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

Toward a Global Dispersive Optical Model for the Driplines

A dispersive-optical-model analysis has been performed for both protons and neutrons on 40,42,44,48Ca isotopes. The fitted potentials describe accurately both scattering and bound quantities and extrapolate well to other stable nuclei. Further experimental information will be gathered to constrain extrapolations toward the driplines.Comment: Invited talk at the "10th International Conference on Nucleus-Nucleus Collisions", Beijing, 16-21 August 200

Mass Distributions of Intermediate-Mass Fragments in Light-Ion-Induced Reactions

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Fragment Isospin as a Probe of Heavy-Ion Collisions

Isotope ratios of fragments produced at mid-rapidity in peripheral and central collisions of 114Cd ions with 92Mo and 98Mo target nuclei at E/A = 50 MeV are compared. Neutron-rich isotopes are preferentially produced in central collisions as compared to peripheral collisions. The influence of the size (A), density, N/Z, E*/A, and Eflow/A of the emitting source on the measured isotope ratios was explored by comparison with a statistical model (SMM). The mid-rapidity region associated with peripheral collisions does not appear to be neutron-enriched relative to central collisions.Comment: 12 pages including figure

Non-Thermal Behavior in Multifragment Decay

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Angular correlation, spin alignment, and systematics of mis-matched 12C + 12C inelastic scattering resonances

Particle gamma-ray angular correlation measurements have been used to study the spin alignment and magnetic-substate population parameters for the 21+ (4.443 MeV) state in 12C, populated in the 12C(12C,12C[02+]) 12C(21+) inelastic scattering reaction in the vicinity of a prominent, narrow peak in the scattering excitation function. The data show a strong alignment of the spin with the orbital angular momentum, and suggest that the cross section peak corresponds to a spin 14+ resonance at Ec.m. = 28.0 MeV. This energy is close to that where a strong peak is also observed in the 01+ + 0 2+ excitation function. A comparison between the data for these two channels lends some support to recent theoretical calculations of resonance behavior for angular-momentum-mismatched channels in 12C + 12C inelastic scattering

Assessing the Evolutionary Nature of Multifragment Decay

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Energy resolution and energy-light response of CsI(TI) scintillators for charged particle detection

This article describes the crystal selection and quality control utilized to develop and calibrate a high resolution array of CsI(TI) scintillator crystals for the detection of energetic charged particles. Alpha sources are used to test the light output variation due to thallium doping gradients. Selection of crystals with better than 1% non-uniformity in light output is accomplished using this method. Tests with 240 MeV alpha beam reveal that local light output variations within each of the tested CsI(TI) crystals limit the resolution to about 0.5%. Charge and mass dependences in the energy - light output relationship are determined by calibrating with energetic projectile fragmentation beams.Comment: 24 pages, 7 figure

High-spin spectrum of 24Mg studied through multiparticle angular correlations

We describe the investigation of high-spin states in 24Mg populated with the 12C(16O,α)24Mg reaction at 62- and 68-MeV beam energy. The excited states were established through the coincident detection of up to four α and γ particles in complete decay cascades toward a final state of angular momentum zero, the ground state of either 20Ne or 16O. We describe a new analysis method for the angular correlations in such events and apply it with the goal to assign spin and parity to α-unbound states in 24Mg. We establish a number of high-spin, natural-parity states between spins 6 and 12, including the lowest known 10+ and 12 + levels. The energy systematics of positive- and negative-parity high-spin states are compared to the predictions of modern shell-model calculations

Identification of the Iπ = 10+ yrast rotational state in 24Mg

The power of quadruple angular correlations combined with a new analysis method was used to identify the first 10+ state at an energy of 19.2(1) MeV in 24Mg. Evidence for the γ decay of this state was also obtained. The results indicate that the rotational band is yrast in 24Mg at spin 10ℏ and is associated with a rotational frequency of ℏω≈2.9 MeV