IM-5502A “Pencil” Dosimeter

 Dosimeters measure the cumulative radiation dose the wearer is exposed to over time. The IM-5502A is an ion-chamber type, containing a fine quartz fibre. This fibre is charged with static electricity using the IM-5120 Charger/Reader, causing it to stand straight.  

 As ionizing radiation passes through the dosimeter, it bleeds away the fibre’s electric charge, causing it to curl. This deflection is read against a calibrated scale by holding the dosimeter up to the light. If no external light source is available, a light bulb in the IM-5120 Charger/Reader can be used.