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posm: positronium continuum

Positronium continuum (Brown & Leventhal 1987)

$\displaystyle A(E) = K{2\over{(\pi^2-9)E_c}} [{E(E_c-E)\over{(2E_c-E)^2}} + {2E... ...2E_c(E_c-E)^2\over{(2E_c-E)^3}}\log({{E_c-E}\over{E_c}}) + {(2E_c-E)\over{E}}] $

for $E < E_c$ = 511 keV, where:

norm $K$, normalization