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Source size scaling of fragment production in projectile breakup  [PDF]
L. Beaulieu,D. R. Bowman,D. Fox,S. Das Gupta,J. Pan,G. C. Ball,B. Djerroud,D. Dore,A. Galindo-Uribarri,D. Guinet,E. Hagberg,D. Horn,R. Laforest,Y. Larochelle,P. Lautesse,M. Samri,R. Roy,C. St-Pierre
Physics , 1996, DOI: 10.1103/PhysRevC.54.R973
Abstract: Fragment production has been studied as a function of the source mass and excitation energy in peripheral collisions of $^{35}$Cl+$^{197}$Au at 43 MeV/nucleon and $^{70}$Ge+$^{nat}$Ti at 35 MeV/nucleon. The results are compared to the Au+Au data at 600 MeV/nucleon obtained by the ALADIN collaboration. A mass scaling, by $A_{source} \sim$ 35 to 190, strongly correlated to excitation energy per nucleon, is presented, suggesting a thermal fragment production mechanism. Comparisons to a standard sequential decay model and the lattice-gas model are made. Fragment emission from a hot, rotating source is unable to reproduce the experimental source size scaling.
Medium mass fragments production due to momentum dependent interactions  [PDF]
Sanjeev Kumar,Suneel Kumar,Rajeev K. Puri
Physics , 2010, DOI: 10.1103/PhysRevC.78.064602
Abstract: The role of system size and momentum dependent effects are analyzed in multifragmenation by simulating symmetric reactions of Ca+Ca, Ni+Ni, Nb+Nb, Xe+Xe, Er+Er, Au+Au, and U+U at incident energies between 50 MeV/nucleon and 1000 MeV/nucleon and over full impact parameter zones. Our detailed study reveals that there exist a system size dependence when reaction is simulated with momentum dependent interactions. This dependence exhibits a mass power law behavior.
Reaction plane dispersion at intermediate energies  [PDF]
J. Lukasik,W. Trautmann
Physics , 2006,
Abstract: A method to derive the corrections for the dispersion of the reaction plane at intermediate energies is proposed. The method is based on the correlated, non-isotropic Gaussian approximation. It allowed to construct the excitation function of genuine flow values for the Au+Au reactions at 40-150 MeV/nucleon measured with the INDRA detector at GSI.
Thermal photon-IMF anticorrelation: a signal of prompt multifragmentation?  [PDF]
R. Alba
Physics , 2005,
Abstract: The mechanism responsible for IMF emission in central $^{58}$Ni + $^{197}$Au reactions at 30 and 45 MeV/nucleon is investigated by looking at the thermal bremsstrahlung photon production. An IMF - photon anticorrelation signal is observed, for central collisions, at 45 MeV/nucleon with IMF velocity around the center of mass value. This observation is proposed as an evidence for prompt nuclear fragmentation events.
Isotopic Composition of Fragments in Nuclear Multifragmentation  [PDF]
P. M. Milazzo,A. S. Botvina,G. Vannini,N. Colonna,F. Gramegna,G. V. Margagliotti,P. F. Mastinu,A. Moroni,R. Rui
Physics , 2000, DOI: 10.1103/PhysRevC.62.041602
Abstract: The isotope yields of fragments, produced in the decay of the quasiprojectile in Au+Au peripheral collisions at 35 MeV/nucleon and those coming from the disassembly of the unique source formed in Xe+Cu central reactions at 30 MeV/nucleon, were measured. We show that the relative yields of neutron-rich isotopes increase with the excitation energy in multifragmentation reaction. In the framework of the statistical multifragmentation model which fairly well reproduces the experimental observables, this behaviour can be explained by increasing N/Z ratio of hot primary fragments, that corresponds to the statistical evolution of the decay mechanism with the excitation energy: from a compound-like decay to complete multifragmentation.
Isospin effects and symmetry energy studies with INDRA  [PDF]
G. Ademard,B. Borderie,A. Chbihi,O. Lopez,P. Napolitani,M. F. Rivet,M. Boisjoli,E. Bonnet,R. Bougault,J. D. Frankland,E. Galichet,D. Guinet,M. Kabtoul,G. Lehaut,P. Lautesse,M. La Commara,N. Le Neindre,P. Marini,M. Parlog,P. Paw?owski,E. Rosato,R. Roy,E. Spadaccini,E. Vient,M. Vigilante,J. P. Wieleczko.
Physics , 2013, DOI: 10.1140/epja/i2014-14033-x
Abstract: The equation of state of asymmetric nuclear matter is still controversial, as predictions at subsaturation as well as above normal density widely diverge. We discuss several experimental results measured in heavy-ion collisions with the INDRA array in the incident energy range 5-80 MeV/nucleon. In particular an estimate of the density dependence of the symmetry energy is derived from isospin diffusion results compared with a transport code: the potential part of the symmetry energy linearly increases with the density. We demonstrate that isospin equilibrium is reached in mid-central collisions for the two reactions Ni+Au at 52 MeV/nucleon and Xe+Sn at 32 MeV/nucleon. New possible variables and an improved modelization to investigate symmetry energy are discussed.
Bimodality in spectator fragmentation  [PDF]
W. Trautmann,the ALADIN Collaboration
Physics , 2007,
Abstract: The fluctuations of the largest fragment charge of a partition and of the charge asymmetries of the two or three largest fragments in spectator decays following 197Au + 197Au collisions at 1000 MeV per nucleon are investigated. The observed bimodal distributions at specific values of the sorting variable Z_bound exhibit features known from percolation theory where they appear as finite-size effects. The underlying configurational fluctuations seem generic for fragmentation processes in small systems.
Quantum Fluctuation Effects on Nuclear Fragment Formation  [PDF]
A. Ohnishi,J. Randrup
Physics , 1996, DOI: 10.1016/S0370-2693(97)00032-4
Abstract: Multifragmentation in Au+Au collisions is investigated at incident energies in the range 100-400 MeV per nucleon by means of a recently developed quantal Langevin model. The inclusion of quantum fluctuations enhances the average multiplicity of intermediate mass fragments, especially in central collisions. This is mainly because the excitation energies of fragments are reduced due to the quantal behavior of intrinsic specific heat.
Multifragmentation with Indra@GSI: From the Fermi to the Participant-Spectator Domain  [PDF]
W. Trautmann,A. Le Fevre,J. Lukasik
Physics , 2004,
Abstract: With INDRA at GSI, multifragmentation was studied in 197Au + 197Au reactions at bombarding energies 40 to 150 MeV per nucleon. The mechanisms of fragment production at mid-rapidity in peripheral collisions and the interplay of collective motion and fragmentation in central collisions were investigated. The balance energy for squeeze-out, i.e. the transition energy from in-plane to out-of-plane enhancement of the particle and fragment emissions is determined as a function of the impact parameter.
Event-by-Event Analysis of Proton-Induced Nuclear Multifragmentation: Determination of Phase Transition Universality-Class in System with Extreme Finite-Size Constraints  [PDF]
M. Kleine Berkenbusch,W. Bauer,K. Dillman,S. Pratt,L. Beaulieu,K. Kwiatkowski,T. Lefort,W. -c. Hsi,V. Viola,S. J. Yennello,R. G. Korteling,H. Breuer
Physics , 2001, DOI: 10.1103/PhysRevLett.88.022701
Abstract: A percolation model of nuclear fragmentation is used to interpret 10.2 GeV/c p+197Au multi-fragmentation data. Emphasis is put on finding signatures of a continuous nuclear matter phase transition in finite nuclear systems. Based on model calculations, corrections accounting for physical constraints of the fragment detection and sequential decay processes are derived. Strong circumstantial evidence for a continuous phase transition is found, and the values of two critical exponents, sigma = 0.5+-0.1 and tau = 2.35+-0.05, are extracted from the data. A critical temperature of T_c = 8.3+-0.2 MeV is found.
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