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Advanced GAmma Tracking Array Performance of an AGATA prototype detector estimated by Compton-imaging techniques Francesco Recchia INFN - Legnaro on behalf.

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Presentation on theme: "Advanced GAmma Tracking Array Performance of an AGATA prototype detector estimated by Compton-imaging techniques Francesco Recchia INFN - Legnaro on behalf."— Presentation transcript:

1 Advanced GAmma Tracking Array Performance of an AGATA prototype detector estimated by Compton-imaging techniques Francesco Recchia INFN - Legnaro on behalf of the AGATA collaboration

2  180 large volume 36-fold segmented Ge crystals packed in 60 triple-clusters  Digital electronics and sophisticated Pulse Shape Analysis algorithms  Operation of Ge detectors in position sensitive mode for  -ray tracking Efficiency: 43% (M  =1) 28% (M  =30) today’s arrays ~10% 5% Peak/Total: 58% (M  =1) 49% (M  =30) today ~55% 40% Angular Resolution: ~1º FWHM (1 MeV, v/c=50%) ~ 6 keV today ~40 keV Design values: 5 mm of position resolution assumed Triple cluster R int = 23 cm R ext = 32 cm The  -ray spectrometer AGATA 180 HPGe

3 Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors · · Identified interaction points (x,y,z,E) i Reconstruction of scattering sequence from Compton vertices Digital electronics to record and process segment signals Reconstructed gamma-rays gamma-rays · · · · · · · ·  Ingredients of  -ray tracking

4 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,10,46) measured (10,30,46)

5 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,10,46) measured calculated

6 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,15,46) measured calculated

7 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,20,46) measured calculated

8 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,25,46) measured calculated

9 Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,30,46) measured calculated

10 Result of Grid Search algorithm Pulse Shape Analysis concept B4B5B3 C4C5C3 CORE A4A5A3 C4 D4 E4 F4 A4 B4 x y z = 46 mm 791 keV deposited in segment B4 (10,25,46) measured calculated

11 A test-beam experiment has been performed to measure this parameter in realistic experimental conditions Simulations suggest that the overall performance depends on the attainable position resolution The position resolution required for the AGATA detectors

12 Setup of the in-beam experiment BEAM 48 Ti100 MeV TARGET 48 Ti + 2 H220 μg/cm 2 Si detector DSSSD Thickness: 300 μm 32 rings, 64 sectors AGATA symmetric triple-cluster d( 48 Ti, 49 Ti)p Symmetric triple cluster Silicon detector Digitizers: 30 XIA DGF 4c cards 40MHz14 bit experiment performed at IKP of Cologne

13 Doppler correction using PSA results Full statistics used 32 keV

14 Doppler correction using PSA results Full statistics used 32 keV 11 keV

15 Doppler correction using PSA results Full statistics used PSA algorithm: Grid Search 32 keV 11 keV 4.8 keV

16 Simulation vs Experiment Grid Search Recursive Subtraction Matrix Method Results obtained with different PSA algorithm Miniball Algorithm

17 Why Compton imaging?  15 days of beam-time to perform the test experiment  1 year of analysis  PSA will be on-line  Need for a simpler procedure  Need an prompt feed-back from on-line analysis

18 Compton imaging  In-beam experiment: typical conditions of future use  Compton imaging of a radioactive source inverse tracking  E1E1 E2E2 target  E1E1 E2E2  -source

19 Compton imaging performance Error on Compton identification of source direction from:  Position resolution (axis)  Energy resolution (scattering angle)  Compton profile (scattering angle) scattering angle [deg] angular error [deg]

20 Imaging setup at LNL AGATA prototype detector TNT2 Digitizers: 4ch 14bit 100MHz 60 Co source

21 Outline of analysis/simulation Event selection PSA Position resolution DAQ Event selection Smearing (position resolution) Image formation MC Image formation

22 Comparison to simulation E E,p MC + E res + pos resExp MC + E res MC ≈ ≈ Simple back-projections

23 Comparison to MC simulation  profile of experimental image Monte Carlo + 5 mm position resolution  profile of experimental image Experiment  [deg]  [deg]  [deg]  [deg] peak FWHM  [deg] position resolution FWHM  [mm]

24 CONCLUSIONS  Position resolution extracted by in-beam experiment and Compton imaging 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 huge impact on nuclear structure studies (first phase of AGATA: LNL 2009…)  Possible applications of  -ray tracking detectors to imaging.

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28 Basic implementation of LMML

29 Requirements to the next generation  -ray spectrometer AGATA is the next generation  -ray spectrometer which will be used at radioactive ion beam facilities:  High efficiency and P/T ratio.  Capability to stand a high counting rate.  Good position resolution on the individual  interactions in order to perform a good Doppler correction and measure the linear polarization

30 Compton imaging application


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