Questions and Answers_0002.pdf

1. Is 1000 cubic inches (1 crystal pack) of thallium doped sodium iodide detectors the minimum requirement for both helicopter and fixed-wing proposals?

Please refer to section 3.2b, item 1, of the Performance-based Work Statement (PWS), which lists the minimum specifications for the aerial gamma-ray spectrometer (no matter which aircraft platform) as

(1) 1000 cubic inches of thallium doped sodium iodide detectors, or alternate detector that has been documented to provide data of equal or better quality.

2. Is there a minimum drape performance requirement for fixed-wing aircraft (i.e %, feet/nautical mile)?

The drape performance of the aircraft must be sufficient to meet the requirements of the survey design for the altitude and topographic relief presented by the areas to be flown. These requirements include nominal terrain clearance of 80-100 m maintained over the broadest area (3.1b) and sustained low flying on approaching Wilderness boundaries (3.1c). In sections 3.1c and 3.1p, it is specified that the vendor needs to adequately document or demonstrate that the survey plan and the capabilities of the aircraft will accomplish these requirements.

3. Is there a maximum tolerated data acquisition ground clearance for the radiometric data?

The maximum tolerated ground clearance for the radiometric data is dependent upon several factors, some of which are currently known only to the vendor, such as crystal volume and data processing procedures. Maintaining the nominal terrain clearance, as specified in section 3.1, will provide the best assurance that data with good signal-to-noise will be collected.