The Beam PWC at GIF

  • Prediction of the hit coordinate in P2 with use of the Beam PWC.

    • - The distributions of number of hits and TDC distributions for the beam chambers (2 stations, each has X and Y view, each view has two output time signals, total 8) are in the Plot . There is significant fraction of events with no signals from these chambers or with more than one hit per output (L,R,U and D outputs). Only 56% of events have correct hits in X planes, 27% - in Y planes and 24% - in X and Y planes. Correct hit means here one hit per output. In our analysis we have not used Y planes.

    - to predict the X-position of the hit in P2 chamber we need to know Z-distances, calibration and alignment constants for the beam chambers. The GIF layout measured by Bryan Smith (Logbook I, pages 150-152) provided Z-distances, for alignment constants the means of beam profiles were used. The simple calibration of the X-planes of beam chambers was done using the fact that the X-distance between centers of anode channels of P2 chamber rotated by 25 degrees is 5.06*cos(25)=4.586 cm. Therefore the predictions for any two adjacent anode channels of P2 chamber should be different in average by this amount. Keeping in mind that the anode wire groups almost 5 cm wide this calibration was good enough for anode data analysis. The special calibration runs were taken by Liza Gorn at the end of run in the GIF and the direct and more accurate calibration will be available soon.

    - Predicted by the beam chambers the X-distribution of the hits in the first plane of P2 chamber is given here (top plot). The bottom plot presents predicted positions when the anode channels 10, 11 or 12 were ON. One can see a significant contribution of the wrong predictions (tails). Therefore the use of the beam chambers as independent reference position detector should be cautious (see also the next plot where the same distributions are presented for the 1-3 planes of P2 in terms of anode channels efficiency). If the track is defined not only by beam chambers but also by several planes of P2 then such wrong predictions could be eliminated. Such tracking will be done later.
    Last modified: Mon May 31 13:25:00 CST 1999

    teren@fnal.gov