GRETINA

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GRETINA

• I-Yang Lee
• Lawrence Berkeley National Laboratory
• NSD Director's Review 2009
• May 11 - 13, 2009

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Outline

• Gamma-ray tracking principles
• Impact on science
• Status
• Schedule and plans

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Principles and advantages of g-ray tracking

• Efficiency (50) Proper summing of scattered
  gamma rays, no solid angle lost to suppressors
• Peak-to-background (0.6) Reject Compton events
• Position resolution (2 mm)
• Polarization Angular distribution of the 1st
  scattering
• Counting rate (100 kHz/xtal) - Many segments

3D position sensitive Ge detector
Resolve position and energy of interaction points
Determine scattering sequence
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Evolution of g-ray detectors
A 4p tracking array will provide 102 103 fold
increase in resolution power
Resolving power is a measure of the ability to
observe faint emissions from rare and exotic
nuclear states.
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Strong world wide support
The science case for a gamma-ray tracking
detector has strong support both in US and
Europe.
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.

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Physics questions

• What is the nature of the nuclear force that
  binds proton and neutrons into stable nuclei and
  rare isotopes?
• What is the origin of simple patterns in complex
  nuclei?
• What is the origin of the elements in the cosmos?
• What are the nuclear reactions that drive stars
  and stellar explosions?

Four of the five nuclear structure questions in
the 2007 Long Range Plan
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New shell structure
One nucleon transfer reactions radioactive
beams low intensity high background GRETA
advantage efficiency peak-to-background
How does structure evolve at extremely large
neutron number?
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New shell structure
Nucleon knock out reactions radioactive
beams high velocity high background GRETA
advantage Doppler correction efficiency peak-to
-background
Wave functions from knock out reactions
GRETA Simulation
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Shape changes
Deep inelastic reactions many reaction
channels low cross sections high background
two-body final state GRETA advantage Doppler
correction efficiency
What drives changes in collectivity?
Gammasphere CHICO 1n transfer
GRETA SuperCHICO 6n transfer
Critical point description
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Structure of heaviest nuclei
Fusion reactions low cross sections high
fission background GRETA advantage efficiency
high counting rate

• What are the heaviest magic numbers?
• How do the fission barriers change
• with spin?

GS FMA
GRETA BGS
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Extreme spin and deformation
Can hyperdeformed nuclei exist?
Fusion reactions low cross sections high g-ray
multiplicity GRETA advantage efficiency peak
-to-background
Woods Saxon Potential
Single Particle Levels (MeV)
?
ND SD HD
Quadrupole Deformation
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GRETINA
Cover ¼ of 4p solid angle Seven 4-crystal
detector modules All the required software

• Critical Decisions
• CD0 Mission need August 2003
• CD1 Preliminary Baseline Range February
  2004
• CD2A/CD3A Start Construction
• long lead time items (Ge) June 2005
• CD2B/CD3B Start Construction October 2007
• CD4 Start of Operation February 2011

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Mechanical structure
Quarter sphere shell
Axle bearings Rotation Axle gear set
Flange Wedge plate - under and
attached to detector flange
All parts ready
Preamp housing
Detector module Cap LN dewar
Railroad car
Hexapod
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Detector modules
Two received
A-type
36 segments/crystal 4 crystal/ module 148
signal channels /module
B-type
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Electronics production
All modules produced
Trigger Timing Control module (ANL) Fast
trigger (lt300 nsec) Trigger conditions
Multiplicity Sum energy Hit pattern
Digitizer module (LBNL) 14bit, 100
MHz Energy Leading edge time Constant fraction
time Pulse shape
Developed with LDRD funds
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Data processing
37 segments per detector
Data from GRETINA Detectors
Segment events
Crystal Event Builder
Crystal events
Signal Decomposition
Interaction points
1-28 crystals
Data from Auxiliary Detectors
Global Event Builder
Global Events
70 nodes 2 cpu / node 4 core / cpu
Tracking
Goal Processing 20,000 Gamma rays /sec
Analysis Archiving
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Pencil beam results
Using the latest decomposition algorithm and
basis, we have achieved lt2 mm (RMS) resolution
x
y
z
z
1 mm diameter pencil beam of 662 keV, in crystal
A1 of module Q1
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System Assembly

• Infrastructure available at the 88 Cyclotron to
  start assembly
• Staff experienced in the assembly of similar
  systems (GAMMASPHERE).
• Preparations in Cave 4C already underway.

Base plates
One of the axles
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GRETINA schedule
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GRETINA at the 88-Inch
At completion (2/14/2011), GRETINA will be at
CAVE 4C
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Engineering runs
From the CD2B/3B review and the Richmond Meeting
- Oct. 14-15, 2007

• Source and In-Beam tests of GRETINA
• Further tests, debugging and characterization in
  battle conditions
• Initial Optimization
• 3-4 months following CD4 ( March June 2011)
• Strong participation from the community
• (3-4 FTEs of redirected scientific effort)

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Commissioning Runs
From the Richmond Meeting - Oct. 14-15,
2007 GRETINA at BGS Structure of heavy elements

• Move to Cave 1 - July 2011 (1 month)
• Community and GAC will help develop the
  experimental program, review by NSD - August -
  November 2011 (4 months)
• Move to NSCL/MSU - December 2011

These are all tentative date Uncertainties in
project schedule DOE yet to approve this plan
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Installation sites
LBNL Cave 4C
ANL FMA
NSCL S800
ORNL RMS
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GRETINA at BGS
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Collaborating Institutions
LBNL is the lead laboratory of GRETINA

• Argonne National Laboratory
• Trigger system
• Calibration and online monitoring software
• Michigan State University
• Detector testing
• Oak Ridge National Laboratory
• Liquid nitrogen supply system
• Data processing software
• Washington University
• Target chamber

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Collaborators

• Mechanical Steve Virostek,
• Tim Loew, Derek Shuman, David C. Radford,
  Demetrios Sarantites
• Detector - Augusto Macchiavelli
• Sebastien Gros, Thomas Glasmacher, Stefanos
  Paschalis, Dirk Weisshaar
• Electronics- Sergio Zimmermann
• Dionisio Doering, John Joseph, Kim Lister, John
  Anderson
• Computing - Carl Lionberger
• Mario Cromaz, Paul Fallon, David C. Radford,
  Karin Lagergren, Torben Lauritsen

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2007 Long Range plan
Supports the construction of the 4p array GRETA
Gamma-Ray Tracking Gamma-ray detector arrays
with high efficiency and high resolution have had
a major impact on our understanding of nuclear
structure over the past decade. But
conventional arrays do not maintain their power
when the particles undergoing decay move at high
speeds. Now a new technology that allows for
tracking of gamma rays promises to make the same
high resolution, and even higher efficiency,
possible for fast particles. A 1p detector array,
GRETINA, is being built based on this new
technology, and its first element has verified
that the device will work as planned. The
implementation of a 4p gamma-ray tracking
detector, GRETA, will revolutionize gamma-ray
spectroscopy and provide sensitivity improvements
of several orders of magnitude. Thus the
construction of GRETA should begin upon
successful completion of GRETINA. This gamma-ray
energy tracking array will enable full
exploitation of compelling science opportunities
in nuclear structure, nuclear astrophysics, and
weak interactions.
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Summary

• GRETINA will have a major impact on nuclear
  physics.
• GRETINA construction is on time and within budget
  with a completion date of 2/14/2011.
• A tentative schedule for engineering runs,
  commissioning runs, and initial siting is in
  place.
• The 4? array GRETA received strong community
  support in the 2007 Long Range Plan.