Speaker
Madhu Dixit
(Carleton University and TRIUMF)
Description
The MPGD readout TPC for the ILC will have to measure ~200 track points with a
resolution close to 100 microns for all drift distances. It may be difficult to meet
the resolution target with conventional MPGD readout techniques if ~2 mm wide pads
were used as is presently envisioned. Reducing the pad width to improve resolution
could add significantly to the detector cost and complexity. The new MPGD readout
concept of charge dispersion has been recently shown to achieve excellent resolution
without resorting to narrower pads in cosmic ray TPC tests in absence of a magnetic
field. We have recently studied the performance of two small prototype MPGD-TPCs with
charge dispersion readout in a 1 T superconducting magnet in a 4 GeV/c test beam at
KEK for several different gas mixtures. One of the TPCs was outfitted with a
Micromegas endplate and the other with interchangeable Micromegas and triple-GEM
endplates. Beam data were recorded both in and outside the magnet for the two TPCs.
Preliminary results are quite encouraging. Transverse resolution close to 50 microns
was achieved with 2 mm wide pads at 1 T for short drift distances for one of the
TPCs. The dependence of resolution on drift distance was consistent with diffusion
and electron statistics. With larger suppression of transverse diffusion at higher
magnetic fields, the resolution goal of 100 microns appears within reach for the ILC
TPC. The present status of charge dispersion MPGD-TPC beam test resolution studies
will be presented.
Author
Madhu Dixit
(Carleton University and TRIUMF)
