  The energy loss of $\beta^-$ emission emitting from a 63-Ni source in a
phosphorus 15-P scintillation medium is theoretically studied. It has shown the
$\beta$ energy spectrum absorption in ${15}P$ had nearly 100% efficiency for
$\leq$ 28 keV in 800 {\mu}m scintillator thickness. This can eventually lead to
the production of light sources using these beta-emitting radiation sources as
a low energy source in the near future.
