Chaoticity parameter {lambda} in Hanbury-Brown-Twiss interferometry
- 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, Vol. 76, Issue 3; Other Information: DOI: 10.1103/PhysRevC.76.034905; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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