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Analysis of A G A T A coincidence line-scan data

Analysis of A G A T A coincidence line-scan data. M.Dimmock mrd@ns.ph.liv.ac.uk. Overview. Radial coincidence data. Effective segmentation issues. Filtering process - sidescan. Comparison of experimental and theoretical pulse-shapes. Analysis summary. Future scans.

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Analysis of A G A T A coincidence line-scan data

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  1. Analysis of AGATA coincidence line-scan data M.Dimmock mrd@ns.ph.liv.ac.uk

  2. Overview • Radial coincidence data • Effective segmentation issues • Filtering process - sidescan • Comparison of experimental and theoretical pulse-shapes • Analysis summary • Future scans

  3. Experimental data NaI energy (keV) Ge core energy (keV) • 3 radial line-scans, 2mm spacing, 12 hours / position 30o 15o 0o • Gate on 374keV Ge and 288keV NaI energy • Gate on segment energy • Filter bad events

  4. Signal noise • CWC converter box fault - FIXED for Cologne triple cluster experiment • Reduction in noise aides IC and real pulse parameterisation 1 event = 7.84keV (0.78mV) <100 events> = 3.15keV (0.32mV) • pk2pk noise 1 event = 2.77keV (0.27mV) <100 events> = 1.11keV (0.11mV) • RMS noise

  5. Problem ! ! ! E6 E5 E4 E3 E2 E1 • Gating on Ge and NaI energies, when each NaI covers multiple depths, does not work for complex segmentation

  6. Filtering multiple depths • Gate on appropriate rise time distributions to split the pulses • Add back pulses with small chi-squared – future work !!! • Exp seg cross-over: • 0o = ~18mm • 15o = ~18mm • 30o = ~18mm • ~100 events in each super-pulse • MGS seg cross-over: • 0o = 16mm • 15o = 18mm • 30o = 18mm

  7. Cs – 137 Side scan • Uniform 662keV energy response • Segment E3 double peaking • Warping of E-filed lines toward central anode Core response Core response, ring gated 100 90 80 70 60 50 40 30 20 10 0 0 10 20

  8. Side scan Projection • 15.5mm collimation depth: E1 6-16mm, E2 18-34mm • Reduced effective E2 segment volume ~17mm Segment energy gated response E1 E2 E3 E4 E5 E6

  9. 6.0 mm 45.5 mm 28.5 mm 15.5 mm Segment pulses Centre contact pulses

  10. Segment pulses 6.0 mm 45.5 mm 28.5 mm 15.5 mm Centre contact pulses

  11. 15.5 mm 6.0 mm

  12. Centre contact pulses Segment pulses 45.5 mm 28.5 mm

  13. Shift in core T90 minimum due to the size of the electrode.

  14. Analysis Summary • Singles and coincidence data agrees well – offset expected due to multiple scattering • Improvements required for super-pulses with < 100 events – Generation of singles super-pulses to understand singles data close to the core • Superpulses are a promising method for initial parameterisation – This analysis is not possible in real-time PSA – NOISE reduction is crucial

  15. MGS segment pulse shapes will agree well when the lattice orientation is corrected • Results are promising for the generation of a basis data set. • Move to 1mm diameter injection collimator – will help resolve ambiguities at segmentation boundaries

  16. Future Measurements • Plan for 2006: • Coincidence scan each of the 3 symmetric detectors. • Compare results between Liverpool, Orsay and GSI scanning system results • Scan the first asymmetric detector. • All data to be distributed via Orsay.

  17. Changes to Liverpool Scanning system for 2006: • Utilise 12cm long 1mm injection collimator. • First 3 z-depths 1.3mm/back 2.6mm • Unique scintillator ring for each depth • Change 11.1 MBq (70PP cps) @2mm 9cm [50/2] •  70.2MBq 137Cs (40PP cps) [20/1] or •  920MBq 137Cs (420PP cps) [200/10] • Will allow half of the detector to be scanned in coincidence. • Will perform 241Am side scan to determine segmentation boundaries.

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