When choosing a portable survey instrument, 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, EH&S 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, C-14 or S-35 use the 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 Ludlum Model 3 survey meter with Model 44-3 "Low Energy Gamma" Sodium Iodide (NaI) detector.
If your are using Cr-51, I-131, Co-57 or other nuclides with gamma energies above 40 keV, use the Ludlum Model 3 survey meter with Model 44-2 "High Energy Gamma" NaI detector.
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 your instrument compatible with similar instruments on campus and easier for us to calibrate.
The address of the area sales representative is:
John Anderson, Jr.
1020 Turnpike St. #9
Canton, Massachusetts 02021
Telephone: (800) 878-9118; (781) 828-9118
FAX: (781) 828-1319
Please let us know when your instrument arrives so that it can be added to our calibration schedule.