Ludlum Model 44-10 Gamma Scintillator Probe (2" x 2" NaI(Tl)), Calibrated

The Ludlum Model 44-10 is the industry-standard high-sensitivity gamma scintillation probe, built around a 2-inch by 2-inch thallium-activated sodium iodide crystal sealed in a rugged aluminum housing. Where a Geiger-Müller pancake probe may miss low-level activity, the 44-10 picks it up readily, making it a favorite for uranium and thorium prospecting, mineral specimen surveys, radioactive material screening, and contamination and area monitoring. Its sensitivity to gamma energies and its fast, stable response have made it a mainstay with field geologists, health physics technicians, emergency responders and serious radioactive mineral collectors for decades.

This probe was calibrated in January 2024, with its high voltage plateau established at 1100 V. That gives the next owner a documented operating point to start from, rather than having to characterize the probe from scratch. It connects to compatible Ludlum count rate meters, such as the Model 3, 2221 and 3000 series, through a standard MHV connector. It is a durable, field-proven detector that is easy to service and well supported, and it holds its value among those who work with radioactive materials.

Please note that this is the probe only, and the meter is sold separately unless stated otherwise. Verify that your meter is compatible and can supply the required high voltage before purchase. Calibration reflects the January 2024 date, and the buyer may wish to have the probe recalibrated to suit their own regulatory or program requirements.