Max Pixel Area for Central Au + Au

Wieman 6/6/04

The hit density for central Au + Au sets the limit for pixel size permitted without excessive pileup. In this exercise the pixel area is determined as a function of radius which limits the pileup hit probability to less than 1 % and 3%. Central Au + Au collisions set the track density limit used in this exercise.

To estimate the track density:

Note: dN/dz is written
as dNdz this is true for all derivatives in this analysis.

This simplifies to:

pseudo rapidity particle density for central Au + Au

Hits/area for a central Au + Au collision at z = 0

The probability for one or more hits in a given area A where

is the hits/unit area, see:

http://www-rnc.lbl.gov/~wieman/PileupProbabilityDerivation.htm

So:

Detector area as a function of pileup probability and radius

Fig. 1 The pixel area limit as a function of r for maintaining 3% pileup and 1% pileup