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.