Portable survey instruments can be very useful in aiding workers in locating radioactive contamination. However, the type of detector (or probe) must be chosen according to the kind of radioactive material that is being used. Generally, thin window Geiger-Mueller (GM) probes are best suited to detect beta radiation with energies above 70 keV while sodium iodide (NaI) scintillators are best for gamma radiation.

For campus laboratories, Radiation Safety recommends the Ludlum Model 3 survey instrument. The Model 3 has the following detectors available:

For Beta Radiation

If you are using P-32, Ca-45, Cl-36 or C-14 and S-35 (in millicurie quantities), there are two types of detectors you can use:

Ludlum Model 3 Survey Meter with Model 44-9 "Pancake" GM Probe

This instrument has a flat detector (1.75" in diameter) at the end of a handle. This style probe is comfortable to handle and is best suited for surveying large areas, such as floors, hoods and bench tops.

For Gamma Radiation

If you are using I-125 or other nuclides with gamma energies between 10 to 40 keV, use the Model 44-3 "Low Energy Gamma" Sodium Iodide (NaI) detector.

Ludlum Model 3 Survey Meter with Model 44-3 "Low Energy Gamma" NaI Probe

If your are using Cr-51, I-131, Co-57 or other nuclides with gamma energies above 40 keV, use the Model 44-2 "High Energy Gamma" NaI detector.

Ordering Information

When ordering the Model 3, you must specify the 0 - 5000 cpm meter face and a MHV detector connector (type UG-932/U). This will make you instrument compatible with similar instruments on campus and easier for us to calibrate.

The address of the area sales representative is:
John Anderson
Atlantic Nuclear
1020 Turnpike St. #9
Canton, Massachusetts 02021
Telephone: (617) 828-9118
FAX: (617) 828-1319

Please let us know when your instrument arrives so that it can be added to our calibration schedule.