Measuring the temperature of hot nuclear fragments

Abstract

A new thermometer based on fragment momentum fluctuations is presented. This thermometer exhibited residual contamination from the collective motion of the fragments along the beam axis. For this reason, the transverse direction has been explored. Additionally, a mass dependence was observed for this thermometer. This mass dependence may be the result of the Fermi momentum of nucleons or the different properties of the fragments (binding energy, spin etc..) which might be more sensitive to different densities and temperatures of the exploding fragments. We expect some of these aspects to be smaller for protons (and/or neutrons); consequently, the proton transverse momentum fluctuations were used to investigate the temperature dependence of the source.

Systematic study of the symmetry energy within the approach of the statistical multifragmentation model

“…It has been reported in the literature [21,34] that better isoscaling can be obtained when selecting two sources with well-defined isotopic compositions rather than performing a system-to-system isoscaling. The isobaric yield ratio values for C sym /T were extracted for a source whose average m s was equal to the difference in m s of the sources used for the isoscaling.…”

Nuclear thermodynamics and isospin degree of freedom

“…[20]. Note that, unlike the ensemble of caloric curves presented in [11], none of those derived in [18][19][20] exhibits a plateau. In [20] the temperature linearly increases with energy between 2 and 8 A MeV, reaching 12 MeV at E * =8 A MeV, well above the empirical value of T lim for light nuclei estimated in [11].…”

Properties of excited A = 40 nuclear systems with varying matter composition

“…A method for measuring the temperature based on momentum quadruple fluctuations of detected particles was proposed in [15]. A quadruple moment Q xy = p 2 x − p 2 y is defined in a direction transverse to the beam axis (z-axis) to minimize non-equilibrium effects [3] [4] [5].…”

“…The average Q xy is zero for a given particle type in the center of mass of the equilibrated emitting source. In the Figure 3 the temperatures extracted for bosons and fermions using the method described in [15] are presented as a function of excitation energy. It can be noticed that the temperature of bosons is lower than the fermions and the temperature of bosons extracted from experimental data is higher than extracted from AMD simulations.…”