Measuring Hanbury Brown-Twiss correlations of pions in high-energy nucleus-nucleus collisions
Popp, James Lewis Jr.
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https://hdl.handle.net/2142/30765
Description
Title
Measuring Hanbury Brown-Twiss correlations of pions in high-energy nucleus-nucleus collisions
Author(s)
Popp, James Lewis Jr.
Issue Date
1997
Director of Research (if dissertation) or Advisor (if thesis)
Baym, Gordon A.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
particle detectors
Hanbury Brown-Twiss (HBT) effect
pion emission
quantum mechanics
Language
en
Abstract
This dissertation examines how particle detectors extract information about correlations
due to the Hanbury Brown-Twiss (HBT) effect for identical pions from the
collision debris of a high-energy collision between two heavy nuclei. The basic ingredients
of HBT correlations are: the exchange symmetry ( antisymmetry) of the wave
function for identical bosons ( fermions) at the detectors, single-particle state noise,
and wave coherence. We analyze how the wave packet nature of pions created in a
high-energy collision affects the form of HBT correlations of like-pions, how gaseous
ionization chambers used in high-energy physics to measure pion momenta detect
the momentum correlations, and we determine the effect the length and time scales
involved in detecting HBT have on measurements of the correlations. We also investigate the effect of pion emission delay times and the effect of an extended distribution of elementary pion radiators on HBT correlation measurements. The results of our investigation show that pairs of pion wave packets must arrive at each detector together, within a time window determined by the atomic ionization time, in order for the momentum correlations of like-pion pairs to be observed. We find that measurements of the HBT correlation for pions are not appreciably affected either by the time scales important for detecting pion correlations or delays in pion emission times much shorter than the ionization time scale of tracking detectors. Using a simple model of pion production, we show that the effective relative momentum scale of the pair correlation function depends on both the overall source size and lifetime and those of the elementary pion radiators. Finally, we have developed a simple framework (by way of examining the HBT effect for pions as detected by wire chamber detectors) from
elementary quantum mechanics for computing measurements of correlations among particles produced in high-energy physics experiments.
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