Critical Limit Spectra ====================== Three 8192 channel spectra with average continuum levels of 100, 1000 and 10,000 counts per channel each containing 50 peaks. Each peak is a Gaussian distribution and contains the number of counts equivalent to the Currie critical limit, taking into account the average continuum level (b), the peak width (n) at the specified. The background width (m) is fixed at 5 channels on each side of the peak when making the critical limit calculation. The equation for Lc is 1.645 × (Std. Uncert of peak background) That reduces to Lc = 1.645 × sqrt[ n × b × (1 + n/2m) ] n is calculated as 2 × FWHM (channels) × 2.807 / 2.355, rounded up to the next integer. 2.807 is the coverage factor for 99.5% of the whole peak area. When SpecMaker created the spectrum ,the counts in the peak were spread, as a Gaussian distribution, across those n channels. The 50 peaks are superimposed on the continuum 40 keV apart from 50 keV up to 2010 keV. Spectrum Continuum (counts per channel) LC-100 100 LC-1k 1,000 LC-10k 10,000 The 'Critical Limit-an1' folder contains spectra in the ORTEC .an1 format. (This folder also holds the GammaVision .sdf and .lib files used in the example tests.) The 'Critical Limit-.chn' folder contains spectra in the ORTEC .chn format. The 'Critical Limit-csv' folder contains the SpecMaker output csv files listing the peaks positions and the expected number of counts in the peaks, together with the expected position and FWHM. An example follows. The 'Critical Limit Info.txt' file is this document. The 'Critical Limit-an1.zip' compressed file carries the an1 files and the associated .csv files. The 'Critical Limit-chn.zip' compressed file carries the chn files and the associated .csv files. The 'Critical Limit Assessments.zip' compressed file carries a number pdf files illustrating the use of SpecMaker in assessing the performance of CompAct, FitzPeaks and GammaVision. These files should be regarded as examples, not as definitive performance indicators. These files carry copyright restrictions and must not be reported or published elsewhere. =================== Spectrum File: LC-100.chn Energy scale: 0.269309 keV/channel Energy Counts Centroid FWHM Actual counts Actual centroid 50 57 200.0230918 0.764702094 58 200.0172414 90 63 348.5515047 0.803048691 62 348.5322581 130 63 497.0799947 0.841067627 64 497.09375 etc. ===================