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S. Sharma et al.
formation, quark gluon plasma, etc. are observed [7–9]. In case of intermediate
energy, both mean field and nucleon-nucleon collisions have contribution. At these
energies, phenomena such as collective flow, sub-threshold particle production and
multifragmentation are the important ones [10–12]. In the present work, we are
focussing on various aspects of reaction dynamics at intermediate energies.
The intermediate energy reactions give us an excellent opportunity to understand
the behavior of nuclear matter at high densities and temperature. This information
is vital to describe the physics of nuclear star formation, supernovae explosion,
and understanding the conditions of early stages of universe evolution. We expect
this information via studying fragmentation, collective flow and particle production.
Among these the fragmentation, which is breaking of nuclei into multiple small and
medium mass nuclei when excitation energy exceeds their binding energies, is the
most promising one. The extensive studies showed that the structure of fragments is
affected by different entrance channels such as incident energy, impact parameter,
mass of colliding nuclei, isospin asymmetry, and mass asymmetry [13–21]. It is
well known that the dynamics of reaction differ significantly for symmetric and
asymmetric reactions. The former has greater share of energy as compression whereas
later has more energy as excitation/thermal. Therefore, to understand the various
aspects of reaction dynamics, mapping of both symmetric and asymmetric reactions
is important.
In previous studies, it was found that the multiplicity of intermediate mass fragments (IMFs) shows a rise and fall behavior when plotted against incident energy of
projectile. The energy at which maximum multiplicity of IMFs is observed is termed
as < E
max
c.m. > and the corresponding IMF’s multiplicity as < N
max
I M Fs >. In experiments, such behavior was observed by Peaslee et al. for the reactions of
84 Kr +
197 Au
in the incident energy range of 35–400 MeV/nucleon [21]. The maximum IMF production was observed at ∼ 100 MeV/nucelon. They also used Quantum Molecular
Dynamics (QMD) and QMD + Statistical Multifragmentation Model (SMM) model
to explain the results. Later, the Michigan State University (MSU) group performed
more systematic study with the reactions of
40 Ar +
45 Sc,
58 Ni +
58 Ni, and
86 Kr +
93 Nb and reported a linear dependence of < E
max
c.m. > and power law dependence of
< N
max
I M Fs > when plotted against system mass [22]. On the theoretical front, the
percolation model calculations were used to explain the observations but remain
unsuccessful. Later, Puri and co-workers were successful in explaining the experimental observations. They did so, first using Quantum Molecular Dynamics (QMD)
model with advanced microscopic clusterization algorithm based on binding energy,
and using the improved QMD, i.e., Isospin-dependent Quantum Molecular Dynamics (IQMD) model with basic spatial correlations-based clusterization algorithm [23,
24]. They also studied the role of different definitions of IMFs on the peak center
of mass energy and found it to be insignificant [25]. Also, the role of various model
ingredients such as equation of state (EOS), nucleon-nucleon cross-section, gaussian
width and isospin effects on energy of peak production of IMFs was investigated.
They reported insensitive behavior of < E
max
c.m. > toward these model ingredients
except isospin effects [24, 26].
S. Sharma et al.
formation, quark gluon plasma, etc. are observed [7–9]. In case of intermediate
energy, both mean field and nucleon-nucleon collisions have contribution. At these
energies, phenomena such as collective flow, sub-threshold particle production and
multifragmentation are the important ones [10–12]. In the present work, we are
focussing on various aspects of reaction dynamics at intermediate energies.
The intermediate energy reactions give us an excellent opportunity to understand
the behavior of nuclear matter at high densities and temperature. This information
is vital to describe the physics of nuclear star formation, supernovae explosion,
and understanding the conditions of early stages of universe evolution. We expect
this information via studying fragmentation, collective flow and particle production.
Among these the fragmentation, which is breaking of nuclei into multiple small and
medium mass nuclei when excitation energy exceeds their binding energies, is the
most promising one. The extensive studies showed that the structure of fragments is
affected by different entrance channels such as incident energy, impact parameter,
mass of colliding nuclei, isospin asymmetry, and mass asymmetry [13–21]. It is
well known that the dynamics of reaction differ significantly for symmetric and
asymmetric reactions. The former has greater share of energy as compression whereas
later has more energy as excitation/thermal. Therefore, to understand the various
aspects of reaction dynamics, mapping of both symmetric and asymmetric reactions
is important.
In previous studies, it was found that the multiplicity of intermediate mass fragments (IMFs) shows a rise and fall behavior when plotted against incident energy of
projectile. The energy at which maximum multiplicity of IMFs is observed is termed
as < E
max
c.m. > and the corresponding IMF’s multiplicity as < N
max
I M Fs >. In experiments, such behavior was observed by Peaslee et al. for the reactions of
84 Kr +
197 Au
in the incident energy range of 35–400 MeV/nucleon [21]. The maximum IMF production was observed at ∼ 100 MeV/nucelon. They also used Quantum Molecular
Dynamics (QMD) and QMD + Statistical Multifragmentation Model (SMM) model
to explain the results. Later, the Michigan State University (MSU) group performed
more systematic study with the reactions of
40 Ar +
45 Sc,
58 Ni +
58 Ni, and
86 Kr +
93 Nb and reported a linear dependence of < E
max
c.m. > and power law dependence of
< N
max
I M Fs > when plotted against system mass [22]. On the theoretical front, the
percolation model calculations were used to explain the observations but remain
unsuccessful. Later, Puri and co-workers were successful in explaining the experimental observations. They did so, first using Quantum Molecular Dynamics (QMD)
model with advanced microscopic clusterization algorithm based on binding energy,
and using the improved QMD, i.e., Isospin-dependent Quantum Molecular Dynamics (IQMD) model with basic spatial correlations-based clusterization algorithm [23,
24]. They also studied the role of different definitions of IMFs on the peak center
of mass energy and found it to be insignificant [25]. Also, the role of various model
ingredients such as equation of state (EOS), nucleon-nucleon cross-section, gaussian
width and isospin effects on energy of peak production of IMFs was investigated.
They reported insensitive behavior of < E
max
c.m. > toward these model ingredients
except isospin effects [24, 26].