Radioactivity & Decay Calculations: Half-Life, Activity & Dosimetry Basics

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn the half-life of iodine-131 into a decay constant, tabulate the undecayed nuclei of a sample over 32 days in two equivalent ways and find when only 1% is left.
• Convert the mass of four sealed sources into atoms, multiply by the decay constant per second to get the activity in becquerel and convert it to microcurie.
• Tabulate the fraction and activity of a cobalt-60 check source over ten half-lives, work out when it falls below a usable level with a base-2 log and chart the decay curve.
• Turn the measured C-14 activity of five museum samples into a fraction of modern carbon, calculate the age with the physical half-life and as a conventional radiocarbon age, and find the oldest age the method can reach.
• Model how yttrium-90 grows into freshly purified strontium-90 with a simple day-by-day step table, compare it with the ingrowth formula and chart the approach to secular equilibrium.
• Calculate how the dose rate of a Cs-137 point source falls with distance and with lead thickness, how much lead brings it to a target, and the dose rate at a work position that uses both.
• Estimate a technician's weekly dose from dose rates and times, scale it to a year, compare it with natural background and work out how much hot-cell time is left within a weekly constraint.
• Work out how much Tc-99m a fictional clinic must order for six scheduled injections, accounting for decay between calibration and each injection time, add a reserve, and compare with F-18 lost during transport.