The threshold energy of the ${}^{38}\mathrm{Ar}{\mathrm{}(p,n)\mathrm{}}^{38}{\mathrm{K}}^m$ reaction has been measured using solid ${}^{38}\mathrm{Ar}$ 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 ${}^{38}{\mathrm{K}}^m$ 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 ${}^{38}{\mathrm{K}}^m$ halflives should be resolved.

• Received 31 March 1998

DOI:https://doi.org/10.1103/PhysRevC.58.821