling in nuclear reactions
GSI-PAC Sep‘04
Reactions governed by the statistical model
ZNCeZNY
ZNYZNR
),(
),(),(
1
212
ZeZNRNS ),()( 12
M.B. Tsang et al., PRL 86 (2001) 5023
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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 mAProduction target: 100 g/cm2 UCxFragmentation target: 20% of range
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Medium-mass neutron-rich isotopes
Sanibel´02
Two-step schemes: fission + cold fragmentation
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Medium-mass neutron-rich isotopes
Sanibel´02
Two-step schemes: fission + cold fragmentation
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Motivation
238U(1 A GeV) + Pb
Residue production in fission reactions
238U(950 A MeV)+Pb (T. Enqvist et al., NPA 658 (1999) 47) 238U(1000 A MeV)+p (M. Bernas et al., NPA 725 (2003) 213) 238U(1000 A MeV)+d (J. Pereira et al., PhD, USC (2004))
GSI Feb.‘06
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Motivation
Residue production in cold-fragmentation reactions
Peripheral heavy-ion reactionsat relativistic energies: large fluctuations in N/Z and excitation energyProton-removal channel: only protons are abraded and the induced excitation energy remains bellow the particle emission threshold
197Au(950 A MeV)+Be (J. Benlliure et al., NPA 660 (1999) 87)
GSI Feb.‘06
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Motivation
Cold fragmentation is not well understood for neutron-rich projectiles
Fragmentation of neutron-rich projectiles
EPAX
ABRABLA
COFRA
GSI Feb.‘06
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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