that are hard to intimate precisely but that are probably near the 6-year payback time of large systems.

This presents an obvious strategy for U.S. government-funded basic research requiring liquid helium. Consider a U.S. government grant where helium expenses are explicitly known. When such a grant is funded, the recipient could be presented with three choices: (1) a helium nonconservation charge would be assessed against the grant, reducing it by the difference between the actual requested amount and what the grant helium costs would have been had a helium conservation system been in place; (2) a plus-up to the grant if helium conservation was not in place but was planned for implementation in the first year of the grant such that the plus-up would cover some large fraction of the implementation cost; or (3) a grantee already conserving helium might get the full nonconserved budget for the project for a year or two as an incentive.