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#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_spline.h>
#include <math.h>
#include "optics.h"
#include "quantum_efficiency.h"
#include "solid_angle.h"
#include "pdg.h"
#include "vector.h"
#include "electron.h"
#include "sno.h"
#include "scattering.h"
#include "pmt_response.h"
#include "misc.h"
static int initialized = 0;
static double *x, *dEdx, *csda_range;
static size_t size;
static gsl_interp_accel *acc_dEdx;
static gsl_spline *spline_dEdx;
static gsl_interp_accel *acc_range;
static gsl_spline *spline_range;
/* Electron critical energy in H2O and D2O.
*
* These values come from
* http://pdgprod.lbl.gov/~deg/AtomicNuclearProperties/HTML/deuterium_oxide_liquid.html for D2O and
* http://pdg.lbl.gov/2018/AtomicNuclearProperties/HTML/water_liquid.html for H2O.
*/
static const double ELECTRON_CRITICAL_ENERGY_H2O = 78.33;
static const double ELECTRON_CRITICAL_ENERGY_D2O = 78.33;
static int init()
{
int i, j;
char line[256];
char *str;
double value;
int n;
FILE *f = fopen("e_water_liquid.txt", "r");
if (!f) {
fprintf(stderr, "failed to open e_water_liquid.txt: %s\n", strerror(errno));
return -1;
}
i = 0;
n = 0;
/* For the first pass, we just count how many values there are. */
while (fgets(line, sizeof(line), f)) {
size_t len = strlen(line);
if (len && (line[len-1] != '\n')) {
fprintf(stderr, "got incomplete line on line %i: '%s'\n", i, line);
goto err;
}
i += 1;
/* Skip the first 8 lines since it's just a header. */
if (i <= 8) continue;
if (!len) continue;
else if (line[0] == '#') continue;
str = strtok(line," \n");
while (str) {
value = strtod(str, NULL);
str = strtok(NULL," \n");
}
n += 1;
}
x = malloc(sizeof(double)*n);
dEdx = malloc(sizeof(double)*n);
csda_range = malloc(sizeof(double)*n);
size = n;
i = 0;
n = 0;
/* Now, we actually store the values. */
rewind(f);
while (fgets(line, sizeof(line), f)) {
size_t len = strlen(line);
if (len && (line[len-1] != '\n')) {
fprintf(stderr, "got incomplete line on line %i: '%s'\n", i, line);
goto err;
}
i += 1;
/* Skip the first 8 lines since it's just a header. */
if (i <= 8) continue;
if (!len) continue;
else if (line[0] == '#') continue;
str = strtok(line," \n");
j = 0;
while (str) {
value = strtod(str, NULL);
switch (j) {
case 0:
x[n] = value;
break;
case 3:
dEdx[n] = value;
break;
case 4:
csda_range[n] = value;
break;
}
j += 1;
str = strtok(NULL," \n");
}
n += 1;
}
fclose(f);
acc_dEdx = gsl_interp_accel_alloc();
spline_dEdx = gsl_spline_alloc(gsl_interp_linear, size);
gsl_spline_init(spline_dEdx, x, dEdx, size);
acc_range = gsl_interp_accel_alloc();
spline_range = gsl_spline_alloc(gsl_interp_linear, size);
gsl_spline_init(spline_range, x, csda_range, size);
initialized = 1;
return 0;
err:
fclose(f);
return -1;
}
double electron_get_range(double T, double rho)
{
/* Returns the approximate range a electron with kinetic energy `T` will travel
* in water before losing all of its energy. This range is interpolated
* based on data from the PDG which uses the continuous slowing down
* approximation.
*
* `T` should be in MeV, and `rho` should be in g/cm^3.
*
* Return value is in cm.
*
* See http://pdg.lbl.gov/2018/AtomicNuclearProperties/adndt.pdf. */
if (!initialized) {
if (init()) {
exit(1);
}
}
return gsl_spline_eval(spline_range, T, acc_range)/rho;
}
double electron_get_dEdx(double T, double rho)
{
/* Returns the approximate dE/dx for a electron in water with kinetic energy
* `T`.
*
* `T` should be in MeV and `rho` in g/cm^3.
*
* Return value is in MeV/cm.
*
* See http://pdg.lbl.gov/2018/AtomicNuclearProperties/adndt.pdf. */
if (!initialized) {
if (init()) {
exit(1);
}
}
if (T < spline_dEdx->x[0]) return spline_dEdx->y[0];
return gsl_spline_eval(spline_dEdx, T, acc_dEdx)*rho;
}
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