Seminar Details

Parallel and Perpendicular Momentum Distributions in Projectile Fragmentation Reactions

Krista Meierbachtol, NSCL/MSU
Monday, April 23, 1:00 PM - Thesis Defense
NSCL Lecture Hall

Projectile fragmentation has been used for decades to produce rare isotope beams for use in advancing nuclear science. Multiple observables are available for studying the underlying reaction mechanism including measurement of the linear momentum of final fragmentation products. Furthermore, the two components of the linear momentum, the parallel momentum distribution and the perpendicular momentum distribution, have been studied very disparately with more measurements of the parallel momentum distribution of fragmentation products.

The full parallel and perpendicular momentum distributions have been measured as a function of fragment mass loss for a wide range of fragments (A=37 to 75, Z=17 to 33) produced from interaction of a Ge-76 beam at 130 MeV/nucleon on either a Be-9 or Au-197 target. The parallel momentum distributions were found to be independent of target species and agree with both previous measured distributions and models of distribution width by Goldhaber and Morrissey. The perpendicular momentum distributions were found to agree with models of the distribution width by Van Bibber for fragments produced with the light beryllium target or fragments with a mass loss greater than 20 produced with the heavy gold target. The distribution widths of the heaviest fragments produced with the gold target had scattering angles that could be described by a calculation of the classical deflection function using a repulsive Coulomb plus an attractive nuclear scattering potential between the fragment and the gold target.

The particle identification procedure used with the S800 spectrometer at the National Superconducting Cyclotron Laboratory has been improved by the addition of the identification of the atomic charge-state of incoming particles. The total kinetic energy of incoming particles can now be measured with a new CsI(Na) hodoscope array, which has been characterized as a function of particle energy, mass, and nuclear charge. The energy resolution was deduced to be approximately 3% in the 100 GeV total kinetic energy regime.