Fernando, I had some questions. Please see the attached PDF file. -- Mark Fernando J. Barbosa wrote: > Hall D Electronics: > > Hi Elke, > > Document 747 on the portal shows the charge deposited on the CDC and > FDC detectors. These numbers were first estimated for the Electronics > Review in July 2003 and were based on geometrical constructs only. You > can find a brief summary on slide 22 (a back-up slide) of my > presentation for the Hall D Drift Chamber Review of 6-8 March 2007, > document 751. Anyway, these numbers have not changed in years.... > > For the CDC, the dynamic range is shown to be 100 fC - 3 pC - a factor > of 30. Because the charge amplifier has a peaking time of about 11 ns, > the dynamic range of the preamp would be about 400 fC for point > ionization (~13% of total charge). The gain of the preamp would then > be ~ 1000 mV (a reasonable maximum amplitude to expect from a > preamplifier) divided by 400 fC times a factor to allow for some > headroom before saturation, say 80%. The result is 2 mV/fC. > > Similarly for the FDC, the dynamic range for the anodes was estimated > to be 300 fC - 3 pC, a factor of 10. For the preamp, 400 fC for point > ionization and 2 mV/fC for gain. > > For the FDC cathodes, the dynamic range was estimated to be 10 fC - 1 > pC, a factor of 100. For the preamp, 133 fC for point ionization and 6 > mV/fC for gain. Note that here, the estimate presumed a 1/3 of the > charge of the anode on the cathode (charge sharing on adjacent > strips). Later, it was decided that this number needed to be changed > to 1/5 based on published data. For the preamp, the point ionization > was then estimated to be 80 fC and 10 mV/fC for gain. > > According to these estimates, the CDC and the FDC anodes require the > same gain (2 mV/fC) and the FDC cathodes require x5 gain or 10 mV/fC. > > Obviously, this numbers must be updated to reflect the physics events > in the detectors. I hope this helps. > > Regards, > Fernando
Charge range on tracking chambers.pdf
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