Diapositiva 1

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6th Japan-Italy symposium on Heavy Ion Physics
11-15th Nov. 2008
Isospin effects on heavy-ion collisions some
results from CHIMERA experiments at LNS and
perspectives with radioactive beams G.Cardella
for the EXOCHIM collaboration
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The Detector
PSD in CsI(Tl) Z and A for light charged
particles
?E(Si)-E(CsI) Charge Z for particles punching
through the Si detector
?E(Si)-ToF Mass for particles stopping in the Si
detector
1192
3-12 cm
300 µm
E(Si)-Rise time Charge Z for particle stopping in
Si detectors (NEW)
?E(Si)-E(CsI) Charge Z and A for light ions
(Zlt9) punching through the Si detector
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PARTICLE EMISSION TIME SCALE
Low identification thresholds ? target-like
fragment measurement
New method to measure the time scale of particle
emission
A.Pagano et al., Nucl. Phys. A734, 504
(2004) J.Wilczynski et al., Int. Jour. Mod.Phys.
E14 353 (2005) E.De Filippo et al. Phys. Rev. C71
044602 (2005) M. Papa et al., Phys. Rev. C75
054616 (2007)
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Comparisons with the CoMD-II (Constrained
Molecular Dynamical Model) and BNV
Separation time for mid-rapidity IMFs ranging
between 40 and 120 fm/c.
PLF
ALL
TLF
Time evolution of the average mass numbers of the
three biggest fragments for ternary (full dots)
and dynamical fission events)
IVF
Midvel. window
BNV
M. Papa et al. (Isospin collaboration), Phys.
Rev. C75 054616 (2007)
Stochastic BNV model well accounts for the
prompt component of IMF emission (V. Baran et
al. Nucl. Phys. A730 329, 2004
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Alignment of emitted particles
F. Bocage et al., Nucl. Phys. A676 (2000), 391.
?prox angle between the direction of the PLF
velocity and the breakup axis.
VREL/VVIOLA(Slow,Mid)
VREL/VVIOLA(Fast,Mid)
The three heaviest fragments are ordered
according to decreasing value of parallel
velocity.
Relative velocities are expressed in units of the
velocity corresponding to the Coulomb repulsion
energy of a given subsystem according to the
Viola systematics (Nucl. Phys. A472, 318 (1987).
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Correlations with IMFs isotopic properties
In order to study correlations between fragments
formation dynamics and fragments isotopic
composition we have plotted ltN/Zgt for different
bins in the Vrel/Vviola(PLF-IMF)
Vrel/Vviola(TLF-IMF) plane
Li
Be
ltN/Zgt
C
B
Be
Li
C
B
The correlation shows clearly that the greatest
neutron enrichment is linked to greater
deviations from Viola systematics for both
(neutron poor and neutron rich) systems
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Alignement vs N/Z properties
?plane
Fission axis
Correlations between alignements and N/Z
fragments properties
PLF
Asystiff more isospin migration to the neck
fragments
BNV transport simulation 124Sn 64Ni 35 A.MeV
ternary events. (M. Di Toro, V. Baran, M.
Colonna et al. IWM2007 proceedings)
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Evolution of ltN/Zgt and proximity angle with
the violence of the collision
The three heaviest fragments are ordered
accordinding to decreasing value of parallel
velocity.
A hierarchy effect in N/Z fragment emission
Dependence of N/Z enrichment on the Multiplicity
and on Relative energy correlation
See P.Russotto et al. Procs of INPC 2007, Tokio.

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Some results Isospin effect on incomplete fusion
cross section
40Ca40,48Ca,46Ti 25MeV/A
N/Z(40Ca)1 N/Z(48Ca)1.4 N/Z(46Ti)1.09
Central Events selected with multiplicitygt6
Complete events (conditions on total charge
total momentum)
Larger mass of the heaviest fragment in the more
neutron rich system
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Some results Isospin effect on incomplete fusion
cross section
CoMD-II model predictions provides constraints on
the stiffness of the nuclear symmetry potential
that is found to be characterized by a form
factor F(S/Sgs)? depending from the overlap
integral of the wave packets S with ?1.10.2
40Ca40,48Ca,46Ti 25MeV/A
m2lt10
Probability ()
?1.0
Primary fragments
F.Amorini et al submitted to Phys.Rev.Lett
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Isotopical effects on the Yield ratio of IMF
40Ca40,48Ca,46Ti 25MeV/A
Yield ratio
I.Lombardo et al in preparation
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EXOCHIM in-flight fragmentation beams on
CHIMERA hall

Primary beam 20Ne 45 MeV/A. Momentum resolution
?P/P1 The beam line towards the new vacuum
chamber shows a transport efficiency of over 50
or better for the fragmentation beams (with 1pnA
on 9Be, 150Hz/pnA 18Ne)
NZ line
For reaction dynamics and also nuclear structure
studies around the proton drip line
Tagging
Fragment Separator
Production target (9Be)
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6.15 (1-) level Two-proton decay
Relative angle
Relative momentum
(66?9) Direct three-body (31?7) 2He
decay (3?2) virtual sequential
CENTER OF MASS REFERENCE SYSTEM
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Proposals to next PAC
Continue and improve the observations done with
40Ca beam Ca48 Ca48 _at_ 24.8 MeV/A Ca42 Fe54
_at_ 25.2 MeV/A Ne20 Ca48 _at_ 23.3 MeV/A Ne18
Cr50 _at_ 26 MeV/A (FRIBS)
13C primary beam ? production of beams 12,13B -
10,11Be Study of transfer/pick-up reactions as
12B(d,3He)11Be13B(p,3He)11Be 12B(d,3He)11Be
11Be(p,d)10Be 10Be(d,p)11Be
Study of Mass dependence of Isospin effects in
the symmetric reactions 96Zr96Zr and 96Ru96Ru
Study of 10Li resonances
QUEST FOR HYPERHEAVY TOROIDAL NUCLEAR STRUCTURES
FORMED IN AU AU COLLISIONS (R.P LANETA)
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Proposals to next PAC
13C primary beam ? production of beams 12,13B -
10,11Be Study of transfer/pick-up reactions as
12B(d,3He)11Be13B(p,3He)11Be 12B(d,3He)11Be
11Be(p,d)10Be 10Be(d,p)11Be We will use
kinematical coincidences in order to clean from
background and improve angular and energy
resolution
The bump of 7Li is resolved in three well defined
peaks With this technique we are also able to
identify neutrons with 5-10 efficiency
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An example Study of 10Li resonances
With the EXCYT 9Li beam we can study the 9Lid
?10Lip?(9Lin)p q-2.2 MeV
See H.B. Jeppesen et al., Phys. Lett. B 642
(2006) 449-- Nucl. Phys. A 748 (2005) 374
10Li is a resonance with a width of the order of
1 MeV we expect a quite good statistics and a
better angular coverage using the 4p CHIMERA
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For both EXCYT and fragmentation beams we will
use as time reference the signal of MCP device
that we are developping and we recently tested
with 7Li beam up to a current of 5 105 p/s
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EXOCHIM phase I HIC as a spectroscopic tool

• Several unbound states produced in a single
  experiment - reconstruct unbound species with
  multi-particle correlations
• Ex 8B---gt p7Be

Spin of 8B states
2.32
3
1.4 (?)
0.774 (?)
1
8B
p7Be
W.P.Tan, PRC (2004)
High angular resolution!
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EXOCHIM Multiparticle Correlations Spectroscopy
(MCS) with Chimera

a-a-a correlation function in the reaction
12C24Mg at E/A53 MeV studied at Ganil with the
INDRA detector.
7.65 MeV 12C
9.65 MeV 12C
Charity et al., PRC 75 (2007)
10C?2a2p
(2p?)??
6Be
9B
INDRA data
8Be
(???p)?p
(??)??p
F. Grenier et al. Nucl. Phys. A811, 233 (2008)
10C
Phase I first test with a stable 12C beam and
standard detector (planned October 2008,
spokepersons A. Chbihi, G. Verde) Phase II
Extend MCS studies to reactions induced by
in-flight beams by coupling Chimera with
ancillary arrays made by double-sided Si strip
detectors.
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EXOCHIM interesting results obtained during such
last measurement

Measurement of fission fragments from 12CPb at
all angles up to 170
R-13 q58
R-8E q23
R-26 q170
R-25 q156
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Collective flows (see ASY-EOS meeting slides
for more)
In-plane
Out-of-plane
y rapidity pt transverse momentum
X
Z
-1 lt V2 lt 1
Letter of intent GSI LAND CHIMERA

• Measure squeeze-out of neutrons and hydrogen
  isotopes with high precision
• as a function of impact parameter and beam
  energy
• with an excellent reaction plane resolution
• Neutron detection with LAND
• and a granular detector with particle
  identification capabilities

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Medium-Term Proposal at GSI
Impact parameter And reaction plane determination
?lab?40?
LAND covers mid-rapidity region for high pt
neutrons/protons

• Use stable beams 112Sn 112Sn and 124Sn
  124Sn reactions
• Letter of Intent was submitted to GSI G-PAC in
  January 2008

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5 years-Term SPES
Multifragment dynamical decay with SPES beams
A. Pagano/ S.Pirrone () INFN Sezione di Catania
First SPES Physics Workshop, Legnaro, October
29-30, 2008
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CONCLUSIONS

• We have developed a new analysis method,
  essentially based on final state (Coulomb)
  interaction, giving information on time sequence
  and time scale of the emission pattern of
  fragment production.
• We have shown that the fragments N/Z ratio can be
  correlated with fragments emission time. Large
  value of N/Z have been measured for those
  fragments produced in the early stage of the
  collisions in both neutron rich and neutron poor
  systems.
• With increasing of the violence of the collision
  we observe a transition from peripheral
  collisions, where coexistence of prompt emission
  and sequential decay is progressively suppressed
  towards a prompt multi-fragment decay.
• We have seen also effects of ISOSPIN on
  incomplete fusion reactions observing the
  production of residual nuclei with larger mass in
  the 40Ca48CA system respect than 40Ca40Ca,46Ti
  systems at 25 MeV/A.
• We are extending such findings to other systems
  also using radioactive beams
• We are also trying to explore the excitation and
  decay of exotic nuclei populated in heavy ion
  reactions

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CHIMERA-EXOCHIM collaboration
MSU
Lanzhou
Rochester