The Satellite Test of the Equivalence Principle (STEP) will test the equality of fall of objects in Earth orbit to an
accuracy approaching one part in 108 by measuring the difference in rate of fall of test cylinders in
cryogenic differential accelerometers in a drag-free satellite. This paper describes the current baseline design and
principles used in the design of the STEP mission.
We report the first experiments in which 5-MeV alpha particles are detected via evaporation from a bath of superfluid helium. The a excites phonons and rotons in the liquid helium, and these excitations are sufficiently energetic to evaporate helium atoms when they reach the free surface of the liquid. The approximate overall efficiency of this process has been determined, and we compare this with expectations. We have also been able to detect evaporation induced by a flux of r's from a 137 Cs source.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.