Difference between revisions of "Minutes-6-24-2010"
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== Electronics == | == Electronics == | ||
| − | - fADC125: Lubomir did further studies of the cutoff seen in the spectra from the wires. As suggested by Gerard on the last meeting now a quadratic interpolation is used to find the maximum from the fADC samples. At page 498 in the FDC logbook, shown are the maximum signal distributions separately for all the channels. The cutoff position varies from channel to channel somehow and probably | + | - fADC125: Lubomir did further studies of the cutoff seen in the spectra from the wires. As suggested by Gerard on the last meeting now a quadratic interpolation is used to find the maximum from the fADC samples. At page 498 in the FDC logbook, shown are the maximum signal distributions separately for all the channels. The cutoff position varies from channel to channel somehow and probably this is the reason we don't see a good peak at the saturation region. Fernando asked if there's a peak in the spectra for the individual channels. Lubomir: there's not enough statistics to see clearly the peaks channel by channel. Lubomir will use the new scope and the differential probe to histogram the signals from the card directly and see if there's a saturation. |
| + | - Bill proposed a modification of the cathode production procedure: cutting the foil from the transfer ring will be done not at the I.D. position but at a larger (by an inch) radius. This will allow to flap the foil over the whole periffery of the cathode | ||
- While Gerard was on the phone, Lubomir presented the results of the fADC tests. During the last (almost) week, the fADC125 was powered continuously, the temperature on the board was ~53degC always and there were no problems with the operation. The plateau, gain and strip resolution vs HV were studied (page 487 in FDC logbook) in order to choose the operational HV. Using lower threshold (~5mV at the fADC input) moves the beginning of the plateau down to ~2000-2050V (field voltage at 500V). However, the strip resolution get worse if lowering the HV. The resolution levels out above ~2225V, so probably ~2225V will be the operational HV. At this voltage some good fraction of the signals most likely saturates. Gerard asked if we are going do particle ID using dE/dX in which case probably we need even lower amplification. Beni and Simon explained that at the forward region the particles are minimum ionizing, so the signals will be similar the these with cosmics. Lubomir is concerned that now the cathode pre-amp cards are at their lowest possible setting (2.6mV/fC) for the high gain region. Fernando will look what modifications can be done so that we can lower the amplification with small steps if needed. | - While Gerard was on the phone, Lubomir presented the results of the fADC tests. During the last (almost) week, the fADC125 was powered continuously, the temperature on the board was ~53degC always and there were no problems with the operation. The plateau, gain and strip resolution vs HV were studied (page 487 in FDC logbook) in order to choose the operational HV. Using lower threshold (~5mV at the fADC input) moves the beginning of the plateau down to ~2000-2050V (field voltage at 500V). However, the strip resolution get worse if lowering the HV. The resolution levels out above ~2225V, so probably ~2225V will be the operational HV. At this voltage some good fraction of the signals most likely saturates. Gerard asked if we are going do particle ID using dE/dX in which case probably we need even lower amplification. Beni and Simon explained that at the forward region the particles are minimum ionizing, so the signals will be similar the these with cosmics. Lubomir is concerned that now the cathode pre-amp cards are at their lowest possible setting (2.6mV/fC) for the high gain region. Fernando will look what modifications can be done so that we can lower the amplification with small steps if needed. | ||
Revision as of 16:03, 25 June 2010
June 24, 2010 FDC meeting
Tentative Agenda
- Production
- 727 B.C. status
- production planning
- plans for wire stringing in 126 pin rail, pos meas cam, pos meas , pos meas parts, pretension screw, string table
- Electronics
- fADC125 status (Gerard, Fernando)
- ground modifications
- Cathode redesign: finalizing (Roger, Bill)
- Full-scale prototype tests
- tests with fADC FDC Log Book, pages 494 - 500 (Lubomir)
- cosmic tests (Beni)
- Other
