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/*
* detector.c
*
* Detector properties
*
* (c) 2007-2009 Thomas White <thomas.white@desy.de>
*
* pattern_sim - Simulate diffraction patterns from small crystals
*
*/
#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include "image.h"
#include "utils.h"
/* Pulse energy density in J/m^2 */
#define PULSE_ENERGY_DENSITY (30.0e7)
void record_image(struct image *image)
{
int x, y;
double ph_per_e;
double twotheta_max, np, sa_per_pixel;
/* How many photons are scattered per electron? */
ph_per_e = PULSE_ENERGY_DENSITY * pow(THOMSON_LENGTH, 2.0)
/ image->xray_energy;
printf("%e photons are scattered per electron\n", ph_per_e);
twotheta_max = image->twotheta[0];
np = sqrt(pow(image->x_centre, 2.0) + pow(image->y_centre, 2.0));
sa_per_pixel = pow(2.0 * twotheta_max / np, 2.0);
printf("sa per pixel=%e\n", sa_per_pixel);
image->data = malloc(image->width * image->height * sizeof(uint16_t));
for ( x=0; x<image->width; x++ ) {
for ( y=0; y<image->height; y++ ) {
double counts;
double val, intensity;
double sa;
val = image->sfacs[x + image->width*y];
/* What solid angle is subtended by this pixel? */
sa = sa_per_pixel * cos(image->twotheta[x + image->width*y]);
intensity = pow(val, 2.0);
counts = intensity * ph_per_e * sa;
image->data[x + image->width*y] = counts;
}
}
}
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