The threshold energy of the Ar-38(p,n)K-38(m) reaction has been measur
ed using solid 38Ar targets and has been found to be 7008.52(12) keV,
with a 1 V standard as reference. This is in agreement with, but more
precise than, the accepted value. The average gives a Q value for the
K-38(m) superallowed positron decay of 6044.34(12) keV and an ft value
of 3049.4(21) s. To improve this last, the discord in the measured (3
8)Km halflives should be resolved.