1 Evolution of Cluster Production with Fragmentation Degree
5
Fig. 1.2 From left to right and top to bottom, mean evolution of the mass fraction with the Z max
observable for the following species: 1 H , 2 H , 3 H , 3 He, and 4 He isotopes and charged products with
mass greater than 4 (A > 4).The different markers and colors stand for the seven beam energies
used in the analysis. The black arrows indicate the entrance and exit of the multifragmentation
window, while the green one indicates the maximum production of A > 4 fragments
of 32 MeV/nucleon, almost pure
4 He events with a continuous decrease in their
contribution when beam energy increases.
1.3.2 Z max and E ∗ Sorting
The previous results were integrated on the whole possible range of dissipation
reached during the reaction. We introduce now the excitation energy to bring an
additional constraint on the studied partitions. To estimated this excitation energy
(E
∗ ), we perform a calorimetry procedure on an event-by-event basis. This procedure
is based on the mass and kinetic energies balance and is summarized by the (1.2). The
main hypothesis concerns the neutron contribution which is estimated through a fermi
gas assumption and the N/Z conservation. Detailed information on the calorimetry
can be found in [8]. In Fig. 1.3, we draw the evolution of the mass fraction with,
this time, an additional constraint on the excitation energy. Only partitions with
E
∗
= 7.5 ± 0.5 MeV/A are kept in the analysis. We only show the highest beam
energies (from 64 to 90 MeV/A) where the statistics are sufficient after this E
∗
5
Fig. 1.2 From left to right and top to bottom, mean evolution of the mass fraction with the Z max
observable for the following species: 1 H , 2 H , 3 H , 3 He, and 4 He isotopes and charged products with
mass greater than 4 (A > 4).The different markers and colors stand for the seven beam energies
used in the analysis. The black arrows indicate the entrance and exit of the multifragmentation
window, while the green one indicates the maximum production of A > 4 fragments
of 32 MeV/nucleon, almost pure
4 He events with a continuous decrease in their
contribution when beam energy increases.
1.3.2 Z max and E ∗ Sorting
The previous results were integrated on the whole possible range of dissipation
reached during the reaction. We introduce now the excitation energy to bring an
additional constraint on the studied partitions. To estimated this excitation energy
(E
∗ ), we perform a calorimetry procedure on an event-by-event basis. This procedure
is based on the mass and kinetic energies balance and is summarized by the (1.2). The
main hypothesis concerns the neutron contribution which is estimated through a fermi
gas assumption and the N/Z conservation. Detailed information on the calorimetry
can be found in [8]. In Fig. 1.3, we draw the evolution of the mass fraction with,
this time, an additional constraint on the excitation energy. Only partitions with
E
∗
= 7.5 ± 0.5 MeV/A are kept in the analysis. We only show the highest beam
energies (from 64 to 90 MeV/A) where the statistics are sufficient after this E
∗