function [det_eff, scan] = detectorcorrection(scan)

[det_eff, vanacorr, vanafile] = getoption('det_eff','vanacorr','vanafile');

det_eff = det_eff(:)';

scan = [];

if vanacorr == 1

vanascan = tasread(vanafile);

if isempty(vanascan)

fprintf('Error: File %s for detector efficiency correction could not be loaded. You may change the settings in the options file.\n',vanafile);

det_eff = [];

return;

end

det_eff = sum(vanascan.MULTI, 1); % do simple summation...

if vanacorr == 0

% no correction

det_eff = [];

det_eff = det_eff / mean(det_eff); % Normalize so that average efficiency is 1

if nargin>0

scan.MULTI = scan.MULTI ./ repmat(det_eff, size(scan.MULTI,1), 1);

scan.DATA.CNTS = scan.DATA.CNTS / det_eff(getvar(scan,'chan'));