Detector characterisation

1
Detector characterisation

• Points for discussion
• AGATA prototype 1 scan
• Sharing of experience with detector
• Preliminary results
• Shipment back to cologne
• Data distribution
• Comparison with MGS simulated pulse shapes
• Scanning systems
• CSNSM Orsay
• GSI
• AOB

How well your basis fits your real data
2
AGATA detector scanning

• Detector scans
• MRD26 connector blocks

3
AGATA detector tests Cabling

• A summary of the cabling used in the tests.
• The LVDS cables are 5m long
• The BNC ? SMA cables are 1m long

4
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

5
AGATA cabling scheme

• AGATA detector connected to CWC modules through 7
  MRD cable cables.
• 37 BNC gt 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.

6
AGATA energy resolutions

• Summary of best values for energy resolution from
  AGATA detector.

Rings
Sectors
7
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

Precise position calibration
GSI / CSNSM Orsay
8
Example traces

• Typical example of from detector for the singles
  scan measurement

9
AGATA Detector Pulse shapes
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21
22
27
26
28
Arbitrary Units
34
32
33
10
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

11
AGATA singles scan

• Detector response vs depth 662 keV on core
• 662keV energy on segments

12
AGATA singles scan Core risetime results
T30
T60
Centre contact risetime results 662keV segments
T90
13
AGATA singles scan T30 vs depth
14
AGATA singles scan T90 vs depth
15
Coincidence measurement

• Sector E has been scanned singles intensity
  profile.

16
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 (250 samples 80Mhz)

17
AGATA coincidence
18
AGATA coincidence scan z values
19
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
• 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 - 7.88mm
• 2nd depth 14.38 17.26mm
• 3rd depth 27.26 30.14mm

• 4th depth 44.14 47.02mm
• 5th depth 61.02 63.9mm
• 6th depth 79.55 82.43mm

20
Coincidence setup

• Utilises a multi-leaf collimator to measure six
  depths simultaneously.
• 2mm injection
• 2mm ring collimators
• Typical count rates for outer radii
• Singles Ge gt60keV 500 c/s
• Coincidence 50 c/min
• True Coincidence 25 c/hour

21
Coincidence results

• Coincident response in segment E2 (11) and E4 (23)

22
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.

23
Coincidence measurements

• 28mm radius / 2mm steps over 80O (-10O ? 70O)
• Total distance moved 40mm / 6 hours per position

24
Coincidence measurements

• 18mm radius / 2mm steps over 80O (-10O ? 70O)
• Total distance moved 26mm / 10 hours per position

25
Coincidence measurement

• Radial scan line 1 12 hours per position

26
Coincidence measurement

• Radial scan line 2 12 hours per position

27
AGATA Segment E1
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AGATA Segment E2
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What data was recorded?
30
AGATA E1 real charge
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Pulse shape rise times sector E2
32
Pulse shape rise times sector E1 azimuthal
33
AGATA D1 image charge
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AGATA D1 image charge
35
Image charge magnitude
36
Image charge asymmetry
37
Pulse shape rise times sector E1 radial
38
AGATA Image charge response vs radius
39
Image charge magnitude
40
AGATA detector crystal vertex points
41
AGATA 23mm and 28mm radial scans
42
AGATA electric field simulation
43
AGATA electric field simulation
44
AGATA parameters

• The length 90mm.
• Bias voltages
• The inner bias voltage 4kV for the AGATA
  prototype
• The outer bias voltage 0 kV
• Impurity concentrations
• Minimum impurity concentration 4.3?109cm-3 for
  the capsule tested
• Maximum impurity concentration 1.5?1010cm-3.
• The crystal temperature can be derived from PT100
  measurements 85k
• Spacing, Im not sure of these values and their
  relative importance
• Forward space surrounding default is 2mm
• Backward space surrounding default is 10mm
• Lateral space surrounding default is 2mm
• Pixel lengths are 8 / 13/ 15 / 18 / 18/ 18 mm for
  AGATA
• Distance to cathode is 13mm (hole drill gap)
• Anode radius is 5mm
• Isolant default is 1.0?1010cm-3 and not used, Im
  not sure of the significance of this therefore it
  is not used.

45
AGATA Impurity concentration

• Low 4.3x109cm-3
• High 1.5x1010cm-3

46
Uncertainty in solution to potential
47
AGATA Potential

• 4000V applied to the anode.

48
AGATA Weighting fields

• Segments E1 and E2.