MRD - RSX-1.pdf

Minimum Requirements Document

RSX-1 Radiation Detector

29 July 2026

Background & Scope: The USAF School of Aerospace Medicine, Occupational and

Environmental Health (USAFSAM/OEC), requires the procurement of one (1) RSX-1 Sodium

Iodide Radiation Detector, measuring 4" x 4" x 16". This acquisition is critical for enabling directional radiation source identification and for conducting comprehensive Health Risk

Assessments (HRAs) to protect Air Force personnel from high levels of ionizing radiation.

USAFSAM/OEC currently possesses a single RSX-1 unit. While this detector provides essential radiation identification and detection capabilities, it lacks the intrinsic ability to determine the directionality of a radiation source. This limitation necessitates the use of secondary equipment and time-consuming procedures to locate the origin of radioactive contamination, reducing operational efficiency and potentially increasing exposure risk.

The acquisition of an additional RSX-1 unit is required to create a networked sensor system. By operating two identical detectors in tandem, personnel can triangulate and pinpoint the exact location of radiation sources with speed and precision. This directional capability is mission-essential for effective contamination control and accurate risk assessment.

The specified 4" x 4" x 16" dimensions and the RSX-1 model are the only specifications that will ensure seamless integration with existing equipment. Compatibility is paramount for creating the multi-detector array necessary for achieving the required directional functionality. The use of any other model would fail to meet this critical interoperability requirement.

Requirements/Salient Characteristics: The proposed system must meet or exceed the following salient characteristics:

1. Detector Physics and Geometry

• Detector Material: Thallium-activated Sodium Iodide (NaI(Tl)) scintillation crystal.

• Crystal Geometry: Rectangular prism measuring 4 inches x 4 inches x 16 inches (101.6 mm x 101.6 mm x 406.4 mm).

• Active Volume: Minimum of 4.0 Liters (approx. 256 cubic inches) of detection volume per unit to ensure high geometric sensitivity.

2. Spectroscopic Performance

• Energy Resolution: Must be <8.5% for accurate nuclide identification.

• Energy Range: Must cover a minimum detection range from 20 keV to 3.0 MeV.

• Spectral Output: Must output a fully linearized, high-resolution 1024-channel energy spectrum.

• Gain Stabilization: Must feature automatic multi-peak gain stabilization utilizing naturally occurring background isotopes (no external radioactive check sources required for routine stabilization).

3. Signal Processing and Electronics

• Digital Integration: The detector pack must contain an internally integrated Advanced

Digital Spectrometer (ADS) or equivalent digital signal processing (DSP) hardware.

• Throughput & Dead Time: Must be capable of processing high count rates up to

250,000 counts per second (cps) per crystal. System must maintain effectively zero dead-time under typical environmental background conditions and <20% dead-time at maximum saturation.

• Linearization: Must support fully linearized spectral summation to allow multiple detector packs to be combined without degrading the spectrum resolution or distorting the

Poisson distribution.

4. Physical and Environmental Characteristics

• Enclosure: Must be housed in a ruggedized, weather-sealed enclosure (e.g., carbon fiber, heavy-duty aluminum) designed to withstand severe vibrations and shocks associated with off-road vehicle or aviation environments.

• Dimensions: Must not exceed approximately 750 mm (L) x 170 mm (W) x 180 mm (H).

• Weight: Total assembly weight must not exceed 25 kg (approx. 55 lbs).

• Operating Temperature: Must operate continuously in extreme field conditions from -

30°C to +45°C.

• Power Consumption: Must be compatible with standard vehicle/aircraft power, operating on 9–40 VDC and drawing no more than 6 Watts under normal operation.

Deliverables:

• One (1) 4L NaI(Tl) Gamma-Ray Scintillation Detector assembly meeting the specifications above.

• Manufacturer calibration certificates and initial quality assurance/resolution test results.

• Integration documentation, mechanical interface drawings, and standard digital interface cables (e.g., Ethernet/USB/Serial as applicable).