Forward baryon distributions in relativistic heavy ion collisions

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7112406

Mitchell, J T

A study of the distributions of protons and neutrons emitted into the forward direction in relativistic heavy ion collisions has been conducted in order to characterize the processes inherent in collisions of 14.6 GeV per nucleon [sup 28]Si incident on [sup 208]Pb, [sup 64]Cu, and [sup 27]Al targets. Two components of the nucleon rapidity and transverse momentum spectra are apparent, corresponding to nucleons that have interacted with the target nucleus during the collision and those that have not been involved in an interaction. The number of non-interacting nucleons has been measured as a function of the collision impact parameter. For the smallest impact parameters, this number is used to extract an in-medium interaction cross section for all three targets that agrees with the free nucleon-nucleon cross section at the collision energy. The transverse momentum and rapidity distributions of both components of the nucleon spectra are measured. The transverse momentum spectra are fit to a thermalized Boltzmann distribution with temperatures approaches 200 MeV at a rapidity of 2.6. This along with the low number of non-interacting nucleons at small impact parameters implies that a volume of very hot and dense matter is being formed in heavy ion collisions at these energies, indicating that conditions are favorable for the formation of a quark-gluon plasma, even though all of the nucleon data are well reproduced by models that do not assume the presence of a plasma. If a quark-gluon plasma is being formed in these collisions, it is not occurring very often. The nucleon measurements are made using the Brookhaven National Lab. Alternating Gradient Synchrotron experiment E814, which consists of four-pi calorimetry for event characterization and a magnetic spectrometer located in the forward direction. The apparatus and technique used to identify and characterize the nucleons is described.

• Research Organization: Yale Univ., New Haven, CT (United States)
• OSTI ID: 7112406
• Country of Publication: United States
• Language: English

Related Subjects

663450* -- Heavy-Ion-Induced Reactions & Scattering-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM 27 TARGET
BARYONS
CHARGED-PARTICLE REACTIONS
COPPER 64 TARGET
CROSS SECTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GEV RANGE
GEV RANGE 10-100
HADRONS
HEAVY ION REACTIONS
LEAD 208 TARGET
NUCLEAR REACTIONS
NUCLEONS
RELATIVISTIC RANGE
SILICON 28 REACTIONS
TARGETS