Feature #1806
Rate analysis based on 7469
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Description
Discussion of rate analysis based on run 7469
Updated by Rogers, Chris over 7 years ago
I reran with the first half of the data set only; the decay solenoid may have gone off towards the end of the run. I am trying to include some study of detector efficiencies, which I believe will get fixed. So, number of events for first HALF of run 7469:
n_events | requirement |
12668 | tku has at least 1 track; tof0 has 1 exactly space point; tof1 has exactly 1 space point |
15676 | tof0 has 1 exactly space point; tof1 has exactly 1 space point |
10995 | tku has exactly 1 track formed by 5 space points; tof0 has exactly 1 space point; tof1 has exactly 1 space point |
15631 | tku has exactly 1 track formed by 5 space points; tof1 has exactly 1 space point |
21456 | tku has at least 4 space points; tof1 has exactly 1 space point |
12819 | tku has at least 1 track; tof0 has at least 1 space point; tof1 has exactly1 space point |
- lines 1 and 2 tell us that the (tku track finding efficiency)*(transmission to tku) is about 12668/15676, tr_eff
- lines 3 and 4 tell us that the (tof0 space point efficiency) is about 10995/15631, tof0_eff
- line 5 is a reasonable guess at the number of actual particle tracks entering tku n_tracks
- line 6 is the number of usable (successfully reconstructed) particle tracks in upstream region n_recon
- assuming that the tracker efficiency is dominated by overzealous PR cuts, then we expect tr_eff*tof0_eff*n_tracks = n_recon
- 12668/15676*10995/15631*21456 = 12196 (approx ~ 12819)
This looks like a self-consistent picture of efficiencies and rates. I think it is reasonable to assume that the detector efficiency issues will be resolved, so one can assume 21456 particles entering the detector during the first half of 7469.
Updated by Rogers, Chris over 7 years ago
I ran with the full dataset for run 4769
n_events | requirement |
23665 | tku has at least 1 track; tof0 has at least 1 space point; tof1 has exactly1 space point |
Compare with 12819*2 (same thing but only first half, *2) and we get 92 % of the rate for full run as compared to first half. Might be worth checking for ISIS downtime also, although I don't think it was logged.
Updated by Boyd, Steven over 7 years ago
So - very roughly then - the observed rate in 7469 is about 23665*0.92 for 69 minutes of running, or about 19k / hour. At the same time the effect of moving from 800 to 700 MeV is (very very roughly and based on extrapolating some p+Be data to p+Ti and integrating in my head...ha - I would need to integrate the Sanford-Wang production double differential cross section and frankly can't be bothered at the moment) a reduction in rate of about 30% which means that the observed rate should be around : tr_eff*tof0_eff*(15/19)*0.7 = 0.30 times that of the STEP I estimate. That's roughly what we are seeing I think. The STEP I estimate was about 6900 muons / hour. If we apply all the inefficiencies we would expect to see 6900 * tr_eff * tof0_eff * 0.7 = 2700 muons / hour, which is not too far from the 19k * 0.12 (to select analysable muons) = 2300 muons / hour.
Updated by Rogers, Chris over 7 years ago
- Status changed from Open to Closed
- Assignee set to Rogers, Chris
- % Done changed from 0 to 100
Good. So I think this means the rate is consistent with Step I and understood, more or less, for run 7469 at least? I will close the issue.