QuickCal Meeting Bob's office 26-Sep-1997 Present Bruce Kennedy Derek Imrie Mark Osborne (Brunel) Paul Jeffreys Bob Brown Paul Flower Ken Bell 1. Bob presented a report from Laurie Lintern, saying that he was continuing with work on the magnet cooling system and hoped to start flushing out the pipes as soon as the sodium hydroxide arrived. This has now been ordered Bruce Kennedy This week Has been working on the simulation of end cap crystals and gaps. He has also been discussing this simulation with Helen Heath (Bristol) He has been testing a program written by Dave Barney (Imperial) which predicts the beam position from pre shower data. Dave Barney claims a resolution of a few 100 microns of the beam position. The same program run here by Bruce only gives a resolution of a few mm. Bruce is checking the code and the compatibility of compilers Bruce showed a plot of energy resolution simulation with the pre shower and pre sampler included. With a Pt of 50 Gev on the 45 degree line this gave a resolution of 0.5% in the main peak Bruce has plotted ISIS and PSI (pedestal subtracted) PWO crystal scans on the same graph. These show better than 5% agreement except at distances very close to the APD where the ISIS scans give a higher value. Next Week Working on Dave Barney's code and simulations Derek Imrie Has now got the model for VPTs working on different PCs Derek presented results from his code which calculates the gain of the APD as a function of field, orientation, grid voltages and geometry. The model is still being developed and at present, its predictions are a little lower than experimental data at higher fields. There was some general discussion on VPTs and Bob reported that new results were presented at Madison. There was also concern expressed that there may be a high partial pressure of He around the CMS experiment and it may be necessary to coat vacuum tubes. A Hamamatsu tube should be available for tests from the end of next week. Electron Tubes is trying to manufacture a tube with a copper grid to test for magnetic field effects. Mark Osborne Has been using three programs to simulate APDs Program 1 models the diffusion of phosphorous into silicon Program 2 models the electric field profiles to estimate gain Program 3 models charge and current distribution, and estimates the effect of irradiation. This program runs in UNIX on an Alpha and takes a couple of days to run. This has been speeded up to a few hours by rationalising memory management but it was suggested that migrating it to UNIX on the lab HPs might further speed the program. At present the results show the simulation breaks down before the real device. It was considered that an assumption that the real device may be of a more complex construction may give better agreement. The simulation program suggested that the effect of radiation would primarily be to increase leakage rather than gain. This should be checked against recent data presented at Madison. Paul Jeffreys Working with Peter Hobson on costing of CMS Bob Brown Has been at Madison. The collaboration endorsed recent changes to barrel size, the radius being reduced from 1430mm to 1290mm The crystals will now be 30,000 fewer and slightly larger. It is proposed that the MSGCs will be designed so as to give as small a gap as possible before the ECAL, and allow the pre sampler to be installed during a winter shut down The Magnet and HCAL TDRs have been approved and it is expected that the tracker TDR will be submitted early next year. The MSGCs are being tested at PSI and gold passivation is giving very promising results. 20 crystals have been manufactured using full production conditions at Bogorodisk and from these 17 good crystals have been produced. These have exhibited good radiation hardness with those having better transmission also having better radiation hardness with attenuation down by less than 5% after 100 Rad. Success with full production techniques is an important milestone as it implied good stocheometry control, the process requiring consecutive crystals from the same production unit. This week Working on a document for PPARC, OST and the Treasury. Paul Flower Glass manufacture Has made samples of glass with pure Merck HfF4 and latest Russian HfF4 Glass measurements Has measured the samples and found it difficult to access relative transmissions. Has measured the transmission of glycerol, ethanol and mineral oil and shown that glycerol which is well matched to fluoride glass in refractive index, has only a small absorption in its transmission range. This has been used to develop a technique of coupling quartz optical flats to fluoride glass to allow more accurate internal transmission measurement. New data taken shows the latest Russian HfF4 has much better transmission than the poor material that gave problems, and better transmission than the JM material that has made the best glass. The best transmission was achieved with the high purity Merck material. Paul has also been working on the Russian PWO data but has not made the irradiation rig yet. Next week Paul should arrange the visit for Valentine's people to test PWO on ISIS Paul to Sheffield Monday to Thursday to make big glass blocks. Ken Bell Working on INTAS document Next week Work on INTAS document Contact Lisbon on contribution Oct 3d, to CERN on OPAL work for 4 weeks. .