C. Leduc

Response of CsI(Tl) scintillators over a large range in energy and atomic number of ions. Part I: recombination and δ-electrons

Abstract A simple formalism describing the light response of CsI(Tl) to heavy ions, which quantifies the luminescence and the quenching in terms of the competition between radiative transitions following the carrier trapping at the Tl activator sites and the electron–hole recombination, is proposed. The effect of the δ-rays on the scintillation efficiency is for the first time quantitatively included in a fully consistent way. The light output expression depends on four parameters determined by a procedure of global fit to experimental data.

Response of CsI(Tl) scintillators over a large range in energy and atomic number of ions (Part II): calibration and identification in the INDRA array

Abstract The light output of the 324 CsI(Tl) scintillators of INDRA has been measured over large ranges in energy: 1– 80 AMeV and in atomic number of incident ions: Z =1–60. An analytical expression for the non-linear total light response as a function of the energy and the identity of the ion is developed. It depends on four parameters. For three of them, connected to CsI(Tl) intrinsic characteristics, fixed values are proposed. Two applications are presented: energy calibration and fragment identification in telescopes using a CsI(Tl) crystal as residual energy detector.

Energy calibration for the INDRA multidetector using recoil protons from 12C+1H scattering

An efficient method of energy scale calibration for the CsI(Tl) modules of the INDRA multidetector (rings 6–12) using elastic and inelastic 12C+1H scattering at E(12C)=30MeV per nucleon is presented. Background-free spectra for the binary channels are generated by requiring the coincident detection of the light and heavy ejectiles. The gain parameter of the calibration curve is obtained by fitting the proton total charge spectra to the spectra predicted with Monte-Carlo simulations using tabulated cross section data. The method has been applied in multifragmentation experiments with INDRA at GSI.

Experimental evidence for spinodal decomposition in multifragmentation of heavy systems

Multifragmentation of fused systems was observed for central collisions between 32 AMeV 129Xe and Sn, and 36 AMeV 155Gd and U. Previous extensive comparisons between the two systems led to the hypothesis of spinodal decomposition of finite systems as the origin of multifragmentation for incident energies around 30 AMeV. New results on velocity and charge correlations of fragments bring strong arguments in favor of this interpretation.

Nuclear multifragmentation and the onset of radial flow: A study of Au+Au collisions between 40 and 100 MeV/A

The influence of radial flow on nuclear multifragmentation is studied using Au+Au central collisions for incident energies between 40 and 100 MeV/A. Central collisions are selected via an impact parameter estimator defined by the transverse energy of light charged particles. At all energies, the fragment size distributions are studied using the Statistical Multifragmentation Model (SMM) in order to extract thermal excitation energies. The excess kinetic energies are analyzed via the hypothesis of a radial, self-similar, but non-isotropic flow. At the lowest energy, this flow is small with respect to the thermal energy whereas, at 100 MeV/A thermal and radial energies are of the same order. The nature and origin of the radial flow is discussed. A comparison with the predictions of the Quantum Molecular Dynamics code is presented.