Discriminator performance data
in the hp process
from Chuck Britton

In the studies of the discriminator performance for the TGV preamp/discriminator prototypes produced in the hp process I have used results which come from an email message Chuck Britton sent to the phenix-mvd-l listerver on 11-Dec-97. This message summarized some performance measurements done at Oak Ridge. The numbers which are used in this study are listed below:

1. Charge gain - approximately 16 mV/fC
2. Noise - 650 e @ 0 pF, 1500 e @ 13 pF
3. Discriminator threshold spread - With nominal 25 mV setting, 2.7 mV rms with peaks from 18 mV - 32 mV.

A "1 mip" signal is about 4 fC, so the charge gain listed above translates to a 64 mV signal for a mip.

In this study, each channel of the MVD was assigned a randomly selected threshold. These random thresholds were selected from a gaussian distribution which had a mean value of 25 mV (0.39 mip) and a sigma of 2.7 mV (0.042 mip) with all values restricted to the range 18-32 mV (0.28-0.5 mip).

The noise specification listed above was not used in this study. The noise (which in the real detector would include the contribution from the TGV-32 preamp listed above as well as other noise sources) was modeled assuming a noise level of 0.1mip (sigma) which was added to all signals in the MVD.

In October 1997 I did a similar study of the discriminator performance using performance measurements done on prototype chips produced in the orbit process. Since we plan to use the chips from the hp process, this older study is irrelevant now. However, if you want to see that older discriminator performance data, here it is.