/******************************************************************************* * McXtrace instrument definition URL=https://www.mcxtrace.org * * Instrument: ILL_NeXT_Xray * * %Identification * Written by: DRAFT, Peter Willendrup with Claude from public ILL / NeXT-Grenoble information * Date: September 2026 * Origin: ILL * %INSTRUMENT_SITE: ILL * * NeXT (ILL) - the X-ray cone-beam tomography arm, operated simultaneously with * and perpendicular to the neutron beam (companion to ILL_H521_NeXT.instr) * * %Description * DRAFT model of the X-ray imaging option of NeXT-Grenoble at the ILL. * * Hardware (Tengattini et al., NIM A 968 (2020) 163939): * - source: Hamamatsu L12161-07 sealed microfocus tube, W target, Be window, * up to 150 kV / 500 uA, minimum focal spot 5 um, 43 deg cone * - detector: Varex PaxScan 2530HE flat panel, CsI scintillator, * 1792 x 2176 pixels of 139 um (portrait), up to 9 Hz (33 Hz bin 2) * - source-detector distance: >= 500 mm (set by the 43 deg cone covering the * ~25 x 30 cm panel), four source positions 20 mm apart * -> SDD = 0.50, 0.52, 0.54, 0.56 m * - the sample sits on the common (neutron) rotation axis; the source-object * distance SOD sets the magnification M = SDD/SOD. The quoted 5 um * resolution needs M ~ 28, i.e. SOD ~ 18-20 mm. * - the ILL web page (2026) quotes a 20-300 kV source, i.e. the tube may have * been upgraded; kV > 150 is allowed here but flagged. * * Geometry: the X-ray axis is the McXtrace z axis. At NeXT it is horizontal and * perpendicular to the neutron beam (neutrons travel along -x or +x here, depending * on the side of the source); the source/detector pivot (+-20 deg) is not modelled. * * The sample defaults to the same object as in ILL_H521_NeXT: a vertical Fe rod, * radius 5 mm, for direct bimodal comparison (the neutron model gives T~0.4 at the * rod centre in white beam). An inner inclusion (e.g. an H2O-filled bore) can be added. * * Detector: two ideal pixelated monitors on the flat-panel plane * Xray_counts: photon counts (photon-counting response) * Xray_energy: energy-weighted intensity [keV/s per pixel], a first-order model * of the energy-integrating CsI flat panel. * NOT modelled: CsI absorption efficiency vs energy, scintillator/optical blur, * focal-spot growth with tube power, heel effect, scatter from the sample * environment, and the 6 mm Pb / 10 mm + 5 mm B4C neutron shielding of the panel * (5 mm B4C over the active area transmits roughly 80-90 % at 40-150 keV). * * ASSUMPTIONS (to be checked): * - Be exit window 0.2 mm (the L12161-07 datasheet value should be checked) * - focal spot = electron-beam footprint on the anode (square, focal_spot) * - anode take-off angle 12 deg (reflection-type microfocus tube, typical) * - Source_lab is a thick-target Kramers model; absolute intensity is indicative * * %Example: kV=150 SOD=0.1 SDD=0.5 Detector: Xray_counts_I=176042000000 * * %Parameters * kV: [kV] Tube acceleration voltage (<=150 for L12161-07; 20-300 per ILL web) * tube_current: [A] Electron beam current (<= 500e-6) * focal_spot: [m] Focal spot size (square electron footprint on the anode) * Emin: [keV] Lowest photon energy simulated * anode: [str] Anode material file * take_off: [deg] Anode take-off angle * Be_window: [m] Be exit window thickness * filter: [str] Pre-filter material file (e.g. "Cu.txt", "Al.txt", "Sn.txt") * filter_t: [m] Pre-filter thickness (0: no filter) * SOD: [m] Source - object (rotation axis) distance * SDD: [m] Source - detector distance (0.50, 0.52, 0.54, 0.56) * sample: [1] 1: sample in beam, 0: flat field (open beam) * sample_mat: [str] Sample (outer) material file * sample_rho: [g/cm3] Sample density (0: take nominal density from file) * sample_radius: [m] Radius of the cylindrical sample * sample_height: [m] Height of the cylindrical sample * incl_mat: [str] Material of a coaxial inner cylinder ("NULL" for none) * incl_radius: [m] Radius of the inner cylinder (0 for none) * incl_rho: [g/cm3] Density of the inner cylinder (0: nominal) * sample_off: [str] Optional OFF/PLY geometry for the outer sample, overrides the cylinder ("NULL": none) * omega: [deg] Tomography rotation angle of the sample about the vertical axis * det_binning: [1] Detector binning (1: 1792x2176 native, 2, 4, ...) * * %Link * https://www.ill.eu/en/for-ill-users/instruments/instruments-list/next/ * %Link * A. Tengattini et al., NeXT-Grenoble, the Neutron and X-ray tomograph in Grenoble, * Nucl. Instrum. Meth. A 968 (2020) 163939, doi:10.1016/j.nima.2020.163939 * %Link * NECSA_MIXRAD_Nikon_Tomo.instr (McXtrace examples) - similar lab-source tomograph * %End *******************************************************************************/ DEFINE INSTRUMENT ILL_NeXT_Xray(kV=150, tube_current=100e-6, focal_spot=5e-6, Emin=5, string anode="W.txt", take_off=12, Be_window=0.2e-3, string filter="Cu.txt", filter_t=0, SOD=0.1, SDD=0.5, int sample=1, string sample_mat="Fe.txt", sample_rho=0, sample_radius=0.005, sample_height=0.05, string incl_mat="NULL", incl_radius=0, incl_rho=0, string sample_off="NULL", omega=0, int det_binning=4) DECLARE %{ /* Varex PaxScan 2530HE, portrait: 1792 (horizontal) x 2176 (vertical), 139 um */ int det_nx_native = 1792; int det_ny_native = 2176; double det_pixel = 139e-6; double det_w, det_h; int det_nx, det_ny; double Emax; double M; /* geometric magnification */ double voxel; /* effective pixel size at the object */ double penumbra; /* focal-spot blur referred to the object */ double cone_hw; /* half-opening of the source cone [rad] */ double open_x, open_y; /* region of the detector used for the open-beam spectrum */ %} USERVARS %{ double Ew; /* saved weight for the energy-weighted detector */ %} INITIALIZE %{ if (kV > 150) fprintf(stderr, "%s: WARNING: kV=%g exceeds the 150 kV of the Hamamatsu L12161-07 " "(the ILL web page quotes up to 300 kV - check the installed tube)\n", NAME_INSTRUMENT, kV); if (tube_current > 500e-6) fprintf(stderr, "%s: WARNING: tube_current=%g A exceeds 500 uA\n", NAME_INSTRUMENT, tube_current); if (SDD < 0.5 || SDD > 0.56) fprintf(stderr, "%s: WARNING: SDD=%g m outside the 0.50-0.56 m range of the NeXT setup\n", NAME_INSTRUMENT, SDD); if (SOD >= SDD) exit(fprintf(stderr, "%s: ERROR: SOD (%g) must be < SDD (%g)\n", NAME_INSTRUMENT, SOD, SDD)); if (det_binning < 1) det_binning = 1; Emax = kV; det_nx = det_nx_native/det_binning; det_ny = det_ny_native/det_binning; det_w = det_nx_native*det_pixel; det_h = det_ny_native*det_pixel; M = SDD/SOD; voxel = det_pixel*det_binning/M; penumbra = focal_spot*(M-1)/M; /* focal-spot unsharpness, object plane */ cone_hw = 43.0/2*DEG2RAD; /* open-beam spectrum window: beside the sample shadow, inside the detector */ open_x = 3*sample_radius*M; if (open_x > det_w/2 - 0.01) open_x = det_w/2 - 0.01; printf("%s: M=%.2f, effective pixel at object %.2f um (binning %d), " "focal-spot unsharpness %.2f um, FoV at object %.1f x %.1f mm\n", NAME_INSTRUMENT, M, voxel*1e6, det_binning, penumbra*1e6, det_w/M*1e3, det_h/M*1e3); if (2*SDD*tan(cone_hw) < sqrt(det_w*det_w+det_h*det_h)) printf("%s: note: the 43 deg cone does not fully cover the detector diagonal at SDD=%g m\n", NAME_INSTRUMENT, SDD); if (sample && 2*sample_radius*M > det_w) printf("%s: note: the magnified sample (%g mm) is wider than the detector (%g mm)\n", NAME_INSTRUMENT, 2*sample_radius*M*1e3, det_w*1e3); %} TRACE COMPONENT Origin = Progress_bar() AT (0,0,0) ABSOLUTE /* ---- microfocus X-ray tube ---------------------------------------------- */ /* focusing on the full detector: every photon heads for the flat panel */ COMPONENT anode_spot = Source_lab( material_datafile = anode, width = focal_spot, height = focal_spot, thickness = 100e-6, E0 = kV, Emin = Emin, Emax = Emax, take_off = take_off, tube_current = tube_current, dist = SDD, focus_xw = det_w, focus_yh = det_h, lorentzian = 1) AT (0,0,0) RELATIVE Origin /* Be exit window (assumed 0.2 mm) */ COMPONENT Be_exit_window = Filter(material_datafile="Be.txt", xwidth=0.02, yheight=0.02, zdepth=(Be_window > 0 ? Be_window : 1e-9)) WHEN (Be_window > 0) AT (0,0,0.005) RELATIVE anode_spot /* optional beam-hardening pre-filter */ COMPONENT prefilter = Filter(material_datafile=filter, xwidth=0.05, yheight=0.05, zdepth=(filter_t > 0 ? filter_t : 1e-9)) /* 1e-9: Filter INITIALIZE runs even when WHEN is false */ WHEN (filter_t > 0) AT (0,0,0.008) RELATIVE anode_spot COMPONENT source_spectrum = E_monitor(nE=300, Emin=0, Emax=Emax, xwidth=0.03, yheight=0.03, restore_xray=1) AT (0,0,0.010) RELATIVE anode_spot /* ---- sample on the common neutron / X-ray rotation axis ------------------ */ COMPONENT sample_axis = Arm() AT (0,0,SOD) RELATIVE anode_spot COMPONENT sample_plane = PSD_monitor(xwidth=4*sample_radius+0.01, yheight=sample_height, nx=100, ny=100, restore_xray=1) AT (0,0,-sample_radius-0.001) RELATIVE sample_axis COMPONENT sample_rot = Arm() AT (0,0,0) RELATIVE sample_axis ROTATED (0,omega,0) RELATIVE sample_axis COMPONENT object = Absorption_sample( material_datafile_o = sample_mat, rho_o = sample_rho, radius_o = sample_radius, yheight_o = sample_height, geometry_o = sample_off, material_datafile_i = incl_mat, rho_i = incl_rho, radius_i = incl_radius, yheight_i = (incl_radius > 0 ? sample_height : 0)) WHEN (sample) AT (0,0,0) RELATIVE sample_rot /* ---- flat-panel detector (Varex PaxScan 2530HE) ------------------------- */ COMPONENT detector_plane = Arm() AT (0,0,SDD) RELATIVE anode_spot /* photon-counting image */ COMPONENT Xray_counts = PSD_monitor(xwidth=det_w, yheight=det_h, nx=det_nx, ny=det_ny, restore_xray=1) AT (0,0,0) RELATIVE detector_plane /* energy-integrating image (weight x E[keV]) - first-order CsI flat-panel response */ COMPONENT Eweight_on = Arm() AT (0,0,0) RELATIVE detector_plane EXTEND %{ Ew = p; p *= sqrt(kx*kx+ky*ky+kz*kz)*K2E; %} COMPONENT Xray_energy = PSD_monitor(xwidth=det_w, yheight=det_h, nx=det_nx, ny=det_ny, restore_xray=1) AT (0,0,0) RELATIVE detector_plane COMPONENT Eweight_off = Arm() AT (0,0,0) RELATIVE detector_plane EXTEND %{ p = Ew; %} /* spectra behind the sample centre and in the open beam (for beam hardening and transmission vs energy), 0.5 mm wide strips on the detector */ COMPONENT spec_sample = E_monitor(nE=150, Emin=0, Emax=Emax, xwidth=0.5e-3, yheight=0.5*sample_height*M, restore_xray=1) AT (0,0,0) RELATIVE detector_plane COMPONENT spec_open = E_monitor(nE=150, Emin=0, Emax=Emax, xwidth=0.5e-3, yheight=0.5*sample_height*M, restore_xray=1) AT (open_x,0,0) RELATIVE detector_plane END