Development of an Electron-Tracking Compton Camera using CF 4 gas at high pressure for improved detection efficiency Michiaki Takahashi N. Higashi, S. Iwaki, S. Kabuki, H. Kubo, S. Kurosawa, K. Miuchi, K. Nakamura, J. D. Parker, T. Sawano, A. Takada A, T. Tanimori, K. Taniue, and K. Ueno Dept. of Physics, Graduate school of Science, Kyoto University, Kyoto, Japan A ISAS/JAXA, Kanagawa, Japan The Twelfth Vienna Conference on Instrumentation, Vienna, Austria 20 February 2010 Outline Introduction Electron-Tracking Compton Camera (ETCC) Medical imaging / MeV gamma-ray astronomy Optimization of gas mixture Operation at high pressure Summary Electron-Tracking Compton Camera (ETCC) TPC (Time Projection Chamber --- 3D track and energy of Compton-recoil electron Scintillation camera --- position and energy of scattered gamma ray Scintillator PIC GEM e-e- B26 K. Ueno, A22 S. Kurosawa 2 events Determination of direction and energy of each incident gamma ray Large FOV ( 3 sr) 10 cm 400 m pitch anode cathode Proton 10cm Electron Example of 3D track Electric field TPC (Time Projection Chamber) for 3D electron track GEM (Gas Electron Multiplier) (F. Sauli (1997)) + PIC (micro PIxel Chamber) 2D readout micro pattern gaseous detector 2D readout + Drift time 3D track Prototype TPC size : 101010 cm 3 Gas : Ar/C 2 H 6 (90:10) at 1 atm, sealed Position resolution : 150 m (1D) Stable gas gain : ( PIC : 3000, GEM : 10) GSO and LaBr 3 Scintillation Cameras GSO 88 Pixel 13 mm 6 mm 15 x 15 cm 2 Camera (GSO or LaBr 3 + Multi anode PMT (H8500, HPK)) Number of pixels: 576 Pixel size 6613 mm 3 (GSO) 6615 or 20 mm 3 (LaBr 3 ) GSO Energy resolution :10.0 % FWHM) LaBr 3 Energy resolution: 6.5% FWHM) Position resolution: 6mm Black :GSO Red : LaBr3 15 cm 5 cm MeV gamma-ray camera projects Astronomy : Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment (SMILE) 1. SMILE-I (2006, launched) Operation test of km Measurement of diffuse cosmic and atmospheric gamma rays ( 400 photons) 4 hours 2. SMILE-II (2011) Observation of Crab Nebula or Cygnus X-1 3 hours Medical : Advantage point: wide energy dynamic range (300 3000 keV) and wide FOV (SPECT < 300 keV, PET 511 keV) 1. Multi RI Tracer Imaging --- The development of new RI drugs 2. Proton Therapy --- Real time monitor of prompt gamma rays to measure Bragg-peak position Scinti : LaBr 3 Scinti : GSO Energy window : 10% 1004 1228 keV Examples of Medical Imaging Zn-65-Porphyrin imaging (1116 keV) Porphyrin was accumulated in RGK-36 which is the tumor of rat stomach cancer. 60cm 180cm 365 keV (Tumor) 511keV (Brown fat cell) Scinti : LaBr 3 2 sources imaging ETCC for medical use Activity : 0.16 MBq Time : hours Events : 173 events Scintillator TPC Time : 6 hours ETCC/CT Spatial resolution 10 mm (FWHM) Improvement of detection efficiency Optimization of gas Operation at high pressure Increase detection area Multi-head camera (101010 cm 3 2,3,) Developing a large size ETCC (303030 cm 3 ) For High Sensitivity 2 times better than our prototypes Demerit of CF 4 gas Low gas gain isoC 4 H 10 gas (penning effect) High dependence of drift velocity on electric field worse position resolution ? Selection of gas sealed in TPC Merit of CF 4 gas Small diffusion better position resolution (for TPC) better angular resolution (for ETCC) low Z (C : Z=6, F : Z=9) and 42 electrons in one molecule Compton scattering is dominant higher efficiency (for ETCC) Ar/C 2 H 6 (90:10) CF 4 gas mixture Drift Cage 10 cm Optimize the gas mixture Electronics TPC source GEM (SciEnergy) PIC Gas Ar/C 2 H 6 (90:10) Ar CF 4 isoC 4 H 10 Measurement 1.Gas Gain 2.Position Resolution Requirements : High CF 4 ratio Gas Gain 20, cm CF 4 45% CF 4 50% Improved by more than 2 by introducing isoC 4 H 10 This gas GEM = 340V The other GEM = 400V CF 4 20% CF 4 30% CF 4 40% Gas Gain at 1 atm Penning effect of isoC 4 H 10 = 162 m D = 81 m/cm 1/2 Ar/CF 4 /isoC 4 H 10 (54:40:6) muon tracks = 156 m D = 175 m/cm 1/2 Better by factor 2 l : Drift length D : Diffusion Constant Position Resolution Ar/C 2 H 6 (90:10) Ar/C 2 H 6 (90:10) at 1 atm Ar/C 2 H 6 (90:10) at 2 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1.4 atm Measurement 1.Gas Gain 2.Drift Velocity 3.Position Resolution 4.Energy Resolution High Pressure 100 mm 2 mm 100 mt GEM 2 mm 100 mm 50 mt GEM PIC Drift Plane (Al Mylar) Electronics TPC source Gas Gain Upper GEM = 350V Lower GEM = 250V Upper GEM = 460V Lower GEM = 360V Upper GEM = 500V Lower GEM = 380V Upper GEM = 610V Lower GEM = 450V Lower gas gain Drift Velocity Difference between simulation and measurement is smaller than 10% Position Resolution Ar/C 2 H 6 (90:10) at 1 atm Ar/C 2 H 6 (90:10) at 2 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1.4 atm = 332 m, D = 246 m/cm 1/2 = 302 m, D = 204 m/cm 1/2 = 378 m, D = 147 m/cm 1/2 = 330 m, D = 128 m/cm 1/2 Better by factor 2 Better by factor 1.6 Energy Resolution 31 keV X-ray from 133 Ba (31 keV) Ar/C 2 H 6 (90:10) at 1 atmAr/C 2 H 6 (90:10) at 2 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1 atm Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1.4 atm 43.8% keV 53.1% keV 56.1% keV 60.0% keV Worse than prototype Imaging with ETCC gamma-ray from 133 Ba (356 keV, 800 kBq) Electronics TPC source GSO Scintillation Camera Measurement 1.Efficiency 2.Angular resolution (ARM and SPD) 15 cm ARM : Angular Resolution Measure SPD : Scatter Plane Deviation Efficiency and Angular Resolution ( 133 Ba 356 keV) GasPressureEfficiencyARM (FWHM)SPD (FWHM) Ar/C 2 H 6 (90:10)1 atm 1.81 114.8 Ar/C 2 H 6 (90:10)2 atm 3.55 105.1 Ar/CF 4 /isoC 4 H 10 (54:40:6)1 atm 2.44 117.9 Ar/CF 4 /isoC 4 H 10 (54:40:6)1.4 atm 3.51 119.1 ARM (FWHM) [degree] SMILE-I 2006 (Xe + GSO) Ar/C 2 H 6 TPC + GSO scintillator the highest spec. This Work (GSO) Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1.4 atm Imaging of 133 Ba 15 cm away from top of TPC better by factor 1.94 Ar/C 2 H 6 TPC + LaBr 3 scintillator Summary In order to improve the efficiency of the ETCC, we have optimized the gas mixture and pressure sealed in the TPC. The highest ratio of CF 4 gas with steady gas gain of 20,000 is Ar/CF 4 /isoC 4 H 10 (54:40:6). The diffusion constant of Ar/CF 4 /isoC 4 H 10 (54:40:6) is 2 times better than that of Ar/C 2 H 6 (90:10), so the position resolution is improved. The efficiency for the ETCC using Ar/CF 4 /isoC 4 H 10 (54:40:6) at 1.4 atm is 2 times higher than that using Ar/C 2 H 6 (90:10) at 1 atm, and those ARMs are comparable ( 11 at 356 keV (FWHM)). Thank you for your attention Vs. Conventional Compton Camera Advanced Conventional Reconstruction : circle Direction error region : donut DO NOT measure the track of a Recoil electron 150 events 600 events X [cm] Y [cm] X [cm] 15 Y [cm] 137 Cs(1MBq) 2, Classical Compton 137 Cs(1MBq) 2, Advanced Compton Measure the 3-D track of a Recoil electron Reconstruction : point Direction error region: arc COMPTEL Our ETCC Position-Sensitive Scintillation Camera 13mm 6 mm 5cm Multi-anode Photo Multiplier Tube (PMT) HPK H8500 8x8 anodes GSO(Ce) 8x8 pixels Pixel size: 6x6x13mm 3 5cm X-position (a. u.) Y-position (a. u) Counts (a. u.) 2-D image in flood-field irradiation 137 Cs Dynamic energy range: MeV Eng. Resolution: 10.5 keV Assembly of LaBr 3 (Ce) array 6.1 mm pitch Using our technique, we assembled an 8 8 array. 54mm 20mm (=multi-anode PMT H8500 anode pitch) GSO array LaBr 3 array LaBr 3 FWHM(%)= (5.7 0.4) (E/662keV) 0.01 GSO FWHM(%)= (10.4 0.3) (E/662keV) 0.01 LaBr 3 hygroscopic Hermetic package GSO monolithic LaBr 3 monolithic 133 Ba E/E = 4.1 keV (FWHM) Angular Res. Simulation including TPC Scattered E : energy Recoil e - K: energy Scattering angle Incident Angular resolution (ARM) Calculated assuming 1, no error in position of Compton point 2, energy Res. of TPC : keV Eng. Res. (FWHM) of LaBr 3 (Ce) : ~ keV Loef et al. (2001) Doppler broadening (Ar) Zoglauer et al. (2003) Angular resolution (FWHM) [degree] 10.5 % 4.2 7% 3.1 5% 2.3 3% 2.1 Sci. Eng. ETCC. Angular Energy Dynamic Range Ce- 139 Cr- 51 Ba- 133 I- 131 Au- 198 Na- 22 F- 18 Cu- 64 Cs- 137 Mn- 54 Fe- 59 Zn- 65 Co- 60 Ener gy [keV] , , , 1333 Energy dynamic range : 167 1333 keV. Measured sources SPECTPET 26 Spatial resolution vs. Energy Goal : Same resolution as human 511keV Spatial Resolution 27 I-131-MIBG & F-18-FDG imaging (365 & 511 keV) PET/SPECT/CT Rainbow PET Orange SPECT Rainbow 511keV Orange 365keV PC12 Brown fat cell PC12 Brown fat cell 6cm Dept. of Bioanalysis, Kyoto University H. Kimura, H. Amano and H. Saji Scinti : LaBr 3 Zn-65 mouse imaging Measurement after dissection Liver :0.04 MBq Spleen :0.02 Pancreas:0.02 Heart :0.02 Stomach : 0.01 Kidney : 0.00 Intestinal:0.11 Brain :0.02 Other :0.79 BG :0.03 Mouse Zn-65 imaging Energy : 1116keV activity : 1.4MBq obs. time : 2784 min Events : 629 events 3x3 LaBr 3 Install to 10cm-ETCC Zn is a good tracer for diabetes All kinds of experiment gas (45 types) No. Gas 1CF 4 /isoC 4 H 10 (95:5) 2CF 4 /isoC 4 H 10 (90:10) 3CF 4 /isoC 4 H 10 (80:20) 4Ar/C 2 H 6 (90:10) 5Ar/C 2 H 6 /CF 4 (72:8:10) 6Ar/C 2 H 6 /CF 4 /isoC 4 H 10 (69.3:7.7:20:3) 7Ar/C 2 H 6 /CF 4 (63:7:30) 8Ar/C 2 H 6 /CF 4 (54:6:40) 9Ar/C 2 H 6 /CF 4 (45:5:50) 10Ar/C 2 H 6 /CF 4 /isoC 4 H 10 (42.3:4.7:50:3) 11Ar/C 2 H 6 /CF 4 (27:3:70) 12Ar/CF 4 /isoC 4 H 10 (95:3:2) 13Ar/isoC 4 H 10 (90:10) 14Ar/CF 4 (90:10) 15Ar/CF 4 (80:20) No. Gas 31Ar/CF 4 /isoC 4 H 10 (64:30:6) 32Ar/CF 4 /isoC 4 H 10 (63:30:7) 33Ar/CF 4 /isoC 4 H 10 (56:40:4) 34Ar/CF 4 /isoC 4 H 10 (55:40:5) 35Ar/CF 4 /isoC 4 H 10 (54:40:6) 36Ar/CF 4 /isoC 4 H 10 (53:40:7) 37Ar/CF 4 /isoC 4 H 10 (52:40:8) 38Ar/CF 4 /isoC 4 H 10 (49:45:6) 39Ar/CF 4 /isoC 4 H 10 (47:50:3) 40Ar/CF 4 /isoC 4 H 10 (46:50:4) 41Ar/CF 4 /isoC 4 H 10 (45:50:5) 42Ar/CF 4 /isoC 4 H 10 (44:50:6) 43Ar/CF 4 /isoC 4 H 10 (43:50:7) 44Ar/CF 4 /isoC 4 H 10 (42:50:8) 45Ar/CF 4 /isoC 4 H 10 (40:50:10) No. Gas 16Ar/CF 4 /isoC 4 H 10 (78:20:2) 17Ar/CF 4 /isoC 4 H 10 (77:20:3) 18Ar/CF 4 /isoC 4 H 10 (76:20:4) 19Ar/CF 4 /isoC 4 H 10 (75:20:5) 20Ar/CF 4 /isoC 4 H 10 (74:20:6) 21Ar/CF 4 /isoC 4 H 10 (73:20:7) 22Ar/CF 4 /isoC 4 H 10 (72:20:8) 23Ar/CF 4 /isoC 4 H 10 (73:25:2) 24Ar/CF 4 /isoC 4 H 10 (72:25:3) 25Ar/CF 4 /isoC 4 H 10 (71:25:4) 26Ar/CF 4 /isoC 4 H 10 (70:25:5) 27Ar/CF 4 /isoC 4 H 10 (69:25:6) 28Ar/CF 4 /isoC 4 H 10 (67:30:3) 29Ar/CF 4 /isoC 4 H 10 (66:30:4) 30Ar/CF 4 /isoC 4 H 10 (65:30:5) CF 4 base Ar/C 2 H 6 (90:10) base Fixing CF 4 ratio changing Ar and isoC 4 H 10 ratio -PIC : 2-D gaseous detector 10cm Size: 10 cm x 10 cm Pixel pitch: 400 m ~ 65,000 pixels Gas gain: ~6,000 (stable operation of more than 1 month) 400m pitch anode cathode Cu -PIC : gain and Energy spectrum Gas gain uniformity RMS ~ 7% Energy spectrum ( 55 Fe) E/E 5.9 keV Ar-escape Energy [keV] We filled with Ar(90%) + C 2 H 6 (10%) gas at 1atm X-ray imaging with -PIC Test chart image Position resolution: 120 m AMP-Discri. Board Based on a chip for ATLAS Thin Gap Chamber 0.8V/pC 1 mm Proton Therapy 150MeV proton 200MeV Depth in Tissue (water) [mm] Attack on Cancerous cells proton Gamma rays neutron Water phantom Simulation study ETCC : ability to detect Prompt gamma rays as the monitor Wide energy range ( MeV) Rejection of Neutron Wide field of view (~3 str.) 511keV 2.2MeV Gamma rays neutron Simulation Monitoring Before treatment: ionization chamber After treatment: PET technique (PET: positron emission tomography) Real time : none We are developing a monitor for Proton Therapy 160 MeV Proton Water Phantom ETCC (10cm) 3 TPC 30cm Experiment in Osaka Univ. Research Center for Nuclear Physics (RCNP) collaborator : J. Kim (Research Institute and Hospital, National Cancer Center, Korea) Sensitivity in X / Gamma-ray Astronomy ba d good 1mCrab EGRET Air Cherenkov Fermi suzaku HXD continuous sensitivity [erg/cm 2 /sec] energy [eV] Our goal keVGeVTeVMeV Energy spectrum diffuse cosmic rays atmospheric rays SMILE-1 Previous results [Energy] Flux [photons / (cm 2 sec str keV)] SMILE-1 Previous results Flux [photons / (cm 2 sec str keV (g / cm 2 ))] [Energy] We detected 420 photons MeV, km for 4 hours