from gretina to greta
TRANSCRIPT
August 17, 2006 The Future of γ-ray Spectroscopy 1
From GRETINA to GRETA
I-Yang Lee
Lawrence Berkeley National Laboratory
Workshop on “The Future of Gamma-ray Spectroscopy”August 17 - 18, 2006, Tallahassee, FL
August 17, 2006 The Future of γ-ray Spectroscopy 2
Outline
• Short history• Case for GRETA in 2007 LRP• Simulation of GRETA performance• Schedule and cost of GRETA• Plan for the white paper
August 17, 2006 The Future of γ-ray Spectroscopy 3
GRETA in1996 Long Range Plan
“It seems possible to develop a gamma-ray detector array which would have a resolving power about a thousand times that of any array currently existing or planned. Such a detector (called GRETA) would consist of a spherical shell of highly segmented, tapered hexagonal Gedetectors, each of which would be able to locate a scattering point in three dimensions to an accuracy between 1 mm and 1 cm. The gamma ray could then be reconstructed using the energy and position of the interactions.”
August 17, 2006 The Future of γ-ray Spectroscopy 4
GRETA in 2002 Long Range Plan
“4π Gamma-ray tracking array -The detection of gamma-ray emissions from excited nuclei plays a vital and ubiquitous role in nuclear science. The physics justification for a 4π tracking array that would build on the success of Gammasphere 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.”
August 17, 2006 The Future of γ-ray Spectroscopy 5
The science case for GRETA
1996 LRP
• 1994 Conceptual design study• 1998 Workshop on GRETA physics (LBNL)• 2000 Workshop on GRETA physics (MSU)• 2000 Proposal for a 3-crystal module cluster peer reviewed and funded• 2001 Workshop on Gamma-ray tracking detectors for nuclear science (Lowell)• 2002 Gamma Ray Tracking Coordination Committee review meeting (ANL)
⇒ “A National Plan for the Development of Gamma-Ray Tracking Detectors in Nuclear Science”
• 2003 NSAC facility review ranked GRETA 1 in science, and 1 in readiness• 2003 Proposal for GRETINA reviewed and received CD0 – mission need
2002 LRP
Workshops on Equipment for Radioactive Beam Facility
Experimental Equipment for an advanced ISOL facilityBerkeley, California, July 23-25, 1998
Workshop on the Experimental Equipment for RIAOak Ridge, Tennessee, March 18-22, 2003
RIA Facility WorkshopEast Lansing, Michigan , March 9-13, 2004
August 17, 2006 The Future of γ-ray Spectroscopy 6
Goal and plan for the 2007 LRP
Re-endorse the science of GRETASupport the completion of GRETA
Produce a white paper to make our caseas input to the LRP writing group
This goal and plan supported by bothGRETINA Advisory CommitteeGRETINA Management Committee
August 17, 2006 The Future of γ-ray Spectroscopy 7
The case for GRETA
• The science case for it remains strong.• It is a major initiative for our field.• It will be an essential part of the future
‘RIA’ facility. • It establishes a world-class capability in the
US in the meantime. • We have made great progress in the
construction of GRETINA.• We are asking to complete what we started.
August 17, 2006 The Future of γ-ray Spectroscopy 8
Simulation
• Reaction kinematics– Beam properties, target thickness.– Three types of reaction : fusion, fragmentation, and 2-
body reaction.– Particle velocity and gamma ray direction, Doppler
broadening.• GRETA efficiency and peak-to-total ratio
– GEANT simulation– Tracking efficiency
• Spectrum– Scale conditions of existing experimental results :
energy resolution, efficiency, peak-to-total, coincidence fold.
August 17, 2006 The Future of γ-ray Spectroscopy 10
Doppler correction
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
0 30 60 90 120 150 180
Lab Angle (degree)
Res
olut
ion
anglevelocity
46Ar → 45Ar, 70 MeV/amuβ= 0.37Δθ=1.0º
Δβ = 0.025
GRETINAAngular coverage
Φ sinθ
θ
θ coverage4 modules at 58º3 modules at 90º
August 17, 2006 The Future of γ-ray Spectroscopy 11
Energy resolution Example 1
• Proton knockout reaction 46Ar → 45Ar, 70 MeV/A• GRETINA angular coverage = 37º - 115º (4@ 58º, 3@90º)• Target to detector distance = 185 mm
GRETINA Energy Resolution Factors Value
(RMS) Resolution (FWHM %)
Beam position on target Δx, Δy 0.85 mm 0.192 Target position Δz 0.85 mm 0.375 Particle angle Δθx, Δθy 0.74 mr 0.069 GRETINA position Δx, Δy, Δz 1 mm 0.496 Particle momentum Δp/p 0.042 % 0.013 Target thickness 188 mg/cm2 0.084 TOTAL 0.641
August 17, 2006 The Future of γ-ray Spectroscopy 12
Experiment simulation 1
Gamma-ray energy (2keV/chan)
30Na from 32Al Beam
30Na from 30Mg Beam
340
370410250
175
190
150
140
340
370410
250
175
770430 (3+--2+)
Simulation SeGA Simulation GRETINA
48 Ca → 30Mg → 30Na
Gamma-gamma coincidence
(NSCL dataE. Rodriguez-Vieitez et al.)
n-rich nuclei from secondary fragmentation reactions
4 × efficiency1/5 × Doppler width
August 17, 2006 The Future of γ-ray Spectroscopy 13
Experiment simulation 2
238U + 170Er 5.7 MeV/uGS + CHICO3 ·109 p/s (0.5 pna), 0.5 mg/cm2
3 days, γ−γ−γ
1n transfer 169Er
SimulationGS + CHICO
Simulation 170Er + 238U 5.7 MeV/u
GRETINA + SuperCHICO1n 3 ·109
GRETINA + SuperCHICO3n 3 ·109
GRETA + SuperCHICO6n 3 ·109
C.Y. Wu et al., PRC 70, 014313 (2004)
n-rich nuclei from transfer reactions
August 17, 2006 The Future of γ-ray Spectroscopy 14
Experiment simulation 3
Simulation GRETA, ε =0.25
4-fold, I=10-5
Simulation GS, ε =0.09
Simulation GS, ε =0.09
3-fold, I=10-4
3-fold, I=10-3
64Ni ( 48Ca, 4n) 108Cd, GammasphereA. Görgen et al., PRC 65, 027302 (2002)
v/c=0.04
High-spin states from fusion reactions
August 17, 2006 The Future of γ-ray Spectroscopy 15
GRETINA
A gamma-ray tracking array covering 1π solid angle.
28 36-fold segmented Ge crystals in 7 cryostats
All signals (1036 channels) are digitized at 100 MHz.
On-line analysis performs signal decomposition and tracking to give position, energy, and scattering sequence of interactions.
August 17, 2006 The Future of γ-ray Spectroscopy 16
Features of GRETINA
• Better position Resolution – 2 mm vs. 20 mm– High recoil velocity experiments
• Compactness – 1 π solid angle is comparable or better than Gammasphere in efficiency– Use with auxiliary detectors, recoil separators etc.
• Higher efficiency for high energy gamma rays– Giant resonances studies
August 17, 2006 The Future of γ-ray Spectroscopy 17
Possible installation sites
ANL FMA
NSCL S800
LBNL Cave 4C
ORNL RMS
August 17, 2006 The Future of γ-ray Spectroscopy 18
GRETINA milestones
Critical DecisionsCD0 : Mission need Aug. 2003
CD1 : Preliminary Baseline Range Feb. 2004
CD2A/CD3A : Start Constructionlong lead time items (Ge) June 2005
CD2B/CD3B : Start Construction July 2007
CD4 : Start of Operation Sept. 2010
CD0: Approve mission needCD1: Approve preliminary baseline range CD2: Approve performance baseline rangeCD3: Approve start of construction CD4: Approve start of operation
August 17, 2006 The Future of γ-ray Spectroscopy 19
ScheduleWBS Task Name
1 GRETINA1.1 Mechanical1.1.2 Design1.1.3 Production1.2 Detector Module1.2.1 Purchasing1.2.2 Test/Characterize Module 11.2.3 Test/Characterize Rest of Modules1.3 Electronics 1.3.2 Prototype 1.3.3 Production1.4 Computing Systems1.4.2 Prototype1.4.3 Production1.5 System Assembly1.5.1 Prototype 1.5.2 Production1.6 Project Management1.7 Environment and Safety1.12 Level 1 Milestones: Critical Decisions CD1 CD2A/3A CD2B/3B CD4
Complete test proc. and apparatusAward module contract
Complete mechanical subsystem
Complete test DSP moduleStart production DSP module
Award computer farm contract
Ready for prototype assemblyReady for final assembly
CD0
3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 32003 2004 2005 2006 2007 2008 2009 2010 2011
Phase A complete
Complete detector purchase
Complete design/draw. support structure
Complete acceptance mod. 1
August 17, 2006 The Future of γ-ray Spectroscopy 20
Detector schedule
Number of detectorsCalendar year
order receive
2005 1
2006 1
2007 4
2008 2 3
2009 3
August 17, 2006 The Future of γ-ray Spectroscopy 21
GRETA costAdditional cost beyond GRETINA
Redirected effort not includedCost ContingencyItem
$k rate $k Mechanical 1,000 25% 250Detector 23,000 15% 3,450Electronics 2,142 25% 536Computing 830 30% 249Assembly 200 25% 50Management 2,000 15% 300Environment and Safety 150 20% 30Total 29,322 17% 4865With contingency 34,187 With escalation 42,391
August 17, 2006 The Future of γ-ray Spectroscopy 22
GRETA Detector Schedule
0
5
10
15
20
25
30
35
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Calendar YearN
umbe
r of d
etec
tor
GRETINAGRETATotal
0
5
10
15
20
25
30
35
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Calendar Year
Num
ber o
f det
ecto
r
GRETINAGRETATotal
Start 20102π 20124π 2016
Start 20082π 20114π 2014
Plan A Plan B
GRETA schedule will most likely be determined by fundingprofile and/or detector production capability
August 17, 2006 The Future of γ-ray Spectroscopy 23EC – NUPECC Meeting 9.3.06 J. Gerl GSI
2001 2003 2005 2007 2009 2011 2013 2015 2017
Preparatory phaseInvest: 6.5 M€Effort: 120 FTE
Well structured organization based on LoIs and MoUs
AGATA Cost and schedule
Construction phaseInvest: 50 M€Effort: 100 FTE
OperationCost: < 1 M€
TMR
I3 EURONS
EC FP7
August 17, 2006 The Future of γ-ray Spectroscopy 24
Outline of white paper
• Executive summary• Introduction• Science case• Technical feasibility• Cost estimates• Conclusion
August 17, 2006 The Future of γ-ray Spectroscopy 25
Schedule of white paper
• 8/17, finalize outline of science case, writing assignments.
• 10/2, complete first draft, send for review• 10/16, receive comments on first draft• 10/23, complete second draft, send for review by
‘outside’ reviewer, discussion at DNP meeting• 11/13, receive comments.• 12/4, Complete final version, start copy
production• January 07, Chicago town meeting
August 17, 2006 The Future of γ-ray Spectroscopy 26
Summary
• GRETINA is under construction, and is planned to be completed in 2010.
• Goal of this workshop is to produce a white paper for the 2007 long range plan process.• Refine and strengthen the science case• Obtain support to start the next step of GRETA
construction in 2008