Total cross-sections

The integration of formula () gives the total cross-section [], [] for Möller scattering ($e$^-e^- ): $\sigma (\; Z,E,DCUTE)\; =\{2\; \pi r$₀²mZβ²(E-m)}[{(γ-1)γ²}({1x}-1) +{1x}-{11-x}-{2γ-1γ²}ln{1-xx}]

and for Bhabha scattering ($e$⁺e^- ): $\sigma (Z,E,DCUTE)\; =\{\; 2\; \pi r$₀²mZ (E-m)}[{1 β²}({1x}-1) + B₁x + B₂(1-x) - {B₃2}( 1-x²) +{B₄3}(1-x³)]

where

$\gamma =\; \{Em\}$	$\beta$2= 1-{1γ2}
$x\; =\{DCUTEE-m\}$	$\gamma =\{1\gamma +\; 1\}$
$B$1=2-y2	$B$2=(1-2y)(3+y2)
$B$3=(1-2y)2+(1-2y)3	$B$4=(1-2y)3

The formulae [] and [] give the total cross-section of the scattering above the threshold energies

$T$_Moller^thr=2DCUTE&sp;and&sp;T_Bhabha^thr= DCUTE

The interaction length for the production of $\delta$ -rays is calculated during initialisation by routine GDRSGA.

PHYS331