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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.

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3 4

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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

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Segment number

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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

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nits 2726

20 21 22

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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

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AGATA singles scan

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

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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

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3mm Dead layer including Al can

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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

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Step number [2mm]

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• 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

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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.