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/* Copyright (c) 2019, Anthony Latorre <tlatorre at uchicago>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option)
* any later version.
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <gsl/gsl_spline.h>
#include <stdlib.h> /* for size_t, strtod() */
#include <errno.h> /* for errno */
#include <string.h> /* for strerror(), strtok() */
#include "sno.h"
#include "misc.h"
static double *x, *dEdx_rad, *dEdx;
static size_t size;
static gsl_interp_accel *acc_dEdx_rad;
static gsl_spline *spline_dEdx_rad;
static gsl_interp_accel *acc_dEdx;
static gsl_spline *spline_dEdx;
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_rad = malloc(sizeof(double)*n);
dEdx = 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 2:
dEdx_rad[n] = value;
break;
case 3:
dEdx[n] = value;
break;
}
j += 1;
str = strtok(NULL," \n");
}
n += 1;
}
fclose(f);
acc_dEdx_rad = gsl_interp_accel_alloc();
spline_dEdx_rad = gsl_spline_alloc(gsl_interp_linear, size);
gsl_spline_init(spline_dEdx_rad, x, dEdx_rad, size);
acc_dEdx = gsl_interp_accel_alloc();
spline_dEdx = gsl_spline_alloc(gsl_interp_linear, size);
gsl_spline_init(spline_dEdx, x, dEdx, size);
return 0;
err:
fclose(f);
return -1;
}
/* Returns the approximate dE/dx for a electron in water with kinetic energy
* `T`. If `T` is outside the bounds of the range table, extrapolate linearly
* using the last two points.
*
* `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. */
double electron_get_dEdx(double T, double rho)
{
if (T < spline_dEdx->x[0]) {
return spline_dEdx->y[0];
} else if (T < spline_dEdx->x[size-1]) {
return gsl_spline_eval(spline_dEdx, T, acc_dEdx)*rho;
}
/* We extrapolate using the last two points. */
return spline_dEdx->y[size-1] + (spline_dEdx->y[size-1]-spline_dEdx->y[size-2])*(T-spline_dEdx->x[size-1])/(spline_dEdx->x[size-1]-spline_dEdx->x[size-2]);
}
/* Returns the approximate radiative dE/dx for a electron in water with kinetic
* energy `T`. If `T` is outside the bounds of the range table, extrapolate
* linearly using the last two points.
*
* `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. */
double electron_get_dEdx_rad(double T, double rho)
{
if (T < spline_dEdx_rad->x[0]) {
return spline_dEdx_rad->y[0];
} else if (T < spline_dEdx_rad->x[size-1]) {
return gsl_spline_eval(spline_dEdx_rad, T, acc_dEdx_rad)*rho;
}
/* We extrapolate using the last two points. */
return spline_dEdx_rad->y[size-1] + (spline_dEdx_rad->y[size-1]-spline_dEdx_rad->y[size-2])*(T-spline_dEdx_rad->x[size-1])/(spline_dEdx_rad->x[size-1]-spline_dEdx_rad->x[size-2]);
}
double electron_get_range(double T0)
{
double T, dx, range;
T = T0;
dx = 1e-5;
range = 0.0;
while (T > 0) {
double dEdx2 = electron_get_dEdx(T, WATER_DENSITY);
T -= dEdx2*dx;
range += dx;
}
return range;
}
int main(int argc, char **argv)
{
int i;
double T0;
double Ts[18] = {
2.000E+04,
3.000E+04,
4.000E+04,
5.000E+04,
6.000E+04,
7.000E+04,
8.000E+04,
9.000E+04,
1.000E+05,
2.000E+05,
3.000E+05,
4.000E+05,
5.000E+05,
6.000E+05,
7.000E+05,
8.000E+05,
9.000E+05,
1.000E+06};
init();
for (i = 0; i < LEN(Ts); i++) {
T0 = Ts[i];
printf("%.3E - %.3E %.3E %.3E - -\n", T0, electron_get_dEdx_rad(T0,WATER_DENSITY), electron_get_dEdx(T0,WATER_DENSITY), electron_get_range(T0));
}
return 0;
}
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