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Merged
willend merged 4 commits into from
Oct 27, 2026
Merged

X: Undulator minor fixes #2913

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956e1cc
X: Undulator minor fixes
farhi Oct 26, 2026
b485995
Merge branch 'main' into 2026-10-farhi-undulator-1
willend Oct 27, 2026
aeb167a
SOLEIL_ANATOMIX: back to old test value. OK
farhi Oct 27, 2026
629ec3e
SOLEIL_ANATOMIX: narrow dE in %Example, target 9.4e17
willend Oct 27, 2026
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2 changes: 1 addition & 1 deletion mcxtrace-comps/examples/SOLEIL/SOLEIL_ANATOMIX/SOLEIL_ANATOMIX.instr
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@
* EH3 | 165.7-174.1 | Guard slits; TXM sample stage and zone-plate table; microtomography sample stage; detector table | EH3
* EH4 | 197.2-208.5 | Guard slits; microtomography sample stage; detector table; X-ray grating interferometer | EH4
*
* %Example: -n 1e6 ANATOMIX_E0=17 Detector: ANATOMIX_psd_monitor_after_cc_I=1e18
* %Example: -n 1e5 ANATOMIX_E0=17 ANATOMIX_dE=0.01 Detector: ANATOMIX_psd_monitor_after_cc_I=9.4e+17
*
* %Parameters
* ANATOMIX_E0: [keV] Energy selected at the Undulator.
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61 changes: 35 additions & 26 deletions mcxtrace-comps/sources/Undulator.comp
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Original file line number Diff line number Diff line change
Expand Up @@ -54,11 +54,11 @@
DEFINE COMPONENT Undulator

SETTING PARAMETERS (E0=0, dE=0, phase=0, randomphase=1, Ee=2.4, dEe=0, Ie=0.4, B=0, K=0,
int Nper=1, lu=16e-3, sigey=0, sigex=0, sigepx=0, sigepy=0, focus_xw=0, focus_yh=0, dist=1, quick_integ=0,
E1st=0, int verbose=0, Br=1.35)
int Nper=1, lu=16e-3, sigey=0, sigex=0, sigepx=0, sigepy=0, focus_xw=0, focus_yh=0, dist=1, quick_integ=0,
E1st=0, int verbose=0, Br=1.35)

DEPENDENCY " @GSLFLAGS@ "
/* X-ray parameters: (x,y,z,kx,ky,kz,phi,t,Ex,Ey,Ez,p) */
/* X-ray parameters: (x,y,z,kx,ky,kz,phi,t,Ex,Ey,Ez,p) */
NOACC

SHARE
Expand Down Expand Up @@ -121,7 +121,6 @@ DECLARE
double alpha;
/*electron mass*/
double MELE;
// double besselj[nharm],besselh[nharm];
%}


Expand Down Expand Up @@ -152,6 +151,11 @@ INITIALIZE
K = sqrt (K);
else
K = 0;
/* K could come out 0 or imaginary (E1st above the undulator reach) */
if (K <= 0) {
fprintf (stderr, "Error (%s): Cannot realize E1st=%g keV with lu=%g m and Ee=%g GeV (K^2 <= 0). Aborting.\n", NAME_CURRENT_COMP, E1st, lu, Ee);
exit (1);
}
} else if (!lu && E1st && K) {
lu = 4 * M_PI * gamma2 / (K * K / 2 + 1) / (E2K * E1st * 1e10);
}
Expand All @@ -174,9 +178,8 @@ INITIALIZE

/* compute gap estimate */
if (Br > B) { // remanent field, rather usual for Nd2Fe14B
double a = 0.55 * Br + 2.835;
double a = 0.55 * Br + 2.835;
double b = -1.95 * Br + 7.22;
double c = -1.3 * Br + 2.97;
gap = -log (B / a) * lu / b;
} else
gap = 3e-3;
Expand All @@ -194,7 +197,12 @@ INITIALIZE
exit (1);
}

// printf("Undulator (%s): gamma=%g, divergence is 1/gamma=%g rad.\n",NAME_CURRENT_COMP,gamma,igamma);
/* without a focus window every ray is emitted exactly on-axis
* (xi = psi = 0) with a unit solid-angle weight - warn loudly */
if (!focus_xw && !focus_yh) {
fprintf (stderr, "Warning (%s): focus_xw and focus_yh are both unset - all rays are forced on-axis (xi=psi=0).\n", NAME_CURRENT_COMP);
}

/*compute characteristic energy in keV*/
double Ec = 0.665 * Ee * Ee * B;
// double Ec=1.5*gamma2*HBAR*CELE*B/MELE *1e-3; /*check units on this one. The 1e-3 factor is because energy is assumed to be in keV*/
Expand Down Expand Up @@ -222,7 +230,7 @@ INITIALIZE
TRACE
%{

double k, e, l, w_u, r, w;
double k, e, w_u, r, w;
double xo, yo, zo, xi, psi, theta2, Omega;
double bsigma_integral, bpi_integral, s_n2;
double bsigma_error, bpi_error;
Expand All @@ -231,11 +239,14 @@ TRACE
e = E0 + randpm1 () * dE;

/* add electron beam energy spread to gamma parameters (if necessary).*/
/* use ray-local copies so the base gamma is not clobbered for
* subsequent rays */
double gamma_l = gamma, gamma2_l = gamma2, igamma_l = igamma;
if (dEe) {
double deltaEe = (randnorm () * dEe * Ee) + Ee;
gamma = (deltaEe * 1e9) / (MELE / CELE * M_C * M_C); /*the extra CELE is to convert to eV*/
gamma2 = gamma * gamma;
igamma = 1.0 / gamma;
gamma_l = (deltaEe * 1e9) / (MELE / CELE * M_C * M_C); /*the extra CELE is to convert to eV*/
gamma2_l = gamma_l * gamma_l;
igamma_l = 1.0 / gamma_l;
}

/* the undulator's fundamental angular frequency*/
Expand All @@ -246,21 +257,15 @@ TRACE
* ... we can now weight properly according to ang. flux density*/
if (focus_xw && focus_yh) {
randvec_target_rect (&xo, &yo, &zo, &Omega, 0, 0, dist, focus_xw, focus_yh, ROT_A_CURRENT_COMP);
} else if (focus_yh != 0) {
xi = 0;
} else if (focus_yh) {
xo = 0;
yo = 0;
yo = randpm1 () * 0.5 * focus_yh;
Omega = 1;
} else if (focus_xw != 0) {
psi = 0;
xo = 0;
} else if (focus_xw) {
yo = 0;
xo = randpm1 () * 0.5 * focus_xw;
Omega = 1;
} else {
xi = 0;
psi = 0;
xo = 0;
yo = 0;
Omega = 1;
Expand All @@ -276,7 +281,9 @@ TRACE
y = randnorm () * sigey;
}

xi = fabs (atan2 (xo, dist));
/* fabs() is deliberate: only theta^2 enters the weighting, so the
* sign of the angle is irrelevant here. */
xi = fabs (atan2 (xo, dist));
psi = fabs (atan2 (yo, dist));
/* This has to be after (xi,psi), else it will be convoluted into the weight calculation.*/
if (sigepx) {
Expand All @@ -300,17 +307,17 @@ TRACE
ky *= k;
kz *= k;

double w1theta = 2 * gamma2 / (1 + K * K / 2.0 + gamma2 * theta2) * w_u;
double w10 = 2 * gamma2 / (1 + K * K / 2.0) * w_u;
double w1theta = 2 * gamma2_l / (1 + K * K / 2.0 + gamma2_l * theta2) * w_u;
double w10 = 2 * gamma2_l / (1 + K * K / 2.0) * w_u;
double w_w1 = w / w1theta;
double w_w10 = w / w10;

double Bsig_integ_prms[4], Bpi_integ_prms[4];
Bsig_integ_prms[0] = Bpi_integ_prms[0] = w_w1; /*relative frequency*/
Bsig_integ_prms[1] = Bpi_integ_prms[1] = 2 * w_w10 * xi * gamma * K / (1 + K * K / 2.0); /*p*/
Bsig_integ_prms[1] = Bpi_integ_prms[1] = 2 * w_w10 * xi * gamma_l * K / (1 + K * K / 2.0); /*p*/
Bsig_integ_prms[2] = Bpi_integ_prms[2] = 0.25 * w_w10 * K * K / (1 + K * K / 2.0); /*q*/
Bsig_integ_prms[3] = xi * gamma / K; /*angle terms*/
Bpi_integ_prms[3] = psi * gamma / K;
Bsig_integ_prms[3] = xi * gamma_l / K; /*angle terms*/
Bpi_integ_prms[3] = psi * gamma_l / K;

/*pass the parameters to the integrand*/
Bsig.params = Bsig_integ_prms;
Expand All @@ -328,7 +335,7 @@ TRACE

s_n2 = mxundulator_S_N (w_w1, Nper);

double prefactor = alpha * Ie / CELE * pow (K * gamma / (1 + K * K / 2.0), 2.0) * Nper * Nper * w_w10 * w_w10;
double prefactor = alpha * Ie / CELE * pow (K * gamma_l / (1 + K * K / 2.0), 2.0) * Nper * Nper * w_w10 * w_w10;

p *= prefactor * (pow (bsigma_integral, 2.0) + pow (bpi_integral, 2.0)) * s_n2;

Expand All @@ -344,12 +351,14 @@ TRACE
Ey = 0;
Ez = 0;
%}

FINALLY
%{
if (!quick_integ) {
gsl_integration_workspace_free (gsl_int_ws);
}
%}

MCDISPLAY
%{

Expand Down
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