las vegas - NA44 parameters
FREEZEOUT PARAMETERS USING NORMALIZED NA44 DATA
In a previous slide, a fit to NA44 PbPb data was shown, using
unnormalized singles spectra. Although the slope was well determined, the
absolute number of pions, kaons and protons was not known.
Here I show the result of a fit using normalized pi+ and K+ data, as
well as 3D Bose-Einstein correlation data from pi+ and pi- pairs.
| parameter |
description |
value and uncertainty
at 99% confidence |
|
|
|
| T |
Nuclear temperature T |
90 +- 13 |
| mu_b/T |
Baryon chemical potential |
|
| lambda_pi |
Pion incoherence fraction |
0.59 +_ 0.07 |
| R |
Transverse freezeout radius |
11.1 +- 1.7 |
| v_t |
Transverse freezeout velocity |
0.5 +- 0.1 c |
| alpha_t |
Transverse freezeout coefficient |
0.06 +- 0.99 |
| y |
Source rapidity |
|
| eta_0 |
Longitudinal spacetime rapidity |
1.3 +- 0.6 |
| tau_f |
Longitudinal freezeout proper time |
10.3 +- 3.9 fm/c |
|
|
The error bar on the parameters has decreased considerably, and the values are
consistent with the earlier determination.
HvH, ACS meeting, September '97, Las Vegas
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