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    User name ulmer

    Log entry time 17:14:07 on October24,2002

    Entry number 88953

    This entry is a followup to: 88881

    keyword=VDC spikes - where are they?

    Results for run 2686 on the Right Arm VDCs are shown below. These spectra were generated by writing data to files from within ESPACE (i.e. not via ESPACE histograms). The first figure shows the spectrum of events vs. wire number for each of the four VDC planes. This spectrum includes all the hits for the chosen cluster (i.e. it's incremented several times per event). The second figure shows only the wire numbers for the smallest channel of the chosen cluster (it's incremented only once per event). Though it's not shown here, I also looked at the spectrum for wires with the smallest drift times and it compares very well with figure 2. Finally, also not shown here is the equivalent of Figure 1 for Run 2595 and though the shapes are different (different physics) it, too, shows no spikes. So none of these results contain the mysterious spikes. So my summary:

    The wire number histograms in ESPACE show spikes at every 96 channels (the same number of channels in our 1877 TDC's). The spikes deplete roughly 6 channels at lower wire numbers. These spikes are on every wire plane in both arms and were there in June (probably a long-standing "feature"). Poking into ESPACE and writing the wire data directly reveals NO spikes. So what is ESPACE doing??

    FIGURE 1

    FIGURE 2