The half life parameter contains the half life times of the radionuclides that have been added to the project. It is only available with the radionuclide toolbox.
The parameter is always dependent on radionuclides and will be synchronized with the radionuclides so that if you change the half life directly in a radionuclide, the value will change in the half life parameter and vice versa.
With this parameter you have access to the half life in your equations, which is useful if you wish to convert between Mol and Bq. As with any other parameter, you can access radionuclide specific values by using brackets; eg. halfLife[Cs-137].
The half life parameter is created automatically when the first radionuclide is added to the project and is given the name halfLife.
If you have removed the parameter and want to re-create it, or if you have opened a project in which there is no half life parameter: