"Direct comparison of Micro Pattern Gas Detector Readouts"

Several groups are currently studying gas-amplification devices in prototype TPCs. Results are encouraging; spatial resolutions of less that 100 micrometers have been measured with micro-pattern gas detector (MPGD) devices. However, measurements of different gas-amplification devices are difficult to compare because they are taken by different groups under various conditions. The goal of this project is to compare multiple examples of various gas-amplification devices, including GEMs, Micromegas and wires, under the same environmental conditions. This comparison will provide input into the TPC endplate design for both the LDC and GLD concepts.

In the past year, the Cornell group has constructed and commissioned a TPC, shown in Figure 1 on the main page, with a 64 cm drift field and 10 cm square readout aperture. To commission and operate the TPC, Cornell has purchased high voltage and data acquisition (DAQ) systems. The high voltage system provides 20kV for the drift potential as well as biasing voltages for the gas-amplification devices. The VME based DAQ has low noise power supplies to improve the signal sensitivity for prototype detectors. TPC signals are digitized with commercial Flash-ADCs. Cornell has purchased four 8-channels Flash-ADC units with 105 MHz sampling rate, +/- 200mV input range, and 14 bit resolution. The Purdue group is supplying the MPGD gas amplification devices mounted on Cornell supplied read-out pad boards. Results from a single-GEM were shown at Snowmass. An early cosmic ray event is shown in Figure 2 on the main page. The Purdue group has mounted a double-GEM in Sept. 2005. There are plans to provide a 3M-produced Micromegas, soon.

Preliminary studies have been done with 5mm pitch pads. In the next year we will increase the number of channels in the DAQ system to allow spatial resolution measurements using 2 mm pad pitch with several gas-amplification devices and several gas mixtures. An aggressive near-term goal is to measure the positive ion feedback for the various devices by directly collecting the ions for single tracks on the field cage termination grid.

Beginning in 2006, we anticipate that the world TPC group will collaborate to build large prototype to be tested at DESY. We expect to contribute by taking responsibility for the design and construction of a major component such as a tiled endplate.

The most critical requirement for future progress is funding for the expanded DAQ syetm and other equipment.

Our support is not sufficient. While we received 2005 LCRD funding, the total was about 30% of the request. Additional funding, would improve the resolution measurements and provide for measurements in an off-site test magnet.

Please address the following questions in your statement.

This topic: ILC/WWS > TrackProjects > TrackCornellTPC > TrackCornellTPCStatement
Topic revision: 22 Dec 2005, DanPeterson
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