1. 3D Position Sensitive CdZnTe Spectrometers Using 3 rd -Generation VAS/TAT Readout Electronics Feng Zhang, Zhong He, Glenn F. Knoll, David K. Wehe, James E. Berry Department of Nuclear Engineering and Radiological Sciences The University of Michigan Acknowledgements Department of Energy, NA-22 Office

2. What is a 3-dimensional position sensitive semiconductor detector? (  E,x,y,z) 1 (  E,x,y,z) 2 (  E,x,y,z) 3 Incident radiation ( , charge particle, etc.)

3. How to achieve 3-D position sensing?  x y 1.27 mm pitch

4. Second generation 3-D CdZnTe detectors can provide (E,x,y,z) i of multiple  -ray interactions Time  t 2  z 2 C a1a2  t 1  z 1 Triggers ……

5. System configuration DAQ card 68 pole cable with SCSI II connectors +5V,-5V power supply VA MCR 3 controller card 4VASTAT II multi-chip-module and detector 50 pole cable with ERNI and SCSI II connectors eV-Products (2001) Ideas ASA

6. Energy spectrum of 137 Cs from single-pixel events (Detector #2.2, from entire 1.5×1.5×1.0 cm 3 volume) (V C = -2200 V; V G = -60 V; Time = 40 h; uncollimated source; room temperature) After correction for gain variation between channels, temperature shift, effects of electron trapping, weighting potential and non-linearity of ASIC 137 Cs 32 keV K x-ray FWHM = 0.93% (6.16 keV) 662 keV

7. Energy spectrum of 137 Cs from single-pixel events (Detector #2.3, from entire 1.5×1.5×1.0 cm 3 volume) (V C = -1400 V; V G = -45 V; Time = 40 h; uncollimated source; room temperature) 137 Cs 32 keV K x-ray FWHM = 0.76% (5.03 keV) 662 keV

8. Energy spectrum of 137 Cs from two-pixel events ( Detector #2.3; 1.5×1.5×1.0 cm 3 ; V C = -1400 V; V G = -45 V; Time = 40 h) Higher peak-to-Compton ratio FWHM = 1.23% (8.14 keV) 662 keV

9. Energy resolution distribution (single-pixel events) (Detector #2.2; 137 Cs 662 keV; V C = -2200 V; V G = -60 V; Time = 40 h)

10. Energy resolution distribution (single-pixel events) (Detector #2.3; 137 Cs 662 keV; V C = -1400 V; V G = -45 V; Time = 40 h)

11. Electron mobility-lifetime products distribution (Detector #2.2)

12. Electron mobility-lifetime products distribution (Detector #2.3)

13. Advantages of 3-D detectors Single polarity charge sensing  Overcome the effects of severe hole trapping Depth sensing  Correct electron trapping 3-D coordinates of interactions  Mitigate the effects of material non-uniformity to the scale of position resolution Minimum electronic noise (leakage current & detector capacitance are shared among pixels) Excellent energy resolution - 0.76% FWHM at 662 keV for single-pixel events (uncollimated, room temperature)  -ray imaging Detector physics (increase sensitivity by recognizing signatures of radiation interactions) Detector operation can be simple for end users Further development: –Larger detectors –Miniaturize ASIC (for tile-able systems)

14. Spectrum for all 1, 2 and 3-pixel events ( Detector #2.3; 1.5×1.5×1.0 cm 3 ; V C = -1400 V; V G = -45 V; Time = 40 h) FWHM = 0.93% (6.16 keV) 662 keV