1. Space time characterization II What have we learned about the internal energy of the fragment pattern ? Thermodynamics
Temperature measurements using correlation function techniques LP-LP/IMF- LP
Method : determination of relative population unbound states
Impact parameter selected excited states
Results
Internal excitation of the fragments using correlation function techniques IMF- LP
Method description : background simulation
Representative results
Determination of the thermal component
Hard photons : Mg-Mimf correlations
Other applications
3-body correlation in Borromean halo nuclei
Spin determination

2. Temperature measurements from excited states unstable nuclei
Idea :
The unstable complex cluster should be emitted early in the decay --> the temperature is expected to be close to the initial temperature of the fragmenting system
Hypothesis :
at least local equilibrium
Advantages
Small sensitivity to collective dynamical effects : rotational, translational, expansion
Direct emission
Etc.
Technique : Correlation function to reconstruct the unstable nuclei
Position-sensitive hodoscope
MSU
Pochodzalla et al., PRC , 1987

3. Results of the excited states
Nayak et al., PRC45 132, 1992

4. Impact parameter selected excited state
F. Zhu et al., PR C52 784–797 (1995)

5. Temperature vs impact parameter / Ein
H.F. XI et al., PRC58 R2636 (1998)
Explanation of the THeLi :
Excluding volume
Emission time of 3He
See thermometry
F. St-Laurent et al., PLB 202, 190 (1988)
Constant temperature over a large range of impact parameter / Ein
Serfling et al., PRL 80, 3928 (1998)

6. explanation of low peak energy alpha particle spectrum ?
Experimental kinetic energy spectrum of a is enhanced in the sub barrier compared to statistical calculations.
sequential a particles from 5He and other clusters ?
R.J. Charity et al., PRC

7. Excitation energy of the primary fragments
Kr + 45A MeV
Dwarf Ball/Wall
IMF-LCP Vrel Correlations
1+R(Vrel) = Nc/Nnc
Background Parameterization
A-1/(BVrel+C)
Evaporated p, d, t, 3He, a
size, E*pr primary fragments
Thermal Contribution
N. Marie et al., PRC 58, 256 (1998)
S. Hudan et al., PhD thesis and PRC67, (2003)
P. Staszel et al., PRC63, (2001)

8. Excitation energy of the fragments
Data
Simulation
Xe + 50A MeV, Indra
Collaboration TAMU-GANIL

9. Evaporated LCP multiplicities
<E> (MeV)
<M>
Zimf
Zimf

10. Evaporated LCP multiplicities

11. Excitation energy of the primary fragments
Primary fragment mass hypothesis

12. Application 1 : Proportion of thermal contribution
Excitation energy saturates at 3 AMeV
Mev/Mtot fraction reflects <E*/A> of the primary fragments
The majority of LCP are not evaporated by excited primary fragments

13. Application 2 : Constraint to statistical calculations
Direct comparison to primary fragments
produced by SMM, before their decay and Coulb.
Total evaporated charge ( z=1, 2 )
In these calculations the size of source was kept fixed, if we decrease this size we may fit the data. It was not our choice. In deed we performed predictive dynamical calculation with AMD.
It was not compared to MMMC since in this model the secondary decay
is included in the final partition

14. Charge distribution for Xe + Sn at 50 and 100 A MeV
Data-AMD Comparison S. Hudan et al., PhD thesis and A. Ono & S. Hudan PRC66, (2002)
Charge distribution for Xe + Sn at 50 and 100 A MeV
Xe+Sn 50 A MeV, 0<b<4
Xe+Sn 50 A MeV, 0<b<4
Reasonable agreement in the limit of the number of simulated events
(a huge cpu time )

15. Application 3 : Direct comparison to AMD before cooling
Xe + 50 AMeV
AMD
For the 22% of protons which are evaporated by the primary fragments we have some problems but for the remaining 78%
The agreement is good.

16. Characteristics of the Quasi-Projectile
Carmen Escano PhD thesis (in preparation)
Stage Josiane Moisan

17. Zbig > 40 30 < Zbig < 40 25 < Zbig < 30 Alpha
Stage Josiane Moisan
Alpha
20 < Zbig < 25
10 < Zbig < 20
5 < Zbig < 10

18. Zbig > 40 30 < Zbig < 40 25 < Zbig < 30 Proton
Stage Josiane Moisan
Proton
20 < Zbig < 25
10 < Zbig < 20
5 < Zbig < 10

19. Evaporated protons Preliminary results :
Carmen Escano PhD thesis (in preparation)
Preliminary results :
Quasi-Projectile
Central collisions
The proton multiplicity evaporated from the quasi projectile spectator vs the charge of this spectator. It has a linear increase with the size of the spectator. Let’s compared to the multiplicity of proton evaporated from the primary fragments produced at central collisions at 50 AMeV. It follow the systematic

20. Nuclear breakup
Dominates, small b
Electromagnetic
dissociation

21. Spin determination of particle unstable levels with particles correlations
8Be : p-7Li
8B : p-7Be
W.P. Tan et al., PRC69, (R) (2004)

22. central collisions: correlation factors as a function of a threshold on the photon energy
1+R g-IMF E
NI + AU 30A MeV
NI + AU 45A MeV
Black: IMF’s velocity in W1
Red: IMF’S velocity in W2
0.28
0.14
0.07
beam
 c.o.m W2 W1
The 45A MeV data strongly support the hypothesis of prompt multifragmentation, while the 30A MeV data are compatible with a late statistical decay of a heavy composite system. This indicates a transition between the two mechanisms just in the region of the Fermi energy
direct
thermal
The photon energy spectra: two component exponential fit
thermal photon source  nucleus-nucleus c.o.m. velocity
direct photon source  nucleon-nucleon c.o.m. velocity

23. Conclusions and perspectives
Correlation function is powerful tool to reconstruct stable or unstable nuclei
 it can be applied to structure study of exotic nuclei far from stability
Temperatures extracted from excited states saturate around 4-5 MeV for a large range of impact parameter and incident energy (up to 200 A MeV).
Experimental study of the Xe + Sn system from the onset of multifragmentation: the fragments are excited and their E* saturates at 3A MeV.
For a fermi gas a = A/8 --> T = 5 MeV comparable to T excited-state
 T=5 consistent with the limiting temperature below which primary frag deexcite only through evaporation
The proportion of thermal LCP does not exceed 35% and decreases with Einc.
Reaction mechanism (HIC) is not able to heat the fragments more than 3A MeV.
 a comparison to the proportion of the fast source component extracted from imaging source technique may provides a good cross check to the two method
Comparison with a statistical and dynamical model calculation :
The assumption that the system is in equilibrium at low densities reproduces the primary fragments excitation energies.
BUT it fails to predict the evolution of the evaporative LCP with the incident energy.
AMD predict almost the total energy spectra of protons (78% of total emission)
But it fails to reproduce the thermal contribution (22%).
Questions :
Why are the excitation energies of the spectator fragments at 100 AMeV and the
participant fragments at 50 AMeV the same ? Thermal energy saturation ?
Same production mechanism ? Or … ?

24. Few hodoscopes inside a 4p ?
4p solid angle
Quasi complete information
Estimation of
E*of all fragments,
Thermal component
Quantitative estimation
Small solid angle
Temperature measurements
Precise reconstruction of fragments
Structure : spin, exotic nuclei
Qualitative partial information
Do we need 4p hodoscope ?
Few hodoscopes inside a 4p ?

25. Comparison between HIPSE model and INDRA data :
Fragment-fragment correlations in central collisions
Relative velocity and relative angle
Of the three biggest fragments
Taken two by two
Selection :
Ztot >80%, Pztot>80%,
flow angle> 30 degree
DATA
HIPSE
Xe+Sn
In HIPSE, clusters are formed from
the very first instant of the reaction
[simultaneous fragmentation]
up to several thousand of fm/c (during
the desexcitation [sequential decay].
In fact, the in-flight decay is
performed to preserve space-time
correlations.
The good reproduction of
Fragment-Fragment correlations
indicates that the HIPSE scenario
is compatible with data
Figure from A. Van Lauwe, Ph.D. Thesis-LPC Caen (2003)

26. Deducing the timescale of multifragmentation using thermal photons (Eg 25 MeV) as a “clock” and the -IMF correlation factors as experimental tool
MEDEA + MULTICS at Laboratori Nazionali del Sud
First compression  direct photon production
Expansion  prompt IMF emission (at t=t0 the system
enters the spinodal region)
If the system survives:
Second compression  thermal photon production, HHS
formation, statistical IMF’s
The chronometer: density oscillation from BNV simulations of the reaction dynamics and location in time of the main processes
thermal photons
hot heavy surviving system
 mmIMF
 m mIMF
The experimental tool: -IMF correlation factors
1+ R -IMF =
Values  1 signal anticorrelation i.e. in a significant fraction of events the emission of fragments inhibits the photon production
(0 if the system always disintegrates before and 1 for independent emission)

27. Evolution of the multifragmentation of the Xe+Sn system from 25-150 AMeV
Abdou CHBIHI
for the INDRA and ALADIN collaborations
Experiments GANIL and GSI with INDRA
Global feature of the fragment emission
Experimental characteristics of fragment production in central collisions (size and E*pr)
Comparison to statistical and dynamical calculations
Characteristics of the 100 AMeV
Preliminary results

33. V. Serfling et al., PRL (1998)

34. V. Serfling et al., PRL (1998)
H.F. XI et al., PRC58 R2636 (1998)
F. St Laurent et al., PLB 202, 190, 1988

37. Primary fragment reconstruction method
N. Marie et al., PRC 58, 256 (1998)
S. Hudan et al., PhD thesis and PRC67, (2003)
Xe + 32 A MeV
IMF-LCP Vrel Correlations
1+R(Vrel) = Nc/Nnc
Background Parameterization
A-1/(BVrel+C)
Evaporated p, d, t, 3He, a
size, E*pr primary fragments
Thermal Contribution
Fonction de corrélation en Vrel = rapport entre les corrélés et non-corrélés, ces derniers sont construits en mélangeant les événements. La fonction différence. Une simulation a permis de comprendre cette forme. La bosse

38. Temperature measurements from excited states unstable nuclei
Idea :
The unstable complex cluster should be emitted early in the decay --> the temperature is expected to be close to the initial temperature of the fragmenting system
Hypothesis :
at least local equilibrium
Advantages
Small sensitivity to collective dynamical effects : rotational, translational, expansion
Direct emission
Etc.
Technique : Correlation function to reconstruct the unstable nuclei

39. Temperature measurements from excited states unstable nuclei
Position-sensitive hodoscope
Pochodzalla et al., PRC , 1987

40. Conclusions
Experiments :
Experimental study of the Xe + Sn system from the onset of multifragmentation
The fragments are excited and their E* saturates at 3 A MeV.
The proportion of thermal LCP does not exceed 35% and decreases with Einc.
Reaction mechanism (HIC) is not able to heat the fragments more than 3A MeV.
 Strong constraints on the statistical and dynamical models.
Comparison with a statistical and dynamical model calculation :
The assumption that the system is in equilibrium at low densities reproduces the primary fragments excitation energies.
BUT it fails to predict the evolution of the evaporative LCP with the incident energy.
AMD predict almost the total energy spectra of protons (78% of total emission)
But it fails to reproduce the thermal contribution (22%).
Questions :
Why are the excitation energies of the spectator fragments at 100 AMeV and the
participant fragments at 50 AMeV the same ? Thermal energy saturation ?
Same production mechanism ? Or … ?