Main INDEX
Monthly INDEX
PREV
NEXT
User name Breuer
Log entry time 00:27:02 on January 11,2003
Entry number 55574
This entry is a followup to: 55252
keyword=beam-line shielding analysis/result
Effects of beam-line shielding
========================
The data taken at 4500 A on the 12C target with 10 uA of beam before and
after beam-line-shielding installation during the Christmas 2002/03 break
(runs 15290,15291 before, 15351,15353 after shielding)
have been analysed in more detail than the on-line analysis reported in
G0log entry # 55252.
The results found now are much better than initially thought!!
The new more elaborate analysis separates the "background" from the
"good data", i.e., from pions+protons (defined as all events with
all 4 signals above threshold) and removes data taken at periods
when the beam was off.
The results are given below in tables as the shielding factors
for all NA detectors. A few data points are bad due to low statistics
in one of the pre-shielding runs.
We find for the anode current:
- for detectors 12 to 16 the backgrounds have the highest reduction factors
-- between 2.5 and above 3.6 -- consistent with their large area and volume;
these results are also consistent with Pavel's simulations;
- the back detectors have higher shielding factors, consistent with background
coming from downstream and containing charged particles, of
which a significant fraction is stopped/degraded in the first detector
encountered; neutrals would show only a small difference between back
and front detector;
- surprisingly, detectors 1 shows much higher shielding factors than
detectors 2 to 8; again the back detectors have higher shielding factors;
it would be interesting to identify the path of the background from
downstream to detectors #1, while #2 - 8 were already better shielded;
- octant 5, detectors 1-6 or 1-8 appear to violate the front-back rule; the
individual good/background ratios indicate correct signal wiring;
octant 5 is at the bottom of the ferris wheel and would be most affected by
any re-scattering from the Hall-C floor.
- for detectors 1-12 the less than 50 % of the anode currents are from
background events after the beam line shielding has been installed
(not shown in tables; results for the LH2 target will be provided later)
tables:
oct det FL FR BL BR
1 1 1.48 1.52 1.57 1.65
1 2 1.13 1.16 1.19 1.29
1 3 1.13 1.19 1.11 1.30
1 4 1.11 1.11 1.17 1.16
1 5 1.06 1.08 1.11 1.11
1 6 1.08(-3.37) 1.11 1.12 FR data problem
1 7 1.23 1.34 1.36 1.39
1 8 1.50 1.26 1.50 1.39
1 9 1.38 (0.86) 1.66 1.64 FR data problem
1 10 1.55 1.57 1.90 1.88
1 11 2.00 1.98 2.43 2.32
1 12 2.40 2.47 2.96 2.88
1 13 2.89 2.94 3.52 3.56
1 14 3.18 3.28 3.85 3.85
1 15 3.15 3.09 3.69 3.71
1 16 3.05 3.09 3.62 3.54
3 1 1.37 1.39 1.49 1.48
3 2 1.07 1.10 1.12 1.14
3 3 1.06 1.08 1.08 1.16
3 4 1.06 1.06 1.28 1.26
3 5 1.05 1.06 1.02 1.05
3 6 1.10 1.05 1.16 1.12
3 7 1.10 1.08 1.23 1.25
3 8 1.20 1.19 1.40 1.30
3 9 1.34 1.38 1.55 1.59
3 10 1.57 1.58 1.92 1.30
3 11 2.03 2.03 2.53 2.47
3 12 2.42 2.47 3.07 2.98
3 13 2.74 2.64 3.28 3.21
3 14 2.98 3.00 3.64 3.54
3 15 3.23 2.95 3.54 3.50
3 16 2.86 3.02 3.42 3.51
5 1 1.64 1.46 1.51 1.30
5 2 1.27 1.28 1.23 1.19
5 3 1.33 1.34 1.21 1.24
5 4 1.13 1.19 1.00 1.09
5 5 1.18 1.19 1.13 1.12
5 6 1.23 1.26 1.19 1.20
5 7 1.37 1.38 1.36 1.37
5 8 1.45 1.42 1.44 1.48
5 9 1.53 1.49 1.58 1.61
5 10 1.73 1.60 2.21 1.92
5 11 2.15 2.16 2.48 2.32
5 12 2.51 2.45 2.86 2.83
5 13 2.76 2.86 3.24 3.27
5 14 3.09 2.79 3.57 3.51
5 15 3.08 3.09 3.47 3.50
5 16 2.93 2.95 3.36 3.37
7 1 1.35 1.42 1.46 1.65
7 2 1.01 1.03 1.11 1.14
7 3 1.09 1.03 1.09 1.08
7 4 1.12 1.09 1.17 1.17
7 5 1.12 1.07 1.13 1.05
7 6 1.06 1.04 1.12 1.10
7 7 1.11 1.12 1.25 1.23
7 8 1.17 1.18 1.25 1.30
7 9 1.33 1.33 1.54 1.52
7 10 1.49 1.51 1.90 1.81
7 11 1.98 1.97 2.36 2.34
7 12 2.40 2.40 3.03 2.96
7 13 2.75 2.72 3.28 3.35
7 14 3.13 3.17 3.79 3.78
7 15 3.14 3.16 3.65 3.68
7 16 3.09 3.10 3.66 3.59