Determining the Half Life of 234mPa
Use a high-quality data plotting and fitting program (e.g. Origin) to analyse the data. The fitting must take the uncertainity into account (do not use Excel), otherwise you will get the wrong result.
Notice that you always shall use the 1/3 of the time into each measuremnent as the "middle time point". This is due to decay - after 1/3 of the time you will have equally many counts before and after the 1/3 point (i.e. it is the "middle point".
- For each datapoint calculate the net count (gross count - background count), the uncertainity of the net count (based on uncertainity of both the gross count and the background count). You might want to use e.g. MS Excel or similar for doing this.
- Enter your data in a table ("worksheet" in Origin jargong): Include measurment time (relative to start of sampling) as x-value, the net count as y-value, and the uncertainity as y-error.
- Plot the data - does it look ok?
- Use the Origin data-fitting functionality to determine the measured half-life and associated uncertainity.
Alternativ/Extra: Plot the gross counts instead of the net counts and ask Origin to fit both the background and the decay.