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My Favourite Year

Picture 1: principle of Micromegas Time Projection Chamber

Carleton University student recalls his year as a member of an ILC TPC Micromegas French group.

At only 23 years old, Dan Burke, an undergraduate student from Carleton University, Canada, had already experienced the scientific excitement and the various activities of research in particle physics. Last year he stayed in a French Laboratory at Dapnia, Saclay and participated in various measurements, test beams and physics analyses and contributed to two scientific publications.

Burke spent a year as a member of the TPC Saclay Team, directed by Paul Colas. This group's major activity is R&D for the Micromegas (MICRO-MEsh GASeous detector) Time Projection Chamber (TPC), within the LC-TPC (Time Projection Chamber) international collaboration (see NewsLine 22 June 2006). While crossing a gas-filled cylinder TPC detector, charged particles ionise the gas. In Micromegas chambers, the produced electrons drift and are amplified between fine metallic micromesh structures and anode pads readout (see picture 1).

Picture 2: Detector endplate realised at Orsay and Saclay, equipped with a resistive film from Carleton University, which was used for the "Multi-Prototype TPC" in the October 2005 test beam at KEK.

Burke started his work analysing beam test data, which were recorded in June 2005 in Japan. One month after his arrival in October 2005, he flew to Japan and participated in another test-beam, where a highly 50μm resistive film (see picture 2) was added on the Micromegas TPC. This test was done in collaboration with institutes from Canada, Germany, France, Japan and the Philippines (see the collaboration picture). Physicists expected the film to improve the spatial resolution of the TPC for small drifts, spreading the electron charges on several pads after amplification. Two different TPCs (see pictures 3 and 4) were exposed to 4GeV pions.

For test-beams analyses, Burke learned to run a special analysis programme in which he compared real data to simulated ones. He also compared the measured TPC resolution to an analytic formula given by a "resolution theory", elaborated during the tests at KEK. In a third test-beam in Japan, the team changed the composition of the TPC gas to understand its effect on the spatial resolution. Burke first presented his result at a SOCLE meeting in Lyon, France (see NewsLine 26 January 2005 issue). "It was my first presentation in French," said Burke. "I was scared, but it went very well".

Picture 3: The Carleton Ottawa Saclay TPC tested in October 2005 at KEK.

Picture 4: The "Multi-Prototype TPC" tested in October 2005 at KEK.

Picture 5: One study of Burke was the discharge of TPC metallic micromesh. An earthquake ("tremblement de terre") at KEK made him miss a record.

Picture 6: Burke visiting the gardens of "Château de Versailles'.

The excellent test beam results were in agreement with the resolution theory, which will help improve the actual TPC design for a future ILC detector. Burke participated in two scientific publications that present these results and will be published soon in "Nuclear Instruments and Methods".

Burke participated in another study pursued at Saclay, together with CERN and NIKHEF, that focused on the Silicon TPC (SiTPC), a gas and pixel detector. The EUDET European contract supports this R&D. (see NewsLine 8 September 2005). Burke wrote a programme to extract and analyse the information of the "Medipix" chips, which will be used for the SiTPC readout.

"When I arrived in France one year ago, it was the first time I travelled outside North America, and one month later I was in Japan," said Burke, who also participated in measurements and test-beams at CERN, DESY and NIKHEF. "I could not imagine how much I would learn, from the preparation of test-beams to real data analyses, it was a real comprehensive work." And this is just the beginning of the story. Burke said, "I am grateful that Paul Colas and the administration at CEA gave me opportunity to discover the world of particle research, and I am eager to start a phD in 2 years."

Read Dan Burke's blog

-- Perrine Royole-Degieux