The probability of pion capture by hydrogen was measured for ${\mathrm{CH}}_3$OH, ${\mathrm{CD}}_3$OH, and ${\mathrm{CH}}_3$OD as a function of temperature from -150 to +250 °C. The nuclear capture of a pion by a proton was identified using the pion charge-exchange reaction. The coincident photons from the ${\mathrm{\pi }}^0$ decay were detected by TRIUMF’s large NaI spectrometers. We have found a relative difference of 1.79±0.11 in the pion capture probability in solid and supercritical ${\mathrm{CD}}_3$OH that is interpreted in terms of the hydrogen-bond-breaking model.

• Received 12 February 1991

DOI:https://doi.org/10.1103/PhysRevA.44.1725