Charged particle spectra in [sup 32]S + [sup 32]S interactions at 200 GeV/nucleon from CCD-imaged nuclear collisions in a streamer chamber
We have measured the transverse momentum spectra 1/p[sub T] dN/dp[sub T] and rapidity distributions dN/dy of negatively charged hadrons and protons for central [sup 32]S + [sup 32]S interactions at 200 GeV/nucleon incident energy. The negative hadron dN/dy distribution is too broad to be accounted for by thermal models which demand isotropic particle emission. It is compatible with models which emphasize longitudinal dynamics, by either a particle production mechanism, as in the Lund fragmentation model, or by introducing one-dimensional hydrodynamic expansion, as in the Landau model. The proton dN/dy distribution, although showing no evidence for a peak in the target fragmentation region, exhibits limited nuclear stopping power. We estimate the mean rapidity shift of participant target protons to be [Delta]y [approximately] 1.5, greater than observed for pp collisions, less than measured in central pA collisions, and much less than would be observed for a single equilibrated fireball at midrapidity. Both the negative hadron and proton dN/dy distributions can be fit by a symmetric Landau two-fireball model. Although the spectrum possesses a two-component structure, a comparison to pp data at comparable center-of-mass energy shows no evidence for enhanced production at low p[sub T]. The two-component structure can be explained by a thermal and chemical equilibrium model which takes into account the kinematics of resonance decay. Using an expression motivated by longitudinal expansion we find the same temperature for both the protons and negative hadrons at freezeout, T[sub f] [approximately] 170 MeV. We conclude that the charged particle spectra of negative hadrons and protons can be accommodated in a simple collision picture of limited nuclear stopping, evolution through a state of thermal equilibrium, followed by longitudinal hydrodynamic expansion until freezeout.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6891312
- Report Number(s):
- LBL-32812; ON: DE93002562
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Charged particle spectra in [sup 32]S + [sup 32]S interactions at 200 GeV/nucleon from CCD-imaged nuclear collisions in a streamer chamber. [CCD (charge-coupled device)]
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Related Subjects
SULFUR 32 TARGET
SULFUR 32 REACTIONS
CHARGE-COUPLED DEVICES
CROSS SECTIONS
DATA ACQUISITION SYSTEMS
EXPERIMENTAL DATA
PARTICLE RAPIDITY
PROTON-PROTON INTERACTIONS
SPECTRA
STREAMER SPARK CHAMBERS
TRANSVERSE MOMENTUM
BARYON-BARYON INTERACTIONS
CHARGED-PARTICLE REACTIONS
DATA
GAS TRACK DETECTORS
HADRON-HADRON INTERACTIONS
HEAVY ION REACTIONS
INFORMATION
INTERACTIONS
LINEAR MOMENTUM
MEASURING INSTRUMENTS
NUCLEAR REACTIONS
NUCLEON-NUCLEON INTERACTIONS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PROTON-NUCLEON INTERACTIONS
RADIATION DETECTORS
SEMICONDUCTOR DEVICES
SPARK CHAMBERS
TARGETS
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