Time distributions in test signals
Special test runs
- The special runs were taken to see the dependence of the anode time signals vs test
signal amplitudes (runs cscdata_anode_cable1 thru cscdata_anode_cable30, total 30, July 14, 1998, GIF). The region of the test signals amplitude was
(in DAC codes) 2000 < DAC < 29000 with step of 3000 (see also the
Table ). The test signal was delivered to anode front end card by one and the same
cable thru the connector inserted to the cable between the anode PC Board and
AD96 Card. In each run 8 channels from two planes were tested,
according the Table ).
Here the results of the first 12 runs are presented. The rest 18 runs do not
give any new information.
- As the examples (run 1) the distribution of the channels ON and set of the
test amplitudes (in DAC codes) are shown in
Fig.1 .
Each value of the DAC code was sent 1000 times. The time distribution of the signal from the first channel of plane 5 for the test signals with amplitudes
DAC(1)=2000 and DAC(4)=11000 is shown in
Fig.2 . The means and RMS of the
time distributions vs test amplitude (DAC(1) thru DAC(10)) for the 8 channels of planes 5 and 6 are in
Fig.3 (pages 1 and 2). The same
Fig.3 (page 3) shows also
how means for DAC(1) and DAC(4) test amplitudes behave with channel number in
planes 5 and 6. Though the RMS for each value of the test amplitude is less than 0.5 nsec, the maximum variation of the mean of time distribution is about
7-8 nsec (compare means at DAC(1)=2000 and DAC(4)=11000 in
Fig.3 ,pages 1 and 2)
and this needs to be discussed and understood. If DAC has no offset and going from DAC=2000 to DAC=11000 means indeed 5.5 times increasing in amplitude than the test data for some extent contradict to the beam data (see the means vs HV
page and the means vs cathode
amplitude
page ) where the maximum
variation was less than 5 nsec for the signal increasing by 4.5-5 times
(see the Cathode Strip ADC page
). Note that the amplitudes of the test signals can be quite different from the beam signals amplitude. We need to have calibration of the test
and beam signals in fC.
- The results as the means of the time distributions for all planes and all channels (32 channels/plane) are presented
in Fig.4 (selected test pulse
amplitude is DAC(1)=2000). The irregularities are due to dependence vs card # and chip # as we can see in
Fig.5 where the means for card 1 are lower than for card 2 and chips ##1,2 on the card 2 have quite different
delays. Note that these delays include delays in output cables and the difference in length for the corresponding cables could be the reason. Finally, the means of the time distributions for all 10 DAC codes are
given
in Fig.6 for all 6 planes and
all available channels. The RMS for all of these signals are not presented since almost all of them are less than 0.5 nsec.
- The questions to study on cosmic muon stand at Fermilab:
1. Efficiency vs test signal (in fC)
2. Delay (in chips, cables excluded) vs test signal (in fC)
The range of the test signal amplitudes should cover the expected
amplitudes of signals from particles. How significant is the difference in
shape and length between test pulses and signals from particles?
Last modified: Mon May 31 13:25:00 CST 1999
teren@fnal.gov