Detectors for High Energy and Nuclear Physics Experiments


Cathode strip chamber (CSC)


Originally developed in the group's synchrotron detector R&D, CSCs have been implemented as a key element in the ATLAS and CMS experiment of CERN's LHC


The principle of operation is illustrated in the diagram below (this particular cathode geometry is called "Two Intermediate Strips" which improves the position linearity using capacitive charge division.)



The avalanche around an anode wire from an ionization event creates an induced charge distribution on the cathode, with a FWHM roughly 1.5 times the anode to cathode distance.  Detailed calculations on the induced charge distribution in a MWPC can be found in this work by E. Mathieson.


The key parameter for optimum position encoding performance is the choice of the strip pitch, relative to the distance between the anode wires and the cathode plane.  The figure below demonstrates calculated differential non-linearity in the reconstructed position, using a simple center of gravity calculation, as a function of the ratio of strip pitch to anode-cathode distance.



Clearly, using amplifier-per-strip encoding requires a relative large number of electronics to cover a large sensing area.  Intermediate Strips and Zigzag Strips readout schemes developed by this group allow reduction of the readout channel count without significant reduction in position resolution.


The figure below illustrates the zigzag strips with a delay-line readout.  The anode wire positions are indicated by the red lines.



References:

G. C. Smith, J. Fischer, and V. Radeka, "Capacitive Charge Division in Centroid Finding Cathode Readouts in MWPCs," IEEE Trans. Nuc. Sci. NS-35 (1), 409-413 (1988).

E. Mathieson and G. C. Smith, " Reduction in Non-Linearity in Position-Sensitive MWPCs," IEEE Trans. Nuc. Sci. NS-36 (1), 305-310 (1989).

E. Mathieson, "Induced Charge Distributions in Proportional Detectors"



Last Modified: Wednesday, 06-Feb-2013 22:33:56 EST