Chaoticity parameter {lambda} in Hanbury-Brown-Twiss interferometry

Journal Article · Sat Sep 15 04:00:00 EDT 2007 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.76.034905· OSTI ID:21064370

Wong, C -Y; Weining, Zhang ^[1]

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1. Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

In Hanbury-Brown-Twiss interferometry measurements using identical bosons, the chaoticity parameter {lambda} has been introduced phenomenologically to represent the momentum correlation function at zero relative momentum. It is useful to study an exactly solvable problem in which the {lambda} parameter and its dependence on the coherence properties of the boson system can be worked out in great detail. We are therefore motivated to study the state of a gas of noninteracting identical bosons at various temperatures held together in a harmonic oscillator potential that arises either externally or from bosons' own mean fields. We determine the degree of Bose-Einstein condensation and its momentum correlation function as a function of the attributes of the boson environment. The parameter {lambda} can then be evaluated from the momentum correlation function. We find that the {lambda}(p,T) parameter is a sensitive function of both the average pair momentum p and the temperature T, and the occurrence of {lambda}=1 is not a consistent measure of the absence of a coherent condensate fraction. In particular, for large values of p, the {lambda} parameter attains the value of unity even for significantly coherent systems with large condensate fractions. We find that if a pion system maintains a static equilibrium within its mean field, and if it contains a root-mean-squared radius, a pion number, and a temperature typical of those in high-energy heavy-ion collisions, then it will contain a large fraction of the Bose-Einstein pion condensate.

• OSTI ID: 21064370
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 76; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BOSE-EINSTEIN CONDENSATION
CORRELATION FUNCTIONS
EXACT SOLUTIONS
HARMONIC OSCILLATORS
HEAVY ION REACTIONS
HYDRODYNAMIC MODEL
INTERFEROMETRY
MEAN-FIELD THEORY
NUCLEAR TEMPERATURE
PIONS
POTENTIALS