Lastest Results from Laser Monitoring
Irradiation Studies at H4 2006
ECAL Testbeam Meeting, Rome
28 March 2007
Toyoko Orimoto
Adolf Bornheim, Chris Rogan, Yong Yang
California Institute of Technology
Outline
 Overview of Irradiation Runs at H4
 Transparency correction studies
 Dividing single crystal into 5x5
 Possibility of looking at irradiated neighbors
 Summary
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T. Orimoto - Irradiation Studies at H4
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Irradiation runs at H4 2006
Period
Sept
Nov:
04.06.11.
Nov:
12.11
28 March 2007
Xtal
Hours
Energ
y
Rate
(S6, S2)
 Normal SPS cycle length
168
~12
120
12k, 6k
 Limited maximum rate available due to
SPS problems and H2 priority, 40s SPS
cycle.
148
~15
90
12k, 6k
552
~12
90
12k, 6k
672
~6
90
30k, 13k
128
~10
90
30k, 13k
88
~12
90
60k,
Comments
 Nicolo suggested running at 90 GeV which
yields highest rates at H4.
 Global timing offset by 1 clock cycle  only
2 samples after the maximum. Corrected
for the laser after 35 hours of running.
 High rates available, 40 s SPS cycle
 Additional timing problems (SPS clock
synchronization lost).
T. Orimoto - Irradiation Studies at H4
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Irradiation SM22 XTAL168
Note : Correlated fluctuations in neighboring channels
 Irradiation at the end of the (second) beam period for SM22.
 Rate : ~12k on S6 ~6k on S2 @ 120 GeV
 Significant drop in APD/PN for 168. Some drop in 167, all other neighbors no
obvious change.
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November Irradiation SM06 Xtal 148
Maximum dose rate limited because of SPS problems and priority to H2 for p0 running.
APD/APD_ref
Irradiation of xtal 148 with ~12k on S6, ~6k on S2 @ 90 GeV (rate maximum for H4)
Linearity scan ?
Very small change on xtal 148 (~0.25%) under direct irradiation.
Neighboring xtals show up to ~1%. Note : Xtals 16* are also in the area of linearity scan.
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November Irradiation SM06 Xtal 552
APD/APD_ref
Irradiation of xtal 552 with ~12k on S6, ~6k on S2 @ 90 GeV
Xtal 552 shows even less change (~0.6%), and all its neighbors even less.
Note : Choice of reference APD not optimal  More noise.
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November Irradiation SM06 Xtal 672
APD/APD_ref
Irradiation of xtal 672 with ~30k on S6, ~13k on S2 @ 90 GeV (improved SPS performance)
Xtal 672 shows even less change (~0.1%), two neighbors show significantly more.
All other neighbors show no change
Note : Choice of reference APD optimal  Very little noise.
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November Irradiation SM06 Xtals 128 & 88
Noticed ‘softness’ of xtal 128 in initial irradiation of xtal148  Irradiate it.
APD/APD_ref
Irradiation of xtal 128 with ~30k on S6, ~13k on S2 @ 90 GeV
Noticed ‘softness’ of xtal 108  Next irradiation should be 88.
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C. Rogan
Irradiation - Xtal 168
Hodoscope hits - entire irradiation period of ~12 hours
Beam events
distributed throughout
crystal
Sufficient statistics
to explore variations in
electron response
within crystal
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C. Rogan
Irradiation - Xtal 168
Hodoscope hits - entire irradiation period
 Reconstruct
electron data for 25
different bins
 Generate R-plot
for each bin
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Irradiation - Xtal 168
C. Rogan
Example energy distribution for
R-plot point (central bin)
 ~ .89%
 Each point in R-plot is
derived from an energy
distribution corresponding to
a continuous time interval
Peak is fit and value is
extracted (and error)
Bin centered at -8, -4 (mm)
 Bins further from center
 ~ 1.1%
suffer from less statistics in
given time interval
More difficult to resolve
electron response
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C. Rogan
Irradiation - Xtal 168
R computed with normalized laser and electron responses
 For each time interval an
interpolated laser response is
calculated
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C. Rogan
28 March 2007
Irradiation - Xtal 168
T. Orimoto - Irradiation Studies at H4
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Irradiation - Xtal 168 (5x5)
C. Rogan
-0.30 ±
0.05
1.47 ±
0.02
1.53 ±
0.03
0.93 ±
0.03
1.26 ±
0.05
1.38 ±
0.02
1.64 ±
0.01
1.48 ±
0.01
1.490±
0.01
1.29 ±
0.02
1.53 ±
0.01
1.38 ±
0.01
1.37 ±
0.01
1.47 ±
0.01
1.18 ±
0.02
1.37 ±
0.01
1.40 ±
0.01
1.39 ±
0.01
1.46 ±
0.01
1.36 ±
0.02
1.44 ±
0.03
1.38 ±
0.02
1.41 ±
0.02
1.17 ±
0.02
1.17 ±
0.05
Central bin
fit for R
Mean = 1.373
RMS = 0.1468
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Irradiation - Xtal 168
C. Rogan
Alpha values used to correct electron response
Uncorrected E9
 ~ 1.2%
Corrected E9
 ~ .53%
No intercalibration constants used
Surrounding crystals uncorrected
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Irradiation - Xtal 128 (5x5)
C. Rogan
6.28 ±
0.23
4.71 ±
0.16
-1.21 ±
0.10
-0.35 ±
0.12
1.63 ±
0.17
1.91 ±
0.08
1.92 ±
0.06
1.73 ±
0.05
1.42 ±
0.05
4.42 ±
0.15
1.74 ±
0.05
1.91 ±
0.04
1.55 ±
0.03
1.43 ±
0.04
1.49 ±
0.01
1.71 ±
0.05
1.61 ±
0.03
1.59 ±
0.03
1.96 ±
0.04
0.38 ±
0.07
1.77 ±
0.07
1.73 ±
0.06
2.54 ±
0.06
2.01 ±
0.06
1.20 ±
0.11
Central bin
fit for R
Mean = 1.73
RMS = 0.28
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Irradiation - Xtal 148 (5x5)
C. Rogan
130.6 ±
33.1
42.4 ±
19.6
-7.4 ±
1.7
14.4 ±
6.0
26.1 ±
6.5
9.8 ±
1.3
1.9 ±
0.3
6.3 ±
0.8
39.8 ±
17.4
18.4 ±
7.0
4.1 ±
0.5
2.8 ±
0.3
4.2 ±
0.4
6.2 ±
0.7
13.0 ±
1.6
4.1 ±
0.5
4.1 ±
0.5
3.2 ±
0.3
3.9 ±
0.4
14.7 ±
1.7
5.8 ±
0.8
6.5 ±
0.8
2.5 ±
0.4
4.7 ±
0.6
102.7 ±
26.6
Central bin
fit for R
Mean = 4.671
RMS = 1.933
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Irradiation - Xtal 552 (5x5)
C. Rogan
9.59 ±
0.41
1.09 ±
0.14
1.85 ± 0.15
-1.22 ±
0.18
1.71 ±
0.24
2.36 ±
0.12
1.12 ±
0.06
1.02±
0.06
1.82 ±
0.08
4.55 ±
0.21
0.68 ±
0.08
1.76 ±
0.05
1.50 ±
0.04
1.41 ±
0.05
3.54 ±
0.15
1.39 ±
0.08
1.47 ±
0.04
1.48 ±
0.05
1.55 ±
0.06
3.29 ±
0.15
0.40 ±
0.14
1.20 ±
0.09
1.59 ±
0.09
1.80 ±
0.10
6.22 ±
0.29
Central bin
fit for R
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Mean = 1.431
RMS = 0.437
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Irradiation - Xtal 672 (5x5)
C. Rogan
28.4 ±
8.4
23.1 ±
6.2
6.8 ±
1.8
26.2 ±
8.8
24.6 ±
8.0
6.3 ±
1.3
4.3 ±
0.8
3.1 ±
0.8
5.0 ±
0.9
14.4 ±
3.4
-±-
4.0 ±
0.7
2.9 ±
0.5
2.4 ±
0.5
24.5 ±
6.8
5.4 ±
1.2
2.2 ±
0.4
4.2 ±
0.7
4.3 ±
0.8
4.6 ±
1.2
-10.4 ±
2.8
4.6 ±
0.9
4.4 ±
1.0
11.8 ±
2.9
36.0 ±
8.9
Central bin
fit for R
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Mean = 4.295
RMS = 1.274
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C. Rogan
Irradiation - neighboring crystals
Example hodoscope profile
for run (Xtal 128)
Studying possibility of
extracting R-values from
neighboring crystals using
hits in those crystals…
However, much lower
statistics
Possible by examining
shower response in
neighbors from central
xtal hits?
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Conclusion
 6 crystals have been irradiated for extended periods at H4 TB in 2006,
most with limited rate.
 3 out of 6 crystals (168, 128, 552) showed clear transparency change. 2
showed little and one almost no change. (148, 672)
 Several neighbor crystals showed clear transparency change. We are
studying how to extract R values from that.
 Transparency corrections and performance after transparency
corrections are under study.
 Begin estimating the systematic uncertainties of the transparency
correction.
 Some limited studies on other aspects of the crystals can be studies, eg.
recovery times, radiation hardness, etc.
 We strongly recommend more irradiation studies, perhaps during
testbeam for endcaps
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Back up Slides
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Irradiation Runs at H4
 September Irradiation :
 Xtal 168 of SM22: ~12 hours, rates ~12k on S6, ~6k on S2 @ 120 GeV, normal
SPS cycle length
 November Irradiation : Many issues due to problems with timing
04.-06.11. :
Limited maximum rate available due to SPS problems and H2 priority, 40s SPS cycle.
Nicolo suggested running at 90 GeV which yields highest rates at H4.
Global timing offset by 1 clock cycle  only 2 samples after the maximum.
Corrected for the laser after 35 hours of running.
 Xtal 148 on SM06 : ~15 hours, ~12k on S6, ~6k on S2
 Xtal 552 on SM06 : ~12 hours, ~12k on S6, ~6k on S2, beam unstable
 Xtal 672 on SM06 : ~6 hours, ~30k on S6, ~13k on S2
 Xtal 128 on SM06 : ~10 hours, ~30k on S6, ~13k on S2
12.11. :
High rates available, 40s SPS cycle, 90 GeV , additional timing problems in H4 (SPS
clock synchronization lost).
 Xtal 88 on SM06 : ~12 hours, ~60k on S6
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T. Orimoto - Irradiation Studies at H4
Next slides : Lots of Scatter plots !
23
APD/PN
APD/APD_ref
APD/APD_ref vs APD/PN
APD/PN
APD/APD_ref
Effect is small on the first period of the November data, larger later after
clock synchronisation loss.
During long term follow up there might also be other incidents (eg.
cooling interlock at ~3925 hours).
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APD/APD_ref
APD/APD_ref
November Irradiation
 More soft neighbors in the area of
xtals 148, 128 and 88.
Xtal 87
 Note : Odd behavior of xtal 87 before
irradiation.
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Transparency Change Correction – Xtal 168
Correction R computed using 1x1
electron response
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Resolution after correction: SM22 168
28 March 2007
SM
Crystal
R
Res before
Res after
22
168
1.41 ± 0.01
0.93%
0.53%
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Transparency Change Correction – Xtal 552
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Resolution after correction: SM06 552
28 March 2007
SM
Crystal
R
Res before
Res after
06
552
1.54 ± 0.05
0.82%
0.77%
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Transparency Change Correction – Xtal 672
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Resolution after correction: SM06 672
28 March 2007
SM
Crystal
R
Res before
Res after
06
672
0.99 ± 0.08
0.69%
0.67%
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Transparency Change Correction – Xtal 128
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Resolution after correction: SM06 128
28 March 2007
SM
Crystal
R
Res before
Res after
06
128
1.82 ± 0.04
0.83%
0.68%
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R values from 5x5 of 168 and 128
168
Mean = 1.373
RMS = 0.1468
28 March 2007
128
Mean = 1.73
RMS = 0.2806
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Relative electron response
C. Rogan
Irradiation - Xtal 168 (center)
Relative Laser Response
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Irradiation - Xtal 168 (5x5)
C. Rogan
-0.30 ±
0.05
1.47 ±
0.02
1.53 ±
0.03
0.93 ±
0.03
1.26 ±
0.05
1.38 ±
0.02
1.64 ±
0.01
1.48 ±
0.01
1.490±
0.01
1.29 ±
0.02
1.53 ±
0.01
1.38 ±
0.01
1.37 ±
0.01
1.47 ±
0.01
1.18 ±
0.02
1.37 ±
0.01
1.40 ±
0.01
1.39 ±
0.01
1.46 ±
0.01
1.36 ±
0.02
1.44 ±
0.03
1.38 ±
0.02
1.41 ±
0.02
1.17 ±
0.02
1.17 ±
0.05
28 March 2007
Mean = 1.373
RMS = 0.1468
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Irradiation - Xtal 128
C. Rogan
Alpha values used to correct electron response
Uncorrected E9
 ~ .82%
Corrected E9
 ~ .67%
No intercalibration constants used
Surrounding crystals uncorrected
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Irradiation - Xtal 128 (5x5)
C. Rogan
6.28 ±
0.23
4.71 ±
0.16
-1.21 ±
0.10
-0.35 ±
0.12
1.63 ±
0.17
1.91 ±
0.08
1.92 ±
0.06
1.73 ±
0.05
1.42 ±
0.05
4.42 ±
0.15
1.74 ±
0.05
1.91 ±
0.04
1.55 ±
0.03
1.43 ±
0.04
1.49 ±
0.01
1.71 ±
0.05
1.61 ±
0.03
1.59 ±
0.03
1.96 ±
0.04
0.38 ±
0.07
1.77 ±
0.07
1.73 ±
0.06
2.54 ±
0.06
2.01 ±
0.06
1.20 ±
0.11
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T. Orimoto - Irradiation Studies at H4
Mean = 1.73
RMS = 0.28
38
Relative electron response
C. Rogan
Irradiation - Xtal 128 (center)
Relative Laser Response
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Laser Light Loss – Electron Signal Loss
# Crystals
Dispersion of  for 28 BTCP crystals
signal from Beam (e-)
slopea:
 = 1.55
2002
2003
2004
a
(fall)
2004 (spring)
/mean  5%
on a ~5% correction due
to the effect of irradiation
signal from Laser

 Coefficient for crystals have relatively small dispersion.
 At startup use same parameters for all crystals from one producer.
An in-situ determination of  is under consideration.
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