GRETA The GammaRay Energy Tracking Array

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GRETAThe Gamma-Ray Energy Tracking Array

• I-Yang Lee
• Lawrence Berkeley National Laboratory

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Outline

• Physics opportunities
• GRETA white paper
• Examples in plenary talks of
• Augusto Macchiavelli
• Thomas Glasmacher
• Technical accomplishments
• Cost and schedule
• Management structure
• Auxiliary detectors
• Demetrios Sarantites

GRETA White paper
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Principle and advantages of g-ray tracking

• Efficiency Proper summing of scattered gamma
  rays, no solid angle lost to suppressors
• Peak-to-background Reject Compton events
• Doppler correction - Position of 1st interaction
• Polarization Angular distribution of the 1st
  scattering
• Counting rate - Many segments

3D position sensitive Ge detector
Resolve position and energy of interaction points
Determine scattering sequence
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Technical Challenges and achievements
We have all the technology on hand

• Advances in Ge detector production
• Segmentation size 2 cm ? 30-40 segment/crystal
• Closely pack irregular tapered hexagon shape
• Fast electronics
• ADC with 10 nsec sampling rate, gt 12 bit
  resolution
• Efficient algorithms
• Signal analysis position resolution 2 mm
• Tracking multiple gamma rays
• Computing power
• Cluster with 200 computer to process 20,000 ?/sec

G. J. Schmid et al., Nucl. Instrum. Methods Phys.
Res. A430, 69 (1999). K. Vetter et al., Nucl.
Instrum. Methods Phys. Res. A452, 105 (2000). K.
Vetter et al., Nucl. Instrum. Methods Phys. Res.
A452, 223 (2000). M. Descovich et al., Nucl.
Instrum. Methods Phys. Res. B241, 931 (2005). M.
Descovich et al., Nucl. Instrum. Methods Phys.
Res. A545, 199 (2005). M. Descovich et al., Nucl.
Instrum. Methods Phys. Res. A553, 535 (2005).
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GRETINA is under construction
Cover ¼ of full solid angle Seven 4-cyrstal
detector modules All the required software On
schedule and on budget No technical problem

• Critical Decisions
• CD0 Mission need Aug. 2003
• CD1 Preliminary Baseline Range Feb. 2004
• CD2A/CD3A Start Construction
• long lead time items (Ge) June 2005
• CD2B/CD3B Start Construction July 2007
• CD4 Start of Operation Sept. 2010

CD0 Approve mission need CD1 Approve
preliminary baseline range CD2 Approve
performance baseline range CD3 Approve start of
construction CD4 Approve start of operation
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GRETINA Status
The first 4-crystal production detector received
2006
Mechanical design completed 2006
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GRETINA Status
Prototype computer farm assembled 2006
Eight nodes 2GHz CPU 2Gbyte memory each LINUX
2 Tbyte disk storage
Mark III digitizer board produced 2007

• 100 MHz sampling rate
• 14 bit resolution
• 10 channels per board
• On board processing

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GRETINA Status
In-beam test carried out at 88 LBNL 2005
3-crystal prototype 82Se 12C _at_ 385 MeV 90Zr
nuclei (v/c 0.09) 2055 keV (10?8) in
90Zr 0.75 Tbyte of data
End-to-end analysis of in-beam data 2006
Signal decomposition - use realistic basis
signal Tracking Position resolution of 2.1 mm
(RMS) in all three dimensions
?
? 12 keV FWHM
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GRETINA Status
In-beam test carried out at NSCL MSU 2006
3-crystal prototype In coincidence with S800 -
use time stamps 36Ar Be _at_ 86 MeV/A v/c 0.4
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28Si
Data are being analyzed
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E g (keV)
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From GRETINA to GRETA

• GRETA will improve the power of GRETINA by
  Factors of 10 100.
• GRETA is the most requested instrument at the
  next generation
• radioactive beam facility
• RIA Facility Workshop. East Lansing,
  Michigan, March 9-13, 2004

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GRETA Cost and Schedule
Start FY08, complete FY16
Physics Starts ?

• As fast as allowed by detector production
  schedule.
• No gap between GRETINA and GRETA
• Physics program to start 2008 with continue
  growth of capabilities.
• Match RIA schedule, ready when RIA starts
• Competing European project AGATA plan to be
  completed in 2016

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GRETINA management structure

• Working Groups and chairs
• Physics M. A. Riley   
• Detector A. O. Macchiavelli
• Electronics D. C. Radford
• Software M. Cromaz 
• Auxiliary Detectors D.G. Sarantites

Management Advisory Committee James
Symons (LBNL) Glenn Young (ORNL) Don Geesaman
(ANL) Konrad Gelbke (MSU)
Project manager I-Yang Lee (LBNL)
Advisory Committee Con
Beausang, University of Richmond Doug Cline,
University of Rochester Thomas Glasmacher,
Michigan State University C. Kim Lister, Argonne
National Laboratory Augusto Macchiavelli,
Lawrence Berkeley Laboratory David Radford
(Chair), Oak Ridge National Laboratory Mark
Riley, Florida State University Demetrios
Sarantites, Washington University Kai Vetter,
Lawrence Livermore National Laboratory/UC Berkeley
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Summary
2002 Long Range Plan

• The detection of gamma-ray emissions from
  excited nuclei plays a vital and ubiquitous role
  in nuclear science. The physics justification for
  a 4p tracking array is extremely compelling,
  spanning a wide range of fundamental questions in
  nuclear structure, nuclear astrophysics, and weak
  interactions. This new array would be a national
  resource that could be used at several existing
  stable and radioactive beam facilities, as well
  as at RIA.

With GRETINA now under construction we are
moving towards this goal. We strongly urge the
timely completion of the full 4p system GRETA.