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Diffstat (limited to 'src/electron.c')
| -rw-r--r-- | src/electron.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/electron.c b/src/electron.c index 957b278..5b4133a 100644 --- a/src/electron.c +++ b/src/electron.c @@ -59,6 +59,29 @@ static gsl_spline *spline_range; static const double ELECTRON_CRITICAL_ENERGY_H2O = 78.33; static const double ELECTRON_CRITICAL_ENERGY_D2O = 78.33; +/* Returns the average number of Cerenkov photons in the range 200-800 nm + * produced by secondary particles in an electron shower. + * + * This comes from fitting the ratio # shower photons/rad loss to the function: + * + * c0 + c1/log(T0*c2 + c3) + * + * I don't really have any good theoretical motivation for this. My initial + * thought was that the number of photons should be roughly proportional to the + * energy lost due to radiation which is why I chose to fit the ratio. This + * ratio turned out to vary from approximately 520 at low energies (10 MeV) to + * a roughly constant value of 420 at higher energies (> 1 GeV). + * + * This functional form just happened to fit the ratio as a function of energy + * pretty well. + * + * `T0` is the initial kinetic energy of the electron in MeV and `rad` is the + * energy lost due to radiation in MeV. */ +double electron_get_shower_photons(double T0, double rad) +{ + return rad*(406.745 + 0.271816/log(5.31309e-05*T0+1.00174)); +} + void electron_get_position_distribution_parameters(double T0, double *a, double *b) { /* Computes the gamma distribution parameters describing the longitudinal |