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Advanced Gamma–Ray Spectroscopy Techniques with the AGATA Segmented Detectors Călin A. Ur * for the AGATA Collaboration INFN – Sezione di Padova * On leave.

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Presentation on theme: "Advanced Gamma–Ray Spectroscopy Techniques with the AGATA Segmented Detectors Călin A. Ur * for the AGATA Collaboration INFN – Sezione di Padova * On leave."— Presentation transcript:

1 Advanced Gamma–Ray Spectroscopy Techniques with the AGATA Segmented Detectors Călin A. Ur * for the AGATA Collaboration INFN – Sezione di Padova * On leave from IFIN–HH Bucharest

2 Layout 01/02/20102ELI NP Workshop Bucharest Principles of the AGATA gamma–ray tracking array Building phases of the array The AGATA Demonstrator First tests at the National Laboratories of Legnaro Compton imaging with segmented detectors Principles of the AGATA gamma–ray tracking array Building phases of the array The AGATA Demonstrator First tests at the National Laboratories of Legnaro Compton imaging with segmented detectors

3 Extreme Experimental Conditions 01/02/20103ELI NP Workshop Bucharest Low intensity High backgrounds Large Doppler broadening High counting rates High  -ray multiplicities Low intensity High backgrounds Large Doppler broadening High counting rates High  -ray multiplicities High efficiency High sensitivity High throughput Ancillary detectors High efficiency High sensitivity High throughput Ancillary detectors FAIR SPIRAL2 SPES REX-ISOLDE EURISOL HI-SIB FAIR SPIRAL2 SPES REX-ISOLDE EURISOL HI-SIB Need instrumentation

4 Extreme Experimental Conditions 01/02/20104ELI NP Workshop Bucharest Low intensity High backgrounds Large Doppler broadening High counting rates High  -ray multiplicities Low intensity High backgrounds Large Doppler broadening High counting rates High  -ray multiplicities High efficiency High sensitivity High throughput Ancillary detectors High efficiency High sensitivity High throughput Ancillary detectors FAIR SPIRAL2 SPES REX-ISOLDE EURISOL HI-SIB ELI ? FAIR SPIRAL2 SPES REX-ISOLDE EURISOL HI-SIB ELI ? Need instrumentation

5 The New Concept of Tracking Arrays 01/02/20105ELI NP Workshop Bucharest 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 AC Compton rejected Full energy accepted

6 Analogue vs Digital Electronics 01/02/20106ELI NP Workshop Bucharest Detector (Germanium) Detector (Germanium) Shaping Amplifier CFD DAQ E t FADC MWD NSR Filters DAQ E t ADC TDC PSA Tracking E t x,y,z E t Present Arrays AGATA SegmentDetectorArray Detector (Germanium) Detector (Germanium)

7 Ingredients of Gamma–Ray Tracking 01/02/20107ELI NP Workshop Bucharest Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors Highly segmented HPGe detectors · · Identified interaction points Identified interaction points (x,y,z,E,t) i Reconstruction of tracks evaluating permutations of interaction points Reconstruction of tracks evaluating permutations of interaction points Digital electronics to record and process segment signals Digital electronics to record and process segment signals Reconstructed gamma-rays Reconstructed gamma-rays

8 Th. Kröll, NIM A 463 (2001) 227 Position Determination – PSA 01/02/20108ELI NP Workshop Bucharest FEM-model of detector Calculate weighting fields                    Calculation of the signals induced on the contacts using the weighting field method transient signals     net charge signals    

9 Pulse Shape Analysis Concept 01/02/20109ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,10,46) measured (10,30,46)

10 Pulse Shape Analysis Concept 01/02/201010ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,10,46) measured calculated

11 Pulse Shape Analysis Concept 01/02/201011ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,15,46) measured calculated

12 Pulse Shape Analysis Concept 01/02/201012ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,20,46) measured calculated

13 Pulse Shape Analysis Concept 01/02/201013ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,25,46) measured calculated

14 Pulse Shape Analysis Concept 01/02/201014ELI NP Workshop Bucharest B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,30,46) measured calculated

15 Pulse Shape Analysis Concept 01/02/201015ELI NP Workshop Bucharest Result of Grid Search algorithm R. Venturelli Result of Grid Search algorithm R. Venturelli B4 B5 B3 C4 C5 C3 CORE A4 A5 A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,25,46) measured calculated

16 Interaction/Reconstruction Algorithms 01/02/201016ELI NP Workshop Bucharest ~ 100 keV ~1 MeV ~ 10 MeV  -ray energy Photoelectric Compton Scattering Pair Production Algorithms: ClusterTracking, FuzzyTracking, BackTracking, … Reconstruction efficiency limited by Position resolution and Compton profile. Probability of interaction depth Isolated hits Angle/Energy Pattern of hits E 1st = E  – 2 mc 2

17 Pulse Shape Analysis Concept 01/02/201017ELI NP Workshop Bucharest Idealized configuration to determine maximum attainable performance. R i = 15 cm R o = 24 cm 230 kg of Ge Events simulated using GEANT4 Response of shell at 1.33 MeV:   ph = 70% P/T = 77% Reconstruction by Cluster-Tracking Packing Distance: 5 mm Position Resolution: 5 mm (at 100 keV) 1.33 MeVM  = 1M  = 30  ph (%) 6536 P/T(%) gammas detected-- 23 in photopeak 16 reconstructed-- 14 in photopeak E  = 1.33 MeV M  = 30 A high multiplicity event D. Bazzacco

18 Possible Array Configurations 01/02/201018ELI NP Workshop Bucharest 120 crystals 180 crystals ConfigurationA120A120FA120C4A180 Crystals (shapes)120 (2)120 (6)120 (2)180 (3) Clusters (shapes) 40 (2) 30 (1) 60 (2) Ge solid angle (%) Ge weight (kg) Centre to Ge (cm) Electronics channels Eff. at M  = 1 (%) Eff. at M  = 30 (%) P/T at M  = 1 (%) P/T at M  = 30 (%) A180 is AGATA’s choice GRETA is for A120C4

19 The Advanced GAmma Tracking Array 01/02/201019ELI NP Workshop Bucharest Requirements efficiency, energy resolution, dynamic range, angular resolution, timing, counting rate, modularity, angular coverage, inner space Quantity Specified forTarget Value Photo-peak efficiency (  ph ) E γ = 1 MeV, M γ = 1,  < 0.5 E γ = 1 MeV, M γ = 30,  < 0.5 E γ = 10 MeV, M γ = 1 50 % 25 % 10 % Peak-to-total ratio (P/T) E γ = 1 MeV, M γ = 1 E γ = 1 MeV, M γ = % % Angular resolution (   )  E/E < 1%better than 1  Maximum event rates M γ = 1 M γ = 30 3 MHz 300 kHz Inner space for ancillaries > 170 mm

20 Construction of the AGATA Array 01/02/201020ELI NP Workshop Bucharest Total weight of the 60 clusters of the AGATA- 180 configuration ~ 2.5 tons Mounted on a self-supporting structure 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 encapsulation: 0.4 mm spacing 0.8 mm thickness Ge crystals: Hexaconical shape mm long 80 mm max diameter 36 segments Al encapsulation: 0.4 mm spacing 0.8 mm thickness Distance between faces of crystals: in same cluster ~ 2.5 mm in adjacent clusters ~ 9.0 mm Triple clusters: 3 encapsulated crystals Al end-cap: 2.0 mm spacing 1.0 mm thickness 111 cold FET preamplifiers Triple clusters: 3 encapsulated crystals Al end-cap: 2.0 mm spacing 1.0 mm thickness 111 cold FET preamplifiers

21 Asymmetric AGATA Triple Cryostat 01/02/201021ELI NP Workshop Bucharest Challenges: - mechanical precision - heat development, LN2 consumption - microphonics - noise, high frequencies Challenges: - mechanical precision - heat development, LN2 consumption - microphonics - noise, high frequencies - integration of 111 high resolution spectroscopy channels - cold FET technology for all signals - integration of 111 high resolution spectroscopy channels - cold FET technology for all signals FWHM 60 keV Core MeV keV

22 Electronics and DAQ 22 Fully synchronous system with global 100 MHz clock and time-stamp distribution (GTS) GTS … detector Preamps Digitizers detector Preamps Digitizers Local processing Local processing 7.4 GB/s/det PSA 5 MB/s/det 100 MB/s/detDigitalpreamplifier On line… Storage … Tracking Event Builder Local processing triggered by Ge common contact. Determine energy and isolate ~ 600 ns of signal around rise-time Digitizers: 100 Ms/s, 14 bit Optical fiber read-out of full data stream to pre-processing electronics Digitizers: 100 Ms/s, 14 bit Optical fiber read-out of full data stream to pre-processing electronics Buffers of time-stamped local events sent to PSA to extract position of interactions Trigger-less system. Global trigger possible. Global event builder and software trigger Trigger-less system. Global trigger possible. Global event builder and software trigger On-line gamma-ray tracking Control and storage ( ~ 1 TB/year), … 50 kHz 01/02/2010ELI NP Workshop Bucharest

23 The Phases of AGATA /02/2010ELI NP Workshop Bucharest 5 Clusters Demonstrator Our days 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

24 The Phases of AGATA /02/2010ELI NP Workshop Bucharest The first “real” tracking array To be used at FAIR-HISPEC, SPIRAL2, SPES, … 15 Clusters 1   = 0  = 0.5 Near future Recoil velocity

25 The Phases of AGATA /02/2010ELI NP Workshop Bucharest Efficient as a 120 ball (20% at high  multiplicity) Ideal for FAIR and EURISOL 45 Clusters 3  Far future

26 The Phases of AGATA /02/2010ELI NP Workshop Bucharest Full ball / full performance Ideal to study extreme deformations and the most exotic nuclear species 60 Clusters 4  Remote future

27 The AGATA Demonstrator 2701/02/2010ELI NP Workshop Bucharest Objective of the R&D phase asymmetric triple-clusters 36-fold segmented crystals 540 segments 555 digital-channels Eff. 3 – 7 M  = 1 Eff. 2 – 4 M  = 30 Full ACQ online PSA and  –ray tracking Cost ~ 5 M€ 5 asymmetric triple-clusters 36-fold segmented crystals 540 segments 555 digital-channels Eff. 3 – 7 M  = 1 Eff. 2 – 4 M  = 30 Full ACQ online PSA and  –ray tracking Cost ~ 5 M€ Present status 3 asymmetric triple-clusters mounted&tested at INFN LN Legnaro +1 in delivery Undergoing commissioning runs detectors, DAQ, PSA, online Physics campaign to start in ~ 1 month 3 asymmetric triple-clusters mounted&tested at INFN LN Legnaro +1 in delivery Undergoing commissioning runs detectors, DAQ, PSA, online Physics campaign to start in ~ 1 month

28 First in–beam Test at LNL 2801/02/2010ELI NP Workshop Bucharest Week 12 (March 16-22) C fus.–evap. reaction in inverse kinematics The system included – full AGATA DAQ chain – PSA and tracking performed in real time (online) Goal – test the whole system under real data taking conditions – test Doppler correction capability of the AGATA detectors

29 Doppler Broadening and Position Res. 2901/02/2010ELI NP Workshop Bucharest   Position resolution Angular resolution Energy resolution Beam Recoil  ray

30 Doppler Broadening and Position Res. 3001/02/2010ELI NP Workshop Bucharest 12.5 keV 40 K 1823 keV  ~ 5% 40 K 1823 keV  ~ 5% full detector segments (17.7 keV) PSA+tracking Full optimization and analysis – 1 month online our target

31 Compton Imaging 3101/02/2010ELI NP Workshop Bucharest In-beam experiment – given the position of the target we track the  rays Compton imaging of a radioactive source – inverse tracking – from the first 2 interaction points get the position of the source  E1E1 E2E2 target  E1E1 E2E2  - source Compton scattering – a tool for testing the position resolution  ray Compton scattering F. Recchia

32 Principles of Compton Imaging 3201/02/2010ELI NP Workshop Bucharest  [deg]

33 Compton Imaging Performance 3301/02/2010ELI NP Workshop Bucharest Sources of error in the identification of the source direction: Position resolution (axis) Energy resolution (scattering angle) Compton profile (scattering angle) scattering angle [deg] angular error [deg]

34 Experimental Setup at LNL 3401/02/2010ELI NP Workshop Bucharest Digital DAQ system provided by IFIN – HH Bucharest 10 x TNT2 NIM Digitizer boards from CAEN with 4ch 14bit /100MHz AGATA prototype detector (one symmetric capsule) 60 Co source

35 Comparison with MC Simulations 3501/02/2010ELI NP Workshop Bucharest  profile of experimental image Monte Carlo + 5 mm position resolution  profile of experimental image Experiment  [deg]  [deg]  [deg] peak FWHM  [deg] position resolution FWHM  [mm] After PSA Projections MC

36 Gamma Background Rejection 3601/02/2010ELI NP Workshop Bucharest characterize the capability of the AGATA detectors to discriminate different gamma source locations using Compton imaging algorithm Experimental Setup: 3  –ray sources 60 Co, 152 Eu and 137 Cs their positions simulate the beam-dump, the beam line and the target M. Doncel & F. Recchia

37 Results 3701/02/2010ELI NP Workshop Bucharest b) a) c) Spectra of the gamma radiation assigned to each source position with the algorithm Spectra assignment a) corresponds to the 60 Co position b) corresponds to the 137 Cs position c) corresponds to the 152 Eu position promising results need more refinement of the method E = 344 keV E = 661 keV E 1 = 1173 keV E 2 = 1332 keV

38 Outlook 3801/02/2010ELI NP Workshop Bucharest To exploit the present and future facilities fully and most efficiently, advanced instrumentation and detection equipment is required – NuPECC recommendation The 4  -array of highly segmented Ge detectors AGATA for  -ray detection and tracking is part of this effort First measurements in-beam and with sources show that the position resolution is ~ 5 mm FWHM; this value is in line with the design assumptions of the AGATA spectrometer, confirming the feasibility of  -ray tracking AGATA will have a strong impact on nuclear structure studies : lifetime measurements of nuclear states down to fs, angular distribution and polarization measurements Is AGATA or part of it of interest for the ELI project?

39 The AGATA Collaboration 3901/02/2010ELI NP Workshop Bucharest 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

40 Outlook 4001/02/2010ELI NP Workshop Bucharest

41 First in–beam test with STC 4101/02/2010ELI NP Workshop Bucharest 32 keV 11 keV 4.8 keV Symmetric triple cluster Silicon detector experiment performed at IKP of Cologne Position resolution extracted through a comparison to detailed Monte Carlo simulations (FWHM vs. pos. resolution) ~ 5.2 mm

42 New Challenges from the RIB Facilities 01/02/201042ELI NP Workshop Bucharest Neutron rich heavy nuclei (N/Z → 2) Large neutron skins (r -r  → 1fm) Shell quenching 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 Proton drip line and N=Z nuclei Spectroscopy beyond the drip line Proton-neutron pairing Isospin symmetry Nuclear Astrophysics Properties of r and rp process nuclei


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