Radiation meters are used to detect ionizing radiation. In general, all laboratories that work with radioactive materials are required to posses a radiation detector. Below are recommendations for the detector type your lab requires, who you may purchase a radiation meter from, and how to get your meter calibrated.

Geiger Mueller (GM)

• Generally used for detecting Beta Emitters
• This model is also known as a "Pancake" probe.
• Detects radiation via the ionization of a gas contained inside the probe. The ejected electrons are then collected and counted.
• Probe has a very thin membrane that is under pressure and easily punctured.
• Capable of detecting alpha and gamma radiation but with very low efficiencies. Not the preferred the meter for detecting these radiation types
• Not able to detect H-3.
• Commonly used to detect: C-14, Ca-45, P-32, P-33, S-35

Scintillating (NaI)

• Generally used for detecting Gamma Emitters
• Detects radiation via the interaction of ionizing radiation with a scintillating crystal containing Sodium Iodide(NaI).
• Laboratory MUST obtain a NaI probe when working with I-125.
• Commonly used to detect: I-125, Cr-51

Purchasing a Meter

When ordering a Meter, both the scaler and detector need to be purchased. The Geiger Mueller and NaI probe are detectors that attach to the survey meter (scaler). The probes are interchangeable with the same type of survey meter. The most common radiation detector, at Rutgers and RWJMS, is the Ludlum Model 3 with a Model 44-9 pancake probe.

Ludlum Vendors:

• Atlantic Nuclear
• Ludlum

Other Vendors:

• Thermo Electron (Bicron, Eberline)
• WB Johnson

Once a meter is ordered and received by the lab, contact REHS so that an efficiency check may be performed and the meter added to the REHS database.

Calibrations/Repair

Laboratory meters are checked once per year via efficiency checks. An efficiency check entails checking the efficiency of the meter against a known P-32 and C-14 check source for pancake probes, and an I-129 source for NaI probes. If the efficiencies fall within certain parameters, the meter is considered acceptable. If the meter fails an efficiency check, REHS can try to resolve the problem in-house, but may need to send it back to the appropriate vendor for repair. The lab is expected to cover the cost of any repairs to a meter should the need arise.

Contact

For Radiation Survey Meter Program Management:
Patti Bruno
(848) 445-2550
radgroup@ipo.rutgers.edu

Health Safety Specialists (By Campus Assignment), or call 848-445-2550