Z-dependent Barriers in Multifragmentation from Poissonian Reducibility and Thermal Scaling

We explore the natural limit of binomial reducibility in nuclear multifragmentation by constructing excitation functions for intermediate mass fragments (IMF) of a given element Z. The resulting multiplicity distributions for each window of transverse energy are Poissonian. Thermal scaling is observed in the linear Arrhenius plots made from the average multiplicity of each element. ``Emission barriers'' are extracted from the slopes of the Arrhenius plots and their possible origin is discussed.Comment: 15 pages including 4 .ps figures. Submitted to Phys. Rev. Letters. Also available at http://csa5.lbl.gov/moretto

Resilient Reducibility in Nuclear Multifragmentation

The resilience to averaging over an initial energy distribution of reducibility and thermal scaling observed in nuclear multifragmentation is studied. Poissonian reducibility and the associated thermal scaling of the mean are shown to be robust. Binomial reducibility and thermal scaling of the elementary probability are robust under a broad range of conditions. The experimental data do not show any indication of deviation due to averaging.Comment: 5 pages, 6 figures, submitted to Physical Review

Do phase transitions survive binomial reducibility and thermal scaling?

First order phase transitions are described in terms of the microcanonical and canonical ensemble, with special attention to finite size effects. Difficulties in interpreting a "caloric curve" are discussed. A robust parameter indicating phase coexistence (univariance) or single phase (bivariance) is extracted for charge distributions.Comment: 10 pages, TeX type, psfig, also available at http://csa5.lbl.gov/moretto/ps/lgm.ps, to appear in the Proceedings of the 1st Catania Relativistic Ion Studies: Critical Phenomena and Collective Observables, Acicastello, May 27-31, 199

Calculation of the number of partitions with constraints on the fragment size

This article introduces recursive relations allowing the calculation of the number of partitions with constraints on the minimum and/or on the maximum fragment size