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.