We have measured the time dependence of the flux of non-thermal phonons gen
erated by alpha particles in a BaF2 single crystal of mass 1 g using a Seri
es Array of Superconducting Tunnel Junctions. Taking advantage of the almos
t perfect elastic symmetry of BaF2, we approximate the equations of quasidi
ffusive propagation to give a simple diffusion equation characterized by an
effective diffusion coefficient D = K-8/9, where K is a material constant
and L the distance between the phonon source and the point of detection. We
use this model to perform pulse-shape analysis on our data and show that a
greement is excellent, and highly preferred over a ballistic pulse shape. T
he distributions of values of K determined for different lengths L are foun
d to overlap strongly, in support of the law D = KL8/9. We suggest that pul
se-shape analysis may provide an alternative to time-difference measurement
s to achieve position sensitivity in a phonon-mediated detector based on a
BaF2 absorber. (C) 1999 American Institute of Physics. [S0021-8979(99)08702
-2].