2
E. Bonnet
In this work, we will address the contribution of the different clusters to the
produced partitions according to the Z max observable. As we deal with finite systems,
we have to consider carefully the trivial conservation of the total number of nucleons.
This a specific point concerning HIC respect to NM, the finite number of nucleons
involved in the collision process has to be considered. This means that depending on
the fragmentation degree associated with different excitation/dissipation/violence,
the available nucleons to build clusters is not the same. This picture of available
nucleons to build cluster points out also the question of time sequence during the
whole process leading to the final partitions. In that sense, the use of Z max has two
advantages: it allows to sample the phase diagram and it allows to consider set of
final partitions where available nucleons to be shared in clusters are a posteriori
equivalent. From the experimental point of view, the charge of the biggest fragment
is a straight forward and robust observable.
1.2 Methodology and Experimental Details
The methodology is as following: in the
58 Ni+
58 Ni reactions collected with INDRA,
we look at evolution of the contributions of the different species:
1,2,3 H,
3,4 He and the
heavier clusters are gathered in the A > 4 family. We choose the
58 Ni+
58 Ni system
because it is a rather light system and in this way, we minimize experimental bias
over the whole range of fragmentation degree. To draw the cluster contributions, we
introduce the mass fraction (X, (1.1)). First, we look at the effect of different beam
energies (from 32 to 90 MeV/nucleon) to evaluate the effect of an increase of the
energy deposition in the system. Then we introduce the excitation energy (E
∗ , (1.2))
to apply an additional sorting and to draw a general picture of the different cluster
contributions under Z max and E
∗ constraints.
X
(i)
= m i A i /(A tot − A max ),
(1.1)
E
∗
=
M Z ≥1
i=1
((
(i)
k + δ
(i)
) + M n (< <
n
k > +δ
n
) − δ ini .
(1.2)
The INDRA apparatus [4] allows the detection and charge identification of all
charged products coming from a collision. In addition, thanks to Cesium Iodide scintillators, the isotopic identification is achieved for elements up to Be. The
58 Ni+
58 Ni
data presented in this analysis have already used to probe isospin diffusion in semiperipheral collisions [5] and to measure fusion cross sections for light systems with
a significant contribution at 32 and 40 MeV/nucleon [6]. A detailed description of
the experiment and the INDRA apparatus can be found in these related publications.
In the following, we focus on the forward part of each event because a complete
isotopic identification up to
10 Be is achieved; the detection efficiency is almost inde-
E. Bonnet
In this work, we will address the contribution of the different clusters to the
produced partitions according to the Z max observable. As we deal with finite systems,
we have to consider carefully the trivial conservation of the total number of nucleons.
This a specific point concerning HIC respect to NM, the finite number of nucleons
involved in the collision process has to be considered. This means that depending on
the fragmentation degree associated with different excitation/dissipation/violence,
the available nucleons to build clusters is not the same. This picture of available
nucleons to build cluster points out also the question of time sequence during the
whole process leading to the final partitions. In that sense, the use of Z max has two
advantages: it allows to sample the phase diagram and it allows to consider set of
final partitions where available nucleons to be shared in clusters are a posteriori
equivalent. From the experimental point of view, the charge of the biggest fragment
is a straight forward and robust observable.
1.2 Methodology and Experimental Details
The methodology is as following: in the
58 Ni+
58 Ni reactions collected with INDRA,
we look at evolution of the contributions of the different species:
1,2,3 H,
3,4 He and the
heavier clusters are gathered in the A > 4 family. We choose the
58 Ni+
58 Ni system
because it is a rather light system and in this way, we minimize experimental bias
over the whole range of fragmentation degree. To draw the cluster contributions, we
introduce the mass fraction (X, (1.1)). First, we look at the effect of different beam
energies (from 32 to 90 MeV/nucleon) to evaluate the effect of an increase of the
energy deposition in the system. Then we introduce the excitation energy (E
∗ , (1.2))
to apply an additional sorting and to draw a general picture of the different cluster
contributions under Z max and E
∗ constraints.
X
(i)
= m i A i /(A tot − A max ),
(1.1)
E
∗
=
M Z ≥1
i=1
((
(i)
k + δ
(i)
) + M n (< <
n
k > +δ
n
) − δ ini .
(1.2)
The INDRA apparatus [4] allows the detection and charge identification of all
charged products coming from a collision. In addition, thanks to Cesium Iodide scintillators, the isotopic identification is achieved for elements up to Be. The
58 Ni+
58 Ni
data presented in this analysis have already used to probe isospin diffusion in semiperipheral collisions [5] and to measure fusion cross sections for light systems with
a significant contribution at 32 and 40 MeV/nucleon [6]. A detailed description of
the experiment and the INDRA apparatus can be found in these related publications.
In the following, we focus on the forward part of each event because a complete
isotopic identification up to
10 Be is achieved; the detection efficiency is almost inde-