From settles@mppmu.mpg.de Wed Feb 14 13:09:09 2007 Date: Sun, 11 Feb 2007 16:21:08 +0100 (CET) From: Ronald Dean Settles To: LC-TPC@desy.de Cc: LCTPC CB/TB combined list -- 'Keisuke FUJII' , A.F.Buzulutskov@inp.nsk.su, alexander.kaukher@desy.de, Anatoliy Krivchitch , Ariane Frey , bamberg@physik.uni-freiburg.de, Dan Peterson , David Nygren , Dean Karlen , desch@physik.uni-bonn.de, Harry van der Graaf , henning.schroeder@physik.uni-rostock.de, Ivor Fleck , jan.timmermans@nikhef.nl, Joachim.Mnich@cern.ch, jpmartin@lps.umontreal.ca, Leif Jonsson , lepeltier@lal.in2p3.fr, Luciano.Musa@cern.ch, Lucie.Linssen@cern.ch, Madhu Dixit , Michael.Hauschild@cern.ch, Paul.Colas@cea.fr, Peter Schade , Peter Wienemann , rickv@fnal.gov, sawyer@phys.latech.edu, Stefan.Roth , Sugiyama Akira , Takeshi Matsuda , ties.behnke@desy.de, Y Gao , rolf-dieter.heuer@desy.de Subject: Summary: 20th LP electronics mtg 31/1/2007 Dear friends, We had an electronics meeting on Wednesday 31/01/2007 and will continue with a normal WP meeting on next week (announcement will follow). Below is Leif's summary of the electronics meeting. Best greetings, Ron Agenda Electronics Meeting 31/01/2007 ------------------------------------- 1. Discussion on the status of the homework - Leif. 2. Drawings by Anders on read-out cards and the cable lengths - Anders. The drawings will be available at http://www.hep.lu.se/staff/oskarsson/ilc just before the meeting. 3.AOB Summary ---------------- Present: --Madhu Dixit --Leif Joensson --Takeshi Matsuda --Anders Oskarsson+Lund group members --Dan Peterson --Ron Settles ...anyone forgotten? 1) List of homework from last meeting - Drawings produced by Lund concerning the positioning of the standard ALICE read-out boards and the resulting cable lengths were distributed the same day as the meeting and were discussed in detail under point 2. - No news about suitable cables with respect to flexibility and capacitance. Everybody should continue to look for such cables. - Lund has now got the files for the pin assignments for the new preamplifier and will start working on the modification of the front-end board. This, however, might be influenced by the organization of the boards and especially where the connectors are going to be placed on the boards. - No documentation concerning the alternative system based on commercial components has been distributed. This should happen as soon as the documentation is in shape that it can be appreciated. - Luciano sent around links to the DAQ system used in the ALICE experiment. It was decided that it didn't make sense to discuss this in the meeting since people should need more time to study the material. 2) Positioning of standard ALICE read-out boards - Drawings had been produced for three different geometries of the pad area covered by approximately 10.000 pads of size 1x4 mm^2. A reasonable separation of the boards was assumed to be 16 mm pitch. This might be reduced somewhat depending on how cooling can be solved. The drawing can be found under http://www.hep.lu.se/staff/oskarsson/ilc - A) a pad geometry that covers the full effective length of the TPC, which was estimated to 640 mm. With 10.000 pads this gives a width of 64 mm. The boards have been organized in two parallel rows with the connectors (not shown) pointing towards the pad plane. In this geometry the cable length would be of the order of 12 cm assuming that the connectors of the boards are placed as on the present boards. From the cable length point of view this is the most favourable geometry. - B) a pad area of 96 x 408 mm^2. - C) a pad area of 128 x 320 mm^2. The more square-like the area becomes the further the distance between the edge of the pad area and the outermost board will be. This leads to increased cable lengths and in the case C) it will be of the order of 20cm. Another option where the boards are rotated by 90 degrees with respect to the pads was also looked into for option A). In case of flatcables such a positioning has the advantage that the cables only have to be twisted by 90 degrees. The disadvantage is the cable length will increase even more. A further possibility would be to have the connectors of the boards in each row to point towards each other instead of pointing towards the pad plane. This could give a cable length somewhat reduced compared to the previously options described. The conclusion from this study is that we in the first approximation have to consider cable lengths of the order of 20 cm. The question is whether this is compatible with the performance of the new preamplifier, also depending on the capacitance of the cable. It was discussed if the connectors could be placed in different positions on the board to decrease the cable length but then the traces on the board will be correspondingly longer. In this case one might consider moving the preamps closer to the connectors. 3) The DAQ system People with some expertise on DAQ systems are urgently needed. The first task would be to look into the options that are available (ALICE test system, ALICE final DAQ system) or possibly consider alternative solutions (Ethernet based system etc.) and to come with suggestions. It should be kept in mind that systems with backplanes have to be compatible with the requirements of testing different geometries. A discussion on the DAQ system is foreseen for the next meeting.