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S. Aplin, M. Ball, T. Behnke, K. Ikematsu, A. Imhof,
M. E. Janssen, A. Kaoukher, K. Komar, T. Lux, J. Mnich,
O. Schäfer, A. Vogel, P. Wienemann
LC TPC WorkshopLAL, Orsay, FranceJanuary 12, 2005
Recent Results from theTPC Activities at DESY
Peter Wienemann 2LC TPC Workshop, LAL, Orsay, January 2005
Synopsis: Data Taking in 2004
5 T Magnet: Electron test beam: 500 000 events 300 000 events 33 %: non-staggered pads, 100 %: non-staggered pads 67 %: staggered pads 80 %: Ar-CH
4-CO
2 (93-5-2), 100 %: Ar-CH
4-CO
2 (93-5-2)
20 %: Ar-CH4 (95-5)
5 T magnet Test beam
Peter Wienemann 3LC TPC Workshop, LAL, Orsay, January 2005
Gas Quality Monitoringd
rift
velo
city
(cm
/s)
data taking time (h)
TDR gas
dri
ft v
elo
city
(cm
/s)
data taking time (h)
P5
Large gas contamination at beginning of data taking
Several hints indicate that water is dominant contributor
Slow control monitoring system is being built to allowa dedicated analysis of the influence of environmentalparameters
Garfield prediction
Garfield prediction
vD/v
D < 1 %
Peter Wienemann 4LC TPC Workshop, LAL, Orsay, January 2005
Gas Quality Monitoring
point of operation
TDR gas P5
Water interpretation yields ~ 50 ppm water contaminationfor both gases
Peter Wienemann 5LC TPC Workshop, LAL, Orsay, January 2005
Gas Quality Monitoring
Water contamination derived from drift velocity:
TDR gas P5
data taking time (h)data taking time (h)
wa
ter
con
ten
t (p
pm
)
wa
ter
con
ten
t (p
pm
)
Peter Wienemann 6LC TPC Workshop, LAL, Orsay, January 2005
Systematics Studies
Continued study of systematics contributing toresolution measurements:
Pad response function correction
Cut dependence of resolution
Biases of different methods to determineresolution
} in progress
Peter Wienemann 7LC TPC Workshop, LAL, Orsay, January 2005
Definition of Resolution?
Residual distributions (2 mm wide, non-staggered pads,B = 4 T):
z=26.4cm z=34.0cm
z=49.1cm z=56.7cm
z=3.8cm z=11.3cm z=18.9cm
z=41.6cm
z=64.2cm
Peter Wienemann 8LC TPC Workshop, LAL, Orsay, January 2005
Definition of Resolution?
Residual distributions (2 mm wide, staggered pads,B = 4 T):
z=26.4cm z=34.0cm
z=49.1cm z=56.7cm
z=3.8cm z=11.3cm z=18.9cm
z=41.6cm
z=64.2cm
Peter Wienemann 9LC TPC Workshop, LAL, Orsay, January 2005
Definition of Resolution?
The only easy conclusion:
2 mm pads seem too widefor TDR-like gases(to get diffusion limited resolution for alldrift distances with “typical” GEM stack setup)
Peter Wienemann 10LC TPC Workshop, LAL, Orsay, January 2005
Triplet Method
Determine residual only from three adjacent pad rows:
Draw straight line through outer hits
Determine distance between straightline and central hit
Resolution assuming same uncertaintyfor all hits: =
d (2/3)
Advantages of triplet method:
Very simple and robust
No difference between straight andcurved tracks
Probably less sensitive to field inhomogeneities
tripletd
Peter Wienemann 11LC TPC Workshop, LAL, Orsay, January 2005
Triplet Method
Check with Gaussian smeared toy MC points (MC
=200 m):R
eco
nst
ruct
ed
re
sidu
al d
istr
ibu
tion
wid
th
pad
Peter Wienemann 12LC TPC Workshop, LAL, Orsay, January 2005
Triplet Method
DESYpreliminary
TDR gas2.2 x 6.2 mm2 pads
Peter Wienemann 13LC TPC Workshop, LAL, Orsay, January 2005
Marlin Tracking Module
MARLIN = Modular Analysis and Reconstruction for theLinear Collider (based on LCIO)
Current user community: CALICE Collaboration Simulation group Physics analysis group
Started design of MARLINtracking processors
MaTRIX = Marlin based Track Reconstruction for ILC Experiments
Your input is welcome!
Advantage of approach: Exchange of experience
Peter Wienemann 14LC TPC Workshop, LAL, Orsay, January 2005
Summary
2004 has been a successful data taking year.
Drift velocity can be kept constant at thesub-percent level (with present simple gas system andafter ~ 3 weeks of flushing).
Continued to study resolution systematics.No final conclusions yet.
Triplet method is a simple and robust way todetermine resolution.
Started with design of MARLIN trackingprocessors. Input from all groups is welcome.
Peter Wienemann 15LC TPC Workshop, LAL, Orsay, January 2005
Future Plans
Determination of double track resolution withUV laser. Chamber is being modified.
Finish slow control system.
Add more readout channels.
Cosmics measurements with other padgeometries and gases.
Investigate electronics alternatives.
Collect ideas for next generation prototype.