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    User name Ole Hansen

    Log entry time 20:56:48 on July 05, 2010

    Entry number 330316

    Followups:

    keyword=R-arm VDC performace/issues

    Attached are four sets of plots showing the performance of the R-arm VDCs in run 1745 (C target, T4 trigger). The plots are:

    Top: basic wire number distribution,

    Middle: distribution of cluster centers (coordinate inverted so it can be directly compared to the wire number spectrum)

    Bottom: fitted cluster time offset t0 (ns) vs. cluster center position (m)

    Observations:

    u1 plane: clearly visible steps with periodicity of 16 wires. Problems for wires 128-143 (noisy card?), 289 (low efficiency channel, resulting in missing clusters around -u1=0.45 (can be fixed by allowing gap in cluster))

    u2 plane: again, visible 16-wire step structure. Problems with wires 272-303 (malfunctioning cards, resulting in poor cluster fits evident in t0 plot), 192-207 (slightly noisy, see dip in t0 plot)

    v1 plane: strong 16-wire step structure. Several problem areas, e.g. 160-171. Hot wires 208, 210, 211. Wires 336-368 missing.

    v2 plane: still 16-wire step structure, but not too bad. Minor problems for wires 304-319.

    If time permits, I suggest experts try to improve some of these problems, especially the bad hole in u2. Also, the step structure worries me - there seems to be significant cross-talk between channels on the same cards. Unclean data like this will lead to reduced tracking efficiency.






    Figure 1



    Figure 2



    Figure 3



    Figure 4