Abstract
A precise measurement of the pion beta decay rate
will allow accurate testing of the unitarity of the
Cabbibo-Kobayashi-Maskawa quark mixing matrix, and
of the Conserved Vector Current Hypothesis. The
PIBETA collaboration intends to measure
this decay rate with an accuracy of better than
0.5%, using a calorimeter comprised of 240 pure CsI
crystals. Extensive calibrations of the CsI
crystals have been done using cosmic muons. Further
studies of the calorimeter response have been made
using monoenergetic 70 MeV beam positrons, and
using the box spectrum of photons ranging in energy
from 55-83 MeV from the single charge exchange reaction
. Finally, a
measurement of the Panofsky Ratio, defined as the
ratio of the rate of single charge exchange to
that of radiative pion capture 
in
pionic hydrogen, has been made.
Beam Line