Speaker
Description
CMS CSC is a particular kind of Multi-Wire Proportional Chambers, or MWPC. Operation principle of MWPC is based on avalanche amplification of the primary charge in vicinity of a thin anode wire. The regions of avalanche development are microscopic areas of plasma, and plasma chemical reactions may lead to formation of deposit on the electrode surfaces of the MWPC, causing degradation of its detection performance.
Careful choice of detector materials and the working gas mixture minimizes the possible chamber aging. Dedicated longevity tests of a considered MWPC type involve a long-term operation of a detector prototype or a production chamber under intense irradiation. Comprehensive analysis of MWPC electrodes can be done after irradiation. It provides additional information on possible chamber degradation processes and increases reliability of the chamber longevity prediction based on the irradiation test results. We present a set of complementary analytical techniques which gives detailed characterization of deposit accumulated on MWPC electrodes. Optical, scanning electron and atomic force microscopy (OM, SEM, AFM) are used to characterize the surface morphology. To define the chemical composition, a combination of energy dispersive X-ray and photoelectron spectroscopy (EDS and XPS) are performed, as well as vibrational techniques, such as Fourier-Transform Infrared (FTIR) and Raman spectroscopy and X-ray diffraction (XRD) method.
