The relative angle correlations of intermediate mass fragments has been studied for
12
C + Au collisions at 22 GeV. Strong suppression at small angles is observed which is due to the Coulomb ...repulsion of fragments. The experimental correlation function was compared to that obtained by the multibody Coulomb trajectory calculations with the various decay time of fragmenting system. It is found that the average decay time of fragmenting system is less than 59 ± 11 fm
c
–1
.
Invariant cross sections of carbon fragments are investigated for
p
(3.6 GeV)
+
Au collisions in terms of longitudinal versus transversal velocity components. It is found that fragments are emitted ...by one slowly moving source.
Critical temperature
T
c
for the nuclear liquid-gas phase transition is estimated from both the multifragmentation and fission data. In the first case, the critical temperature is obtained by ...analysis of the intermediate-mass-fragment yields in
p
(8.1 GeV) + Au collisions within the statistical model of multifragmentation. In the second case, the experimental fission probability for excited
188
Os is compared with the calculated one with
T
c
as a free parameter. It is concluded for both cases that the critical temperature is higher than 15 MeV.
The kinetic energy spectra of intermediate mass fragments (IMF) has been studied for 4.4 GeV
d
+ Au collisions at the Dubna Nuclotron with the 4π detector array FASA. Experimental kinetic energy ...spectra were compared to that obtained by the multi-body Coulomb trajectory calculations with the initial break-up conditions given by the combined model INC + SMM. It was found good agreement of measured and calculated kinetic energy spectra including a radial flow.
Thermal multifragmentation of hot nuclei is interpreted as the nuclear
liquid-fog phase transition. The charge distributions of the intermediate mass fragments produced in
p(3.6 GeV) + Au and
p(8.1 ...GeV) + Au collisions are analyzed with in the statistical multifragmentation model with the critical temperature for the
nuclear liquid-gas phase transition
T
c as a free parameter. The analysis presented here provides strong support for a value of
T
c > 15MeV.
The multifragmentation time scale is measured for
d
(4.4 GeV) + Au collisions by the analysis of the relative angle correlation function for the intermediate-mass fragments. The experiment was ...performed with the FASA 4
π
setup installed at the external beam of the superconducting accelerator Nuclotron. A combined approach of intranuclear cascade prescription followed by the Statistical Model of Multifragmentation is used for the analysis of the data. Multifragmentation of a target spectator is measured to be 100 fm/
c
(CL > 99.5%) delayed in relation to the collision moment. The latter is fixed by the registration of the fast fragment with
Z
= 4, produced at the collisionmoment.
The paper is devoted to the experimental determination of the space-time characteristics for the target multifragmentation in p(8.1 GeV)+Au collisions. The experimental data on the fragment charge ...distribution and kinetic energy spectra are analyzed within the framework of the statistical multifragmentation model. It is found that the partition of hot nuclei is specified after expansion of the target spectator to a volume equal to V{sub t}=(2.9{+-}0.2)V{sub o}, with V{sub o} as the volume at normal density. However, the freezeout volume is found to be V{sub f}=(11{+-}3)V{sub o}. At freezeout, all the fragments are well separated and only the Coulomb force should be taken into account. The results are in accordance with a scenario of spinodal disintegration of hot nuclei.
The relative velocity correlation function of pairs of intermediate mass fragments has been studied for d + Au collisions at 4.4 GeV. Experimental correlation functions are compared to that obtained ...by multi-body Coulomb trajectory calculations under the assumption of various decay times of the fragmenting system. The combined approach with the empirically modified intranuclear cascade code followed by the statistical multifragmentation model was used to generate the starting conditions for these calculations. The fragment emission time is found to be less than 40 fm
c
−1
.
Thermal multifragmentation of hot nuclei is interpreted as the nuclear
liquid–fog phase transition inside the spinodal region. The experimental data for
p
(
8.1
GeV
)
+
Au
collisions are analyzed. ...It is concluded that the decay process of hot nuclei is characterized by
two size parameters: one density at the transition state and one at the kinetic freeze-out. The similarity between the dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multiscission point, which corresponds to the kinetic freeze-out configuration.
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