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/*******************************************************************************
*
* Mcstas, neutron ray-tracing package
* Copyright (C) 1997-2012, All rights reserved
* Risoe National Laboratory, Roskilde, Denmark
* Institut Laue Langevin, Grenoble, France
*
* Component: ESS_moderator
*
* %I
* Written by: P Willendrup and E Klinkby, February 2014, derived from K Lefmann ESS_moderator_long
* Modified by:
* Version: $Revision: 4592 $
* Origin: DTU
* Release: McStas 2.1
*
* A parametrised pulsed source for modelling ESS long pulses.
*
* %D
* Produces a time-of-flight spectrum, from the ESS parameters
* Chooses evenly in lambda, evenly/exponentially decaying in time
* Adapted from ESS_moderator_long by: K Lefmann, 2001
*
* 2014-updates:
* <ol>
* <li>Selectable between simple flat single-moderator (planar=1) and MCNPX-like dual-moderator (thermal and cold) setup.
* <b>IMPORTANT</b>: In case of the dual-moderator geometry, the origin of the component is inside the cylindrical
* moderator, i.e. take care when positioning the next components! (E Klinkby)
* <li>The spectrum from the source(s) is defined via the sourcedef string input parameter which allows these values:
* <ul>
* <li>sourcedef="2001", legacy "Mezei moderators" from the original F. Mezei documents
* "ESS reference moderator characteristics for generic instrument performance evaluation", but rescaled to ESS TDR frequency, pulselength and power.
* <li>sourcedef="TDR", Mezei moderators, with a wavelength-dependent correction term to the cold flux, derived from
* 2012 MCNPX calculations by ESS neutronics group. Corrections calculated by K Lieutenant (Vitess) and
* implemented here by E Klinkby. NOTE: uses the 2001 brilliance for the thermal moderator!
* <li>sourcedef="2014", updated brilliance using formulation by Troels Schoenfeldt, including support for the "pancacke", i.e. flat geometry.
*</ul>
* <li>The component can use target_index for focusing to a given beam port. Use an Arm() and ROTATED to position
* relatively to the moderator.
* <li>Time focusing option: Adjusts neutron departure time to match a 'first chopper' defined by parameters tfocus_dist, tfocus_time, tfocus_width (K Lefmann).
* NOTE: Currently only applies to the Mezei-moderator.
* <li>The component relies on the new ess_source-lib which is expected to become further enriched during design-finaliziation and construciton of the ESS.
* </ol>
*
* Units of flux: n/cm^2/s/AA/ster
* (McStas units are in general neutrons/second)
*
* Derived from ESS_moderator_long which was debugged intensively against Mezei note (4/12 2000) and VitESS @ Rencurel 2006.
*
* %VALIDATION
* Validated against VitESS and Mezei note (4/12 2000) @ Rencurel 2006
*
* %P
* Input parameters:
*
* yheight_c: (m) Height of the cylindershaped cold source
* yheight_t: (m) Height of the rectangular thermal source
* cyl_radius:(m) Radius of the cylindershaped cold source - coupled to width_c
* width_t: (m) Edge of cube shaped thermal source
* width_c: (m) Arc-length opening of cylindershaped cold source - coupled to cyl_radius. (Used as width of rectangular geometry if planar=1)
* Lmin: (AA) Lower edge of wavelength distribution
* Lmax: (AA) Upper edge of wavelength distribution
* dist: (m) Distance from source to focusing rectangle; at (0,0,dist)
* focus_xw:(m) Width of focusing rectangle
* focus_yh:(m) Height of focusing rectangle
* target_index:(1) relative index of component to focus at, e.g. next is +1
* this is used to compute 'dist' automatically.
* n_pulses: (1) Number of pulses simulated. 0 and 1 creates one pulse.
* The integrated intensity is constant
* cold_frac: (1) Fraction of neutron statistics from cold source. It is implicitely assumed
* that supermirror allows each beamline to choose the desired fraction
* of cold and thermal neutrons (i.e. extreme idealization).
* tfocus_dist: (m) Position of time window
* tfocus_time: (s) Time position of window
* tfocus_width: (s) Time width of window
* beamport_angle: (deg) Direction within the beamport sector (0 < angle < 60) to direct neutrons
* acc_power: (MW) Accelerator power in MW
* sourcedef: (string) ESS source "database", values: "TDR", "2001", "2013", "2014"
* planar: (boolean) If set to 1, source geometry is flat and rectangular. Can only be used if cold_frac is 1 or 0, i.e. for fully thermal or fully cold source. May overwrite other geometry input.
* isleft: (boolean) If set to 1, place thermal wing left of cold cylinder, if set to 0, place thermal wing right of cold cylinder.
*
* %E
*******************************************************************************/
DEFINE COMPONENT ESS_moderator
DEFINITION PARAMETERS ()
SETTING PARAMETERS (cyl_radius=0.085, width_c=0, yheight_c=0.12, yheight_t=0.12, width_t=0.12, beamport_angle=30, planar=0, isleft=1,
Lmin, Lmax, cold_frac=1.0,
dist=0, focus_xw, focus_yh, int target_index=0,
tfocus_dist=0.1, tfocus_time=0.0, tfocus_width=0.0,
int n_pulses=1, string sourcedef="TDR", acc_power=5)
OUTPUT PARAMETERS (cold_bril, thermal_bril, l_range, w_mult, w_geom, w_geom, w_geom_t, yheight)
/* Neutron parameters: (x,y,z,vx,vy,vz,t,sx,sy,sz,p) */
SHARE
%{
%include "ess_source-lib"
%}
DECLARE
%{
double l_range, w_mult, w_geom, w_geom_c, w_geom_t, yheight;
double tx,ty,tz;
double t1x,t1y,t1z,t2x,t2y,t2z;
/* Target station geometry... */
double r_empty = 2.0; /* two meters from moderator surface and out... */
double r_optics;
ess_moderator_struct modextras;
functype cold_bril;
functype thermal_bril;
%}
INITIALIZE
%{
n_pulses=(double)floor(n_pulses);
if (n_pulses == 0) n_pulses=1;
if (target_index && !dist)
{
Coords ToTarget;
ToTarget = coords_sub(POS_A_COMP_INDEX(INDEX_CURRENT_COMP+target_index),POS_A_CURRENT_COMP);
ToTarget = rot_apply(ROT_A_CURRENT_COMP, ToTarget);
coords_get(ToTarget, &tx, &ty, &tz);
dist=sqrt(tx*tx+ty*ty+tz*tz);
} else if (target_index && !dist) {
printf("ESS_moderator: %s: Please choose to set either the dist parameter or specify a target_index.\nExit\n", NAME_CURRENT_COMP);
exit(-1);
} else {
tx=0, ty=0, tz=dist;
}
if (focus_xw < 0 || focus_yh < 0)
{
printf("ESS_moderator: %s: Please specify both focus_xw and focus_yh as positive numbers.\nExit\n", NAME_CURRENT_COMP);
exit(-1);
}
if (dist < r_empty && dist > 0)
{
printf("ESS_moderator: %s WARNING: Provided dist parameter is %g and hence inside the vacated zone of the beam extraction system!\nYou might be placing optics in a restricted area!!!\n", NAME_CURRENT_COMP, dist);
}
if (beamport_angle < 0 || beamport_angle > 60)
{
printf("ESS_moderator: %s: Please select a beamport_angle between 0 and 60 degrees!\nExit\n", NAME_CURRENT_COMP);
exit(-1);
}
if (width_c && cyl_radius) {
printf("ESS_moderator: %s: Please specify EITHER cold-moderator radius (cyl_radius) or length of visible arch (width_c)!\nExit\n", NAME_CURRENT_COMP);
exit(-1);
} else if (cyl_radius) {
width_c = 2*PI*cyl_radius*60/360;
} else {
cyl_radius = 360*width_c/(2*PI*60);
}
r_optics = 6.0 - r_empty - cyl_radius;
if (Lmin<=0 || Lmax <=0 || dist == 0)
{
printf("ESS_moderator: %s: Check parameters (lead to Math Error).\n Avoid 0 value for {Lmin Lmax dist d tau branch1/2/tail} and 1 value for {n n2 branch1/2/tail}\n", NAME_CURRENT_COMP);
exit(-1);
}
if (planar==1 && !(cold_frac==1 || cold_frac==0))
{
printf("ESS_moderator: %s: Planar==1 can only be used with cold_frac==1 or cold_frac==0, i.e. purely cold or thermal moderator\n", NAME_CURRENT_COMP);
exit(-1);
}
l_range = Lmax-Lmin;
w_geom_c = width_c*yheight_c*1.0e4; /* source area correction */
w_geom_t = width_t*yheight_t*1.0e4;
w_mult = l_range; /* wavelength range correction */
w_mult *= 1.0/mcget_ncount(); /* Correct for number of rays */
if (planar==1) {
if (cold_frac==0) {
/* Flat thermal source, horz basis vector(s) along x */
t1x=1;
t1y=0;
t1z=0;
t2x=1;
t2y=0;
t2z=0;
} /* Flat cold source is handled below */
} else if (planar==0){
/* Calculate location of thermal wings wrt beamport_angle (z) direction */
/* Wing 1 (left) is at -beamport_angle */
t1z = cyl_radius*cos(-DEG2RAD*beamport_angle);
t1x = cyl_radius*sin(-DEG2RAD*beamport_angle);
t1y = 0;
/* Wing 2 (right) is at 60-beamport_angle */
t2z = cyl_radius*cos(DEG2RAD*(60-beamport_angle));
t2x = cyl_radius*sin(DEG2RAD*(60-beamport_angle));
t2y = 0;
/* We want unit vectors... */
NORM(t1x,t1y,t1z);
NORM(t2x,t2y,t2z);
} else {
printf("ESS_moderator: %s: Planar is a boolean input parameter, please give either 0 or 1\n", NAME_CURRENT_COMP);
exit(-1);
}
if (strcasestr(sourcedef,"TDR")) {
w_mult *= ESS_SOURCE_FREQUENCY; /* Correct for frequency */
w_mult *= acc_power/5; /* Correct for accelerator power */
printf("Using ESS TDR brilliance\n");
cold_bril=ESS_2012_Lieutenant_cold;
thermal_bril=ESS_Mezei_thermal;
} else if (strcasestr(sourcedef,"2001")) {
w_mult *= ESS_SOURCE_FREQUENCY; /* Correct for frequency */
w_mult *= acc_power/5; /* Correct for accelerator power */
printf("Using ESS 2001 brilliance\n");
cold_bril=ESS_Mezei_cold;
thermal_bril=ESS_Mezei_thermal;
} else if (strcasestr(sourcedef,"2014")) {
// w_mult *= ESS_SOURCE_FREQUENCY; /* Is already in per-second units */
w_mult *= acc_power; /* Is already in per-MW units */
printf("Using ESS 2014 brilliance\n");
// Fix: transfer in m units rather than cm's...
modextras.height_c=100.0*yheight_c;
modextras.height_t=100.0*yheight_t;
cold_bril=ESS_2013_Schoenfeldt_cold;
thermal_bril=ESS_2013_Schoenfeldt_thermal;
} else {
printf("Soure def %s not implemented!\n",sourcedef);
exit(-1);
}
/* For drawing */
yheight = fmax(yheight_t, yheight_c);
%}
TRACE
%{
double v,tau_l,E,lambda,k,r,xf,yf,dx,dy,w_focus,tail_flag,cor,dt,xprime,yprime,zprime;
/* Bispectral source - choice of spectrum and initial position */
int cold = ( rand01() < cold_frac ) ? 1 : 0;
/* Geometry adapted from ESS MCNPX model, mid 2012 */
if (cold) { //case: cold moderator
if (planar==1) {
x = 0.5*randpm1()*width_c;
y = 0.5*randpm1()*yheight_c;
z = 0;
} else {
double theta_tmp;
//choose random point on cylinder surface
theta_tmp = randpm1()*PI/6 + PI/2 + (- 30 + beamport_angle)*DEG2RAD;
x = cyl_radius * cos(theta_tmp);
y = 0.5*randpm1()*yheight;
z = cyl_radius * sin(theta_tmp);
}
w_geom = w_geom_c;
} else { //case: thermal moderator
double poshorz, posvert;
if (planar==1) {
x = 0.5*randpm1()*width_t;
y = 0.5*randpm1()*yheight_t;
z = 0;
} else {
poshorz = cyl_radius+rand01()*width_t;
posvert = 0.5*randpm1()*yheight;
if (isleft) {
x = t1x * poshorz;
z = t1z * poshorz;
} else {
x = t2x * poshorz;
z = t2z * poshorz;
}
y = posvert;
}
w_geom = w_geom_t;
}
randvec_target_rect_real(&xf, &yf, &r, &w_focus,
tx, ty, tz, focus_xw, focus_yh, ROT_A_CURRENT_COMP, x, y, z, 2);
dx = xf-x;
dy = yf-y;
r = sqrt(dx*dx+dy*dy+dist*dist);
lambda = Lmin+l_range*rand01(); /* Choose from uniform distribution */
k = 2*PI/lambda;
v = K2V*k;
vz = v*dist/r;
vy = v*dy/r;
vx = v*dx/r;
/* Determine delta-t needed to reach first chopper */
if (tfocus_width>0) {
dt = tfocus_dist/vz; /* Flight time to time window (chopper) */
}
if (cold) { //case: cold moderator
cold_bril( &t, &p, lambda, tfocus_width, tfocus_time, dt, modextras);
} else { //case: thermal moderator
thermal_bril( &t, &p, lambda, tfocus_width, tfocus_time, dt, modextras);
}
p*=w_focus*w_geom*w_mult;
t+=(double)floor((n_pulses)*rand01())/ESS_SOURCE_FREQUENCY; /* Select a random pulse */
/* Correct weight for sampling of cold vs. thermal events. */
if (cold) {
p /=cold_frac;
} else {
p/=(1-cold_frac);
}
%}
MCDISPLAY
%{
if (planar==0) {
/* Draw cold moderator as cylinder */
circle("xz", 0, yheight_c/2.0, 0, cyl_radius);
circle("xz", 0, -yheight_c/2.0, 0, cyl_radius);
line(0, -yheight_c/2.0, cyl_radius, 0, yheight_c/2.0, cyl_radius);
line(0, -yheight_c/2.0, -cyl_radius, 0, yheight_c/2.0, -cyl_radius);
line(cyl_radius, yheight_c/2.0, 0, cyl_radius, yheight_c/2.0, 0);
line(-cyl_radius, -yheight_c/2.0, 0, -cyl_radius, yheight_c/2.0, 0);
/* Draw thermal moderators as a couple of squares + some lines */
// Left
multiline(4, t1x*cyl_radius, -yheight_t/2.0, t1z*cyl_radius,
t1x*(cyl_radius + width_t), -yheight_t/2.0, t1z*(cyl_radius + width_t),
t1x*(cyl_radius + width_t), yheight_t/2.0, t1z*(cyl_radius + width_t),
t1x*cyl_radius, yheight_t/2.0, t1z*cyl_radius);
// Right
multiline(4, t2x*cyl_radius, -yheight_t/2.0, t2z*cyl_radius,
t2x*(cyl_radius + width_t), -yheight_t/2.0, t2z*(cyl_radius + width_t),
t2x*(cyl_radius + width_t), yheight_t/2.0, t2z*(cyl_radius + width_t),
t2x*cyl_radius, yheight_t/2.0, t2z*cyl_radius);
/* Dashed lines for indicating "beam extraction" area... */
dashed_line(t1x*cyl_radius, -yheight/2.0, t1z*cyl_radius, t1x*r_empty, -yheight/2.0, t1z*r_empty,10);
dashed_line(t1x*cyl_radius, yheight/2.0, t1z*cyl_radius, t1x*r_empty, yheight/2.0, t1z*r_empty,10);
dashed_line(t2x*cyl_radius, -yheight/2.0, t2z*cyl_radius, t2x*r_empty, -yheight/2.0, t2z*r_empty,5);
dashed_line(t2x*cyl_radius, yheight/2.0, t2z*cyl_radius, t2x*r_empty, yheight/2.0, t2z*r_empty,5);
/* Circles indicating extent of the "empty" zone where optics is not allowed */
circle("xz", 0, yheight/2.0, 0, r_empty);
circle("xz", 0, -yheight/2.0, 0, r_empty);
/* Circles indicating the builk shielding of the target monolith at 6 m */
circle("xz", 0, focus_yh/2.0 , 0, 6);
circle("xz", 0, -focus_yh/2.0 , 0, 6);
circle("xz", 0, 2, 0, 6);
circle("xz", 0, -2, 0, 6);
/* Rectangle indicating the chosen focus rectangle - where the optics starts... */
rectangle("xy",tx,ty,tz,focus_xw,focus_yh);
} else {
/* Simple 'flat', single-spectrum geometry */
double tmpheight,tmpwidth;
if (cold_frac==0) {
tmpheight = yheight_t;
tmpwidth = width_t;
} else {
tmpheight = yheight_c;
tmpwidth = width_c;
}
rectangle("xy",0,0,0,tmpwidth,tmpheight);
rectangle("xy",tx,ty,tz,focus_xw,focus_yh);
}
%}
END
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