AGATAAGATA and the Physics and the Physics

ProgrammeProgramme

Dino BazzaccoINFN Padova

on behalf of the AGATA collaboration

NuPECC Meeting with Funding AgenciesNovember 29, 2004, CNRS, Paris

Neutron rich heavy nuclei (N/Z → 2)• Large neutron skins (r-r→ 1fm)• New coherent excitation modes• Shell quenching

132+xSn

Nuclei at the neutron drip line (Z→25)• Very large proton-neutron asymmetries• Resonant excitation modes• Neutron Decay

Nuclear shapes• Exotic shapes and isomers • Coexistence and transitions

Shell structure in nuclei• Structure of doubly magic nuclei • Changes in the (effective) interactions

48Ni100Sn

78Ni

Proton drip line and N=Z nuclei• Spectroscopy beyond the drip line• Proton-neutron pairing• Isospin symmetry

Transfermium nucleiShape coexistence

New challenges in Nuclear Structure

Experimental conditions and challenges

• Low intensity• High backgrounds• Large Doppler broadening• High counting rates• High -ray multiplicities

High efficiencyHigh sensitivityHigh throughputAncillary detectors

FAIRSPIRAL2SPESREX-ISOLDEMAFFEURISOLHI-SIB

Need instrumentation

Tracking Arrays based onPosition Sensitive Ge Detectors

Gamma Arrays based on Compton Suppressed Spectrometers

50 — 25 % ( M=1 — M=30)

10 — 7 % ( M=1 — M=30)

GAMMASPHEREEUROBALL GRETAAGATA

Ingredients of Gamma-Ray Tracking

Highly-segmented HPGe detectors1.5 kg crystals, hexaconical, encapsulated, 36-pixel cathode

Digital electronic to digitise segment signals100 MHz continuous sampling with 14 bit FADC

Calculation/measurement of pulse shapes as a function of position inside the germanium crystalNet and transient signals

Pulse Shape Analysis algorithms to decompose pulses into positions and energiesStill a major problem for real time operation (but Moore’s law

helps)

Reconstruction of “tracks” by likelihood methodsPerformance depends on quality of PSA

Result of 8 (+2) years of worldwide R&D byTMR, MARS, AGATA, GRETAFirst segmented EU arrays MINIBALL, EXOGAM

Gamma-Ray Tracking

1.33 MeVM =

1

M =

30

ph (%) 65 36

P/T(%) 85 60~50% correct identification

M = 30

Simulation of a high multiplicity event detected by an ideal shell

Algorithm treats also photoelectric absorption and pair-production events

cosθ1cm

E1

EE

20

γ

γγ'

Not only efficiency !

scarce

good

Def

initi

on o

f th

e ph

oton

dire

ctio

n

Dop

pler

cor

rect

ion

capa

bilit

yDetector

Segment

Pulse shapeanalysis

+

tracking

v/c = 50 %

AGATAAGATA(Advanced GAmma Tracking Array)

Main featuresEfficiency: 40% (M=1) 25% (M=30)today’s arrays ~10% (gain ~4) 5% (gain ~1000)

Peak/Total: 65% (M=1) 50% (M=30)today ~55% 40%

Angular Resolution: ~1º FWHM (1 MeV, v/c=50%) ~ 6 keV !!!today ~40 keV

Rates: 3 MHz (M=1) 300 kHz (M=30)today 1 MHz 20 kHz

180 large-volume, 36-fold segmented, encapsulated Ge crystals, 3

shapes

60 triple-clusters

6660 high-resolution digital electronics channels

Sophisticated Pulse Shape Analysis position sensitive operation

mode

Gamma-ray tracking

Total weight of the 60 clusters of the AGATA-180 configuration ~2.5 tonsMounted on a self-supporting structure

Ge crystals:Hexaconical shape90-100 mm long80 mm max diameter36 segmentsAl encapsulatation: 0.4 mm spacing 0.8 mm thickness

Distance between faces of crystals: in same cluster ~2.6 mm in adjacent clusters ~9.0 mm

AGATA Detectors

Triple clusters: 3 encapsulated crystalsAl end-cap: 2.0 mm spacing 1.0 mm thickness111 cold FET preamplifiers

The AGATA DemonstratorObjective of the final R&D phase 2003-2007

1 symmetric cluster4 asymmetric clusters

36-fold segmented crystals540 segments555 digital high-resolution

channels

Eff. 3 – 8 % @ M = 1

Eff. 2 – 4 % @ M = 30

Full ACQwith on line PSA and -ray

tracking

Operational in 2007Cost ~ 5 M€

AGATA Prototypes•Symmetric detectors

–3 ordered

–2 deliveredwork very well !!

•Asymmetric detectors–2 (+3) ordered in 2004

–4 to be ordered in 2005

–delivery starts end 2005

–Sweden and Turkey are bidding for the 5th cluster

• Demonstrator ready in 2007

• Final geometry defined in June 2004• Next phases discussed in 2005-2006

• New MoU and bids for funds in 2007• Start construction in 2008

– 6 triples/year, 5 M€/yearIssues: cost & production capability

– 1 ready in 2010 (10 M€)– 3 ready in 2015 (20 M€)– 4 ready in 2018 (10 M€)

Status and Evolution

a pe

rson

al v

iew

5 Clusters5 ClustersDemonstratorDemonstrator

The Phases of AGATA

GSI FRS RISINGLNL PRISMA CLARAGANIL VAMOS EXOGAMJYFL RITU JUROBALL

12007

Main issue is Doppler correction capability coupling to beam and recoil tracking devicesImprove resolution at higher recoil velocity

Extend spectroscopy to more exotic nuclei

Peak efficiency3 – 8 % @ M = 1

2 – 4 % @ M = 30

Replace/Complement

15 Clusters 15 Clusters 11

The Phases of AGATA 22010

The first “real” tracking arrayUsed at FAIR-HISPEC, SPIRAL2, SPES, HI-SIBCoupled to spectrometer, beam tracker, LCP arrays …Spectroscopy at the N=Z (100Sn), n-drip line nuclei, …

0

5

10

15

20

25

30

35

40

45

50

1 2

Effi

cie

ncy

(%

)

Solid Angle (%)

Efficiency M = 1

Efficiency M = 10

Efficiency M = 20

Efficiency M = 30

= 0 = 0.5

The Phases of AGATA 345 Clusters45 Clusters

33

Efficient as a 120-ball (~20 % at high -multiplicity)Ideal instrument for FAIR / EURISOLAlso used as partial arrays in different labsHigher performance by coupling with ancillaries

2015

60 Clusters60 Clusters44

The Phases of AGATA 42018

Full ball, ideal to study extreme deformationsand the most exotic nuclear speciesMost of the time used as partial arraysMaximum performance by coupling to ancillaries

Synergies

• GRETA– common developments

• Hypernuclear -spectroscopy– PANDA @ FAIR/HESR

• Fundamental studies– (0) decay of 76Ge (GERDA@LNGS)

• Astrophysics– ground, underground, space

• Imaging– applications

Mostly due to the development of position sensitive germanium detectors

The AGATA Collaboration

Bulgaria: SofiaDenmark: CopenhagenFinland:Finland: JyväskyläFrance: GANIL, Lyon, Orsay, Saclay, StrasbourgGermany: Berlin, Bonn, GSI, Darmstadt, Jülich, Köln,

MünchenHungary: DebrecenItaly: Padova, Milano, LNL, Firenze, Camerino, Napoli, GenovaPoland: Krakow, Swierk, WarsawRomania: BucharestSwedenSweden: Lund, Stockholm, UppsalaTurkeyTurkey: Ankara, IstanbulUK: Daresbury, Brighton, Keele, Liverpool,

Manchester, Paisley, Surrey, York

Long Range Plan 2004Recommendations and priorities…In order to exploit present and future facilities fully and most efficiently, advanced instrumentation and detection equipment will be required to carry on the various programmes.The project AGATA, for a 4-array of highly segmented Ge detectors for -ray detection and tracking, will benefit research programmes in the various facilities in Europe. NuPECC gives full support for the construction of AGATA and recommends that the R&D phase be pursued with vigour.