Basic simulation of scalar readings for variable thicknesses of lead. Readings are valid but change randomly and can be used to determine the half thickness.
Version 1.2 allows you to take a background count. You can change the background count parameters in the secret [Settings] tab.
The password to find the secret [Settings] tab (unlock the workbook in Review > Unprotect Workbook/Sheet) is physics.
In case 1.2 borks, here is version 1.0: