Moderation and Absorption Times for Negative Pions in Liquid Deuterium

The moderation and absorption times for negative pions stopping in liquid deuterium have been measured using the same technique and the same apparatus as were used by Doede, Hildebrand, Israel, and Pyka to obtain the corresponding times in liquid hydrogen. In deuterium the mean time for a negative pion to go from an initial velocity $v_0<~0.006c$ to nuclear capture was found to be (2.1±0.5)×${10}^{-12\mathrm{}}$sec. The relationship of this capture time to that for liquid hydrogen, (2.3±0.6)×${10}^{-12\mathrm{}}$sec, is discussed in detail. Results are also presented for the moderation times of pions with initial velocities between $0.05c$ and $0.006c$.