1. Is the caloric curve a robust signal of the phase transition
in hot nuclei ?
E.Vient
IWM-EC 2016
Thursday, April 12th 2016

2. INDRA systematic study of caloric curves of QP
With the different campaigns of the INDRA
collaboration, we can build different caloric curves of QP
for different symmetric or quasi symmetric systems
With the same multidetector array
and an only one experimental protocol
[2] E.Legouée, Ph.D Thesis, Université de Caen-Basse Normandie (2013)
[1] E. Vient, Mémoire d’habilitation à diriger des recherches, Université de Caen -Basse Normandie (2006).
With a new calorimetry called “3D calorimetry of the QP”
[1,2]
With measured temperatures from the slopes
of kinetic energy spectra of protons,
deuterons and tritons
[1,2]
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]

3. Necessity to do certain event selections
Use of an event generator like HIPSE and an INDRA Software Filter to understand and to control our experimental work
[3]
[3] D. Lacroix, A. Van Lauwe, D. Durand, Phys. Rev. C 69 (2004)
Event selections with a correct
detection of the QP products
We lose an important cross section
at all impact parameters
Completeness in the
forward hemisphere of the c.m.
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie] 3

4. Necessity to do certain event selections
Event selections of the collision violence and centrality
Selection according to the Normalized Etr12, dividing its distribution in ten slices of the same cross section
Etr12 Normalized
Counts
b (fm)
, , ,5
Ni + Ni 52 A.MeV
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie] 4

5. Reminders on the 3D Calorimetry
The QP frame is built with IMF and fragments located in the forward hemisphere of the c.m.
In the QP frame the whole space is divided
in six spatial zones
[INDRA-FAZIA workshop on Symmetry Energy and Isospin physics, 20/04/2016, Vient Emmanuel] 5

6. Reminders on the 3D Calorimetry
HIPSE
Data
Counts
Counts
 [120°,180°]
[60°,120°]
QP HIPSE
Others HIPSE
Ekin (MeV)
Ekin (MeV)
Counts
Counts
 [0°,60°]
 [-60°,0°]
Ekin (MeV)
Ekin (MeV)
Counts
Counts
[-180° ,-120°]
 [-120°,-60°]
Ekin (MeV)
Ekin (MeV)
[INDRA-FAZIA workshop on Symmetry Energy and Isospin physics, 20/04/2016, Vient Emmanuel]

7. Reminders on the 3D Calorimetry
Principle of the 3D calorimetry of the QP
All the particles emitted in
the angular domain [0° ; -60°]
in the QP frame are assumed
solely evaporated by the QP
Estimate of an evaporation probability according to the kinetic energy for an angular domain by comparison with this reference domain :
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie] 7

8. Reminders on the 3D Calorimetry
Use the probabilities Probn(Ek, 𝜃SPIN, 𝜑,Etr12) to be emitted
by the QP to do a calorimetry of the QP event by event
In the reconstructed QP frame
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie] 8

9. Application of this 3D Calorimetry to obtain caloric curves
Observed breaks of slope seeming
to correspond to a change
of the mode of de-excitation of the nuclei.
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie] 9

10. Limits of existence of hot nuclei
Does it mean that we have reached the limiting
temperature of existence of hot nuclei ?
Lines correspond to calculations of limiting temperatures due to Coulomb instability
extracted from two theoretical models [4] et [5].
[4] Y. Zhang, Physical Review C 54 (1996) 1137
[5] L. Zhang, Physical Review C 59 (1999) 3292
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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11. Limits of existence of hot nuclei
Understand what happens with HIPSE?
There is an effect due to a pollution by the others contributions
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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12. Possible signals of phase transition : Rise and fall
[6]
What do we observe for the QP contribution
in the angular domain of reference ?
LCP × 6
Li × 6
IMF×6
[6] P. Kreutz , Nucl. Phys. A556, 672 (1993)
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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13. Possible signals of phase transition : ∆-scaling in the liquid
[7]
∆= 1
∆= 1/2
central
Very peripheral
[7] J.D.Frankland, Physical Review C 71 (2005)
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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14. Conclusions and outlooks
The response is no for the moment !
Improve the calorimetry of the QP
Determine the efficiency of the multi detector array with an event generator and correct its effec
Optimize the separation criteria between the different contributions (QP, QT, mid-rapidity) with the help of an event generator or a model
Take into account the entrance channel by a selection
according to the QP mass
Try to ameliorate the thermometry of the QP by the same
recipes and correct well the cooling of the hot nucleus.
Correlate the evolution of the correct caloric curves with
the others signals of phase transition
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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15. [IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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16. Influence of the entrance channel
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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17. Different caloric curves
[7,8]
What happens with another thermometer ?
A/8
A/8
[7] S.Albergo, Il Nuevo Cimento A, Vol 89, Issue 1 (1985) 1
[8} J. Pochodzalla, Phys. Rev. Lett., 75 (1995), p. 1040
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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18. Possible Signals of phase transition :
Evolution and fluctuations of the largest fragments
Evolution of <Zmax2>
Evolution of <Zmax >
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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19. Possible signals of phase transition : ∆-scaling in the liquid
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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20. [IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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21. Possible signals of phase transition : ∆-scaling in the liquid
[IWM-EC 2016 GANIL (Caen), 9/05/2016, Vient Emmanuel, LPC Caen ENSICAEN-Université Caen Normandie]
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