  The complete absence of radio pulsars with periods exceeding a few seconds
has lead to the popular notion of the existence of a high period death line. We
have recently postulated the existence of another radio quiescence boundary at
high magnetic fields ($B\gtrsim 4\times 10^{13}$G) in the upper portion of the
period-period derivative diagram, a domain where no radio pulsars are observed.
The origin of this high B boundary is also due to the suppression of magnetic
pair creation, $\gamma\to e^{\pm}$, but mainly because of competition with the
exotic QED process of magnetic photon splitting, $\gamma\to\gamma\gamma$,
coupled with ground state pair creation. This mechanism could also explain the
low spectral cutoff energy of the gamma-ray pulsar PSR1509-58, which lies near
the high B death-line. In this paper, we summarize the hypothesis of this new
``death line,'' and discuss some subtleties of pair suppression that relate to
photon polarization and positronium formation. We identify several ways in
which Integral will serve as a useful tool in probing high field pulsars, given
that the radio quiescence boundary is transparent to the high energy bands.
