advanced gamma tracking array agata
DESCRIPTION
Advanced Gamma Tracking Array AGATA . Dino Bazzacco INFN Padova On behalf of the AGATA Collaboration. AGATA. 180 hexagonal crystals 3 shapes 60 triple-clusters all equal Inner radius ( Ge ) 23.5 cm Amount of germanium 362 kg Solid angle coverage 82 % - PowerPoint PPT PresentationTRANSCRIPT
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Advanced Gamma Tracking Array AGATA
Dino BazzaccoINFN Padova
On behalf of the AGATA Collaboration
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180 hexagonal crystals 3 shapes 60 triple-clusters all equalInner radius (Ge) 23.5 cmAmount of germanium 362 kgSolid angle coverage 82 %36-fold segmentation 6480 segmentsSingles rate ~50 kHz
Efficiency: 43% (Mg=1) 28% (Mg=30)Peak/Total: 58% (Mg=1) 49% (Mg=30)
AGATA
6660 high-resolution digital electronics channels Detectors operated in position-sensitive mode Digital EDAQ + Pulse Shape Analysis + g-ray TrackingCoupling to ancillary detectors for added selectivity
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AGATAConventional array
Segmented detectors
g-ray tracking
Energy (keV)
Using the detectors in position-sensitive modewill provide very high efficiency and excellent energy resolution , making AGATA ideal for spectroscopic studies of weak channels
Effective energy resolution maintained at “extreme” v/c
v/c = 50%
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Mg = 30
MC simulation of a high-multiplicity event Efficiency depends on position resolution
Reconstruction of 0.1÷10 MeV gammas
Position resolution (FWHM, mm)
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
791 keV deposited in segment B4
measured
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,10,46)
measuredcalculated
791 keV deposited in segment B4
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,15,46)
measuredcalculated
791 keV deposited in segment B4
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,20,46)
measuredcalculated
791 keV deposited in segment B4
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,25,46)
measuredcalculated
791 keV deposited in segment B4
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Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,30,46)
measuredcalculated
791 keV deposited in segment B4
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Result of Grid SearchAlgorithm
Pulse Shape Analysis concept
B4 B5B3
C4 C5C3
CORE
A4 A5A3
C4
D4
E4 F4
A4
B4
x
y
z = 46 mm
(10,25,46)
measuredcalculated
791 keV deposited in segment B4
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Examples of signal decomposition
A B C D E F CC
Eg = 1172 keV net-charge in A1
Eg = 1332 keV net-charge in C3, E1, E3
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Status after more than 10 years of R&D
Germanium detectors Pulse Shape Analysis Gamma-ray Tracking AGATA Demonstrator Electronics and DAQ Problems encountered Performance Experiments Evolution
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AGATA Crystals
Volume ~370 cc Weight ~2 kg(the 3 shapes are volume-equalized to 1%)
80 mm
90 mm
6x6 segmented cathode
Manufactured byCanberra France
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Asymmetric AGATA Triple CryostatChallenges: - mechanical precision - heat development, LN2 consumption - microphony, noise, high frequencies
- integration of 111 high resolution spectroscopy channels- cold FET technology for all signals
A. Wiens et al. NIM A 618 (2010) 223–233D. Lersch et al. NIM A 640(2011) 133-138
Energy resolution at 1332 keVCore: 2.4 keV Segments: 2.1 keV
Manufactured by CTT
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The AGATA Demonstrator Objective of the R&D phase 2003-2009
Used for Physics at LNL in 2010-20115 asymmetric triple-clusters
15 36-fold segmented crystals
540 segments555 high-resolution digital-
channelsEff. 3 – 8 % @ Mg = 1Eff. 2 – 4 % @ Mg = 30
Real time operation Pulse Shape Analysis g-ray TrackingHosting sitesLNL
2009-2011GSI
2012-2013GANIL 2014
S. Akkoyun et al. NIM A 668 (2012) 26–58A. Gadea et al. NIM A 654 (2011) 88-96
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AGATA Demonstrator + PRISMAinfrastructure at completed mid 2009, all clusters in place May 2011
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AGATA: Structure of Electronics and DAQ
TRACKINGControl,
Storage…EVENT
BUILDER
GL TriggerClock
100 MHzT-Stamp
Other detectors
Fast 1st Level Trigger
DetectorLevel
Other Detectors
GTS
DIGITIZERPREAMPL.
Global LevelDAQ-NARVALRUN- & SLOW-Control
High throughput pre-processingFor one crystal:2 ATCA carriers 1 GTS + 7 processing mezzanines
Other detectors:interface to GTS, merge time-stamped data into event builder, prompt local trigger from digitisers
Digital preamplifier concept
100MB/s/detector
200MB/s/seg.
GTS
Processing
Processing
Processing
PSA farm
Core +36 segments
LAN
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GTS : the system coordinatorAll detectors operated on the same 100 MHz clock
Downwards 100 MHz clock + 48 bit Timestamp (updated every 16 clock cycles)Upwards trigger requests, consisting of address (8 bit) and timestamp (16 bit)
max request rate 10 MHz total, 1 MHz/detectorDownwards validations/rejections, consisting of request + event number (24 bit)
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Some important issues
• Cross talk among the channels of one crystal• Need to run at very high counting rates• Neutron damage and degradation of energy
resolution of the segments• Annealing of crystals to restore the original
energy resolution is a delicate procedure
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Sum of segment Energies vs fold
• Crosstalk is present in any segmented detector• Creates strong energy shifts proportional to
fold• Tracking needs segment energies !
Crosstalk
Segment sum energies projected on fold2-folds : centroid of Core and Segment-sum
…all 1260 possible 2-fold combinations
Ener
gy [k
eV]
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Cross talk correction: Results
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High counting rate• The detection efficiency of AGATA is, so far, provided by a
small number of crystals. Experiments want to collect big statistics and push for running at high singles counting rates.
• Thanks to digital signal processing, we can work in conditions impossible with conventional electronics.
• Under these «extreme» conditions, the performance of the detectors is still acceptable.
• A limit exists, due to pileup of the signals which exhaust the dynamical range of the FADC. Counteract this by reducing the gain of the preamplifiers but then energy resolution worse also at low counting rate.
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Singles rates and shaping time6 different rates x 4 trapezoid risetimes x 6 BLR lengths
Two independent sources of dead-time: pile-up rejector and GTS
60Co - fixed
137Cs – 6 positions Francesco Recchia, Padova
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Neutron damage: shape of the 1332 keV line
Blue: April 2010 FWHM(core) ~2.3 keV FWHM(segments) ~2.0 keVRed: July 2010 FWHM(core) ~2.4 keV FWHM(segments) ~3 keVDamage after 3 high counting-rate experiments (3 weeks of beam at 30-80 kHz singles)Worsening seen in most of the detectors; more severe on the forward crystals;segments are the most affected, cores almost unchanged (as expected for n-type HPGe)
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Crystal C002
The 1332 keV peak as a function of crystall depth (z) for interactions at r = 15mm
The charge loss due to neutron damage is proportional to the path length to the electrodes. The position is provided by the PSA (which is barely affected by the amplitude loss).
corrected
Knowing the path, the charge trapping can be modeled and corrected away (Bart Bruyneel, IKP Köln)
CCr=15mm
SGr=15mm
April 2010
CCr=15mm
SGr=15mm
July 2010
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Energy resolution at the end of the LNL campaignBefore and After charge-trapping correction
CoreSum of 15 spectra
SegmentsSum of 15*36=540 spectraFWHM 5.5 keV 2.9 keVFWTM 15.5 keV 6.8 keV
FWHM 3.2 keV 2.8 keVFWTM 7.2 keV 5.6 keV
Undamaged detectors: FWHM ~2.5 keV, FWTM ~4.8 keVEg (keV)
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Performance of the AGATA Demonstrator
Just a few examples
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Doppler correction usingcenter of crystalsFWHM ~20 keV
Detector FWHM = 2.2 keV
Doppler correction using center of hit segmentsFWHM = 7 keV
Doppler Correction Capability, “small” v/c220 MeV 56Fe 197Au (ATC1 + DANTE, July 2009)
Doppler correction using PSA (AGS) and trackingFWHM = 3.5 keV(3.2 keV using only single hits)
Eg (keV)
v/c 8%E(2+) = 846.8 keV
56Fe 2+ 0+
846.8 keV56Fe 4+ 2+
1238.3 keV4.8 keV FWHM
Au recoils also seen by Dante
OriginalCorrected
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Doppler Correction Capability, “large” v/cinelastic scattering 17O @ 20 MeV/u on 208Pb
FO
N
C
B
Be
a
Li
No Doppler Corr.Crystal CentersSegment CentersPSA+Tracking
16O
TKE (MeV)
dE (M
eV)
Fabio Crespi, Milano
v/c 20%
Charged particles detected in TRACE
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gg capabilities 135 MeV 32S 110Pd (6 AGATA crystals only)
138Sm6 gates on:347keV,545keV,686keV,775keV,552keV,357keV
871 keV 22+ - 20+
The performance of AGATA using g-ray tracking is comparable to conventional arrays with a much larger number of crystals
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Imaging of Eg=1332 keV gamma rays AGATA used as a big Compton Camera
Francesco Recchia
Far Field Backprojection
Near Field Backprojection
All 9 detectors One detector
All 9 detectors One detector20
111cos cmEE
gg
Source at 51 cm Dx ~Dy ~2 mm Dz ~2 cm
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neutrons
pro
tons
Neutron drip-line
Lifetime of the 6.792MeV state in 15O
n-rich nuclei
Lifetimes in n-rich Ni, Cu and Zn isotopes
Lifetimes of the
n-rich Cr isotopesLifetimes near
the island of inversion
The Experimental Campaign at LNL
Pygmy and GQR states
Neutron-rich nuclei populated by fission
N=51 nuclei
Lifetimeof 136Te
Neutron-rich nuclei in the vicinity of 208Pb
Proton drip-line
Molecular structure of 21Ne
Coulexof 42Ca
Isospin Mixingin 80Zr
Octupole-deformedRa and Th nuclei
Shape transition in 196Os
N=84 isotone 140Ba
n-rich Th and U
g.s. rotationin Dy, Er, Yb
High-lying statesin 124Sn and 140Ce
20 exp.148 days
Order-to-chaos
transition in 174W
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LNL: 2010-20115 TCTotal Eff. ~6%
GSI: 2012-2013≥ 5 TC + 5 DC Total Eff.~10%
GANIL: 2014-201515 TCTotal Eff. ~15%
AGATA+VAMOS
From the Demonstrator to AGATA 1πPlans for the next few years
AGATA D.+PRISMA AGATA + FRS
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Status of AGATA at GSI
Mechanics & detector support infrastructure
7 crystals (2 DC, 1 TC) used in the 3rd commissioning test (May 23-28). more detectors added in the next few months.
Electronics and DAQ ready for 15 crystals Second batch of electronics modules under
test to instrument the up 25 crystals. Coupling to FRS, LYCCA, HECTOR done.
First experiments Q4 2012
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The AGATA Collaboration
Bulgaria: SofiaFinland: JyväskyläFrance: GANIL, Grenoble, Lyon, Orsay, Saclay, StrasbourgGermany: Darmstadt, GSI, Köln, MünchenItaly: Firenze, LNL, Milano, PadovaPoland: Krakow, WarsawRomania: BucharestSpain: Valencia, Madrid, SalamancaSweden: Göteborg, Lund, Stockholm, UppsalaTurkey: Ankara, IstanbulUK: Brighton, Daresbury, Edinburgh, Liverpool,
Manchester, Paisley, Surrey, York
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First implementations of the g-ray tracking array concept
AGATA Demonstrator GRETINA
15 crystals in 5 Triple ClustersCommissioned in 2009 at LNL (with 3 TC)Experiments at LNL in 2010-2011Being reinstalled and expanded at GSI
28 crystals in 7 Quadruple ClustersEngineering runs started early 2011 at LBNLExperiments at LBNL in 2011Being reinstalled at NSCL