Implementation of the Implementation of the concept: AGATA/GRETA concept: AGATA/GRETA • Specs • Configurations of 4 π Arrays • Monte Carlo simulations • The detectors • Status
Requirements for a Gamma Tracking Array Requirements for a Gamma Tracking Array efficiency, energy resolution, dynamic range, angular resolution, timing, counting rate, modularity , angular coverage, inner space Target Value Specified for Quantity 50 % E γ = 1 MeV, M γ = 1, β < 0.5 Photo-peak efficiency ( ε ph ) 25 % E γ = 1 MeV, M γ =30, β < 0.5 10 % E γ =10 MeV, M γ = 1 60 - 70 % E γ = 1 MeV, M γ = 1 Peak-to-total ratio (P/T) 40 - 50 % E γ = 1 MeV, M γ = 30 Angular resolution ( Δθ γ ) better than 1 ° for Δ E/E < 1% at large β 3 MHz M γ = 1 Maximum event rates 300 kHz M γ = 30 Inner diameter for ancillary detectors > 34 cm
Building a Geodesic Ball (1) Building a Geodesic Ball (1) Start with a platonic solid On its faces, draw a e.g. an regular pattern of icosahedron triangles grouped as Project the faces hexagons and pentagons. on the enclosing E.g. with 110 hexagons sphere; flatten the and (always) 12 pentagons hexagons.
Building a Geodesic Ball (2) Building a Geodesic Ball (2) Al capsules 0.4 mm spacing 0.8 mm thick Al canning 2.0 mm spacing 1.0 mm thick A radial projection of the spherical tiling generates the shapes of the detectors. Ball with 180 hexagons . Space for encapsulation and canning obtained cutting the Add encapsulation and crystals. In the example, 3 part of the cryostats for crystals form a triple cluster realistic MC simulations
Building a Geodesic Ball (3) Building a Geodesic Ball (3)
Geodesic Tiling of Sphere Geodesic Tiling of Sphere using 60– –240 hexagons and 12 pentagons 240 hexagons and 12 pentagons using 60 60 80 110 120 150 200 240 180
GRETA vs. AGATA GRETA vs. AGATA Ge crystals size: Length 90 mm Diameter 80 mm 120 hexagonal crystals 2 shapes 180 hexagonal crystals 3 shapes 30 quadruple-clusters all equal 60 triple-clusters all equal Inner radius (Ge) 18.5 cm Inner radius (Ge) 23.5 cm Amount of germanium 237 kg Amount of germanium 362 kg Solid angle coverage 81 % Solid angle coverage 82 % 4320 segments 6480 segments Efficiency: 41% (M γ =1) 25% (M γ =30) Efficiency: 43% (M γ =1) 28% (M γ =30) Peak/Total: 57% (M γ =1) 47% (M γ =30) Peak/Total: 58% (M γ =1) 49% (M γ =30)
Expected Performance Expected Performance Response function Absolute efficiency value includes the effects of the tracking algorithms! Values calculated for a source at rest.
Effect of ancillary devices Effect of ancillary devices Absolute photopeak Peak-to-total ratio efficiency (tracking included) (response function) Ancillary devices have an impact comparable to Ancillary devices have an impact comparable to the case of conventional arrays the case of conventional arrays (tracking is “robust”!) (tracking is “robust”!)
The AGATA Demonstrator The AGATA Demonstrator Objective of the final R&D phase 2003- -2008 2008 Objective of the final R&D phase 2003 5 asymmetric triple-clusters 36-fold segmented crystals 555 digital-channels Main issue is Doppler Eff. 3 – 8 % @ M γ = 1 correction capability Eff. 2 – 4 % @ M γ = 30 → coupling to beam and Full EDAQ with on line PSA and γ -ray tracking recoil tracking devices In beam Commissioning First installation site: LNL
AGATA Demonstrator + PRISMA AGATA Demonstrator + PRISMA ps, , Y ~ 350 ps X = 1 mm Δ X = 1 mm t ~ 350 Y = 1 mm Δ Y = 1 mm Y position Δ Y = 2 mm Y = 2 mm Y position Δ t Δ Δ AGATA Δ Δ X Demonstrator Dipole MCP Ion Chamber Quadrupole MWPPAC 195 MeV 195 MeV 36 36 S + S + 208 208 Pb, Pb, θ lab = 80 = 80 o o θ lab Z=28 Z=28 Δ Z ~ 60 for Z=20 Z ~ 60 for Z=20 X position X position First installation site ps < 500 ps E/E < 2% Δ E/E < 2% t < 500 X = 1 mm Δ X = 1 mm for the Demonstrator: .) a.u.) E (a.u the PRISMA Δ E ( Δ t Δ Δ Δ spectrometer at LNL Δ Z=16 Z=16 Z/ Δ Z/ E. Fioretto E. Fioretto INFN - LNL INFN - LNL E ( E (a.u a.u.) .)
From CLARA to AGATA From CLARA to AGATA March 2008 April 2010
Some pictures Some pictures
Some pictures Some pictures
Effect of the recoil velocity Effect of the recoil velocity The comparison between spectra β =20% obtained knowing or not knowing the event-by-event velocity vector shows that additional information will be essential to fully exploit the concept of tracking β (%) 5 20 50 δ s (cm) 1.5 0.5 0.3 2 0.6 0.3 σ dir (degrees) Δ β (%) 2.4 0.7 0.3 Uncertainty on the recoil direction (degrees)
Effect of the recoil velocity Effect of the recoil velocity AGATA Agata Geant4 code + Demonstrator PRISMA simulation + PRISMA 90 Zr recoils with E~350 MeV (with 10% dispersion) assumed. β from reconstructed trajectory length and TOF. Direction from start detector.
Doppler correction capabilities Doppler correction capabilities AGATA AGATA Demonstrator Demonstrator + PRISMA + PRISMA With the Demonstrator it will be possible to increase the detection efficiency of a factor 2 with respect to CLARA, while keeping a good quality of the spectra (essential point for the physics campaign).
Performance Performance Photopeak efficiency P/T Ratio ~14cm: Possible target-detector distance for the Demonstrator on PRISMA 1 MeV photons, point source at rest. Tracking is performed.
Effect of the recoil velocity Effect of the recoil velocity Peak FWHM Photopeak efficiency Typical values for reaction products at PRISMA 1 MeV photons, M γ = 1. Tracking is performed.
AGATA Demonstrator/1 π π AGATA Demonstrator/1 Experimental Program Experimental Program 2010 � LNL 2012 � GSI/FRS 2014 � GANIL/SPIRAL2 5TC ≥ 8TC ~15TC AGATA D. + VAMOS AGATA D.+PRISMA AGATA D. @ FRS + EXOGAM Total Eff. ~6% Total Eff. > 10% Total Eff. > 20%
GRETINA GRETINA Cost 17 M$ (full project including man-power and contingency) 30 36-fold segmented detectors � 10 triple-clusters Start construction 2007 Start operation 2010
AGATA/GRETINA Prototypes 1 AGATA/GRETINA Prototypes 1 Tapered regular hexagonal shape Taper angle 10º Diameter (back) 80 mm Length 90 mm Weight 1.5 kg Outer electrode 36-fold segmented Al encapsulation 0.7 mm (side walls) Encapsulation of crystal in a permanent vacuum is essential for highly segmented Ge detectors Courtesy Canberra-Eurisys
Segmentation of the AGATA detector Segmentation of the AGATA detector Implementation in GEANT4 Pulse Shape Simulations A.Wiens et al. NIMA 618 (2010) 223 Th. Kröll, A. Görgen E.Farnea et al. NIMA 621 (2010)331
AGATA/GRETINA Prototypes 2 AGATA/GRETINA Prototypes 2 Courtesy J.Eberth, IKP Cologne Courtesy I-Yang Lee, LBNL
The GRETINA Module (Prototype I) The GRETINA Module (Prototype I) 3 Ge crystals 111 channels
Asymmetric AGATA Triple Cryostat Asymmetric AGATA Triple Cryostat - integration of 111 high resolution Challenges: spectroscopy channels - mechanical precision - cold FET technology for all signals - heat development, LN2 consumption - microphonics - noise, high frequencies
The first GRETINA Quadruple Cluster The first GRETINA Quadruple Cluster A-type B-type
Structure of Electronics and DAQ Structure of Electronics and DAQ Fast 1 st Level Trigger DIGITIZER PREAMPL. Other Detectors GL Trigger Clock Digital preamplifier concept 100 MHz 200MB/s/ Detector T-Stamp segment Level ATCA Carrier Other detectors GTS GTS PSA Core + FARM 36 seg . HIGH THROUGHTPUT PRE- 100MB/s/ PROCESSING detector CARRIER / MEZZANINES EVENT Control, Global Level TRACKING BUILDER Storage… DAQ-NARVAL Other RUN- & SLOW-Control detectors interface to GTS, merge time-stamped data into event builder, prompt local trigger from digitisers
Data rates in Full- Data rates in Full -AGATA AGATA (300 kHz of M γ = 30 � � 50 kHz singles) 50 kHz singles) (300 kHz of M γ = 30 SEGMENT Local Process. save 600 ns of 200 MB/s pulse rise time + Energy & 100 Ms/s ADC - Classification 14 bits ~ 200 B/segment ~ 10 MB/s GL-Trigger LL-Trigger DETECTOR Suppression / 20 μ s/event E, t, x, y, z,... Compression Pulse 100 B/ev 36+1 � 7.5 kB/event 1.5 ··· 7.5 kB/ev Shape 380 MB/s ~ 100 MB/s 5 MB/s Analysis GLOBAL < 100 MB/s Event γ -ray HL-Trigger , Storage Builder Tracking On Line Analysis 5*n � max. 900 MB/s GL-Trigger to reduce event rate to whatever value PSA will be able to manage
AGATA hybrid charge sensitive preamplifiers AGATA hybrid charge sensitive preamplifiers INFN-Milano, GANIL, IKP-Köln F.Zocca, A.Pullia, G.Pascovici
Mixed reset technique: continuous + pulsed Mixed reset technique: continuous + pulsed Saturated output without Ideal non-saturated pulsed-reset output without pulsed-reset ADC overflow voltage level Preamplifier output with continuous-reset (50 μ s Output with decay time constant) pulsed-reset A pulsed-reset mechanism allows a An ADC overflow condition fast recovery of the output would saturate the system for quiescent value, so minimizing the a long while system dead time F.Zocca, A.Pullia, G.Pascovici INFN-Milano, GANIL, IKP-Köln
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