Oct 04 2007

Analysis of: Yoshiki et al., Observation of Ultracold-Neutron Production by 9-Angstrom Cold Neutrons in Superfluid Helium, 1992

Published by at 7:49 pm under Neutron Experimentation

This represents an experiment where gravity is assumed to be the force that collects ultracold neutrons.  In contrast to other gravity trap efforts where the effect is assumed, this particular experiment actually uses a UCN counter.  Since neutrons are not pulled by gravity unless bound to a proton through the strong nuclear force, and with at least one electron in orbit, the only neutrons that should be expected at the counter at the bottom of the “gravity acceleration tube” are those which go into the tube by random, albeit straight, trajectory.  Supporting this concept is the statement by Yoshiki et al.:  ”(3) The poor ratio of the detected UCN to the expected UCN [3,21,22] in this experiment is not well understood.  We are left with an unresolved attenuation factor of about 100 in order of magnitude.”  The paper suggests that this is due to “bad conductance” in the gravity tube which “might give rise to counterflow of UCN back to the container,”.

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