These are resources I've developed to tackle problems in geochronology, statistics, mass spectrometry, or all of the above. They're available here for free use and download. For questions or support, contact noahmc@ku.edu.

### ion counter Deadtime

This MATLAB code estimates the deadtime for an ion counter, based on analyses of a Pb standard (NBS 981) run at different intensities. It assumes only the 208Pb/206Pb and calculates that deadtime that shifts the measured data onto a fractionation line through the assumed isotopic composition.

### STRAIGHT LINE REGRESSION IN 2+ DIMENSIONS

Code for calculating and plotting a straight line through data with correlated uncertainties in two or more dimensions. This problem is well-known in two dimensions, solved by York (1966, 2004), where it is used by isotope geochemists for straight line fitting though isochrons, fractionation lines, mixing lines, and other linear arrays of measured data. This contribution produces the same output as a York fit for two dimensions, and is extensible for systems with more than just two variables.

### How Long Should I Measure Baselines?

Faraday analyses on TIMS and ICPMS consist of a baseline and an on-peak measurement, where the ion beam intensity of interest is the on-peak intensity minus the baseline. The baselines are often measured between the mass spectrum peaks while a finite-sized sample is ionizing. How long the baseline and on-peak portions of the analysis are measured is specified by the user. What is the best ratio of baseline to on-peak measurement time? The answer depends on the size of the ion beam and the size of the resistors in the Faraday amplifiers.