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 <settles@mppmu.mpg.de>
To: LC-TPC@desy.de
Cc: LCTPC CB/TB combined list -- 'Keisuke FUJII' <keisuke.fujii@kek.jp>,
A.F.Buzulutskov@inp.nsk.su, alexander.kaukher@desy.de,
Anatoliy Krivchitch <kriv@pnpi.spb.ru>, Ariane Frey <ariane@mail.cern.ch>,
bamberg@physik.uni-freiburg.de, Dan Peterson <dpp@mail.lns.cornell.edu>,
David Nygren <drnygren@lbl.gov>, Dean Karlen <karlen@uvic.ca>,
desch@physik.uni-bonn.de, Harry van der Graaf <vdgraaf@nikhef.nl>,
henning.schroeder@physik.uni-rostock.de,
Ivor Fleck <fleck@hep.physik.uni-siegen.de>, jan.timmermans@nikhef.nl,
Joachim.Mnich@cern.ch, jpmartin@lps.umontreal.ca,
Leif Jonsson <leif.jonsson@hep.lu.se>, lepeltier@lal.in2p3.fr,
Luciano.Musa@cern.ch, Lucie.Linssen@cern.ch,
Madhu Dixit <msd@physics.carleton.ca>, Michael.Hauschild@cern.ch,
Paul.Colas@cea.fr, Peter Schade <pschade@mail.desy.de>,
Peter Wienemann <wiene@mail.desy.de>, rickv@fnal.gov,
sawyer@phys.latech.edu, Stefan.Roth <Stefan.Roth@physik.rwth-aachen.de>,
Sugiyama Akira <sugiyama@cc.saga-u.ac.jp>,
Takeshi Matsuda <takeshi.matsuda@kek.jp>, ties.behnke@desy.de,
Y Gao <gaoyn@mail.tsinghua.edu.cn>, 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.