Overview of GRETINA Status

1
Overview of GRETINA Status

• I-Yang Lee
• Lawrence Berkeley National Laboratory
• The AGATA Week, 21-25th February 2005, GSI

2
Outline

• Physics opportunities
• High lights of recent achievements
• Plan for 2005
• Schedule and cost
• Management structure

3
Capabilities of a 4p g-ray tracking detector

• ? Angular resolution (0.2º vs. 8º)
• N-rich exotic beams
• Coulomb excitation
• Fragmentation-beam spectroscopy
• Halos
• Evolution of shell structure
• Transfer reactions
• ? Count rate per crystal (100 kHz vs. 10 kHz)
• More efficient use of available beam intensity
• ? Linear polarization
• ? Background rejection by direction

• ? Resolving power 107 vs. 104
• Cross sections down to 1 nb
• Most exotic nuclei
• Heavy elements (e.g. 253,254No)
• Drip-line physics
• High level densities (e.g. chaos)
• ? Efficiency (high energy) (15 vs. 0.5 at
  E?15 MeV)
• Shape of GDR
• Studies of hypernuclei
• ? Efficiency (slow beams) (48 vs. 8 at E? 1.3
  MeV)
• Fusion evaporation reactions
• ? Efficiency (fast beams) (48 vs. 0.5 at E?
  1.3 MeV)
• Fast-beam spectroscopy with low rates -gt RIA

4
Advantages of g- ray Tracking
For Radioactive Beam Experiments

• High position resolution
• High efficiency
• High P/T
• High counting rate
• Background rejection

• Large recoil velocity
• Fragmentation
• Inverse reaction
• Low beam intensity
• High background rate
• Beam decay
• Beam impurity

5
Important Features of GRETINA
GRETINA ¼ GRETA

• Better position Resolution 2 mm vs. 20 mm
• High recoil velocity experiments
• Higher efficiency for high energy gamma rays
• Giant resonances studies
• Compactness ¼ GRETA is comparable or better
  than Gammasphere
• Use with auxiliary detectors, recoil separators
  etc.

6
Physics Opportunities with GRETINA

• How does nuclear shell structure and
  collectivity
• evolve in exotic n-rich nuclei?
• What is the influence of increasing charge on
  the dynamics and structure for the heaviest
  nuclei?
• How do the collective degrees of freedom and
  shell structure evolve with the excitation
  energy and angular momentum?
• What are the characteristics of the Giant Dipole
  Resonances built on superdeformed states and
  loosely bound nuclei?

7
Recent Achievements

• Received CD1 approval start design phase
• Developed design concept for mechanical support
• Received 3-crystal detector prototype III
• Extensive testing with sources and beam
• Analyzed in-beam test results of prototype II
• Set up a data acquisition system
• Finalized detector module design
• Written requirement documents
• MOUs signed with collaborating institutions
• Carried out safety and risk analysis

CD0 Approve mission need CD1 Approve
preliminary baseline range CD2 Approve
performance baseline range CD3 Approve start of
construction CD4 Approve start of operation
8
Concept of Mechanical Support

• Two quarter-spheres
• 17 detector mounting positions
• Allow translation and rotation
• Wedge plate for detector alignment
• Tool for detector installation
• Movable among laboratories (e.g. ANL, LBNL, MSU,
  ORNL)

9
Three-crystal Prototype
Received June 4, 2004

• Tapered hexagon shape
• Highly segmented 6 ? 6 36
• Close packing of 3 crystals
• 111 channels of signal

• Tests performed
• Mechanical dimension
• Temperature and LN holding time
• Energy resolution
• Singles and preliminary coincidence scan
• In-beam measurements

10
Prototype Test Results
Segment boundary
Electron drift velocity
In-beam measurements
Signal shapes
Under analysis
11
Detector Module Design

• Design Choices
• 4 crystals per cryostat
• Warm FETs

• Reasons
• Simpler geometry 2 types of crystal, one
  cryostat
• Easier FET replacement 1 day vs. 9 days
• Higher availability near 100 vs. 85
• Lower price 400k cost difference, with one
  more crystal

12
Detector Geometry

• Packing scheme 12 pentagons, 120 hexagons
• Pentagon size W 5.2, fit a OD 1.7 tube
• Ge crystals W 81.1
• Target-to-crystal distance r 185 mm

Packing scheme
Optimization of shapes
Optimization of distance

• Geant4 program from Dino Bazzacco and Enrico
  Farnea

13
Crystal Shapes
14
Data Acquisition System

• Signal digitizer
• Trigger/timing system
• Network switch
• Processing farm
• Data storage

• Signal digitizer prototype
• 100 MHz, 12 bit
• Energy
• trapezoidal filter
• P/Z correction
• Leading edge time
• Constant fraction time
• Pulse shape

15
Electronics

• Produced twenty units of the 2nd version of the
  signal digitizer. Fifteen are in use.
• Added P/Z cancellation algorithm to FPGA.
• Studied the performance of Ge detector
  preamplifier
• Tested Ge signal cables and connectors
• Completed draft of requirement document

Before P/Z
After P/Z
16
Detector Testing System

• Use 15 prototype DSP boards in VME crate to
  acquire data from all 111 channels of prototype
  detector
• Acquisition rate gt 8 Mbytes/sec
• Data stored to a redundant disk array (2 Tbytes)
  over Gigabit network
• Three data processing computers
• Online histogramming during in-beam test
• Offline analysis programs

Setup for detector testing
17
Computing Requirements

• Assumptions
• Movable among labs, expandable to more detectors
• Performance Requirements
• Process 20,000 gamma/sec, store 10 Mbytes/sec
• Data Processing Components
• Readout, event building, signal decomposition,
  tracking
• Services
• Controls, configuration management, online
  monitoring, data archiving

18
Pulse Shapes with n-damage
Pulse shapes from an undamaged detector (solid)
and a neutron damaged detector after 1010 n/cm2
(dashed)

• Neutrons cause
• Reduction of charge collection efficiency
• Residual charge in neighboring segments

19
Neutron Damage effects

• Degradation in E resolution occurs for llt100 cm,
  before correction and for llt30 cm, after
  correction.
• But only for llt17 cm position resolution becomes
  worse than 1 mm.

A measurable effect of neutron damage on position
resolution is never reached before annealing is
required for energy resolution!
20
Impurity Concentration
Impurity gt Space Charge gtElectric Field gt
Drift velocity gt Pulse shape

• Impurity concentration is not constant in the
  crystal.

From the manufacturer (z-variation) ? Vop
5000 V Crystal A r (0.45 _ 1.5 ) x 1010 a/cm3
? Vfd 2500 V Crystal B r (0.76 _ 1.2 ) x
1010 a/cm3 ? Vfd 2000 V Crystal C r (0.83 _
1.8) x 1010 a/cm3 ? Vfd 3750 V

• Impurity concentration from r 0 to r 1.4 x
  1010 a/cm3.
• Position resolution has been calculated.
• The capability of reconstructing the interaction
  position is not affected, if the impurity
  concentration is known with accuracy of

Dr 0.75 x 1010 atoms/cm3 gt 1 mm
21
Improve Tracking Speed

• Optimal permutation sequence
• Track energy ordered
• interactions (Learning mode)
• Arrange permutation by success rate
• Track with learned order of
• permutation (production mode)

1 2 3 5 6 7 4
1 2 3 7 5 6 4
1 2 3 5 7 6 4
1 3 2 5 6 7 4
1 2 3 6 5 7 4
1 2 4 5 7 6 3
1 2 6 5 7 4 3
1 2 5 4 6 7 3
1 2 6 4 5 7 3
1 2 5 7 4 6 3
1.33 MeV, N 7 7! 5040 Permu.
Event 3.4 50 5.0 59 7.0 64
8.4 65
22
Plan for 2005

• Receive CD2A/3A approval for detector
• Receive and approve drawings of the 4-crystal
  detector module and award contract
• Complete design of the Mechanical Support
  Structure
• Complete design of the Liquid Nitrogen System
• Complete analysis of in-beam data of prototype
  III
• Finalize Electronics Requirement Document
• Finish electronics RD preamp, trigger etc.
• Finalize Computing System Requirement Document
• Continue signal decomposition and tracking
  algorithm developments

23
Schedule (Fiscal Years)
24
GRETINA Cost (Jan. 04)
Includes overhead Does not include RD and
scientific efforts

• Item Cost (M)
• Mechanical 0.91
• Detector 6.95
• Electronics 1.52
• Computer 1.15
• Assembly 0.18
• Management 2.22
• Safety 0.12
• Sub total 13.05
• Contingency 2.85 (22)
• Escalation 1.10
• Total (TEC) 17.0

25
Management Structure
26
Collaborating Institutions
Role defined by MOUs

• 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

27
Management Advisory Committee

• Don Geesaman, Argonne National Laboratory
• Konrad Gelbke, Michigan State University
• James Symons, (Chair) Lawrence Berkeley National
  Laboratory
• Glenn Young, Oak Ridge National Laboratory

28
Gretina Advisory Committee

• Con Beausang, Yale University
• 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

29
Working Groups

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

ANL, LANL, LBNL, LLNL, NRL, ORNL, FSU, Georgia
Tech, MSU, Miss. SU, Purdue, U. Mass. Lowell,
Rochester, Notre Dame, Vanderbilt, Wash. U., Yale
ANU, CEA Saclay, Cologne, Daresbury, CNEA-UNSAM,
CSNSM, Guelph, IFIC Valencia, INFN Podava, INFN
Milano, Jyväskylä, Keele, KTH RIT, Liverpool,
Lund, Manchester, Paisley, S. Paulo, Surry,
TRIUMF, Tsinghua, TU Munich, Toronto, York,
Uppsala, Warsaw
30
Working Group Meetings

• Detector
• March 19-20, 2004, ORNL
• Software
• June 22-23, 2004, LBNL
• Electronics
• July 24-25, 2004, ANL

31
Summary

• Received CD1 Started design phase
• No technical show stoppers
• Project on schedule and within cost so far
• Construction starts in 2007
• Completion in 2010

32
Summary

• Collaboration with AGATA has benefited
  GRETA/GRETINA
• We would like to continue and expand the
  collaboration
• Software working group meeting on signal
  decomposition May 2005
• Postdoc position available at Berkeley