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AGATA and the Physics Programme

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

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  1. AGATAand the Physics Programme Dino Bazzacco INFN Padovaon behalf of the AGATA collaboration NuPECC Meeting with Funding Agencies November 29, 2004, CNRS, Paris

  2. 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

  3. 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

  4. 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)

  5. 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

  6. 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

  7. Not only efficiency ! v/c = 50 % scarce Detector Doppler correctioncapability Segment Definition of the photon direction Pulse shapeanalysis + g-tracking good

  8. 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

  9. 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

  10. 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€

  11. 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

  12. 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

  13. 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

  14. 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, …

  15. 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

  16. 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

  17. Synergies Mostly due to the development of position sensitive germanium detectors • GRETA • common developments • Hypernuclear g-spectroscopy • PANDA @ FAIR/HESR • Fundamental studies • bb(0n) decay of 76Ge (GERDA@LNGS) • Astrophysics • ground, underground, space • Imaging • applications

  18. 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

  19. 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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