Speaker
Mr
Konstantinos Kousouris
(Nuclear Physics, NCSR Demokritos)
Description
A micropattern gaseous detector has been designed for the CERN Axion
Search experiment CAST, based on the Micromegas technology. The
twodimensional readout, with XY strip structure, allows for
sufficient spatial sensitivity and the low natural radioactivity
materials used for its construction meet the experiment demands for
low background. The detector is operated with an Argon/Isobutane (95%
5%) mixture and is controlled by a VME data acquisition system. It is
optimized for soft Xrays (110keV) detection, exhibiting linear
response and good energy resolution (19% FWHM at 5.9 keV). The
Micromegas detector operated efficiently during the 2003 and 2004
data taking periods of CAST and its upgrade for the 2004 run,
supported by the development of sophisticated software analysis
tools, improved the background rejection leading to a rate of about
5.105 events/keV/cm2/s with 92% efficiency. Detailed Monte Carlo
studies, using the GEANT4 package, indicate that the measured
background is induced by muons hitting the surrounding materials as
well as neutrons from the experimental site and environmental
radioactivity (Radon).
Primary author
Mr
Konstantinos Kousouris
(Nuclear Physics, NCSR Demokritos)
