S. Costa

Temperature and free-nucleon densities of nuclear matter exploding into light clusters in heavy-ion collisions

SummaryA new statistical approach is adopted which, through a suitable analysis of light clusters emitted in heavy-ion collisions, allows us to evaluate temperature and free-nucleon densities of the emission source. All known data concerning the emission of2H,3H,3He,4He measured in a common experiment are used. These data refer to 19 heavy-ion reactions studied at projectile energies between 26 and 2100 MeV per nucleon. Analysed events are only those attributable to the equilibrium component through carefully adopted selections. Among the results, a correlation is observed between temperatureT and total free-nucleon density ϱtF of the emission source. A nuclear-matter model is formulated in order to compare its quantitative predictions with the observed (T, ϱtF) correlation. A good agreement is found by this comparison.RiassuntoSi adotta un nuovo approccio statistico che, mediante un’opportuna analisi delle particelle leggere emesse nelle reazioni tra ioni pesanti, permette di calcolare le densità dei nucleoni liberi e la temperatura della sorgente di emissione. Si usano tutti i dati noti riguardanti l’emissione di2H,3H,3He,4He misurati in un unico esperimento. Questi dati si riferiscono a 19 reazioni tra ioni pesanti studiate a energie comprese tra 26 e 2100 MeV per nucleone. Gli eventi analizzati sono soltanto quelli che, mediante accurate selezioni, possono essere attribuiti alla componente di equilibrio. Tra i risultati, si osserva una correlazione tra la densità totale dei nucleoni liberi ϱtF e la temperaturaT della sorgente. Si formula un modello della materia nucleare per confrontare le previsioni quantitative di tale modello con la correlazione osservata traT e28-2. Questo confronto dà un accordo soddisfacente.

Multifragmentation and the phase transition: A systematic study of the multifragmentation of1AGeVAu, La, and Kr

A systematic analysis of the multifragmentation (MF) in fully reconstructed events from 1A GeV Au, La and Kr collisions with C has been performed. This data is used to provide a definitive test of the variable volume version of the statistical multifragmentation model (SMM). A single set of SMM parameters directly determined by the data and the semi-empiricalmass formula are used after the adjustable inverse level density parameter,

Experimental results on neutron production by muons at 4300 m w.e.

epsilon_{o}

Thermodynamic quantities deduced from the emission at large angles of isotopically resolved composite particles

is determined by the fragment distributions. The results from SMM for second stage multiplicity, size of the biggest fragment and the intermediate mass fragments are in excellent agreement with the data. Multifragmentation thresholds have been obtained for all three systems using SMM prior to secondary decay. The data indicate that both thermal excitation energy

The modified SOD method related to a simple model of the scattering process

E_{th}^{*}

5Li elastic transfer in27Al+32S collision atEinc=100 MeV

and the isotope ratio temperature

Searhh of quantum and fragment decay effects on observable emission yields of isotopically resolved fragments

T_{He-DT}

A possible solution of controversies between measured and expected entropy production in heavy-ion collisions at intermediate energies

decrease with increase in system size at the critical point. The breakup temperature obtained from SMM also shows the same trend as seen in the data. The SMM model is used to study the nature of the MF phase transition. The caloric curve for Kr exhibits back-bending (finite latent heat) while the caloric curves for Au and La are consistent with a continuous phase transition (nearly zero latent heat) and the values of the critical exponents

Observed changes of the neutron to proton ratio from the initial to final stage of nuclear reactions. A possible interpretation and some deduced information

tau

Electric-quadrupole inelastic transitions in27Al+32S collision atEinc=100 MeV

,