N-Type HPGE Detector System

Posted Date: September 4, 2008

Procurement Office: U.S. Environmental Protection Agency, Headquarters Procurement Operations Division, Administrative Contract Service Center (3803R) 1200 Pennsylvania Ave NW, Washington, DC 20460

Response Date: September 29, 2008* NB: The response date has been extended from the original posting.

NAICS Code: 334519 Other Measuring and Controlling Device Manufacturing

This page was created for prospective vendors to access the specifications for the subject requirement. The specifications are posted below. The required detector system is intended to be used for general purpose high resolution gamma spectrometry of a wide range of sample types in a fixed laboratory. Separate quotations are requested for Item 1 (detector, electronics, and cooling system), Item 2 (low background shield), Item 3 (dewar leveling stand), and for any combination of Items 1, 2 and 3. Separate contracts may be awarded for each item if it is determined that this will provide the greatest value to the government.

EPA requires that all equipment be purchased FOB destination. Quotations are to include all costs associated with shipping, handling, and insurance for delivery FOB the National Air and Radiation Environmental Laboratory in Montgomery, Alabama.

General Requirements :

• All items must be warranted to be free of defects in material and workmanship for at least one year from the time of acceptance by EPA. The warranty must provide for repair or replacement at no cost to the government, and shall not require the government to pay for shipping or handling costs for return of defective equipment for repair. Any software shall be expressly warranted to be fit and suitable for the purpose for which it is provided and that it will operate satisfactorily on the platform specified; disclaimers of warranty of fitness for purpose are unacceptable.

• Documentation provided with equipment shall include instruction manuals that completely describe how to set up, configure, calibrate, maintain, and use the equipment furnished, both hardware and software. Schematic and component layout drawings shall be provided for all circuit boards. Assembly drawings shall be provided for all mechanical assemblies. All drawings shall identify components by part number and be accompanied by part lists that include all components shown in the drawings. This documentation may be provided either in printed form, or on CD-ROM in portable document format (PDF) files.

Item 1 – Detector, Electronics, and Cooling System

• The detector shall be a coaxial N-type High Purity Germanium (HPGE) with a synthetic fiber or plastic end window and integral signal pre-amplifier. The detector shall be a standard product with a maximum detector capsule outer diameter of 3.25 inches. It shall have the following performance characteristics, as determined in accordance with ANSI/IEEE 325-1996:

• Nominal relative photopeak efficiency shall be at least 60 percent

• Resolution shall be 2.3 keV Full Width at Half Maximum (FWHM) or less at 1332 keV and 1.3 keV or less at 122 keV.

• Peak to Compton ratio shall be at least 55:1.

• The detector is to be mounted to a vertical dipstick cryostat assembly. A 30L liquid nitrogen dewar with collar and liquid nitrogen fill tubing shall be provided.

• Supporting electronics for the detector shall be integrated in a single enclosure, shall use digital signal processing, and shall provide all of the functions required for a fully functioning high resolution gamma spectrometry system, including but not limited to:

• High Voltage detector bias

• Detector pulse shaping, amplification, and processing

• A Multi-channel analyzer with minimum analog to digital conversion gain of 8192 channels

• All interconnecting cables and/or interface adapters as required to have a fully functioning system that is interfaced with and controlled by a personal computer.

• The supporting electronics shall be controlled by computer software, which must be provided at no additional cost. The software must run on an i386-based Personal Computer with a Windows XP Service Pack 2 operating system. The software must be capable of:

• Controlling the functions of the detector and supporting electronics as required for gamma spectrum acquisition

• Saving the resultant gamma spectrum as an electronic file, in the format specified in ANSI N42.42.

• Other than the computer operating system, if any third party Commercial-Off-The-Shelf software is required for operation, it shall be provided.

Item 2 – Low Background Shield

The low-background shield is intended to be used in conjunction with the detector in Item 1 to reduce background gamma radiation.

• The shield shall be a standard top-opening cylindrical design intended for use with vertical dipstick cryostat HPGe detectors.

• The shield shall be fabricated from low background materials that provide gamma radiation shielding equivalent to at least 4 inches of virgin lead with a liner of copper and tin to attenuate lead x-rays Nominal inside dimensions shall be 11 inches diameter and 16 inches high.

• A support table shall be provided for the shield. Each table leg must incorporate a mechanism for height adjustment to allow leveling the shield.

Item 3 – Dewar Leveling Stand

The dewar leveling stand is intended to be used in conjunction with the detector in Item 1 and the shield in Item 2 to provide a means of leveling the detector/dewar as well as providing electrical and mechanical vibration isolation.

The leveling stand shall provide a square platform for supporting standard 30L liquid nitrogen dewars. The nominal length and width of the platform shall be 18 inches. The platform shall either be made of, or the top covered with, an electrically insulating material.
The platform shall have independently adjustable legs at each of its four corners. The minimum range of height adjustment shall be 2 through 7 inches between the floor and top of the leveling stand platform.
The bottom of each leg shall have rubber or similar material of sufficient thickness to absorb mechanical vibrations.

The point of contact for this procurement is Trina Fisher, Contract Specialist, at fisher.trina@epa.gov.

N-Type HPGE Detector System

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