36 Radon Testing Laboratory L. L. Stockman and G. M. Temmer This laboratory is concerned with the testing of room air and breath samples for the presence of radon, The assays of ores and sludges are also carried out (AEC Project 2908). he Alpha Ray Measurement Laboratory G. M, Temmer This laboratory calibrates alpha ray standards chiefly for use with monitoring instruments, In addition, equipment is available for the resolution of alpha rays of various energies and an investigation is also being carried out into the development of scintillation crystal counting equipment for the determination of the radon content of room air and breath samples, De Radioisotopes Laboratory H, H. Seliger The function of this laboratory is to standardize artificially prepared radioactive nuclides and it chiefly relies upon the method of 477 counting. The routine distribution of P-32 ani I-131 standards every three months is a regular part of this laboratory's program and it is hoped soon to set up standards of a great many other isotopes including Na-24, Sr-90, Au-198 and T1-204. An ionization chamber is also to be used for the routine standardization of gamma ray emitters. Beta Ray Applicator Program (AEC Project 2955) T. I. Davenport Using an extrapolation type ionization chamber in conjunction with a vibrating reed electrometer, a standard method for the measurement of RaD+E and Sr-90 beta ray opthalmic applicators has been set up. Preliminary results have been inter-—compared with Dr. Failla's laboratory in New York and with the National Research Council Laboratory in Ottawa. The only discrepancy which exists is that arising from the varying criteria adopted by the different laboratories regarding the area of the applicator to be measured.