From GRETINA to GRETA

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


Outline

• Short history• Case for GRETA in 2007 LRP• Simulation of GRETA performance• Schedule and cost of GRETA• Plan for the white paper


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.”


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.”


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


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


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.


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.


GRETA SimulationFirst hit distribution

Φ sinθ

θ


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


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


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



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



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


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.


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


Possible installation sites

ANL FMA

NSCL S800

LBNL Cave 4C

ORNL RMS


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


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


Detector schedule

Number of detectorsCalendar year

order receive

2005 1

2006 1

2007 4

2008 2 3

2009 3


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


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


Outline of white paper

• Executive summary• Introduction• Science case• Technical feasibility• Cost estimates• Conclusion


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


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

From GRETINA to GRETA

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