Defects in Silver-Doped Mercuric Iodide Crystals and their Effect on X-Ray and Gamma-Ray Detector Performance

1993 ◽  
Vol 302 ◽  
Author(s):  
R. B. James ◽  
X. J. Bao ◽  
T. E. Schlesinger ◽  
A. Y. Cheng ◽  
V. M. Gerrish
Keyword(s):  
Gamma Ray ◽  
Electrical Contacts ◽  
Source Material ◽  
Broad Emission Band ◽  
Interfacial Region ◽  
Mercuric Iodide ◽  
Detector Performance ◽  
X Ray ◽  
Silver Silver ◽  
Gamma Ray Detector

ABSTRACTThe processing steps associated with purification of source material, crystal growth, and attachment of electrical contacts can introduce defects into mercuric iodide (HgI2) that degrade the performance of detectors. We have employed low-temperature photoluminescence (PL) spectroscopy to study radiative recombination centers in the interfacial region between a thin semitransparent film of silver and mercuric iodide. The Ag film was found to introduce a new broad emission band centered at 5490 Å in the photoluminescence spectrum of HgI2. This PL feature can be used as a signature to identify the existence of Ag as a contaminant in HgI2 crystals and detectors. Experiments were also conducted on mercuric iodide surfaces that had been doped with silver, and the results showed that Ag is a rapid diffuser in bulk HgI2. Detectors with silver electrodes were also fabricated and tested using an americium-241 gamma-ray source. Large increases in the leakage currents were observed for the Ag-doped HgI2 devices, indicated that Ag impurities are electrically active in HgI2. These measurements show that silver is unacceptable as an electrode material for mercuric iodide x-ray and gamma-ray detector applications. In addition, they reveal that caution must be taken during handling of mercuric iodide source material, crystals, and detectors to avoid contact with silver, silver compounds, or with any material that contains silver as a contaminant.

The Fabrication of Mercuric Iodide Detectors for Use in Wavelength Dispersive X-Ray Analysers and Backscatter Photon Measurements

1982 ◽  
Vol 16 ◽  
Author(s):  
John H. Howes ◽  
John Watling
Keyword(s):  
Room Temperature ◽  
Gamma Ray ◽  
Surface Passivation ◽  
Electrical Contact ◽  
Scintillation Counter ◽  
Radiation Detectors ◽  
Nuclear Radiation ◽  
Gamma Ray Spectrometry ◽  
Mercuric Iodide ◽  
X Ray

ABSTRACTThis paper describes the fabrication of mercuric iodide nuclear radiation detectors suitable for X and gamma ray spectrometry at room temperature. The active area of the detectors studied are between 0.2 and 1.5cm sq and they are up to 0.5mm thick. The method of producing a stable electrical contact to the crystal using sputtered germanium has been studied. The X-ray resolution of a 1.5cm sq. area detector at 32 keV is 2.3 keV FWHM when operated at room temperature in conjunction with a time variant filter amplifier. A factor which is important in the fabrication of the detector is the surface passivation necessary to achieve a useful detector life.This type of detector has been used on a wavelength dispersive X-ray spectrometer for energy measurements between 10 and 100 keV. The advantages over the scintillation counter, more commonly used, is the improved resolution of the HgI2 detector and its smaller size. The analyser is primarily used for the detection of low levels of heavy metals on particulate filters. The detectors have also been used on an experimental basis for gamma ray backscatter measurements in the medical field.

Development of a Mercuric Iodide Detector Array For In-Vivo X-Ray Imaging

1994 ◽  
Vol 38 ◽  
pp. 615-624
Author(s):  
Bradley E. Patt ◽  
Jan S. Iwanczyk ◽  
Martin P. Tornai ◽  
Craig S. Levin ◽  
Edward J. Hoffman
Keyword(s):  
Gamma Camera ◽  
Gamma Ray ◽  
Active Area ◽  
Detector Array ◽  
Mercuric Iodide ◽  
X Ray ◽  
X Ray Imaging ◽  
Spatial Performance ◽  
Gamma Ray Imaging

Abstract A nineteen element mercuric iodide (HgI2) detector array has been developed in order to investigate the potential of using this technology for in-vivo x-ray and gamma-ray imaging. A prototype cross-grid detector array was constructed with hexagonal pixels of 1.9 mm diameter (active area = 3.28 mm2) and 0.2 mm thick septa. The overall detector active area is roughly 65 mm2. A detector thickness of 1.2 mm was used to achieve about 100% efficiency at 60 keV and 67% efficiency at 140 keV The detector fabrication, geometry and structure were optimized for charge collection and to minimize crosstalk between elements. A section of a standard high resolution cast-lead gamma-camera collimator was incorporated into the detector to provide collimation matching the discrete pixel geometry. Measurements of spectral and spatial performance of the array were made using 241-Am and 99m-Tc sources. These measurements were compared with similar measurements made using an optimized single HgI2 x-ray detector with active area of about 3 mm2 and thickness of 500 μm.

PUC Program: the pulse pile up correction for X-ray and gamma ray spectrometry

2020 ◽  
Vol 98 (9) ◽  
pp. 877-882
Author(s):  
S.M. Karabıdak ◽  
S. Kaya
Keyword(s):  
Gamma Ray ◽  
Systems Design ◽  
Main Peak ◽  
Gamma Ray Spectrometry ◽  
Background Count ◽  
X Ray ◽  
Quantitative Accuracy ◽  
Pile Up ◽  
Gamma Ray Detector ◽  
Time Limitations

Pile up and dead time are two important corrections in the analysis of X-ray and gamma ray spectra. The most important of these is pile up correction because these peaks do not really exist in the spectra; they only seem to exist. For this reason, these peaks affect both the qualitative and quantitative accuracy of the analysis. In addition, the pile up pulses forming the pile up peaks increase the background count in the spectrum. Companies that produce X-ray or gamma ray detector systems design pile up reject circuits and integrate them into detector systems to prevent these pulses. These circuits have time limitations because they are made up of electronic devices. For this reason, the pile up problem cannot be solved completely in these circuits. Therefore, mathematical models based on a statistical approach are needed. Such a model was developed in this study. A computer program based on this model was developed. This developed program has been applied to X-ray and gamma ray spectra. It has been shown that this model provides about 2% correction in the main peak regions and significantly reduces background counts.

Study of gamma-ray detector performance of Cd1-xZnxTe crystal treated by different etchants

1996 ◽  
Author(s):  
Henry Chen ◽  
Stephen U. Egarievwe ◽  
Z. Hu ◽  
J. Tong ◽  
Detang T. Shi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Detector Performance ◽  
Gamma Ray Detector

scholarly journals Thermal Design for Soft Gamma-ray Detector and Hard X-ray Imager on ASTRO-H Satellite

2014 ◽  
Vol 12 (ists29) ◽  
pp. To_4_11-To_4_16
Author(s):  
Keita FUKUZAWA ◽  
Shuji ITO ◽  
Kazunori MASUKAWA ◽  
Yoshikatsu KURODA ◽  
Kazuhiro NAKAZAWA ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Thermal Design ◽  
X Ray ◽  
Gamma Ray Detector
Sign in / Sign up

Export Citation Format

Share Document