;+ ; ; NAME: ; ; stx_subc_transmission ; ; PURPOSE: ; ; Compute STIX subcollimators' transmission: ; - Low-energy transmission is derived from self-calibration using fully illuminated CFL pixels ; - High-energy transmission is based on a wedge model for grid imperfections ; ; CALLING SEQUENCE: ; ; subc_transmission = stx_subc_transmission(flare_loc, ph_in, simple_transm = simple_transm) ; ; INPUTS: ; ; flare_loc: bidimensional array containing the X and Y coordinate of the flare location ; (arcsec, in the STIX coordinate frame) ; ; ph_in: an array of photon energies [keV] (restricted to range 1-1000) ; ; OUTPUTS: ; ; Transmission value for every subcollimator ; ; KEYWORDS: ; ; simple_transm: if set, the energy-dependence of the grid transmission is not considered ; ; silent: if set, no message is displayed ; ; HISTORY: May 2025, Massa P., based on the previous version by ECMD. ; Working only for detectors 3 to 10. ; March 2026, Massa P., new sub-collimator transmission including also 1a,b,c and 2a,b,c ; ; CONTACT: ; paolo.massa@fhnw.ch ;- function stx_subc_transmission, flare_loc, ph_in, simple_transm = simple_transm, silent = silent, _extra=extra ; For backwards compatibility if no photon energy array is passed in the transmission is calculated for 1 keV ; (the lowest tabulated value). This should provide a reasonable approximation to the previously assumed ; fully opaque grids. if ~keyword_set(ph_in) then begin ph_in = 1. if ~keyword_set(silent) then begin if ~keyword_set(simple_transm) then message, 'No photon energies passed, calculating low energy approximation at 1 keV.', /info $ else message, 'Simple grid transmission selected, calculating opaque approximation.', /info endif endif ;;************ Read grid parameters restore,loc_file( 'grid_temp.sav', path = getenv('STX_GRID') ) fff=read_ascii(loc_file( 'grid_param_front.txt', path = getenv('STX_GRID') ),temp=grid_temp) rrr=read_ascii(loc_file( 'grid_param_rear.txt', path = getenv('STX_GRID') ),temp=grid_temp) ;; Orientation of the slits of the grid as seen from the detector side grid_orient_front_all = fff.o grid_orient_rear_all = rrr.o pitch_front_all = fff.P pitch_rear_all = rrr.P thickness_front_all = fff.THICK thickness_rear_all = rrr.THICK sc = fff.SC ;;************ Read intercept and slope of the transmission linear fits fpath = loc_file( 'stix_subcoll_transmission_10_15keV.csv', path = getenv('STX_GRID') ) ; Ensure the transmission file exists before attempting to read it if ~file_exist(fpath) then message, 'stx_subc_transmission: Transmission file not found.' ; Read the transmission parameters with error trapping catch, error_status if error_status ne 0 then begin ; An error occurred during READCOL catch, /cancel message, 'stx_subc_transmission: Error reading transmission file: ' + !error_state.msg endif subc_transmission = read_csv(fpath, n_table_header=1) subc_n_all = subc_transmission.FIELD1 subc_label = subc_transmission.FIELD2 intercept_all = subc_transmission.FIELD3 slope_all = subc_transmission.FIELD5 ; Cancel error trapping now that READCOL has completed catch, /cancel ; Basic sanity checks on the loaded columns if (n_elements(subc_n_all) eq 0) or $ (n_elements(subc_label) ne n_elements(subc_n_all)) or $ (n_elements(intercept_all) ne n_elements(subc_n_all)) or $ (n_elements(slope_all) ne n_elements(subc_n_all)) then begin message, 'stx_subc_transmission: Malformed transmission file (unexpected number of columns/rows): ' + fpath endif if ~keyword_set(simple_transm) then begin ;;************ Compute path length in tungsten (L) ; To determine the transmission through the tungsten slats a Linear Attenuation Coefficient [mm-1] ; (1/absorption length in mm) is estimated for an each expected incoming photon energy and passed to stx_grid_transmission. ; The mass attenuation coefficient [cm^2/gm] is calculated using the xcom tabulated values in xsec.pro ; and a value of 19.3 g/cm3 is used for the density of tungsten. This is then divided by 10 to convert from [cm-1] to [mm-1]. mass_attenuation = xsec(ph_in, (Element2Z('W'))[0], 'AB', /cm2perg, error=error, use_xcom=1) gmcm = 19.30 L = f_div(1., (mass_attenuation*gmcm/10.)) ;; in mm subc_transmission=fltarr(n_elements(L),32) for subc_n=0,31 do begin if ((subc_n+1) eq 9) or ((subc_n+1) eq 10) then continue ;; Exclude CFL and BKG ;;-------- FRONT GRID subc_n_front = fff.SC idx = where(subc_n_front eq (subc_n+1), count) if count ne 0 then begin if ((subc_n+1) ne 11) and ((subc_n+1) ne 12) and ((subc_n+1) ne 13) and ((subc_n+1) ne 17) and ((subc_n+1) ne 18) and ((subc_n+1) ne 19) then begin ;; Detectors from 3a,b,c to 10a,b,c grid_orient_front = grid_orient_front_all[idx] pitch_front = pitch_front_all[idx] thickness_front = thickness_front_all[idx] endif else begin if ((subc_n+1) eq 12) or ((subc_n+1) eq 17) or ((subc_n+1) eq 19) then begin ;; Detectors 2a,b,c grid_orient_front = mean(grid_orient_front_all[idx]) pitch_front = mean(pitch_front_all[idx]) / 2. thickness_front = 0.2 endif else begin ;; Detectors 1a,b,c grid_orient_front = mean(grid_orient_front_all[idx]) pitch_front = mean(pitch_front_all[idx]) / 3. thickness_front = 0.133 endelse endelse endif ;;-------- REAR GRID subc_n_rear = rrr.SC idx = where(subc_n_rear eq (subc_n+1), count) if count ne 0 then begin if ((subc_n+1) ne 11) and ((subc_n+1) ne 12) and ((subc_n+1) ne 13) and ((subc_n+1) ne 17) and ((subc_n+1) ne 18) and ((subc_n+1) ne 19) then begin ;; Detectors from 3a,b,c to 10a,b,c grid_orient_rear = grid_orient_rear_all[idx] pitch_rear = pitch_rear_all[idx] thickness_rear = thickness_rear_all[idx] endif else begin if ((subc_n+1) eq 12) or ((subc_n+1) eq 17) or ((subc_n+1) eq 19) then begin ;; Detectors 2a,b,c grid_orient_rear = mean(grid_orient_rear_all[idx]) pitch_rear = mean(pitch_rear_all[idx]) / 2. thickness_rear = 0.2 endif else begin ;; Detectors 1a,b,c grid_orient_rear = mean(grid_orient_rear_all[idx]) pitch_rear = mean(pitch_rear_all[idx]) / 3. thickness_rear = 0.133 endelse endelse endif grid_orient_avg = (grid_orient_front + grid_orient_rear) / 2. ;;------ Off-axis angle theta flare_loc_deg = flare_loc / 3600. ;; Convert coordinates to deg theta = flare_loc_deg[0] * cos(grid_orient_avg * !dtor) + flare_loc_deg[1] * sin(grid_orient_avg * !dtor) ;;------ Subcollimator transmission at low energies idx = where(subc_n_all eq (subc_n+1), count) if count eq 0 then message, 'File ' + fpath + ' does not contain information on subcollimator '+ STRTRIM(STRING(subc_n+1), 2) intercept = intercept_all[idx] slope = slope_all[idx] value = intercept + slope * theta if value le 0.0 then message, "Transmission value for subcollimator " + STRTRIM(STRING(subc_n+1), 2) + " is <= 0. Please, check if the provided flare location is correct." subc_transm_low_e = value ;;------ Transmission of front and rear grid slit_to_pitch = sqrt(subc_transm_low_e) slit_front = slit_to_pitch*pitch_front slit_rear = slit_to_pitch*pitch_rear if ((subc_n+1) ne 11) and ((subc_n+1) ne 12) and ((subc_n+1) ne 13) and ((subc_n+1) ne 17) and ((subc_n+1) ne 18) and ((subc_n+1) ne 19) then begin ;; Detectors from 3a,b,c to 10a,b,c transm_front = stx_grid_transmission(pitch_front, slit_front, thickness_front, L, simple_transm=simple_transm, _extra=extra) transm_rear = stx_grid_transmission(pitch_rear, slit_rear, thickness_rear, L, simple_transm=simple_transm, _extra=extra) endif else begin transm_front = stx_grid_transmission(pitch_front, slit_front, thickness_front, L, simple_transm=simple_transm, ds=0, dh=0, _extra=extra) transm_rear = stx_grid_transmission(pitch_rear, slit_rear, thickness_rear, L, simple_transm=simple_transm, ds=0, dh=0, _extra=extra) endelse subc_transmission[*,subc_n] = transm_front * transm_rear endfor endif else begin ;;************ SIMPLE GRID TRANSMISSION: NO ENERGY DEPENDENCE subc_transmission=fltarr(32) for subc_n=0,31 do begin if ((subc_n+1) eq 9) or ((subc_n+1) eq 10) then continue ;; Exclude CFL and BKG ;;-------- FRONT GRID subc_n_front = fff.SC idx = where(subc_n_front eq (subc_n+1), count) if count ne 0 then begin if ((subc_n+1) ne 11) and ((subc_n+1) ne 12) and ((subc_n+1) ne 13) and ((subc_n+1) ne 17) and ((subc_n+1) ne 18) and ((subc_n+1) ne 19) then begin ;; Detectors from 3a,b,c to 10a,b,c grid_orient_front = grid_orient_front_all[idx] endif else begin ;; Detectors 1a,b,c, 2a,b,c grid_orient_front = mean(grid_orient_front_all[idx]) endelse endif ;;-------- REAR GRID subc_n_rear = rrr.SC idx = where(subc_n_rear eq (subc_n+1), count) if count ne 0 then begin if ((subc_n+1) ne 11) and ((subc_n+1) ne 12) and ((subc_n+1) ne 13) and ((subc_n+1) ne 17) and ((subc_n+1) ne 18) and ((subc_n+1) ne 19) then begin ;; Detectors from 3a,b,c to 10a,b,c grid_orient_rear = grid_orient_rear_all[idx] endif else begin ;; Detectors 1a,b,c, 2a,b,c grid_orient_rear = mean(grid_orient_rear_all[idx]) endelse endif grid_orient_avg = (grid_orient_front + grid_orient_rear) / 2. ;;------ Off-axis angle theta flare_loc_deg = flare_loc / 3600. ;; Convert coordinates to deg theta = flare_loc_deg[0] * cos(grid_orient_avg * !dtor) + flare_loc_deg[1] * sin(grid_orient_avg * !dtor) ;;------ Subcollimator transmission at low energies idx = where(subc_n_all eq (subc_n+1), count) if count eq 0 then message, 'File ' + fpath + ' does not contain information on subcollimator '+ STRTRIM(STRING(subc_n+1), 2) intercept = intercept_all[idx] slope = slope_all[idx] value = intercept + slope * theta if value le 0. then message, "Transmission value for subcollimator " + STRTRIM(STRING(subc_n+1), 2) + " is <= 0. Please, check if the provided flare location is correct." subc_transmission[subc_n] = value endfor endelse return, subc_transmission end