The proton separation energy of Cl-34 has been measured to be 5143.30(
5) keV in a series of overlapping and self-consistent experiments invo
lving the study of three resonances in the S-33(p, gamma) reaction, us
ing a variety of techniques in laboratories in Auckland and Florence.
This figure is in disagreement with the only other published value. By
combining the proton separation energy with the only measured value f
or the S-34 neutron separation energy, the Q(ec) for the Cl-34 superal
lowed decay becomes 5491.48(12) keV. Some comments are offered on the
associated S-34(p, n)Cl-34 threshold energy measurement.