Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
권호 표지
DOI QR코드

DOI QR Code

ANALYSIS OF CHARGE COLLECTION EFFICIENCY FOR A PLANAR CdZnTe DETECTOR

  • Kim, Kyung-O (Department of Nuclear Engineering, Hanyang University) ;
  • Kim, Jong-Kyung (Department of Nuclear Engineering, Hanyang University) ;
  • Ha, Jang-Ho (Advanced Radiation Detection Instrument & Sensor Lab, Korea Atomic Energy Research Institute) ;
  • Kim, Soon-Young (Innovative Technology Center for Radiation Safety, Hanyang University)
  • Published : 2009.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

The response property of the CZT detector ($5{\times}5{\times}5\;mm^3$), widely used in photon spectroscopy, was evaluated by considering the charge collection efficiency, which depends on the interaction position of incident radiation, A quantitative analysis of the energy spectra obtained from the CZT detector was also performed to investigate the tail effect at the low energy side of the full energy peak. The collection efficiency of electrons and holes to the two electrodes (i.e., cathode and anode) was calculated from the Hecht equation, and radiation transport analysis was performed by two Monte Carlo codes, Geant4 and MCNPX. The radiation source was assumed to be 59.5 keV gamma rays emitted from a $^{241}Am$ source into the cathode surface of this detector, and the detector was assumed to be biased to 500 V between the two electrodes. Through the comparison of the results between the Geant4 calculation considering the charge collection efficiency and the ideal case from MCNPX, an pronounced difference of 4 keV was found in the full energy peak position. The tail effect at the low energy side of the full energy peak was confirmed to be caused by the collection efficiency of electrons and holes. In more detail, it was shown that the tail height caused by the charge collection efficiency went up to 1000 times the pulse height in the same energy bin at the calculation without considering the charge collection efficiency. It is, therefore, apparent that research considering the charge collection efficiency is necessary in order to properly analyze the characteristics of CZT detectors.

Keywords

References

  1. Glenn F. Knoll, Radiation Detection and Measurement, $2^{nd}$ ed., p. 337, John Wiley & Sons, Republic of Singapore (1989)
  2. Tadayuki Takahashi and Shin Watanabe, “Recent Progress in CdTe and CdZnTe Detectors,” IEEE Transactions on Nuclear Science, 48, 100-108 (2000) https://doi.org/10.1109/23.958705
  3. Se-Hwan Park, Yong-Kyun Kim, Sung-Dae Jeon, Jang- Ho Ha, and Duk-Geun Hong, “Mean Free Paths of Charge Carriers in CZT Crystal,” Nuclear Instruments and Methods in Physics Research A, 579, 130-133 (2007) https://doi.org/10.1016/j.nima.2007.04.023
  4. Goro Sato, Tadayuki Takahashi, Masahiko Sugiho, Manabu Kouda, Takefumi Mitani, et al., “Characterization of CdTe/CdZnTe Detectors,” IEEE Transactions on Nuclear Science, 49, 3, 1258-1263 (2002) https://doi.org/10.1109/TNS.2002.1039648
  5. K. Hecht, “Zum Mechanismus des Lichtelekrischen Primastomes in Isolierenden Kristallen,” Zeits. Phys., 77, 235- (1932) https://doi.org/10.1007/BF01338917
  6. C. L. Lingren, B. Apotovsky, J. F. Butler, R. L. Conwell, et al., “Cadmium-Zinc-Telluride, Multiple-Electrode Detectors Achieve Good Energy Resolution with High Sensitivity at Room-Temperature,” IEEE Transactions on Nuclear Science, 45, 3, 433-437 (1998) https://doi.org/10.1109/23.682422
  7. S. Agostinelli, et al., “Geant4-A Simulation Toolkit,” Nuclear Instrument and Method in Physic Research A, 506, 250-303 (2003) https://doi.org/10.1016/S0168-9002(03)01368-8
  8. D. Pelowitz (Ed.), “MCNPX User’s Manual Version 2.5.0,” LA-CP-05-0369, Los Alamos National Laboratory (2005)
  9. Koji Iwata and B. H. Hasegawa, “Numerical Simulation of Pixellated CdZnTe Detector for Medical Radionuclide Imaging Application,” IEEE Transactions on Nuclear Science, 46, 3, 385-391 (1999) https://doi.org/10.1109/23.775549
  10. Ansoft Corporation, “Maxwell Software,” Elmwood Park, NJ: Ansoft Corporation (1998)
  11. H. Nishizawa, H. Inujima, T. Usami, H. Fujiwara, and H. Nakamura, “Response Calculation of a Stacked CdZnTe Detector for 16N -ray Measurement,” Nuclear Instruments and Methods in Physics Research A, 463, 268-274 (2001) https://doi.org/10.1016/S0168-9002(01)00226-1
  12. I. O. Ewa, D. Bodizs, Sz. Czifrus, and Zs. Molnar, “Monte Carlo Determination of Full Energy Peak Efficiency for a HPGE Detector,” Applied Radiation and Isotopes, 55, 103-108 (2001) https://doi.org/10.1016/S0969-8043(00)00366-3
  13. P. P. Maleka and M. Maucec, “Monte Carlo Uncertainty Analysis of Germanium Detector Response to -rays with Energies below 1 MeV,” Nuclear Instrumsents and Methods in Physics Research A, 538, 631-639 (2005) https://doi.org/10.1016/j.nima.2004.09.012