New scalings in nuclear fragmentation.

Fragment partitions of fragmenting hot nuclei produced in central and semiperipheral collisions have been compared in the excitation energy region 4-10 MeV per nucleon where radial collective expansion takes place. It is shown that, for a given total excitation energy per nucleon, the amount of radial collective energy fixes the mean fragment multiplicity. It is also shown that, at a given total excitation energy per nucleon, the different properties of fragment partitions are completely determined by the reduced fragment multiplicity (i.e., normalized to the source size). Freeze-out volumes seem to play a role in the scalings observed.

Characterisation of a BC501A compact neutron spectrometer for fusion research.

The compact neutron spectrometer used at the ASDEX Upgrade tokamak is characterised to obtain its response matrix. This paper describes the characterisation procedure and the derived response matrix, based on a campaign at the PTB ion accelerator facility (PIAF) and on the subsequent time-of-flight (TOF) analysis of neutrons from a field with a broad energy distribution. The response of mono-energetic neutrons generated at the PIAF is used as reference for the TOF analysis. The detector's response functions for spectrum deconvolution are obtained by Gaussian broadening of the simulated responses to fit the experimental ones, using a maximum-entropy ansatz. In this way, the response functions are smooth enough to ensure a reliable unfolding of pulse height spectra into neutron emission spectra, which provide information on the fast ion velocity distribution in neutral beam heated tokamak plasmas.

Characterization of single crystal chemical vapor deposition diamond detectors for neutron spectrometry.

Detectors made from artificial chemical vapor deposition single crystal diamond have shown great potential for fast neutron spectrometry. In this paper, we present the results of measurements made at the Physikalisch-Technische Bundesanstalt accelerator using neutron fields in the energy range from 7 MeV to 16 MeV. This study presents the first results of the characterization of the detector in this energy range.

Bimodal behavior of the heaviest fragment distribution in projectile fragmentation.

The charge distribution of the heaviest fragment detected in the decay of quasiprojectiles produced in intermediate energy heavy-ion collisions has been observed to be bimodal. This feature is expected as a generic signal of phase transition in nonextensive systems. In this Letter, we present new analyses of experimental data from Au on Au collisions at 60, 80, and 100 MeV/nucleon showing that bimodality is largely independent of the data selection procedure and of entrance channel effects. An estimate of the latent heat of the transition is extracted.