Drift speed and gain measurements in the T2K time projection chambers
Date
2009-10-30T22:21:53Z
Authors
Gaudin, André Joseph Luigi
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Initial results are presented for two analyses using data from the recently completed laser calibration system of the time projection chambers for the Tokai-to-
Kamioka long baseline neutrino oscillation experiment. Data taken with the first two
production time projection chambers, while tested at TRIUMF, has been used to investigate the signal arrival time and subsequently the ionization drift speed and the relative gain of the micromegas and electronics systems. It has been found that an analytic Gaussian t produces the best overall results for establishing an arrival time, having both the lowest standard deviation, of 11 ns, and good amplitude dependence while remaining fast. Using the analytic fit technique the drift speeds of ionization has been found to be in agreement with the expected values at the 2% level. The largest of the contributing errors were found to be due to systematics involved in the calculation of the ionization production time and will be reduced in future. Relative
gain analysis results have shown that the gain can be calculated based on a simple
model relating the mean signal size of data channels to the variance. Further gain
results have shown that an offset found in the laser data can be corrected for by
sampling signal amplitudes from channels that do not detect ionization or can remain
uncorrected if the fitting for the relative gain includes a correction parameter.
Preliminary results of the gain's dependence on the gas temperature and pressure have shown a positive nonzero slope. However, systematic errors were found be large relative to the temperature and pressure ranges. This dependence and its use as a
correction for such changes will need to be investigated further at the experiment site
in Japan.
Description
Keywords
Drift Speed, Gain, T2K, Neutrino, Time Projection Chamber, TPC