Speaker
Thomas Zerguerras
(Uni Paris-Sud)
Description
Micropattern Gaseous Detectors (MPGD), like Micromegas or GEM, are used
or foreseen in particle physics experiments for which a very good spatial
resolution is required. We have developed an experimental method to
separate the contribution of transverse diffusion and the multiplication
process by varying the number of primary electrons generated by a point-
like source. A pulsed nitrogen laser is focused by an optical set-up on the
drift electrode, which is made of a thin metal layer deposited on a quartz
lamina. The number of primary electrons can be adjusted from a few to
several thousands on a spot which size is less than 100 μm RMS. The
detector can be positioned with an accuracy of 1 μm by a motorized three
dimensional system. This method was applied to a small Micromegas
detector with a gain set between 10 3 and 2.104 and an injection of 60 to
2000 photoelectrons. Spatial resolutions as small as 5 μm were measured
with 2000 primary electrons. An estimation of the minimum value of the
energy resolution can also be extracted.
Author
Thomas Zerguerras
(Uni Paris-Sud)
