Etude de bruit de fond induit par les muons dans l'expérience ...

tel-00724955, version 1 - 23 Aug 2012
6
122 Analysis of Run 10
rate (event / 8 hr file)
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
15/07
2008
84.3 d
all data
without the overflow
29/07
2008
12/08
2008
26/08
2008
09/09
2008
23/09
2008
all data
07/10
2008
21/10
2008
rate (event / 8 hr file)
Figure 6.2: Rate of the muon veto per 8-hour file when the veto is closed, see text
for details. The rate is shown over time (left) and as a histogram (right) with a
Gaussian fit. The points with a much smaller rate are from files less than 8-hours
long. In lighter shade is the rate without the very high energy events. The mean of
the Gaussian fit is 0.161 Hz (calculated rate from data is also 0.161 Hz).
t t10µs (10 µs)
10µs (10 µs)
1000
800
600
400
200
x10 9
0 200
400 600 800 1000 1200
event number
events per 25 ms
x10 3
per 0.8 ms
04/11
2008
18/11
2008
(s)
∆t veto (s)
Figure 6.3: Left: Timeline of the veto events during Run 10, with the condition
of having a time difference of consecutive events lower than 600 s. The timeline is
broken twice when the muon veto DAQ was stopped, due to the installation of the
neutron counter, see also Figure 6.2. Right: Time difference of consecutive muon
veto events in log scale up to 10 s and zoomed over the first four 25 ms. At −0.25 s
are plotted ∆tveto > 600 s, at −0.75 s are plotted ∆tveto < 0 s.