-------------------------------------------------------------------- Short Summary of the LC-TPC Meeting 15 Oct.02 19:00 MET ---------------------------------------------- -------------------------------------------- The usual reminder: the websites where more details are available: Aachen http://www.physik.rwth-aachen.de/group/IIIphys/TESLA/TESLA_en.html LBNL http://www.lbl.gov/~ronan/docs/lctpc Carleton/Montreal/Victoria http://www.physics.carleton.ca/~karlen/gem http://www.physics.carleton.ca/~gmd/ CERN http://skappler.home.cern.ch/skappler/feecard/gemtpc.html DESY http://www.desy.de/flc/tpc/index.html http://www.desy.de/flc/LC/LCdetector.html Orsay http://www.lal.in2p3.fr/recherche/flc Saclay http://www-dapnia.cea.fr/Spp/Experiences/FELICE/tpc_micromegas.shtml Wayne State http://motor1.physics.wayne.edu/~schrein/science/nitpc.htm MPI-Munich http://alephwww.mppmu.mpg.de/~settles/tpc/welcome3.html ----------------------------------------------- 1. General: This video meeting turned out to be VERY successful! Eight groups joined in by video and Ties Behnke by telephone from Slac, and there was a lively discussion, which also went smoothly because presentations were prepared in advance and good timing was exercised during the question-and-answer periods. So it looks like we are learning how to conduct these meetings and can use this technique in future. All groups are requested to keep their web pages above up to date. 2. Reports from the groups: ------------------------------ Novosibirsk It was midnight in Novosibirsk when our meeting started, so Alexei Buzulutskov sent their report via email: At the moment N-sk group is planning to study: Task1: Gating GEM electrodes for ion feedback suppression. Task2: Measuring ion mobility in different gases. Task3: Manufacturing GEM foils in Russia. Task1: For this, we are developing a HV pulse generator with the following parameters: a) A specifics pulse pattern, namely 1st pulse for opening the gate for electrons transfer and 2nd pulse for opening the gate for ion transfer. b) 500V maximum pulse height. c) 1mks pulse rise. d) Controlled pulse widths, inter-pulse distances and pulse period, in the range of 0-500 mks. e) Gating grid would be just the GEM foil. Different GEM geometry (hole/pitch) will be studied, to minimize the pulse heigt and to maximize the ion feedback suppression. Task2: Using this pulse generator, we plan to measure ion mobility by measuring the ion current at the cathode as a function of the delay between 2 pulses (one pulse opens the gate for electrons, the second pulse opens the gate for backdrifting ions), similar to that people did in the past. Task3: We have a contract with one company in Nijnii Novgorod on GEM production of two types, 3*3 cm^2 and 10*10 cm^2 active area. At the moment we got only one foil of 1 st type (with 4 active areas), which has acceptable leakage current (5 nA at 600V) and expect to get in a couple of weeks GEM foils of the 2nd type. ------------------------------- Aachen Only a brief statement today; Sven Lotze will be giving the full group report at the Prague workshop. ------------------------------ Desy/Hamburg Markus Hamann reported that the sparking problem in the big TPC prototype seems to have been solved by changing the HV setup so that the pads run at ground. Data was being taken for the last 4 days, and while sparks occur from time to time, they don't destroy the chamber. There is a new TPC prototype being desiged using carbon fibre and honeycomb to fit in the 5T magnet. Thorsten Lux is making E x B measurements in the 1T magnet using a "miniTPC"; the current is measured on each electrode. Similar 5T measurements with the new TPC will follow as soon as everything is ready. The 5T magnet is undergoing cryo and pressure tests and should be ready to run before xmas. A Yag laser is being delivered for use in the 5T studies. Nabil Ghodbane is working on the Aleph RO but the VME crate doesn't work yet: maybe a clock is missing? Thorsten Kuhl has been comparing his with Dean Karlen's simulations to better understand the differences (see minutes from last video meeting on 07.08.02). Main differences seem to be the gas (Ar2%CF4 instead of Ar5%CH42%CO2) which has different diffusion, the larger gem induction gap (10mm instead of 4mm) and the averaging over several pad rows (5 instead of 1) as assumed by Dean compared to Thorsten. Taking these into account, the results seem to agree reasonably well. ------------------------------ Slac Ties pointed out that, for future meetings the groups should post their talks on the web beforehand if possible, so that the telephone participants can follow better what is being discussed. ------------------------------ Wayne State There was a problem with Wayne State telephone number (below), but Giovanni Bonvincini was able to dial in later using Victoria's number (Dean was not able to join us this time). Giovanni explained the principle of the negative-ion TPC: obviously it only works for certain gases. The gas molecules capture the ionization electrons (within about 50 microns) and then drift with ca. 1mm/microsecond to the endplate. Since \omega\tau is essentially zero, it is also possible to drift perpendicular to the B field. For the case of gas-amplification on wires, E x B effects are eliminated because an ion does not lose its electron to the wire until it gets close to the wire. It was recommended that Giovannio study different drift-direction scenarios "on the back of the envelope", where it is easy to understand the consequences. Giovanni has created a website (see above) where many more details about the negative-ion TPC can be found. ------------------------------- Carleton Kirsten Sachs gave the report. A new set-up for testing charge spreading using resisitive foils is working. Tests are being done with a foil having 1Megaohm/square. The foils are made by a company in StPaul Minnesota and are composed of mylar coated with CrSiO; the foil is simply glued onto the pad plane. The test cell for these studies has 5mm drift and long pads of widths 1.5mm, 2.0mm and 2.5mm. Tracking studies with a 20cm-drift TPC with 174 pads in another setup will follow with pads of 2.5mm width; test rows with 2mm and 3mm pads are also available, as well as ArCO2 and P10 gases. A new test TPC is being built and will be sent to Dean in Victoria. More details directly from Kirsten: - We did some tests of charge dispersion with the current setup of 1 Megaohm/square. But since the spread is too narrow to significantly improve the resolution we did mainly a 'proof of principle'. These tests use a so called test-cell with 5mm drift distance. Width for (long) strips for these tests are 1.5mm, 2.0mm and 2.5mm. - We have another independent setup of a 20cm long TPC for tracking. This uses 174 pads, most of them 2.5mm wide, two test rows with pad width of 2mm and 3mm (this was not mentioned at the meeting, just to clarify the above statement). - The TPC send to UVIC is brand new, i.e. is being built. It is a 30cm long TPC to be used for tracking and has nothing to do with the tests on charge dispersion. - The slides are on http://www.physics.carleton.ca/~gmd/ There you can also find a description of the changes made to the STAR electronics. ---------------------------------Victoria As said above, Dean Karlen was not able to join this time. ---------------------------------Nikhef Jan Timmerman joined from CERN. The video part at the CERN room was not working, so Jan described everything orally. Harry van der Graaf and Jan concentrated on getting their hardware into operation, to study the feasibility of reading out a TPC with a pixel Si detector (Medipix). A test TPC just constructed at Nikhef has, for a start, 2 Gem planes followed by a wire plane where the signals were read out; the total gas gain was about 10^3. P10 gas, a drift field of 200V/cm and an Fe55 source were used. There was some sparking around the glue which also caused some Cu to disappear, but in spite of these annoyances is was possible to measure pulse heights and the noise was reasonable (ca.100 e-). Jan and Harry are waiting on the Medipix2 chip, and the hope is to have something to show by the Prague meeting. -----------------------------------LBNL Mike Ronan described the activities. He and Fred Biser have been working on the Star electronics test-rig being commissioned by Karlsruhe, Munich, Aachen, CERN, etc. The rig can handle up to 1152 pads and up to 1000 time buckets. There was a failure of a VME RO module and an optical receiver, which were fixed, and the set-up is working now. Mike had put together a similar test-rig for Saclay/Orsay and worked with them on the Micromegas effort. Mike is collaborating with Victoria, Carleton, BNL,.. on developing Java analysis, VXWorks-based codes,..; help is needed on developing a Geant4 TPC tracking package. Cornell (Dan Peterson) and Perdue (Ian Shipsey) as well as KEK (Hiro Aihara) have shown interest in the TPC R&D. -----------------------------------Saclay/Orsay Paul Colas reported that construction of the 40cm chamber for test in the 2T magnet is well underway. All parts are ordered and the field cage is being manufactured. W.r.t. their Star testrig, protection diodes are being implemented, and the dynamic range (LBNL, Carleton, Montreal,..) for negative pulses is being increased. Paul pointed out that the ability to handle positive signals must be maintained, because the wire version is still a viable option. Upcoming events are a big meeting on LC physics in Strassbourg and a visit by Mike the 2nd half of November. ------------------------------------Karlsruhe Jochen Kaminski describe that the Star test-rig (see LBNL, Salcay above) that was commissioned at Munich, Karlsruhe and then CERN, where meanwhile test beam data have been taken. Jochen demonstrated to the video audience some TPC data dynamically on his PC (it can be seen on Steffen Kappler's website at CERN). The next steps are to take the Star rig to Munich for further tests with Mike the first week in November. -------------------------------------Munich RS told that Mike, Jochen and Steffen will be in Munich the first week of November for further commissioning of the Star set-up. The idea at the moment is that the Star rig ulitmately should go to Desy for studies using the 5T magnet by all groups. Work at MPI on wire-chamber prototype for the 5T magnet is continuing. RS is looking for help to revisit the momentum-measuring performance of the TPC to understand the impact of a \sigma_point resolution in the TPC of below 100\mum and the effect of an externally-measured point in an Ecal silicon layer. Apparently Brahams should have the appropriate tools for such a study. ---------- Forwarded message ---------- >From dcs-notice@es.net Mon Oct 14 16:46:05 2002 Date: Mon, 14 Oct 2002 07:06:06 -0700 From: dcs-notice@es.net To: felix.sefkow@desy.de, roth@physik.rwth-aachen.de, Jan.Timmermans@cern.ch, ronan@lbl.gov, settles@mppmu.mpg.de, colas@hep.saclay.cea.fr, Hans.Frese@desy.de, artb@mailbox.slac.stanford.edu, vcs@desy.de, videoc@hep.saclay.cea.fr, video_conf@lbl.gov, d.lanske@physik.rwth-aachen.de, kielas@mppmu.mpg.de, standard.telephone@cern.ch, gillian.bezard-brown@cern.ch, christine.alliod.masson@cern.ch, paulus.gelissen@cern.ch, suzanne.barras@cern.ch Subject: DCS Modification: LC-TPC Meeting A conference has been modified by hfrese URL: https://dcs2.es.net/dcs-cgi-bin/gps_confs?action=View&aid=223954 DCS ID: 223954 Title: LC-TPC Meeting Time: 2002-10-15 19:00 (MET) Duration: 2 Hours Type: multi-room Speed: 2x64 kbps Email: settles@mppmu.mpg.de Meeting Comment: no comment Room Participants Local Date Local Time Directory Number AACHEN Stefan Roth 2002-10-15 19:00 (MET) +1 510 704-5881 CERN-14-4- Jan Timmermans 2002-10-15 19:00 (MET) +1 510 704-5883 DESY-1C134 Felix Sefkow 2002-10-15 19:00 (MET) +1 510 704-5879 GUEST Wayne State 2002-10-15 19:00 (MET) +1 510 704-5897 GUEST Dean Karlen 2002-10-15 19:00 (MET) +1 510 704-5931 GUEST Madhu Dixit 2002-10-15 19:00 (MET) +1 510 704-5864 GUEST Karlsruhe 2002-10-15 19:00 (MET) +1 510 704-5882 GUEST Novosibirsk 2002-10-15 19:00 (MET) +1 510 704-5865 LBL-50F Mike Ronan 2002-10-15 10:00 (US/Pacific) +1 510 704-5888 MPI-MUNICH Ron Settles 2002-10-15 19:00 (CET) +1 510 704-5938 SACLAY Paul Colas 2002-10-15 19:00 (MET) +1 510 704-5851 SLAC-2 Thies Behnke 2002-10-15 10:00 (US/Pacific) +1 510 704-5870 If there are problems, you may be able to contact the rooms in this meeting at the following phone numbers: Room Conference Room Phone Number AACHEN +49 241 80-27326 CERN-14-4-030 +41.22.767.6604 DESY-1C134-HAMB +49 40 8998-3285 LBL-50F 510-486-6599 MPI-MUNICH +49 89 32354-254 SACLAY 33-16-908-8564 SLAC-2 650-926-8507 Conference Owner: Hans Frese, +49 40 8998-2588, Hans.Frese@desy.de Conference Requester: Felix Sefkow, +49-40-8998-3402, felix.sefkow@desy.de If you have a problem that you feel is related to ESnet's video/data/audio conferencing equipment, please contact the ESnet Operations staff at 1-800-333-7638 or 1-510-486-7600 or send email to dcs-admin@es.net. 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