GEM High-Purity Germanium (HPGe)
Coaxial Detectors (in PopTop Capsule)

GEM Series HPGe detectors are manufactured with ORTEC’s own HPGe and represent the state of the art in “conventional”, i.e., outer contact Li diffusion and inner contact ion-implanted HPGe coaxial detectors. Because of the superior quality of ORTEC’s HPGe material, GEM detectors feature the best available energy resolution, peak-to-Compton ratios, and peak symmetry ratios at 1.33 MeV. Note that energy resolution and symmetry ratios are warranted to two decimal places.

  • Large stocklist at all times
  • Efficiencies to 150%, higher on request
  • New “Application-Tuned” PROFILE Series available
  • PopTop flexibility
  • Excellent energy resolution and peak symmetry
  • Automatic high-voltage shutdown protects preamplifier input FET
  • Indicator warns of excessive counting rate
  • PLUS preamplifier option for ultra-high-rate applications


GEM HPGe Coaxial Detectors


PROFILE GEM detectors are a first in germanium detectors; a range of detectors from which you can choose the best solution for your application from specified crystal dimensions. They are available in 2 series of endcap sizes. Nominal relative efficiency specifications are provided in order to help relate relative efficiency to terms of crystal dimensions. The resolution is measured according to the IEEE standard.

Avalilable in F series which employ “over-square” (diameter > length) coaxial structures, FX series (with an ULTRA-thin Entrance Window) or M series optimized for use with Marinelli Beakers.

GAMMA-X HPGe Coaxial Detectors
(in PopTop Capsule or Streamline Cryostats)


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-µm thick, the entrance window of the GAMMA-X detector is a 0.3-µm-thick, ion-implanted contact. Ion implantation results in a totally stable contact which will not deteriorate with repeated cycling.

For Compton-suppressed gamma spectroscopy, for measurements involving spectroscopy over the widest energy range, and in any situation where neutron damage is likely.

  • Efficiencies to over 100%
  • PopTop flexibility
  • Spectroscopy from 3 keV to 10 MeV
  • ULTRA thin, ultra stable boron ion implanted outer contact
  • High resistance to neutron damage
  • Excellent timing characteristics
  • Be window supplied with protective cover; Al or carbon fiber window option available at no additional charge
  • High-rate indicator
  • PLUS preamplifier option for ultra-high-rate applications
  • Automatic high-voltage shutdown protects preamplifier input FET

LO-AX™ Low-Energy Photon Detector

The LO-AX is a large active area, “short” coaxial detector which supplies the best possible energy resolution for the energy range from 3 to 400 keV. A typical application for the LO-AX is in vivo quantitative actinide monitoring. This measurement, frequently performed in the past using phoswich scintillation counters, is now routinely performed using a LO-AX, usually in a low-background cryostat.

The LO-AX provides optimum peak-to-background ratio from 10 to 400 keV on large-area samples. It is also ideal for in vivo actinide monitoring using L x rays.

  • Large active area
  • 36-, 51-, 60-, and 70-mm diameter available
  • Ideal for in vivo actinide monitoring
  • Excellent for uranium monitoring
  • PopTop flexibility
  • ULTRA-thin rugged Ion-implanted pointer contact sensitive at front and sides

SMART-1 Detector

ORTEC’s unique SMART-1 detector interface module is a new technology for the preamplifier and electronics interface. SMART-1 detectors contain a microprocessor that monitors the state of health of a detector at all times. Crystal temperature, preamplifier power (±12 and ±24), high voltage level and overload status are all monitored periodically while data is being acquired. If any single parameter fails, a latched bit is set. At the end of the measurement, SMART-1 enabled electronics (digiDART for instance) poll the state-of-health bit and if it is latched, the operator is warned that a parameter had exceeded limits during some part of the measurement. This feature ensures that the data acquired is of the highest possible integrity.

905 Series NaI(Tl) Scintillation Detectors

The high Z of iodine in NaI(Tl) crystals result in high efficiency for gamma-ray detection. Resolution for a 3-inch diameter by 3-inch length crystal is typically about 7% for 137Cs and slightly worse for larger sizes. The light decay time constant for a NaI(Tl) crystal is about 0.23 ms. Typical charge-sensitive preamplifiers translate this into an output voltage pulse with a rise-time of about 0.5 ms. Fast coincidence measurements cannot achieve the very short resolving times that are possible for plastic scintillators, especially at low gamma-ray energies.

The Model 905 Series offers various sizes of Nal(TI) detectors.

905-1 (1” x 1”): 0.17 @0.5 MeV and 0.09 @2.0 MeV
905-3 (2” x 2”): 0.75 @0.5 MeV and 0.45 @2.0 MeV
905-4 (3” x 3”): 2.00 @0.5 MeV and 1.30 @2.0 MeV