On the aging of the scintillation counters for RUN II Muon System at CDF

The CDF II Muon System has an important role in the CDF detector, particularly in investigations of processes, as with heavy quarks. JINR and INFN physicists at FNAL are responsible for maintenance to perform the highly efficient functioning of the scintillation counters involved into the CDF Muon system.In the course of several years, we carried out the light yield measurements, at ends farthest from photomultiplier, of the various types of scintillation counters installed at CDF. On the basis of the results obtained, conclusions about the aging rate of the counters and long-range forecast of their efficiency during physics data taking at CDF RUN II could be made.One can see that the new generation counters with wavelength-shifter fibers technology for light collection have higher long-range efficiency compared to counters using a classic plexiglas light-guide for light propagation.