John Simpson Nuclear Physics Group Daresbury Laboratory The AGATA project NUSTAR ’05 University of Surrey January 2005

John Simpson Nuclear Physics Group Daresbury Laboratory

AGATA the ultimate gamma-ray spectrometer! Next generation spectrometer based on gamma-ray tracking Based on years of worldwide R&D No suppression shields 4  germanium array Very high efficiency and spectrum quality Stable, radioactive beams, low-high velocities AGATA The Advanced Gamma Ray Tracking Array

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

AGATA AGATA (Advanced GAmma Tracking Array) 4   -array for Nuclear Physics Experiments at European accelerators providing radioactive and high-intensity stable beams Main features of AGATA Efficiency: 40% (M  =1) 25% (M  =30) today’s arrays ~10% (gain ~4) 5% (gain ~1000) Peak/Total: 55% (M  =1) 45% (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 Ge crystals in 60 triple-clusters Digital electronics and sophisticated Pulse Shape Analysis algorithms allow Operation of Ge detectors in position sensitive mode   -ray tracking

Exogam, Miniball, SeGa: optimized for Doppler correction at low  -multiplicitiy   up to 20% Tracking Arrays based on Position Sensitive Ge Detectors Large Gamma Arrays based on Compton Suppressed Spectrometers   40 — 20 % ( M  =1 — M  =30)   10 — 5 % ( M  =1 — M  =30) GAMMASPHEREEUROBALLGRETAAGATA Idea of  -ray tracking

Tracking requires: Good position determination from Digital pulse processing Previous/current projects: EU V th Framework TMR `Development of  –ray tracking detectors’ (6 EU countries) Miniball and Exogam (European collaborations) Mars, Italy UK Instrumentation grant ‘Digital Pulse Processing and  –ray tracking’ (Liverpool, Surrey, Daresbury) GRETA, USA Proved that position resolution can be achieved, tracking algorithms developed, Highly segmented detectors developed Next step Build a sub array of few highly segmented detectors, prove tracking in real situations Scale up to full array, fund full array AGATA Europe (10 (12) countries, 42 (46) laboratories) Research and Development Phase Funding approved in France, Germany, Italy, UK, other countries bidding. GRETA U.S.A. Funded for development modules GRETINA U.S.A. Funded for 30 crystals

The AGATA Collaboration Memorandum of Understanding 2003 Research and Development Bulgaria: Univ. Sofia Denmark: NBI Copenhagen Finland: Univ. Jyvaskyla France: GANIL Caen, IPN Lyon, CSNSM Orsay, IPN Orsay, CEA-DSM-DAPNIA Saclay, IreS Strasbourg Germany: HMI Berlin, Univ. Bonn, GSI Darmstadt, TU Darmstadt, FZ Jülich, Univ. zu Köln, LMU München, TU München Italy: INFN and Univ. Firenze, INFN and Univ. Genova, INFN Legnaro, INFN and Univ. Napoli, INFN and Univ. Padova, INFN and Univ. Milano, INFN Perugia and Univ. Camerino Poland: NINP and IFJ Krakow, SINS Swierk, HIL & IEP Warsaw Romania: NIPNE & PU Bucharest Sweden: Chalmers Univ. of Technology Göteborg, Lund Univ., Royal Institute of Technology Stockholm, Uppsala Univ. UK: Univ. Brighton, CLRC Daresbury, Univ. Keele, Univ. Liverpool, Univ. Manchester, Univ. Paisley, Univ. Surrey, Univ. York Turkey Hungary

The First Step: The AGATA Demonstrator Objective of the final R&D phase symmetric triple-cluster 5 asymmetric triple-clusters 36-fold segmented crystals 540 segments 555 digital-channels Eff. 3 – 8 M  = 1 Eff. 2 – 4 M  = 30 Full ACQ with on line PSA and  -ray tracking Test Sites: GANIL, GSI, Jyväskylä, Köln, LNL Cost ~ 7 M €

The AGATA RESEARCH and DEVELOPMENT PHASE Develop 36 fold segmented encapsulated detector of right shape Develop cryostat for groups “clusters” of these detectors Develop digital electronics (700 channels) Finalise signal algorithms for energy, position and time Develop tracking algorithms Build demonstration unit to prove tracking in real situations Write technical proposal for full array

Ingredients of  -Tracking Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors · · · · Identified interaction points (x,y,z,E,t) i Reconstruction of tracks e.g. by evaluation of permutations of interaction points Digital electronics to record and process segment signals  reconstructed  -rays

AGATA Detectors 3 encapsulated crystals 111 preamplifiers with cold FET ~230 vacuum feedthroughs LN 2 dewar, 3 litre, cooling power ~8 watts Hexaconical Ge crystals 90 mm long 80 mm max diameter 36 segments Al encapsulation 0.6 mm spacing 0.8 mm thickness 37 vacuum feedthroughs

AGATA Prototypes Symmetric detectors –3 ordered, Italy, Germany –3 delivered –Acceptance tests in Koln –2 work very well –3 rd under test First results very good: 36 outer contacts keV at 60keV and keV at 1.3MeV Core 1.2keV at 60keV and 2.1keV at 1.3MeV Cross talk less than 10 -3

AGATA Prototypes Asymmetric detectors for the 180 geometry –8 ordered in 2004 –4 to be ordered in 2005 –delivery starts end 2005 Full scan of first in Liverpool Assembly of triple cryostat (CTT) Cluster ready by March 2005 First triple cryostat in Cologne

AGATA Design and Construction GRETINA

The 4  180 detector Configuration 180 hexagonal crystals3 shapes 60 triple-clusters all equal Inner radius (Ge) 25 cm Amount of germanium 374 kg Solid angle coverage 78 % Singles rate ~50 kHz 6480 segments Efficiency: 39% (M  =1) 25% (M  =30) Peak/Total:53% (M  =1) 46% (M  =30) Ge crystals size: length90 mm diameter80 mm

Segment level processing: energy, time Detector level processing: trigger, time, PSA Global level processing: event building, tracking, software trigger, data storage

Scanning with collimated source to characterise rise time responses Detector characterisation Detector scanned with collimated source

First AGATA detector being scanned in Liverpool Liverpool System Parker linear positioning table Pacific scientific stepper motors 0.3mCi 137 Cs 2mm steps collimator Singles/coincidence 8 NaI system GRT4 cards Preliminary results Core response to 662keV Scanning in progress

PSA –Apply and test Genetic Algorithm on measured data with the AGATA prototypes –Develop new and specialised algorithms –Implement for on-line analysis –Gamma-neutron differentiation Detector characterisation –Crystal scanning for pulse-shape data base construction –Simulation of charge carrier transport –Test neutron damage on PSA efficiency γ-tracking –Optimise and couple the different tracking algorithms for improved AGATA performance –Determine the impact on AGATA performance of the use of additional detectors –Determine the AGATA response to simulated physics events

Timescale Five year research and development phase of AGATA Start January end December 2007 First three symmetric capsules expected mid 2004  Test individual as 3-unit module by Easter 2005 Start ordering asymmetric capsules in 2004  First asymmetric cluster end 2005 Test first crystals/ modules with “existing electronics” Electronics and DA required mid 2006 Time for R&D, GUI, algorithms PSA, tracking… Test sub array 2007

Demonstrator ready in 2007 Next phases discussed in New MoU and bids for funds in 2007 Start construction in 2008 Rate of construction depends on production capability Stages of physics exploitation, facility development Status and Evolution

The Phases of AGATA-180

5 Clusters 1111 3333 55 Clusters 4  Array The Phases of AGATA-180

5 Clusters Demonstrator The Phases of AGATA GSIFRSRISING LNLPRISMACLARA GANILVAMOSEXOGAM JYFLRITUJUROGAM 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 2 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

60 Clusters 4  The Phases of AGATA 4 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

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.

Tracking Arrays based on Position Sensitive Ge Detectors   40 — 20 % ( M  =1 — M  =30) GRETAAGATA AGATA New physics Reveal the inner secrets of the atomic nucleus

AGATA web page The Second AGATA Week th February 2005 GSI All welcome

The Management