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Feature #1806

Rate analysis based on 7469

Added by Rogers, Chris almost 7 years ago. Updated almost 7 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Start date:
05 January 2016
Due date:
% Done:

100%

Estimated time:

Description

Discussion of rate analysis based on run 7469

#1

Updated by Rogers, Chris almost 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
So:
  • 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.

#2

Updated by Rogers, Chris almost 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.

#3

Updated by Boyd, Steven almost 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.

#4

Updated by Rogers, Chris almost 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.

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