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GRETA @ ReA12 separator

GRETA @ ReA12 separator. Chris Campbell July 12, 2014. GRETINA Design. 7 modules of 4 crystals each 6 x 6 external segmentation Covers ≈ 1 π steradian solid angle (to cover 4 π will take 30 modules - GRETA).

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GRETA @ ReA12 separator

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  1. GRETA @ ReA12 separator Chris Campbell July 12, 2014

  2. GRETINA Design • 7 modules of 4 crystals each • 6 x 6 external segmentation • Covers ≈ 1πsteradian solid angle (to cover 4π will take 30 modules - GRETA). • Modules can be placed at 58.3º (4), 90º (8), 121º (4), and 148º (5 positions) . • On-line processing gives g-ray energy and position.

  3. Gretina DAQ (I) Each of the 28 crystals has: Separate VME backplane and IOC Slow control in EPICS Reads & timesorts digitizer data Passes data to compute cluster 4 LBNL Digitizer Modules 10 channels (9 segments + core) 1 Flash ADC / ch, 14bit 100MHz On-board FPGA filters Leading Edge (trigger primitive) Energy (trapezoid) Pole-zero correction Baseline Restoration Event data includes: Timestamp Filter data Waveform subset

  4. Gretina DAQ (II): Computing Data from GRETINA Detectors 37 segments per detector Segment events Crystal Event Builder Crystal events Signal Decomposition Interaction points 1-28 crystals Data from Auxiliary Detectors Global Event Builder Global Events This is where “events” may be defined! Tracking 60 nodes 2 cpu / node 4 core / cpu Specification: Processing 20,000 Gamma rays /sec Analysis & Archiving

  5. 92Mo case: energy resolution in GT is much better at 2 MeV GS sort using side channels Simple GS root sort FWHM in GT at 2 MeV is ~7.8 keV Double gated spectra (GT not full statistics) 12C(84Kr[394MeV],4n)92Mo v/c ~8.5% (4.7 MeV/u)

  6. (Find) GRETINA in S3

  7. GRETINA timing GRETINA leading edge timing This timing quality is available asprompt signal (~200 ns latency) fora trigger logic. GRETINA ‘t0’ timing: This timing quality is available after decomposition, i.e. in thedata analysis. Coincidence with 1.3 MeV γ ray of 60Co source energy energy 600 ns 600 ns

  8. END

  9. GRETINA experiments with fast beams at NSCL γ rays of 28Si at v/c = 0.38 in GRETINA ϴ [rad] in GRETINA energy [keV] (laboratory frame) Doppler-reconstructed gamma-ray spectrum for 3-6 interactions in GRETINA for 28Si • Fragmentation data collected with three 9Be targets: 47, 100, 375 mg/cm2 • Coulex of 36Ar on a 197Au target: 184 mg/cm2 FWHM: 1%

  10. Closed packed configuration Source data collected with all modules in one hemisphere in a close-packed configuration. More crystals are surrounded by other crystals, thus this configuration more closely approximates GRETA. Analysis of this data will improve understanding of the geometry dependence of GRETINA performance. MSU

  11. 36Ar experiment configuration MSU

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