Presentations for radiation biology, underground agriculture, and algal biomass were given at the April meeting. In the future, low dose radiation biology has the best rationale for being completely integrated into a low background counting facility, as it will benefit the most from shielding, reduced Radon air, and other items. 4850 would be deeper than any other underground facility that currently studies low dose effects. Brookhaven is currently looking at low dose effects in the shielded room once used by Ray Davis (which reduces the cosmic ray flux by a factor of 10).

Initial studies for radiation biology at Homestake (or elsewhere) with a glove box made of low activity material within or nearby low background counting (or with a “MULE” used in biology) may suffice. However, both the irradiation of native microbes (for biofuels and deep life studies), and low dose radiation biology of human/mammalian tissue samples will eventually require a source of ionizing radiation, which most likely will be an X-ray source. Autoclaves, incubators, refrigerators, chemical storage, etc. commonly used in biology will also be needed. Radiation biology will also need a surface facility to process/prepare incoming and outgoing samples and study control samples. Biological containment and/or physical separation from sensitive detectors for low background counting must be addressed.

Underground agriculture and algal biomass can be users of LBC to assay mineral content in soils, plant material, etc. However, they are different enough that integration with LBC for S4/S5 may be unwarranted since (1) they could use space throughout the Mine, and (2) most plants are radiation resistant enough that these projects do not require shielding or Radon mitigation. Radon levels are roughly 3-4 pCi/Liter throughout the Mine, which is similar to surface levels at Homestake.

Another element of the energetic particles working group is the testing of microelectronics. It has been proposed that an environmentally controlled facility at the 300 foot level (to reduce, but not eliminate cosmics) would be feasible to study the response that radiation-hardened circuits have to lower doses of radiation. Such circuit testing is often done at much higher levels than are seen in practice (for instance in telecommunication satellites). This affects the predicted lifetime of many systems since the response to lower doses is often different. Reduced Radon air, HEPA filtration, temperature/humidity control would be needed. In the future, actual production of such electronics or other materials would probably need access to clean rooms in another part of the mine that may share infrastructure with other detector development.

Rob McTaggart.