GRETA @ ReA12 separator Chris Campbell July 12, 2014.

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GRETA @ ReA12 separator Chris Campbell July 12, 2014

Transcript of GRETA @ ReA12 separator Chris Campbell July 12, 2014.

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

GRETA @ ReA12 separator

Chris CampbellJuly 12, 2014

Page 2: GRETA @ ReA12 separator Chris Campbell July 12, 2014.

GRETINA Design• 7 modules of 4 crystals each • 6 x 6 external segmentation• Covers ≈ 1π steradian 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.

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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

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Gretina DAQ (II): Computing

Crystal Event Builder

Segment events

Crystal events

Signal Decomposition

Interaction points

Global Event Builder

Tracking

37 segmentsper detector

1-28 crystals

Global Events

Data fromAuxiliaryDetectors

Analysis & Archiving

Data fromGRETINADetectors

Specification:

Processing 20,000Gamma rays /sec

60 nodes 2 cpu / node 4 core / cpu

This is where “events” may be defined!

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92Mo case: energy resolution in GT is much better at 2 MeV

FWHM inGT at 2 MeVis ~7.8 keV

Simple GS root sort GS sort using side channels

Double gated spectra (GT not full statistics)

12C(84Kr[394MeV],4n)92Mo v/c ~8.5% (4.7 MeV/u)

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(Find) GRETINA in S3

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GRETINA timing

600 ns600 ns

GRETINA leading edge timingThis 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 rayof 60Co source

ener

gy

ener

gy

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GRETINA experiments with fast beams at NSCL

ϴ [r

ad] i

n G

RETI

NA

energy [keV] (laboratory frame)

Doppler-reconstructed gamma-ray spectrumfor 3-6 interactions in GRETINA for 28Si

γ rays of 28Si at v/c = 0.38 inGRETINA

FWHM: 1%

• Fragmentation data collected with three 9Be targets: 47, 100, 375 mg/cm2

• Coulex of 36Ar on a 197Au target: 184 mg/cm2

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MSU 25

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.

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MSU 26

36Ar experiment configuration