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AGATA and the Physics Programme. Dino Bazzacco INFN Padova on behalf of the AGATA collaboration. NuPECC Meeting with Funding Agencies November 29, 2004, CNRS, Paris. Shape coexistence. Transfermium nuclei. 100 Sn. 48 Ni. 132+x Sn. 78 Ni. New challenges in Nuclear Structure.

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Agata and the physics programme
AGATAand the Physics Programme

Dino Bazzacco

INFN Padovaon behalf of the AGATA collaboration

NuPECC Meeting with Funding Agencies

November 29, 2004, CNRS, Paris


New challenges in nuclear structure

Shape coexistence

Transfermium nuclei

100Sn

48Ni

132+xSn

78Ni

New challenges in Nuclear Structure

  • Shell structure in nuclei

  • Structure of doubly magic nuclei

  • Changes in the (effective) interactions

  • Proton drip line and N=Z nuclei

  • Spectroscopy beyond the drip line

  • Proton-neutron pairing

  • Isospin symmetry

  • Nuclear shapes

  • Exotic shapes and isomers

  • Coexistence and transitions

  • Neutron rich heavy nuclei (N/Z → 2)

  • Large neutron skins (rn-rp→ 1fm)

  • New coherent excitation modes

  • Shell quenching

  • Nuclei at the neutron drip line (Z→25)

  • Very large proton-neutron asymmetries

  • Resonant excitation modes

  • Neutron Decay


Experimental conditions and challenges
Experimental conditions and challenges

FAIR

SPIRAL2

SPES

REX-ISOLDE

MAFF

EURISOL

HI-SIB

  • Low intensity

  • High backgrounds

  • Large Doppler broadening

  • High counting rates

  • High g-ray multiplicities

High efficiency

High sensitivity

High throughput

Ancillary detectors

Need instrumentation


Gamma Arrays based on Compton Suppressed Spectrometers

Tracking Arrays based on

Position Sensitive Ge Detectors

EUROBALL

GAMMASPHERE

AGATA

GRETA

e~ 10 — 7 %

( Mg=1 —Mg=30)

e~ 50 — 25 %

( Mg=1 —Mg=30)


Ingredients of gamma ray tracking
Ingredients of Gamma-Ray Tracking

  • Highly-segmented HPGe detectors

    1.5 kg crystals, hexaconical, encapsulated, 36-pixel cathode

  • Digital electronic to digitise segment signals

    100 MHz continuous sampling with 14 bit FADC

  • Calculation/measurement of pulse shapes as a function of position inside the germanium crystal

    Net and transient signals

  • Pulse Shape Analysis algorithms to decompose pulses into positions and energies

    Still a major problem for real time operation (but Moore’s law helps)

  • Reconstruction of “tracks” by likelihood methods

    Performance depends on quality of PSA

Result of 8 (+2) years of worldwide R&D by

TMR, MARS, AGATA, GRETA

First segmented EU arrays MINIBALL, EXOGAM


Gamma ray tracking

Mg = 30

Gamma-Ray Tracking

Simulation of a high multiplicity event detected by an ideal shell

~50% correct identification

Algorithm treats also photoelectric absorption and pair-production events


Not only efficiency
Not only efficiency !

v/c = 50 %

scarce

Detector

Doppler correctioncapability

Segment

Definition of the photon direction

Pulse shapeanalysis

+

g-tracking

good


Agata a dvanced ga mma t racking a rray
AGATA(Advanced GAmma Tracking Array)

Main features

Efficiency: 40% (Mg=1) 25% (Mg=30)

today’s arrays ~10% (gain ~4) 5% (gain ~1000)

Peak/Total: 65% (Mg=1) 50% (Mg=30)

today ~55% 40%

Angular Resolution: ~1º 

FWHM (1 MeV, v/c=50%) ~ 6 keV !!!

today ~40 keV

Rates: 3 MHz (Mg=1) 300 kHz (Mg=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


Agata detectors
AGATA Detectors

Ge crystals:

Hexaconical shape

90-100 mm long

80 mm max diameter

36 segments

Al encapsulatation:

0.4 mm spacing

0.8 mm thickness

Triple clusters:

3 encapsulated crystals

Al end-cap:

2.0 mm spacing

1.0 mm thickness

111 cold FET preamplifiers

Distance between faces of crystals:

in same cluster ~2.6 mm

in adjacent clusters ~9.0 mm

Total weight of the 60 clusters of the AGATA-180 configuration ~2.5 tons

Mounted on a self-supporting structure


The agata demonstrator objective of the final r d phase 2003 2007
The AGATA DemonstratorObjective of the final R&D phase 2003-2007

1 symmetric cluster

4 asymmetric clusters

36-fold segmented crystals

540 segments

555 digital high-resolution channels

Eff. 3 – 8 % @ Mg = 1

Eff. 2 – 4 % @ Mg = 30

Full ACQ with on line PSA and g-ray tracking

Operational in 2007

Cost ~ 5 M€


Agata prototypes
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


Status and evolution
Status and Evolution

  • 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€/year

      Issues: cost & production capability

    • 1p ready in 2010 (10 M€)

    • 3p ready in 2015 (20 M€)

    • 4p ready in 2018 (10 M€)

a personal view


The phases of agata

5 ClustersDemonstrator

1

The Phases of AGATA

2007

Peak efficiency

3 – 8 % @ Mg = 1

2 – 4 % @ Mg = 30

Replace/Complement

GSI FRS RISING

LNL PRISMA CLARA

GANIL VAMOS EXOGAM

JYFL RITU JUROBALL

Main issue is Doppler correction capability

 coupling to beam and recoil tracking devices

Improve resolution at higher recoil velocity

Extend spectroscopy to more exotic nuclei


The phases of agata1

15 Clusters 1p

b = 0 b = 0.5

2

The Phases of AGATA

2010

The first “real” tracking array

Used at FAIR-HISPEC, SPIRAL2, SPES, HI-SIB

Coupled to spectrometer, beam tracker, LCP arrays …

Spectroscopy at the N=Z (100Sn), n-drip line nuclei, …


The phases of agata2

45 Clusters3p

3

The Phases of AGATA

2015

Efficient as a 120-ball (~20 % at high g-multiplicity)

Ideal instrument for FAIR / EURISOL

Also used as partial arrays in different labs

Higher performance by coupling with ancillaries


The phases of agata3

60 Clusters4p

4

The Phases of AGATA

2018

Full ball, ideal to study extreme deformationsand the most exotic nuclear species

Most of the time used as partial arrays

Maximum performance by coupling to ancillaries


Synergies
Synergies

Mostly due to the development of position sensitive germanium detectors

  • GRETA

    • common developments

  • Hypernuclear g-spectroscopy

    • PANDA @ FAIR/HESR

  • Fundamental studies

  • Astrophysics

    • ground, underground, space

  • Imaging

    • applications


The agata collaboration
The AGATA Collaboration

Bulgaria: Sofia

Denmark: Copenhagen

Finland: Jyväskylä

France: GANIL, Lyon, Orsay, Saclay, Strasbourg

Germany: Berlin, Bonn, GSI, Darmstadt, Jülich, Köln, München

Hungary: Debrecen

Italy: Padova, Milano, LNL, Firenze, Camerino, Napoli, Genova

Poland: Krakow, Swierk, Warsaw

Romania: Bucharest

Sweden: Lund, Stockholm, Uppsala

Turkey: Ankara, Istanbul

UK: Daresbury, Brighton, Keele, Liverpool, Manchester, Paisley, Surrey, York


Long range plan 2004 recommendations and priorities
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 4p-array of highly segmented Ge detectors for g-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.


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