CALICE MAPS Meeting, RAL, 08/12/08 ================================== Present: Jamie Crooks, Paul Dauncey, Marcel Stanitzki, Mike Tyndel, John Wilson Minutes: Paul Minutes of last meeting: No comments not covered later. Paul arranged for a spare USB_DAQ to get to RAL and Jamie now has all the existing sensor PCBs and aluminium baseplates. Conferences: The conference presentation web page is up-to-date. Marcel has submitted his IPRD08 proceedings which will be published in a special NIM volume. Jamie had also submitted his TWEPP proceedings. Paul reported that following strong objections from one of the referees, Giulio has withdrawn his SORMA proceedings contribution. Sensor V1.1: Jamie showed some slides on progress with V1.1; see the usual web page. The laser parts are on order (and in fact arrived just after the meeting) although he is not sure the bulb aging would explain the slow variations observed. It was decided to only mount sensors offset from the nominal position which will be used for test pixel studies. These should be easily identifiable since they will need the "Konstantin" modifications to the test pixel outputs. To clarify the table on Jamie's slide 4; for the 12um with DPW, then 16/60 sensors did not have a power-ground short. Of these 16 sensors, 9 sensors have been bonded, of which 1 has a bad column. Also, there were 8 sensors bonded which had a power-ground short (before we knew to check for this first). Hence, 17 sensors have been bonded in total, of which 1 has a bad column and 8 are unusable, meaning there are 8 good ones. There are then 7 of the 16 sensors without a power-ground short left to bond. Jamie estimated the oscillation region would be around 10TU wide. If it is due to two metal traces being too close, then a change to one mask, probably Metal 1, would be sufficient. He thinks this problem is not related to any bad processing by the foundry. The foundry have still not supplied the missing quality check data and Jamie thinks there is an issue with the n-well minimum separation. The layout violates the design rules in the pixel as the two shaper capacitors are too close together. However, the rules apparently are also violated by the foundry's own proprietary design for the I/O pad layouts. Jamie suspects this might be the source of the power-ground shorts. Each mask would cost around 5kpounds to remake. There is no money left within CALICE but if the CfI could fund this, it would clearly be worth doing if we will be testing the newer sensors long-term. Renato needs to negotiate with the foundry about what will be done but it is clear it is not worth releasing the second batch until we can fix the noise problem (or know it is unfixable). The ideal outcome would be that we can fix the address bug and the oscillation with a couple of mask fixes and then get the original sensors remade (at the foundry's expense) in parallel with making the second batch. The second batch will contain 12mu standard, 12mu hi-res and 18mu hi-res, all with deep p-well. Realistically, any new sensors will not start being fabricated before Jan. Paul showed some slides on results from bulk pixels on V1.1; see slides on the usual web page. These results seem consistent with the oscillation as seen by Jamie although the width is ~40TU rather than the 10TU Jamie estimated. Jamie thought the available range of the external biases from varying the PCB DACs would not be sufficient to remove the oscillation and that he would have to adjust the resistors. Marcel reported that a new Fe55 source would cost ~3kpounds, although the paperwork to order it would be significant. Mike mentioned that Diamond have a 20keV photon beam which can be focussed to ~1mu. This would be very useful for calibration (assuming the intensity is not too high) and he thinks it would be available to RAL/PPD without cost. The volume in which the energy would be deposited would still be very small, even at these larger energies compared with Fe55, and so could still be fully contained within the signal diode. Marcel showed some results on the old and new sensors; see slides on the usual web page. He finds the pedestal depends on the threshold common mode so a consistent value for the common mode must be used for all studies. On his slide 13 onwards, Shaper A is the new design while Shaper B is the old design (implemented on V1.1). The peaks for both are around 200mV which (give or take a gain of 0.8) would correspond to ~500TU assuming the usual 0.4mV/TU conversion factor. This is much larger than the ~160TU that Marcel finds for the Fe55 peak in the bulk pixels and this is not understood. Taking the 200mV as the Fe55 1600e- peak, then this would correspond to 1mV being 8e-. Hence, the 3.6mV of noise would be 29e- which is close to the expected value. Mike thinks lower threshold Fe55 data are needed to understand the spectrum low-end shape better. News from LCWS: Marcel reported that IDAG has now said they will expect supporting documentation to back up the LoIs. Marcel is writing the SiD MAPS section and so we could use the paper(s) as the supporting documents if they can be got into a reasonable shape by Mar, when the LoIs are to be submitted. It is not clear how much on MAPS will be included in the ILD LoI. IDAG will report back by the end of the summer with the "validation" (or not) of the LoIs. Marcel and Jan Strube now have the SiD simulation running on the Grid so they would be able to generate events on request. Paul and Anne-Marie may need something for a MAPS vs standard ECAL pi0 study. The CLIC CDR is foreseen for 2010; there may be a stronger MAPS case at higher energies although this needs further study. There is now a US DOE concept-specific R&D fund which will be given out directly to SiD and ILD and then internally distributed by the concepts groups. Unfortunately, it cannot be used to fund non-US groups. Next meeting: This was scheduled for 10am on Wed 14 Jan. [Note added after meeting: it was rearranged to Fri 16 Jan at 10am.]