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

Neutron rich heavy nuclei (N/Z → 2) Large neutron skins (r -r  → 1fm) New coherent excitation modes Shell quenching 132+x Sn 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 48 Ni 100 Sn 78 Ni Proton drip line and N=Z nuclei Spectroscopy beyond the drip line Proton-neutron pairing Isospin symmetry Transfermium nuclei Shape coexistence New challenges in Nuclear Structure

Experimental conditions and challenges Low intensity High backgrounds Large Doppler broadening High counting rates High  -ray multiplicities High efficiency High sensitivity High throughput Ancillary detectors FAIR SPIRAL2 SPES REX-ISOLDE MAFF EURISOL HI-SIB Need instrumentation

Tracking Arrays based on Position Sensitive Ge Detectors Gamma Arrays based on Compton Suppressed Spectrometers   50 — 25 % ( M  =1 — M  =30)   10 — 7 % ( M  =1 — M  =30) GAMMASPHEREEUROBALLGRETAAGATA

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 1.33 MeVM  = 1M  = 30  ph (%) 6536 P/T(%)8560 ~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

Not only efficiency ! scarce good Definition of the photon direction Doppler correction capability Detector Segment Pulse shape analysis +  tracking v/c = 50 %

AGATA AGATA (Advanced GAmma Tracking Array) Main features Efficiency: 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 tons Mounted on a self-supporting structure Ge crystals: Hexaconical shape mm long 80 mm max diameter 36 segments Al 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 crystals Al end-cap: 2.0 mm spacing 1.0 mm thickness 111 cold FET preamplifiers

The AGATA Demonstrator Objective of the final R&D phase symmetric cluster 4 asymmetric clusters 36-fold segmented crystals 540 segments 555 digital high-resolution channels Eff. 3 – 8 M  = 1 Eff. 2 – 4 M  = 30 Full ACQ with on line PSA and  -ray tracking Operational in 2007 Cost ~ 5 M€

AGATA Prototypes Symmetric detectors –3 ordered –2 delivered work 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 5 th cluster

Demonstrator ready in 2007 Final geometry defined in June 2004 Next phases discussed in New MoU and bids for funds in 2007 Start construction in 2008 –6 triples/year, 5 M€/year Issues: 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 personal view

5 Clusters Demonstrator The Phases of AGATA GSIFRSRISING LNLPRISMACLARA GANILVAMOSEXOGAM JYFLRITU 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 Peak efficiency 3 – 8 M  = 1 2 – 4 M  = 30 Replace/Complement

15 Clusters 1  The Phases of AGATA 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 ( 100 Sn), n-drip line nuclei, …  = 0  = 0.5

The Phases of AGATA 3 45 Clusters 3  Efficient as a 120-ball (~20 % at high  -multiplicity) Ideal instrument for FAIR / EURISOL Also used as partial arrays in different labs Higher performance by coupling with ancillaries 2015

60 Clusters 4  The Phases of AGATA Full ball, ideal to study extreme deformations and the most exotic nuclear species Most of the time used as partial arrays Maximum performance by coupling to ancillaries

Synergies GRETA –common developments Hypernuclear  -spectroscopy FAIR/HESR Fundamental studies –  (0 ) decay of 76 Ge Astrophysics –ground, underground, space Imaging –applications Mostly due to the development of position sensitive germanium detectors

The AGATA Collaboration Bulgaria: Sofia Denmark: Copenhagen Finland: 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 Sweden: Lund, Stockholm, Uppsala Turkey Turkey:Ankara, Istanbul UK: Daresbury, Brighton, Keele, Liverpool, Manchester, Paisley, Surrey, York

Long Range Plan 2004 Recommendations 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.