PROFILE GEM P-type Coaxial and Semi-Planar HPGe Radiation Detectors

• "Application-Matched" P-type HPGe Detectors, optimized for specific sample types, gamma energy ranges and measurement geometries.
• Know how your new HPGe detector will perform before you buy it!
• Best absolute efficiency for the given IEEE standard relative efficiency in your counting geometry.
• Stable thin front contact, no front dead layer growth if stored warm (PROFILE GEM S, SP, and C Series).
• Warranted crystal dimensions ensure measurement performance.
• Reproducible dimensions mean reproducible performance. . .  no surprises.
• Full range of PopTop Cryostats and options.

The ORTEC PROFILE Series of P-type High Purity Germanium (HPGe) detectors offers specific crystal dimensions from which you can choose the best solution in YOUR application. Nominal relative efficiency specifications are provided to help relate relative efficiency to terms of crystal dimensions. The resolution is measured according to the IEEE standard. If a particular PROFILE series detector is available from the ORTEC detector stock list, then the ACTUAL MEASURED specifications may be inspected before purchase.

F-Series PROFILE GEM Detectors
F-Series PROFILE detectors employ "over-square" (diameter > length) structures. This crystal geometry is often referred to as semi-planar structure. For a given relative (IEEE) efficiency, the F-Series represents the "best use" of germanium material producing the maximum absolute counting efficiency for on-endcap or "close geometry" extended samples, such as:

• Point sources on-endcap
• Filter paper samples on-endcap
• Samples presented in bottles and pots on-endcap
• Bio-assay applications (e.g., lung monitoring)
• Waste drum monitoring

In addition, the over-square geometry helps improve (lowers) low-energy resolution by reduced crystal capacitance as compared to coaxial crystal geometry.

S-Series PROFILE GEM Detectors

• All the advantages of the F-Series PROFILE detector with an ultra-thin, stable entrance window.
• Excellent warranted performance.
• Excellent sensitivity down to 3 keV energy.
• No dead layer growth (change in efficiency) from the front of the crystal due to prolonged warm storage.

S-Series PROFILE GEM detectors have a semi-planar crystal geometry and employ a proprietary ultra-thin, stable entrance window to improve low energy efficiency. The S-Series entrance window extends the useful energy range down to 3 keV, while maintaining the excellent peak shape and resolution characteristics of the PROFILE series.

SP-Series PROFILE GEM Detectors

• All the advantages of the F- and S-Series PROFILE detectors with a proprietary low noise back contact.
• Premium warranted resolution performance.

Semi-planar SP-Series PROFILE GEM detectors use a low-noise back contact in addition to the proprietary ultra-thin, stable entrance window introduced with the S- and C-Series. As in the S-Series, the front contact delivers excellent transmission at low energies. Thermal cycling or warm storage of the detector will not degrade the transmission efficiency of the front contact.

Unique to the SP-Series detector is the proprietary back contact that dramatically improves detector resolution at low energies.

General Guidelines for Choosing an F-, S- or SP-Series PROFILE GEM Detector
For a close or on-endcap sample, the detector diameter should exceed the sample diameter by 20% or more. Beyond 30% the gain in efficiency is small. In addition, if the detector diameter exceeds the sample diameter by 20% or more, errors due to irreproducibility of the sample position will be minimal.

If budget constraints must be considered, first select the largest diameter in comparison with the optimum diameter. Selection of a deeper detector will further increase the absolute efficiency, specifically at higher energies. For samples counted in geometries similar to those listed above, choose an F-Series PROFILE detector with a diameter 20% (or more) larger than the sample to ensure a high absolute efficiency for a given relative (IEEE) efficiency. Choose an S-Series PROFILE detector with a diameter 20% (or more) larger than the sample to ensure the highest absolute efficiency at lower energies between 3 to 50 keV. If the application or situation includes prolonged storage of the detector in an ambient environment, selection of the S-Series PROFILE detector will maintain excellent performance, with no degradation in the low-energy range. Over-square detectors can often achieve better low-energy resolution than longer, smaller diameter detectors of the same relative efficiency.

Choose an SP-Series PROFILE detector for premium resolution performance at low and medium energies. The premium resolution advantage is vital for applications using multi-nuclide (multi-peak) identification. Better resolution enhances the performance of peak locate algorithms, which leads to fewer false positives and double peaks. Better resolution performance of SP-Series PROFILE detectors translates into an improved Peak to Background ratio, which in turn implies lower MDA and shorter counting times.

M-Series PROFILE GEM Detectors
The M-Series detectors are designed for use with Marinelli beakers to provide an optimum solution and efficiency. M-Series detectors provide the same resolution and better absolute efficiency (below 50 keV) than GEM series detectors, and better resolution but lower absolute efficiency (below 50 keV) than GMX series detectors. These are made where the endcap diameter is "filled with the crystal" and the length is slightly longer than the diameter. The overall absolute efficiency for a Marinelli beaker is maximized. This is the most common beaker where the well diameter is equal to its length. Additionally, M-Series for a given relative (IEEE) efficiency, represents the optimum “use” of germanium material, generating the maximum absolute counting efficiency for on-endcap or “close geometry” extended samples with a higher energy range requirement than F-, S-, or SP-Series, such as:

• Point sources on-endcap
• Filter paper samples on-endcap
• Samples presented in bottles and pots on-endcap
• Waste drum monitoring

C-Series PROFILE GEM Detectors
The C-Series detectors provide all the attributes of the M-Series detectors combined with an ultra-thin, stable entrance window. This extends the lowest usable energy down to 3 keV while maintaining the efficiency at higher energies. Nuclides such as ²⁴¹Am and ²¹⁰Pb may be measured while providing excellent efficiency for higher energy emitters; all in a single detector. The largest of these detectors provides the maximum efficiency available in a single detector for energies greater than 3 MeV.

General Guidelines for Choosing an M-Series or C-Series PROFILE GEM Detector
Choosing the optimum M- or C-Series detector for use with a specific Marinelli beaker could not be easier: simply choose the detector with the tightest fit inside the Marinelli beaker well!

An F-, S-, or SP-Series detector may be used in a Marinelli geometry, it will have better resolution performance, but will have lower efficiency than an M- or C-Series detector of the same diameter. Correspondingly, an M- or C-Series detector may be used as a substitute for an F-, S-, or SP-Series detector in an on-endcap geometry. For the same diameter, the M- or C-Series will give slightly higher efficiency (improvement increasing with increasing energy).

Integrated Cryocooling System Option (-ICS-E)
The Integrated Cryocooling System (ICS) cryostat is sealed with a cryocooler and is immune to thermal short cycling. Unlike the typical three day loss of use of the detector with a standard type cryostat, the ICS can be re-cooled immediately, minimizing any time lost for temporary warm up. The ICS for PROFILE series detectors includes an external preamplifier.

SMART-1 Option  (-SMP)
The SMART-1 option monitors and reports on vital system functions, and can save authentication codes and report the code at a later time. It has the high voltage included, so none of the instruments require an external high-voltage power supply. The SMART-1 is housed in a rugged ABS molded plastic enclosure and is permanently attached to the detector endcap via a molded-strain-relieved sealed cable. This eliminates the possibility that the detector will suffer severe damage from moisture leaking into high-voltage connectors. The SMART-1 can be positioned in any convenient place and does not interfere with shielding or other mounting hardware.

Ultra-High Count-Rate Preamplifier Option  (-PL)
The Ultra-High Count-Rate Preamplifier (transistor-reset preamplifier), can handle input count rates up to 1,000,000 counts/s at 1 MeV, offers the added benefit of having no feedback resistor.

Harsh Environment Option  (-HE)
The Harsh Environment option is a rugged carbon fiber endcap with a sealed electronics housing featuring a replaceable desiccant pack which ensures that the electronics stay 100% dry and indicates when it needs to be replaced. PROFILE series detectors in PopTop capsules of 76 mm diameter or larger can be supplied with this option. 

Remote Preamplifier Option  (-HJ)
This option allows all the preamplifier and high voltage connections to be outside a shield and removes the preamplifier and high voltage filter from the “line-of-sight” to the Ge crystal. For low background applications, this option eliminates any possible preamplifier or high voltage filter components that may add to the background inside a shield.

Beryllium Window Option  (-B)
Provides improved performance between 3 and 5 keV.

Low-Background Carbon Fiber Endcap Options  (-RB, -LB-C, and -XLB-C)
The Low-Background Carbon Fiber Endcap is as strong as Al, Mg, and Cu, creates less background, does not corrode, and can detect energies less than 10 keV. This lower background material allows for lower Minimum Detectable Activity (MDA) for a specific counting time, which provides another step in increasing sample throughput in low-background counting applications. The lower Z of Carbon Fiber provides a low-energy window without the additional background found in most alloys.

See the PROFILE Series GEM HPGe Radiation Detector Configuration Guide to configure your detector.