Draft Summary of 4th WP meeting 06/07/2006
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Thursday 6 July
West Coast East Coast W.Europe Japan
07.00 10.00 16.00 23.00
Present:
Paul Colas
Madhu Dixit
Keisuke Fujii
Leif Jonnson
Sasha Kaoukher
Takeshi Matsuda
Joachim Mnich
Dan Peterson
Peter Schade
Ron Settles
Akira Sugiyama
Jan Timmermans
Excused: Dean Karlen, Luciano Musa
AGENDA
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See the agendafoils
http://www.mppmu.mpg.de/~settles/tpc/lp/wpmtg/wpconveners4thmeeting6july2006.ppt
AGENDA Items
-1.News
-2.R&D planning for the LP (Takeshi)
-3.Proposal for the electronics (Leif,Luciano,Madhu)
-4.More ideas on the endplates (Dan,Paul)
-5.Future meetings
-6.AOB
1.News (foils#3,4)
---------------------------------
1a. The email from Rolf Heuer (26June/4July) announced the start of steps
towards a more formal structure for our work which is necessary:
for now in order to properly plan and execute the LP work, and
for later to make the transition to building the LCTPC itself.
He has asked a small committee of one person per region
(Dean Karlen, Takeshi Matsuda and Ron Settles) to prepare a proposal
for the organization of the LCTPC/LP collaboration. They would
appreciate it if you would send your opinions on the structure of the
collaboration within one week. The proposal will be circulated the
middle of next week (12 July), in time for a continuation of the
discussion at the LCTPC meeting in Vancouver.
1b. The LCTPC website www.lctpc.org is working in principle. At the moment
it is simply linked to http://www.mppmu.mpg.de/~settles/tpc/welcome3.html
The last few days I have cleaned up my website and the setup for the
workpackages. From the above URL click on LP, then e.g. WP meetings,
then e.g. to today's meeting At the site I shall try to keep all of the
relevant files/information. (Take a look and let me know if anything is
missing.)
2.R&D planning for the LP (Takeshi)(foils#5-7)
-------------------------------------------------
For details, click on 'File by Takeshi' at
http://www.mppmu.mpg.de/~settles/tpc/lp/wpmtg/wpmtg.html
Takeshi reviewed our R&D phases, what we have learned up to now with the
small prototypes and pointed out that there are still many tests to do.
He then showed what we can expect: the scaled resolution curve calculated
by Keisuke.
The R&D for the LP in general should demonstratd full volume tracking with
the best-at-present TPC candidate(s) for ILC and achieving the target
resolution of LC TPC in the non-uniform magnetic field. Gas, gating,
backgrounds, and padsize(=>achievable electronics density) are key issues.
An example of resolution using a low-diffusion gas (ArCF4) calulated by
Makoto was shown for 1.27mm pads. The PRF via diffusion spreading in
Gem enables sub-100micron resolution; Micromegas with its narrow
PRF is limited by the hodoscope effect and would probably need
another charge-spreading mechanism to get the resolution needed.
Takeshi pointed out that the pixel TPC idea which will also be part
of the LP R&D will be very interesting and that simulation can help
understand its potential. Simulation for many other TPC questions will
be a valuable tool. Engineering issues should also be tested at the
LP, for example surface-mounted electronics on the endplate and the
optimum sector arrangement. The review ended with a possible sequence of
steps for constructing the LP.
In the discussion Joachim asked how many endplates should be built; most
thought that two, one version for Gem and the other for Micromegas, would
be the right number to start with. The two should have the same sector
layout and small areas dedicated to pixel-tpc tests. In addition e.g. a
'dummy' or 'pre-prototype' endplate (Dan's question) for commissioning
the fieldcage or testing mechanics might be useful. Akira emphasized that
simulation should be done first on possible configurations (e.g.
padsize/shape) to be tried at the LP. Leif asked about the number of
channels (1000 by end 2007, Nx1000 later); they can be
positioned/moved on the endplate as needed by the tests.
3a.Proposal for the LP electronics (Leif,Luciano)(foils#8,9)
--------------------------------------------------------------
Leif reviewed the ideas for the connectors at the LP.
http://www.mppmu.mpg.de/~settles/tpc/lp/wpmtg/wpmtg.html
-> click on 'Latest on LP electronics' where there ar links to various
drawings of connectors. The transition between Alice FE and LP FE is
proposed via 'pico coax'?? cable (drawings to be sent), about 10cm
long. Leif and Dan discussed details of mounting connectors on the
endplate; more understanding is needed here.
3b.Proposal for the LCTPC electronics (Madhu)(foils#10-12)
-------------------------------------------------------------
Madhu explained his note,
http://alephwww.mppmu.mpg.de/~settles/tpc/lp/wpmtg/wpmtg.html
-> click on 'Writeup by Madhu'
which compiles certain info on pulse shapes (rise time and pulse length)
we can expect in the LCTPC. He pointed out that the preamp rise time does
not have to be extremely fast, since several different effects
(driftlength, diffusion, track angle) smear out the signal. Considering
all effects he proposes two possibilites (Trise is 10-90%):
1) Charge preamp with Trise ~ 40ns, TDecay ~ 2?s similar to Aleph.
Shaper integrator with ~200ns to 500ns adjustable.
~10 MHz digitizer.
2) Charge preamp, with Trise ~ 40 ns, TDecay ~ 2 ?s.
No shaper integrator.
~25 MHz digitizer.
RS and Madhu discussed that fact that fast signals track segments with
short driftdistance (e.g. where tracks leave the endplate) are accompanied
by slow signals from tracks diffused by long drift (e.g. theta ~
90degrees) at the same position on the endplate; this is a delimma for
a shaper integrator (1 above); simulation here may help make the choice.
Digitized pulse shapes (2 above) could be corrected 'offline' for
geometrical effects.
(Note added by RS: this seems to say the the LCTPC should not have a
shaper integrator.)
4.More ideas on the endplates Dan,(foils#13-15),Paul(foils#16-19)
-------------------------------------------------------------------
4a. Dan showed an next iteration with 10 curved panels/sectors:
http://w4.lns.cornell.edu/~dpp/linear_collider/LargePrototype.html
An O-ring has been included now. Leif noticed that the connectors should
be rotated by 90degrees, to lineup with the padrow direction. Dan will be
iterating on this after Vancouver (see below), also to increase the
sector size, as said at the phonemeeting.
A discussion followed. Small panels for the Pixel-TPC studies are
foreseen. The geometry with small silicon detectors inside the magnet on
the outside of the fieldcage must be specified. Dan is planning the
mounting of the electronics in a way that does not put stress on the
endplate. Sasha asked: do we want to be able to rotate the chamber,
e.g. for cosmics? Joachim: how will the laser system be implemented?
4b. We didn't succeed in putting Paul's file on the website before the
meeting, but now it is there:
http://www.mppmu.mpg.de/~settles/tpc/lp/wtmtg/wpmtg.html
-> click on 'LPgoals-Colas.ppt'
There are, among other things which are self-explanatory, examples
of endplates with 6 or 7 panels.
5.Future meetings
----------------------------------
The bi-weelkly phonemeetings was considered appropriate for now.
The next will be 18 July (Vancouver) where there will be a general
LCTPC/LP meeting and a workpackage meeting; the agenda is being worked
out.
After Vancouver, there are the following possibilities, in addition to
phonemeetings (which will continue):
-Paul/Akira plan an 'endcap meeting' in Paris 12-15 September; details
will be sent soon. At the end of it there will be a workpackage phone
meeting where the happenings will be summarized.
-The annual Eudet meeting will be in Munich 18-20 October.
-The European LC workshop is in Valencia 6-10 November.
There are minutes attached to this event.
Show them.
