/******************************************************************************* * * McStas, neutron ray-tracing package * Copyright (C) 1997-2008, All rights reserved * Risoe National Laboratory, Roskilde, Denmark * Institut Laue Langevin, Grenoble, France * * Component: SasView_stickyhardsphere * * %Identification * Written by: Jose Robledo * Based on sasmodels from SasView * Origin: FZJ / DTU / ESS DMSC * * * SasView stickyhardsphere model component as sample description. * * %Description * * SasView_stickyhardsphere component, generated from stickyhardsphere.c in sasmodels. * * Example: * SasView_stickyhardsphere(radius_effective, volfraction, perturb, stickiness, * model_scale=1.0, model_abs=0.0, xwidth=0.01, yheight=0.01, zdepth=0.005, R=0, * int target_index=1, target_x=0, target_y=0, target_z=1, * focus_xw=0.5, focus_yh=0.5, focus_aw=0, focus_ah=0, focus_r=0, * pd_radius_effective=0.0) * * %Parameters * INPUT PARAMETERS: * radius_effective: [Ang] ([0, inf]) effective radius of hard sphere. * volfraction: [] ([0, 0.74]) volume fraction of hard spheres. * perturb: [] ([0.01, 0.1]) perturbation parameter, tau. * stickiness: [] ([-inf, inf]) stickiness, epsilon. * Optional parameters: * model_abs: [ ] Absorption cross section density at 2200 m/s. * model_scale: [ ] Global scale factor for scattering kernel. For systems without inter-particle interference, the form factors can be related to the scattering intensity by the particle volume fraction. * xwidth: [m] ([-inf, inf]) Horiz. dimension of sample, as a width. * yheight: [m] ([-inf, inf]) vert . dimension of sample, as a height for cylinder/box * zdepth: [m] ([-inf, inf]) depth of sample * R: [m] Outer radius of sample in (x,z) plane for cylinder/sphere. * target_x: [m] relative focus target position. * target_y: [m] relative focus target position. * target_z: [m] relative focus target position. * target_index: [ ] Relative index of component to focus at, e.g. next is +1. * focus_xw: [m] horiz. dimension of a rectangular area. * focus_yh: [m], vert. dimension of a rectangular area. * focus_aw: [deg], horiz. angular dimension of a rectangular area. * focus_ah: [deg], vert. angular dimension of a rectangular area. * focus_r: [m] case of circular focusing, focusing radius. * pd_radius_effective: [] (0,inf) defined as (dx/x), where x is de mean value and dx the standard devition of the variable * * %Link * %End *******************************************************************************/ DEFINE COMPONENT SasView_stickyhardsphere SETTING PARAMETERS ( radius_effective=50.0, volfraction=0.2, perturb=0.05, stickiness=0.2, model_scale=1.0, model_abs=0.0, xwidth=0.01, yheight=0.01, zdepth=0.005, R=0, target_x=0, target_y=0, target_z=1, int target_index=1, focus_xw=0.5, focus_yh=0.5, focus_aw=0, focus_ah=0, focus_r=0, pd_radius_effective=0.0) SHARE %{ %include "sas_kernel_header.c" /* BEGIN Required header for SASmodel stickyhardsphere */ #define HAS_Iq #ifndef SAS_HAVE_stickyhardsphere #define SAS_HAVE_stickyhardsphere #line 1 "stickyhardsphere" double Iq_stickyhardsphere(double q, double radius_effective, double volfraction, double perturb, double stickiness) { double onemineps,eta; double sig,aa,etam1,etam1sq,qa,qb,qc,radic; double lam,lam2,test,mu,alpha,beta; double kk,k2,k3,ds,dc,aq1,aq2,aq3,aq,bq1,bq2,bq3,bq,sq; onemineps = 1.0-perturb; eta = volfraction/onemineps/onemineps/onemineps; sig = 2.0 * radius_effective; aa = sig/onemineps; etam1 = 1.0 - eta; etam1sq=etam1*etam1; //C //C SOLVE QUADRATIC FOR LAMBDA //C qa = eta/6.0; qb = stickiness + eta/etam1; qc = (1.0 + eta/2.0)/etam1sq; radic = qb*qb - 2.0*qa*qc; if(radic<0) { //if(x>0.01 && x<0.015) // Print "Lambda unphysical - both roots imaginary" //endif return(-1.0); } //C KEEP THE SMALLER ROOT, THE LARGER ONE IS UNPHYSICAL radic = sqrt(radic); lam = (qb-radic)/qa; lam2 = (qb+radic)/qa; if(lam2test) { //if(x>0.01 && x<0.015) // Print "Lambda unphysical mu>test" //endif return(-1.0); } alpha = (1.0 + 2.0*eta - mu)/etam1sq; beta = (mu - 3.0*eta)/(2.0*etam1sq); //C //C CALCULATE THE STRUCTURE FACTOR //C kk = q*aa; k2 = kk*kk; k3 = kk*k2; SINCOS(kk,ds,dc); //ds = sin(kk); //dc = cos(kk); aq1 = ((ds - kk*dc)*alpha)/k3; aq2 = (beta*(1.0-dc))/k2; aq3 = (lam*ds)/(12.0*kk); aq = 1.0 + 12.0*eta*(aq1+aq2-aq3); // bq1 = alpha*(0.5/kk - ds/k2 + (1.0 - dc)/k3); bq2 = beta*(1.0/kk - ds/k2); bq3 = (lam/12.0)*((1.0 - dc)/kk); bq = 12.0*eta*(bq1+bq2-bq3); // sq = 1.0/(aq*aq +bq*bq); return(sq); } #endif // SAS_HAVE_stickyhardsphere /* END Required header for SASmodel stickyhardsphere */ %} DECLARE %{ double shape; double my_a_v; %} INITIALIZE %{ shape = -1; /* -1:no shape, 0:cyl, 1:box, 2:sphere */ if (xwidth && yheight && zdepth) shape = 1; else if (R > 0 && yheight) shape = 0; else if (R > 0 && !yheight) shape = 2; if (shape < 0) exit (fprintf (stderr, "SasView_model: %s: sample has invalid dimensions.\n" "ERROR Please check parameter values.\n", NAME_CURRENT_COMP)); /* now compute target coords if a component index is supplied */ if (!target_index && !target_x && !target_y && !target_z) target_index = 1; if (target_index) { 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, &target_x, &target_y, &target_z); } if (!(target_x || target_y || target_z)) { printf ("SasView_model: %s: The target is not defined. Using direct beam (Z-axis).\n", NAME_CURRENT_COMP); target_z = 1; } my_a_v = model_abs * 2200 * 100; /* Is not yet divided by v. 100: Convert barns -> fm^2 */ %} TRACE %{ double t0, t1, v, l_full, l, l_1, dt, d_phi, my_s; double aim_x = 0, aim_y = 0, aim_z = 1, axis_x, axis_y, axis_z; double arg, tmp_vx, tmp_vy, tmp_vz, vout_x, vout_y, vout_z; double f, solid_angle, vx_i, vy_i, vz_i, q, qx, qy, qz; char intersect = 0; /* Intersection neutron trajectory / sample (sample surface) */ if (shape == 0) { intersect = cylinder_intersect (&t0, &t1, x, y, z, vx, vy, vz, R, yheight); } else if (shape == 1) { intersect = box_intersect (&t0, &t1, x, y, z, vx, vy, vz, xwidth, yheight, zdepth); } else if (shape == 2) { intersect = sphere_intersect (&t0, &t1, x, y, z, vx, vy, vz, R); } if (intersect) { if (t0 < 0) ABSORB; /* Neutron enters at t=t0. */ v = sqrt (vx * vx + vy * vy + vz * vz); l_full = v * (t1 - t0); /* Length of full path through sample */ dt = rand01 () * (t1 - t0) + t0; /* Time of scattering */ PROP_DT (dt); /* Point of scattering */ l = v * (dt - t0); /* Penetration in sample */ vx_i = vx; vy_i = vy; vz_i = vz; if ((target_x || target_y || target_z)) { aim_x = target_x - x; /* Vector pointing at target (anal./det.) */ aim_y = target_y - y; aim_z = target_z - z; } if (focus_aw && focus_ah) { randvec_target_rect_angular (&vx, &vy, &vz, &solid_angle, aim_x, aim_y, aim_z, focus_aw, focus_ah, ROT_A_CURRENT_COMP); } else if (focus_xw && focus_yh) { randvec_target_rect (&vx, &vy, &vz, &solid_angle, aim_x, aim_y, aim_z, focus_xw, focus_yh, ROT_A_CURRENT_COMP); } else { randvec_target_circle (&vx, &vy, &vz, &solid_angle, aim_x, aim_y, aim_z, focus_r); } NORM (vx, vy, vz); vx *= v; vy *= v; vz *= v; qx = V2K * (vx_i - vx); qy = V2K * (vy_i - vy); qz = V2K * (vz_i - vz); q = sqrt (qx * qx + qy * qy + qz * qz); double trace_radius_effective = radius_effective; if (pd_radius_effective != 0.0) { trace_radius_effective = (randnorm () * pd_radius_effective + 1.0) * radius_effective; } // Sample dependent. Retrieved from SasView.///////////////////// float Iq_out; Iq_out = 1; Iq_out = Iq_stickyhardsphere (q, trace_radius_effective, volfraction, perturb, stickiness); float vol; vol = 1; // Scale by 1.0E2 [SasView: 1/cm -> McStas: 1/m] Iq_out = model_scale * Iq_out / vol * 1.0E2; l_1 = v * t1; p *= l_full * solid_angle / (4 * PI) * Iq_out * exp (-my_a_v * (l + l_1) / v); SCATTER; } %} MCDISPLAY %{ if (shape == 0) { /* cylinder */ circle ("xz", 0, yheight / 2.0, 0, R); circle ("xz", 0, -yheight / 2.0, 0, R); line (-R, -yheight / 2.0, 0, -R, +yheight / 2.0, 0); line (+R, -yheight / 2.0, 0, +R, +yheight / 2.0, 0); line (0, -yheight / 2.0, -R, 0, +yheight / 2.0, -R); line (0, -yheight / 2.0, +R, 0, +yheight / 2.0, +R); } else if (shape == 1) { /* box */ double xmin = -0.5 * xwidth; double xmax = 0.5 * xwidth; double ymin = -0.5 * yheight; double ymax = 0.5 * yheight; double zmin = -0.5 * zdepth; double zmax = 0.5 * zdepth; multiline (5, xmin, ymin, zmin, xmax, ymin, zmin, xmax, ymax, zmin, xmin, ymax, zmin, xmin, ymin, zmin); multiline (5, xmin, ymin, zmax, xmax, ymin, zmax, xmax, ymax, zmax, xmin, ymax, zmax, xmin, ymin, zmax); line (xmin, ymin, zmin, xmin, ymin, zmax); line (xmax, ymin, zmin, xmax, ymin, zmax); line (xmin, ymax, zmin, xmin, ymax, zmax); line (xmax, ymax, zmin, xmax, ymax, zmax); } else if (shape == 2) { /* sphere */ circle ("xy", 0, 0.0, 0, R); circle ("xz", 0, 0.0, 0, R); circle ("yz", 0, 0.0, 0, R); } %} END