GMX0 pages

ORTEC®
GMX Series Coaxial HPGe Detector
Product Configuration Guide
GAMMA-X: N-type Coaxial HPGe Detectors for High-Performance Gamma Spectroscopy in
the Energy Range of ~3 keV and Upward
The GAMMA-X detector is a coaxial Germanium (Ge) detector with an ultra-thin entrance window. While most coaxial detectors have
entrance windows from 500- to 1000-ìm thick, the entrance window of the GAMMA-X detector is a 0.3-ìm-thick, ion-implanted
contact, extending the lower range of useful energies to around 3 keV. Ion implantation results in a totally stable contact which will not
deteriorate with repeated cycling. Moreover, N-type HPGe detectors have been shown to be resistant to damage by fast neutrons.
All GAMMA-X Series detectors feature:
• Efficiencies to 100%, higher on request.
• Spectroscopy from 3 keV to 10 MeV.
• ULTRA thin boron ion implanted radiation window, ideal for Compton Suppression systems.
• Neutron damage resistant; user self-repair neutron damage option.
• Excellent energy resolutona nd peak symmetry.
• SMART bias option.
• Harsh Environment (-HE) option.
• Be window supplied with protective cover; Al or carbon fiber window option
available at no additional charge.
• Low-background carbon fiber endcap option.
• PLUS preamplifier option for ultra-high-rate applications.
• Huge configuration flexibility, PopTop, Streamline, and mechanically cooled
options.
GAMMA-X Series detectors are manufactured from ORTEC- grown germanium
crystals processed in our advanced manufacturing facility in Oak Ridge, TN. The
detectors are fabricated from N-type germanium with an inner contact of diffused
Li and an outer, ultra thin, contact of ion-implanted boron .
The wide energy range of application of the GAMMA-X detector is illustrated in
Figure 1 which compares the relative efficiencies of a GAMMA-X, a GEM (P-type
coaxial), and a GLP planar detector. The GAMMA-X detector, uniquely,
demonstrates excellent efficiency at both high and low energies.
ORTEC offers GMX Series HPGe detectors with relative efficiencies from 10% to
100% and beyond.
ORTEC maintains a large stocklist of HPGe detectors. Some of these have "super
specifications," that is, a warranted energy resolution better than the usual warranted
specifications.
High- and Low-Energy Performance of the GAMMA-X Detector
The high-energy performance of a GAMMA-X detector is defined by its relative
efficiency, resolution, and peak-to-Compton ratio at 60Co.
The low-energy performance of this detector is defined by its resolution at 5.9 keV, its
active surface area, and the detector window thickness.
The thickness of the entrance contact of the GAMMA-X detector is described by the ratio of the areas of two peaks of a readily
available source. The peaks chosen are those of the 88-keV gamma rays from the 109Cd and of the 22.16-keV Ag K x rays from the
same source. The warranted window attenuation ratio is 20.
WE = peak area at 22.16 keV
peak area at 88 keV
22-keV Peak/88-keV Peak Area
This specification quantifies the thinness of the entrance window in GAMMA-X detectors. The natural ratio of gamma rays from the 22-
keV and 88-keV lines of a 109Cd source is ~21:1. A GAMMA-X detector typically displays a ration >20:1.
Fig. 1. Comparison of the Efficiency-Energy Curve of
the LEPS, HPGe Coaxial, and GAMMA-X Detectors.
Fig. 2. Configuration of GMX Coaxial Germanium
Crystal.