The radiation detection efficiency and spectral resolution of mercuric iodide detectors can be improved significantly by
increasing the volume of the detectors and by using a pixellated anode structure. Detector bodies with a thickness of
nominally 10 mm and an active area of approximately 14 mm x 14 mm have been used for these experiments. The
detectors were cut from single crystals grown by the physical vapor transport method. The cut surfaces were polished
and etched using a string saw and potassium iodide solutions. The Palladium contacts were deposited by magnetron
sputtering through stainless steel masks. The cathode contact is continuous; the anode contacts consist of an array of
11 x 11 pixels surrounded by a guard ring. The resistance between a pixel and its surrounding contacts should be larger
than 0.25 Gohm. The detector is mounted on a substrate that makes it possible to connect the anode pixels to an ASIC,
and is conditioned so that it is stable for all pixels at a bias of -3000 Volts. Under these conditions the spectral resolution
for Cs-137 gamma rays (662 keV) is approximately 5% FWHM. When depth sensing correction methods are applied,
the resolution improves to about 2% FWHM or better. It is expected that the performance of the devices can be
improved by the careful selection of crystal parts that are free of structural defects. Details of the fabrication
technologies will be described. The effects of material inhomogeneities and transport properties of the charge carriers
will be discussed.
KEYWORDS: Sensors, Xenon, Signal processing, Digital signal processing, Signal detection, Ionization, Detector development, Electronics, Spectroscopy, Monte Carlo methods
Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities (~0.3 g/cm3-0.5
g/cm3) and good energy resolution (2%-4% at 662 keV), fill an important niche between more familiar technologies
such as NaI(Tl) scintillators and Germanium detectors. Until recently, difficulties with obtaining sufficient Xenon
purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals
have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose
experience with xenon detectors goes back to the mid 1990's, has made significant progress in these areas and has
developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Here
we will discuss our development of a mobile, large area, spectroscopic array.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.