This is a compilation of links describing the detector performance.
- The phi distributions of 4-hit stubs found in even half-cells and 2-hit triggers
are displayed in these plots. As may perhaps
be expected the rate is higher in the West than the East.
- Most of our stubs are from the rear of the chambers. We use time division
on cells ganged at the front (interaction point end) and read out at the rear.
The distribution of time differences shows
very clearly that most of the hits are in the rear. This also shows that there
are discoverable channel-to-channel variations in t0.
- I used this root command file to generate the
efficiency plots for the BSU paddles. As you can
see most of the efficiencies vary between .7 and .9 when I require that the
track be good and lie in the half-cell matching the center of the BSU.
When I cut on the time
difference between matching cells to try to select hits from the front part of
the detector I lose statistics and have to rely on the front BSU paddles.
I do not get satisfactory statistics that way.
- Bob's work suggests that we currently get efficiencies of 88% in cells 0
and 3, and 97% in cells 1 and 2. Geometric efficiencies for 4-hit stubs are
of the order of 20% for odd half-cells. Even half-cells are entirely within
a single stack.
- The t0 found from the stub fit
agrees nicely with the time of the scintillator hit. There is a time
offset of course, but the rms is not very large, and undoubtedly has a
cell-dependent t0 variation component.
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