Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter
M. Pichon
(1)
,
B. Tamain
(1)
,
R. Bougault
(1)
,
F. Gulminelli
(1)
,
O. Lopez
(1)
,
Eric Bonnet
(2)
,
B. Borderie
(2)
,
A. Chbihi
(3)
,
R. Dayras
(4)
,
J.D. Frankland
(3)
,
E. Galichet
(5)
,
D. Guinet
(6)
,
P. Lautesse
(6)
,
N. Le Neindre
(2)
,
M. Pârlog
(7)
,
M.F. Rivet
(2)
,
R. Roy
(8)
,
E. Rosato
(9)
,
E. Vient
(1)
,
M. Vigilante
(9)
,
C. Volant
(4)
,
J.P. Wieleczko
(3)
,
B. Zwieglinski
1
LPCC -
Laboratoire de physique corpusculaire de Caen
2 IPNO - Institut de Physique Nucléaire d'Orsay
3 GANIL - Grand Accélérateur National d'Ions Lourds
4 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
5 CNAM - Conservatoire National des Arts et Métiers [CNAM]
6 IPNL - Institut de Physique Nucléaire de Lyon
7 NIPNE - Horia Hulubei National Institute of Physics and Nuclear Engineering
8 ULaval - Université Laval [Québec]
9 INFN, Sezione di Napoli - Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
2 IPNO - Institut de Physique Nucléaire d'Orsay
3 GANIL - Grand Accélérateur National d'Ions Lourds
4 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
5 CNAM - Conservatoire National des Arts et Métiers [CNAM]
6 IPNL - Institut de Physique Nucléaire de Lyon
7 NIPNE - Horia Hulubei National Institute of Physics and Nuclear Engineering
8 ULaval - Université Laval [Québec]
9 INFN, Sezione di Napoli - Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
R. Bougault
- Fonction : Auteur
- PersonId : 940570
- IdHAL : bougault-remi
- ORCID : 0000-0002-2866-7398
F. Gulminelli
- Fonction : Auteur
- PersonId : 940738
- ORCID : 0000-0003-4354-2849
O. Lopez
- Fonction : Auteur
- PersonId : 737418
- IdHAL : olivier-lopez1966
- ORCID : 0000-0003-0818-4564
- IdRef : 233548580
Eric Bonnet
- Fonction : Auteur
- PersonId : 171676
- IdHAL : eric-bonnet
- ORCID : 0000-0003-2625-6971
J.D. Frankland
- Fonction : Auteur
- PersonId : 737417
- IdHAL : john-frankland
- ORCID : 0000-0002-4907-5041
N. Le Neindre
- Fonction : Auteur
- PersonId : 749506
- IdHAL : nicolas-le-neindre
- ORCID : 0000-0001-5419-6764
M. Pârlog
- Fonction : Auteur
- PersonId : 828878
- ORCID : 0000-0002-7566-0244
E. Vient
- Fonction : Auteur
- PersonId : 940571
- ORCID : 0000-0002-6891-7750
B. Zwieglinski
- Fonction : Auteur
Résumé
We have observed a bimodal behaviour of the distribution of the asymmetry between the charges of the two heaviest products resulting from the decay of the quasi-projectile released in binary Xe+Sn and Au+Au collisions from 60 to 100 MeV/u. Event sorting has been achieved through the transverse energy of light charged particles emitted on the quasi-target side, thus avoiding artificial correlations between the bimodality signal and the sorting variable. Bimodality is observed for intermediate impact parameters for which the quasi-projectile is identified. A simulation shows that the deexcitation step rather than the geometry of the collision appears responsible for the bimodal behaviour. The influence of mid-rapidity emission has been verified. The two bumps of the bimodal distribution correspond to different excitation energies and similar temperatures. It is also shown that it is possible to correlate the bimodality signal with a change in the distribution of the heaviest fragment charge and a peak in potential energy fluctuations. All together, this set of data is coherent with what would be expected in a finite system if the corresponding system in the thermodynamic limit exhibits a first order phase transition.