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 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 | + | - 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. The spectra from the strips look OK, the signals extend up to 16000 fADC units, the 14bit limit of the fADC. Lubomir will use the new scope and the differential probe to histogram the signals from the wire cards 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 copper foil over the whole periphery of the cathode ring to improve the grounding connections. Thus, no modifications of the cathode g10 ring are needed. The back of the cards will be glued on the copper foil with conductive epoxy. The aluminum ground foil will be glued at one side to the cathode copper foil and Bill proposed to use conductive ink to connect the other side of the aluminum foil to the cathode. Fernando: conductive ink may not be the right choice | + | - Bill proposed a modification of the cathode production procedure: cutting the foil from the transfer ring will be done not at the transfer ring I.D. position but at a larger (by an inch) radius. This will allow to flap the copper foil over the whole periphery of the cathode ring to improve the grounding connections. Thus, no modifications of the cathode g10 ring are needed. Everybody is happy with the new design. The back of the cards will be glued on the copper foil with conductive epoxy. The aluminum ground foil will be glued at one side to the cathode copper foil and Bill proposed to use conductive ink to connect the other side of the aluminum foil to the cathode. Fernando: conductive ink may not be the right choice, we will think about other options. |
| − | + | - Fernando will be in vacations next week; the extra ground cards we need to put the cathodes of the second layer on ground, will be ready on Friday. | |
| − | - | + | <!-- |
== Cathode redesign == | == Cathode redesign == | ||
| − | - Roger | + | - Roger has prepared the drawings of the cathode foils according to the Bill's modifications from the last week, but with the change of the procedure the flaps at the periphery are not needed. Instead, Bill asked for marks to be placed at the periphery to cut the foil. Some of the cutting positions are fixed by the position of the cards, the other positions are not so important. Roger also showed his modifications at the connector region to make sure they are OK. He showed also the modified daughter card with a ground on the back of the card so that it can be glued to the cathode copper foil. Roger will work on the modifications that were proposed today by Bill. |
== Full-scale prototype test results == | == Full-scale prototype test results == | ||
| − | - Lubomir | + | - Lubomir is analyzing the FADC data |
- After the fADC tests, Beni connected the cards to the middle layer using the standard set-up (conventional ADCs for the strips, discriminators and TDCs for the wires). Beni had problems with the conditioning of the middle layer. For now he was able to work at the nominal HV of 2225V only at one sector. He will try changing the polarity to condition the chamber. Beni showed (logbook page 485) a plot with the ratio of the top to bottom strip sum; the result is similar to the one shown by Lubomir on the previous meeting using fADC: the signals on the top strips are bigger than on the bottom and this varies along the chamber by up to 20-30%. For now we explain it by shifts of the wires closer to the top cathode. | - After the fADC tests, Beni connected the cards to the middle layer using the standard set-up (conventional ADCs for the strips, discriminators and TDCs for the wires). Beni had problems with the conditioning of the middle layer. For now he was able to work at the nominal HV of 2225V only at one sector. He will try changing the polarity to condition the chamber. Beni showed (logbook page 485) a plot with the ratio of the top to bottom strip sum; the result is similar to the one shown by Lubomir on the previous meeting using fADC: the signals on the top strips are bigger than on the bottom and this varies along the chamber by up to 20-30%. For now we explain it by shifts of the wires closer to the top cathode. | ||
Revision as of 16:52, 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
Minutes
Participants: Bill, Glenn, Casey, Roger, Mark, Fernando, Beni, Simon, and Lubomir.
Production
- Bill: the PR for the clean room is in place but not for the ACs. We will need the AC, the one for the whole bay area, to start moving there some stuff and do some dirty work that doesn't require clean environment. Teresa Danforth is the person to be contacted and Glenn will help us in that.
- Bill: the cathode production plan is in a good shape: Fast Track procedure will be posted soon. The wire production planing will require more information since we have not done the stringing. Therefore, first we need to start setting up the fixtures from UVA and exercising and then clarify the procedure.
- We will set up the stringing initially in the tent in 126. The other option, F117, is no longer an option since there's not enough space. We decided to use the granite table in 126 for stringing. We are going to put wheels on that table. For the cathode production we will need another two granite tables. Lubomir: According to Eugene there are money for equipment so that we can buy two granite table right now. Glenn confirmed that and said that he could sign for Eugene, who is away from JLab till July 7. The plan is to put the tables directly in 727 B.C.
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 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. The spectra from the strips look OK, the signals extend up to 16000 fADC units, the 14bit limit of the fADC. Lubomir will use the new scope and the differential probe to histogram the signals from the wire cards 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 transfer ring I.D. position but at a larger (by an inch) radius. This will allow to flap the copper foil over the whole periphery of the cathode ring to improve the grounding connections. Thus, no modifications of the cathode g10 ring are needed. Everybody is happy with the new design. The back of the cards will be glued on the copper foil with conductive epoxy. The aluminum ground foil will be glued at one side to the cathode copper foil and Bill proposed to use conductive ink to connect the other side of the aluminum foil to the cathode. Fernando: conductive ink may not be the right choice, we will think about other options.
- Fernando will be in vacations next week; the extra ground cards we need to put the cathodes of the second layer on ground, will be ready on Friday.
