space point within a
detecting plane and thereby improving the tracking efficiency at high rates. A
prototype chamber has been tested with a variety of etched cathode strips using
cosmic rays and the results show resolutions well below 200 microns and
efficiencies of 99%. Finite element simulations of the mechanical frames of a
full station 2 octant have been performed and demonstrate that adequate
stiffness can be achieved.
m
have been achieved on chambers as large as 2 meters[1]. For a CSRC to serve as a candidate for the
muon tracking system tracking chambers, the issues that must be addressed are,
spatial resolution, identification of a suitable gas with a small Lorentz
angle, radiation length, preparation and metrology of the cathode foils, and
mechanical design issues related to frame stiffness, frame thickness, and
creep. Cost and simplicity in design will be very important.
This document describes the current status of work aimed at determining a
suitable design of cathode strip readout chambers as an alternative to drift
chambers for tracking in the muon arm of PHENIX. A set of criteria and the CSRC
measured or expected performance for the tracking chambers has been prepared
and is attached as Appendix A. Previous studies have shown CSRC are capable of
the needed position resolution, provide high efficiency, and robust tracking.
These previous designs, however, are not optimal for the present application
because of their thick cathode structures which would introduce too much
multiple scattering and degrade the momentum resolution of the system. Also,
these designs have aimed at better than 100 m position resolution which requires a readout scheme with
several amplifiers/cm. The present study presents alternative designs that have
a smaller radiation length and require lower, less expensive readout density.
This work was performed at LANL using the PHENIX muon chamber test set up and was performed in parallel with the drift chamber prototype tests. The designs we have studied were constrained by using existing frames and electronics surplus to the Neutral Meson Spectrometer (NMS) project at LAMPF.