las vegas - who determines what

WHO DETERMINES WHAT (SINGLES/PAIRS) ?

Some of the nine parameters are sensitive mostly to the singles data, while being insensitive to the Bose-Einstein correlations. For other parameters the inverse is true, and there are parameters that are sensitive to both data types.

To test these sensitivities in the model, Ray took the E802 data, and fed first only the singles spectra to freezer, and in a separate run, only the 2-particle correlations. The results are shown below. The error bars indicate the sensitivity of the parameter to the data type.

Nine independent source freezeout parameters for central Si-Au at 14.6 GeV/nucleon
	Value and uncertainty at 99% confidence
Property	from one-particle	from correlations
n/n_0	0.145 +0.079 -0.057	1.1 +2.5 -1.1
T (MeV)	92.9 +- 4.7	70 +89 -70
v_t (c)	0.700 +- 0.095	0.95 _0.05 -0.36
v_l (c)	0.904 +0.049 -0.094	0.92 _0.08 -0.92
v_s (c)	0.972 +0.015 -0.017	0.96 +0.02 -0.12
R_t (fm)	9 +20 -9	9.6 +-4.9
tau_f (fm/c)	7 +23 -7	9.6 +- 7.2
delta_tau (fm/c)	3.9 +2.4 -3.9	8.9 +4.3 -6.5
lambda_pi	-	0.75 +- 0.18

Clearly the temperature is determined by the singles, and the radii by the correlations. Note that the transverse expansion is sensitive to both singles and pairs. Since T and v_t are highly anti-correlated, T is indirectly sensitive to pairs data also.

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