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Laura Nelson, The University of Liverpool ln@ns.ph.liv.ac.uk

Scanning of the First AGATA Symmetric Prototype Detector at Liverpool and the Detector’s Azimuthal Response. Acknowledgements: M.R. Dimmock a , A.J. Boston a , H.C. Boston a , J.R. Cresswell a , P.J. Nolan a , I. Lazarus b , J. Simpson b , P. Medina c , C. Santos c , C. Parisel c .

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Laura Nelson, The University of Liverpool ln@ns.ph.liv.ac.uk

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  1. Scanning of the First AGATA Symmetric Prototype Detector at Liverpool and the Detector’s Azimuthal Response Acknowledgements: M.R. Dimmocka, A.J. Bostona, H.C. Bostona, J.R. Cresswella, P.J. Nolana, I. Lazarusb, J. Simpsonb, P. Medinac, C. Santosc, C. Pariselc. a Oliver Lodge Laboratory, The University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK. bCCLRC Daresbury Laboratory, Warrington WA4 4AD, UK. c Institut de Recherches Subatomiques, Strasbourg BP28 67037, France Laura Nelson, The University of Liverpool ln@ns.ph.liv.ac.uk

  2. 24 30 36 6 12 25 29 31 35 18 1 5 7 11 13 17 19 23 2 4 8 10 14 16 20 22 26 28 32 34 3 9 15 21 27 33 Physical & Electrical Details Labelling scheme adopted for ease of programming; Physical segmentation: Sectors labelled A-F (anticlockwise) Rings labelled 1-6 (bottom-top) • +4000V, ±12V supplied using NIM modules • Differential signals -> single ended using CWC converter boxes • GRT4 digitiser cards sample over ±1V using 80MHz FADCs • Each of the 37 channels provides 250 samples of data for each event • External CFD on central contact triggers the cards • No global clock Scans performed: • Front face singles scan • Tapered side singles scan • Front face coincidence scan of 1 sector (E) 1

  3. Front Face Singles Scans • 11.1MBq Cs-137 source (E = 662keV) • Cartesian grid in 2mm steps • 2 minutes per position • Injection collimator: 2mm diameter, 80mm long • CFD threshold on central contact of 650keV • ~500 counts per second (core) • Data reduced to ~30% using active geometric zero suppression z Incident photons Intensity of counts as a function of position Energy Gate 646keV->699keV (applied to the central contact) No Energy Gate y y x x

  4. Intensity Plots Intensity of counts as a function of position for each ring of segments. Energy gate (646keV->699keV) applied to both electrodes

  5. T90 Polar Plots Outer Contact Central Contact Core and segment energy gate 640->677keV Counts threshold >300 in the segment Core energy gate 640->677keV Counts threshold >1600 in the ring

  6. T30 Polar Plots Outer Contact Central Contact Core and segment energy gate 640->677keV Counts threshold >300 in the segment Core energy gate 640->677keV Counts threshold >1600 in the ring

  7. NaI Energy Region of Interest 288 keV 374 keV Ge Energy Front Face Coincidence Scans • System triggered on any of the 8 NaIs AND the correct energy (~374keV) on the Ge central contact • 11.1MBq Cs-137 source (E = 662keV) • Injection collimator: 2mm diameter, 80mm long 3d interaction position information for 6 depths

  8. 3 2 4 1 5 6 Coincidence Scanning 1 – 18mm radius, 10 hrs per position 2 – 23mm radius, 8 hrs per position 3 – 28mm radius, 6 hrs per position 4 – 30, 12 hrs per position 5 – 15, 12 hrs per position 6 – 0, 12 hrs per position Statistics: At 18mm radius Front: 50c/h Back: 1.5c/h Collimation gap centred on (w.r.t. crystal base): Physical segmentation depth: 90mm 81.15mm 72mm 62.5mm 54mm 45.6mm 36mm 3mm 28.5mm 21mm 15.5mm 8mm 6mm 0mm

  9. Azimuthal Geometry of Outer Contacts 3 2 4 1 5 6

  10. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV

  11. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV Hitsegment pulse shows decaying preamp

  12. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV Preamp decay correction

  13. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV Preamp decay correction 100 events

  14. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV Preamp decay correction 100 events Time alignment

  15. Coincidence Analysis R.M.S. noise ~7keV P2P noise ~10keV Preamp decay correction 100 events Sum 100 events R.M.S. noise ~1.8keV P2P noise ~2.5keV Time alignment

  16. Transients F1 A1 Transient charges produced in segments either side of that containing the FEE (segment E1) for each azimuthal angle of the r=28mm scan E1 B1 D1 Z = 6mm C1 Image in Segment D1 Image in Segment F1

  17. Transient Magnitudes FEE in Segment 5 Z = 6mm FEE in Segment 11 Z = 15.5mm FEE in Segment 17 Z = 28.5mm

  18. Outer Contact Risetimes – 1st depth Z = 6mm T90 Polar Plot

  19. Central Contact Risetimes – 1st depth Z = 6mm T90 Polar Plot

  20. Outer Contact Risetimes – 2nd depth Z = 15.5mm T90 Polar Plot T90

  21. Central Contact Risetimes – 2nd depth Z = 15.5mm T90 Polar Plot T90

  22. Outer Contact Risetimes – 6th depth Z = 81.5mm T90 Polar Plot

  23. Central Contact Risetimes – 6th depth Z = 81.5mm T90 Polar Plot

  24. MGS Simulation Results Z=14mm Z=8->21mm

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