Charged particle and LCT rates
To estimate the deadtime and digitized data rate for cathode DAQ,
a rough and conservative estimate of the LCT rate in a
chamber is needed.
The LCT rate is dominated by background charged particle flux.
A Monte Carlo calculation (CMS TN/96-070) using 2000 minimum
biased background events generated by CMSIM and the baseline LCT algorithm
gives the following average LCT rates
at LHC designed luminosity (10**34cm-2s-1)
in each of the different chamber types:
Chamber Type LCT rate in kHz
ME1/1 30
ME1/2 7
ME1/3 <1
ME2/1 16
ME2/2 12
ME3/1 18
ME3/2 7
ME4/1 56
ME4/2 265
The highest rate occurs in ME4/2, reflecting issuficient shielding againt
back-scattered particles with the shielding model
used. The calculated rates
are probably accurate to within factor of 2.
For conservative estimate of the LCT rate, we use 300 KHz per chamber
independent of chamber types. The LCT rate in a chamber section covered by 1
FEB is, conservatively, 300kHz/(5 FEB's) = 60 KHz.
The rate of (Lev-1)(LCT) coincidence is 100kHz x 300kHz x 100ns = 3 kHz per
chamber or 0.6kHz in a chamber section covered by 1 FEB.