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Detector Characterisation Group
A. Boston and the Liverpool groupCCLRC Daresbury Laboratory
Characterisation Group
Preliminary report on AGATA detector #1
• Full characterisation of prototype crystal– Detailed source scans– Coincidence measurement
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• Prototype symmetric triple cluster• Ordered from CE• Segmentation scheme 8, 13, 15, 18, 18, 18 mm
90 × 80 mm10º tapering angle
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AGATA data analysis summary
• A number of measurements have been made:• Analogue energy resolution results
– A 370kBq 60Co source was placed near the detector.– An Ortec 671 Spectroscopy amplifier was used with 6us of
shaping to produce energy resolutions.– The count rate was <1000cps.– The core energy resolution was measured to be 2.6 keV.
• Efficiency measurement• Digital electronics
– Energy resolution– Scattering / Addback
• Singles scan• Coincidence scan
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AGATA detector scanning
• Detector scans• MRD26 connector blocks
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AGATA detector measurements
• Performance tests of the AGATA prototype detector.• Fitted with GANIL differential preamplifiers• CWC differential to single ended converters (manufactured
at TU Munich) used to provide single ended signal to electronics.
• GRT4 digital electronics cards
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AGATA cabling scheme
• AGATA detector connected to CWC modules through 7 MRD cable cables.
• 37 BNC > SMA cables connect to GRT4 modules.• The cabling scheme groups segments in rings:
– 1-6 ring 1– 7-12 ring 2 etc.
• The core is channel 37.
12
3 4
65
7
8
9 10
11
12 13
14
15 16
17
18 19
20
21 22
23
24 25
26
27 28
29
30 31
32
33 34
35
36
Front Back
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Digital Pulse Shape Processing
• GRT 4 cards with 80Mhz sampling 14bit dynamic range• The cards now have MWD implemented, courtesy of Ian
Lazarus and Martin Lauer.• Digital CFD is implemented.• Common card time stamping (48bit) is implemented.
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Seg ID Energy Seg ID Energy[keV] [keV]
A1 1 2.40 A4 19 2.69B1 2 1.93 B4 20 1.94C1 3 2.75 C4 21 2.87D1 4 1.98 D4 22 2.59E1 5 2.04 E4 23 2.07F1 6 2.80 F4 24 2.19A2 7 2.73 A5 25 4.08B2 8 2.05 B5 26 2.48C2 9 1.99 C5 27 2.52D2 10 2.73 D5 28 2.61E2 11 2.31 E5 29 1.91F2 12 1.97 F5 30 2.16A3 13 2.17 A6 31 2.04B3 14 2.07 B6 32 2.10C3 15 2.08 C6 33 1.81D3 16 2.09 D6 34 2.24E3 17 1.98 E6 35 1.89F3 18 1.90 F6 36 2.05
AGATA energy resolution results
• Best energy resolution results from AGATA• Segment problems >2.8 keV A5 / C4 / F1
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AGATA energy resolutions
• Summary of best values for energy resolution from AGATA detector.
1 2 3 4 5 6A 2.40 2.73 2.17 2.69 4.08 2.04B 1.93 2.05 2.07 1.94 2.48 2.10C 2.75 1.99 2.08 2.87 2.52 1.81D 1.98 2.73 2.09 2.59 2.61 2.24E 2.04 2.31 1.98 2.07 1.91 1.89F 2.80 1.97 1.90 2.19 2.16 2.05
Rings Sectors
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AGATA energy analogue vs digital
0
1
2
3
4
5
6
0 1 2 3 4 5 6 7
Segment number
En
erg
y r
es [
keV
]
Analogue
Digital
• Typical results -> specifically for sector F.
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Automated Scanning Tables
Liverpool System
• Parker linear positioning table• Pacific scientific stepper motors• 0.3mCi 137Cs/0.2mCi 57Co• 1-2mm collimator• Singles/coincidence system
GSI / CSNSM Orsay
Precise position calibration
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Example traces
• Typical example of from detector for the singles scan measurement
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AGATA Detector Pulse shapes
Arb
itra
ry U
nits 2726
20 21 22
28
32 33 34
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AGATA detector scan
• AGATA singles scan• Intensity map for 662keV interaction on centre contact• 2mm collimator / 2 minutes per position• 0.3mCi 137Cs source• 300Gb of data on SDLT tape
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AGATA singles scan
• Detector response vs depth: 662 keV on core• Any energy on segments
1
23
4
56
7
89
10
1112
13
1415
16
1718
19
2021
22
2324
25
2627
28
2930
31
3233
34
3536
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AGATA singles scan
• Detector response vs depth: 662 keV on core• 662keV energy on segments
1
23
4
56
7
89
10
1112
13
1415
16
1718
19
2021
22
2324
25
2627
28
2930
31
3233
34
3536
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Scattering / Cross talk results
• Multiplicity two scatter plot for AGATA segments (singles scan)
2 (B1) – 27 (C5)34085 counts (695 bkgrd)
3 (C1) – 21 (C4)164556 counts (1235 bkgrd)
7 (A2) – 25 (A5)132227 counts(1124 bkgrd)
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AGATA singles scan : Core risetime results
T30 T60
T90 Centre contact risetime results
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AGATA singles scan – T30 vs depth
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AGATA singles scan – T90 vs depth
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Coincidence measurement
• Sector E has been scanned – singles intensity profile.
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What data was recorded?
• Coincidence data was recorded on three lines and three radii.
• 2mm steps.• The data was recorded to
SDLT tape.
• Position from scanning table and step number• High resolution energy from core and NaIs from Silena ADCs• TAC of Ge core vs NaI firing.• GRT 4 data from 37 channels (512 samples 80Mhz)
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AGATA coincidence
0
34mm44mm53.38mm
66.26mm
83.14mm
100.02mm
118.55mm
80mm
36
8
15
18
13
18
18
3mm Dead layer including Al can
8
21
36
54
72
90
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AGATA coincidence
• Coincidence data has been recorded along 3 lines and 3 radii inside sector E of the detector.
• The data is in rings w.r.t. centre (x,x):– Ring 1 : 28mm radius / 6 hours per position– Ring 2 : 23mm radius / 8 hours per position– Ring 3 : 18mm radius / 10 hour per position
• In lines– Line 1 : 0O 26mm / 12 hours per position– Line 2 : 15O 26mm / 12 hours per position– Line 3 : 30O 26mm / 12 hours per position
• The z depths are:
1st depth = 5 - 7.88mm2nd depth = 14.38 – 17.26mm3rd depth = 27.26 – 30.14mm
4th depth = 44.14 – 47.02mm5th depth = 61.02 – 63.9mm6th depth = 79.55 – 82.43mm
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288keV
374keV
662 keV
• Utilises a multi-leaf collimator to measure six depths simultaneously.
• 2mm injection • 2mm ring collimators• Typical count rates for outer
radii– Singles Ge >60keV : 500 c/s– Coincidence : 50 c/min – True Coincidence : 25 c/hour
Coincidence setup
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Coincidence results
• Coincident response in segment E2 (11) and E4 (23)
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Region of Interest
Ge Energy
NaI
Ene
rgy
374 keV
288
keV
Coincidence results
• Matrix of Ge energy vs Total NaI derived from Silena ADCs
• The region of interest for “true” coincidences is highlighted in red.
• The data was presorted to keep only the data in this region.– This leaves ~ 400Mb of data
per line.
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Coincidence measurements
0
50
100
150
200
250
300
350
400
1 2 3 4 5 6 7 8 9 10 11 12 13
Step number [2mm]
Nu
mb
er
of
tru
e c
oin
cid
en
ce
s
E1
E2
E3
E4
• 18mm radius / 2mm steps over 80O (-10O +70O)• Total distance moved 26mm / 10 hours per position
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Coincidence measurement
• Radial scan : line 1 : 12 hours per position
0
100
200
300
400
500
600
700
800
4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Radius [mm]
Nu
mb
er o
f tr
ue
co
inc
iden
ce
s
E1
E2
E3
E4
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AGATA summary
• The detector has been scanned.• Data is available:
– Singles data 300Gb– Coincidence data
• The detector performance was reasonable. Improvements are possible.
• Detail will be discussed in the detector characterisation group meeting this afternoon.