Nuclear Physics and imaging in Medical, Security and Environmental applications

Transcription

1 Nuclear Physics and imaging in Medical, Security and Environmental applications Andy Boston

2 Overview of presentation We are utilising segmented HPGe & CZT for Nuclear Structure Physics & Gamma-ray imaging applications: Nuclear Physics: AGATA Medical Imaging: SmartPET/ProSPECTus Environmental/Decommissioning: PorGamRayS Explosives/Drugs: Distinguish (Ge/CsI) Hostile environment: GammaKEV Energies 60 kev 10 MeV

3 What are the requirements? Ideally would want: Good energy resolution (Good light yield/charge collection) < few% High efficiency (High Z) Good position resolution (in some applications) Timing resolution Detector materials: Semiconductors (Si, Ge, CdZnTe) Scintillators (LaBr 3, CsI(Tl), NaI(Tl), BaFl)

4 AGATA (Advanced GAmma Tracking Array) 4π γ-array for Nuclear Physics Experiments at European accelerators providing radioactive and high-intensity stable beams Main features of AGATA Efficiency: 43% (M γ =1) 28% (M γ =30) today s arrays ~10% (gain ~4) 5% (gain ~1000) Peak/Total: 58% (M γ =1) 49% (M γ =30) today ~55% 40% Angular Resolution: ~1º FWHM (1 MeV, v/c=50%) ~ 6 kev!!! today ~40 kev Rates: 3 MHz (M γ =1) 300 khz (M γ =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 γ-ray tracking

5 AGATA 1 st symmetric capsule

6 Ingredients of γ-tracking γ AGATA detector characterisation Highly segmented HPGe detectors 1 Digital electronics to record and process segment signals Identified interaction points (x,y,z,e,t) i Pulse Shape Analysis to decompose recorded waves Reconstruction of tracks e.g. by evaluation of permutations of interaction points 3 e e 3 1 θ Eγ 1 Eγ Eγ 1 θ 2 e 2 reconstructed γ-rays

7 Detector Characterisation and PSA Calibrate detector response function Comparison of real and calculated pulse shapes Coincidence scan for 3D position determination Validate codes How well your basis fits your real data

8 AGATA detector scanning AGATA PSD8 Glasgow

9 Azimuthal detector sensitivity r = 24mm z = 7.3mm θ = o F1 A1 E1 B1 D1 0 o C1

10 Experiment vs Theory Performance

11 Medical Imaging Applications

12 Double Sided HPGe Strip Detectors SmartPET detectors o 60mm x 60mm x 20mm active area o 7mm x 20mm guard ring o 12 x 12 orthogonal strips - 5mm pitch - 5mm x 5mm x 20mm voxels o 1mm Aluminium entrance window o Thin contact technology o Fast charge sensitive preamplifiers Energy resolution: 1.5 kev@122 kev & 3.25keV FWHM at 511keV Intrinsic photopeak efficiency 19% at 511keV

13 Am-241 AC x-y surface intensity distribution AC01 AC12 DC12 DC1 The results are presented for 60 kev with 2 minutes of data per position.

14 SmartPET detector depth response superpulse pulse shapes for 137 Cs events versus depth DC signals AC signals DC signals AC signals

15 Position Sensitivity Image charge asymmetry varies as a function of lateral interaction position - Calibration of asymmetry response Asymmetry = Area Area left left + Area Area right right 700 AC AC AC AC AC07 Magnitude (kev) Time (ns) Time (ns) e h Time (ns) Time (ns) Time (ns)

16 The SmartPET System Detector Separation 130mm Absolute PET Sensitivity 0.99% (CFOV point source)

17 Point Source Imaging Three 22 Na point source have been imaged with the SmartPET system 60mm 60mm From MLEM reconstruction the point sources display FHWM of ~1.4mm Over 60% of events processed

18 Compton Imaging 10µCi 152 Eu 60mm from SPET1 Source rotated Zero degrees in 15º steps up to 60º Detector separation 3 11cm in 2cm steps Gates set on energies 779, 1408keV 2 22 Na sources at different x and y

19 Research : Compton Imaging o Compton Cones of Response projected into image space γ Φ E 1 E 2 cosφ = 1 m e c E E 1 + E 2

20 Research : Compton Imaging o Compton Cones of Response projected into image space γ Φ E 1 E 2 cosφ = 1 m e c E E 1 + E 2

21 Research : Compton Imaging o Compton Cones of Response projected into image space γ Φ E 1 E 2 cosφ = 1 m e c E E 1 + E 2

22 Research : Compton Imaging o Compton Cones of Response projected into image space γ Φ E 1 E 2 cosφ = 1 m e c E E 1 + E 2

23 Research : Compton Imaging o Compton Cones of Response projected into image space γ Φ E 1 E 2 cosφ = 1 m e c E E 1 + E 2

24 Imaging Progress : Compton Camera 152 Eu point source imaging. 30 kev gate on 1408 kev. 30mm detector separation with 1.6mm position resolution. Single interactions in each detector. Cone beam reconstruction with 10 iterations. ~8mm image resolution x-y. 3 cm crystal to crystal 6 cm source to crystal

25 Compton Imaging with SmartPET Compton Imaging 2D Imaging ~7 º Angular Resolution Multi-nuclide imaging 152 Eu 22 Na 152 Eu 2cm source separation

26 ProSPECTus Next generation Single Photon Emission Computed Tomography Nuclear Physics Group, Dept of Physics, University of Liverpool, Nuclear Physics & Technology Groups, STFC Daresbury Laboratory, MARIARC & Royal Liverpool University NHS Trust, CCO NHS Foundation Trust

27 ProSPECTus: What is new? ProSPECTus is a Compton Imager Radical change No mechanical collimator Utilising semiconductor sensors Segmented technology and existing electronics Position resolution 7-10mm 2-3mm Sensitivity factor ~100 larger Simultaneous SPECT/MRI

28 PorGamRayS The PorGamRayS project is developing a portable gamma-ray spectrometer with Compton imaging capability (60keV 2MeV) Gamma-ray spectroscopy/imaging with CZT detectors. Pulse Shape Analysis to refine spatial resolution and correct charge collection issues

29 CZT + Nucam2 4 CZT detectors bonded to daughter boards by RAL

30 PorGamRayS perfromance

31 PorGamRayS perfromance 344 kev transition with a 20 kev gate 40mm move 20mm FWHM from BP algorithm.

32 Summary of presentation We are utilising segmented HPGe & CZT for Nuclear Structure Physics & Gamma-ray imaging applications: Nuclear Physics: AGATA Medical Imaging: SmartPET/ProSPECTus Environmental/Decommissioning: PorGamRayS Explosives/Drugs: Distinguish (Ge/CsI) Hostile environment: GammaKEV Energies 60 kev 10 MeV

33 Credit where it s due A.J. Boston a, H.C. Boston a, R.J. Cooper a, D.M. Cullen c, M.R. Dimmock a, A.N. Grint a, L.J. Harkness a, I. H. Lazarus b, M. Jones a, P.J. Nolan a, D.C. Oxley a, J. Simpson b, M. Slee a, A. Sweeney a and C. Unsworth a. a Department of Physics, University of Liverpool, L69 7ZE, UK b STFC Daresbury Laboratory, Daresbury, WA4 4AD, UK c Department of Physics and Astronomy, University of Manchester, UK