-413. Magnetic Spectrometer (AEC Project 2961) J. Motz This instrument measures absolute intensity of spectral distribution by determining the number of Compton electrons ejected in the forward direction from a thin beryllium foil. It is now set up to measure the spectra from a 1400 kv X-ray tube. Electron Tube Studies (AEC Project 2910) H. 0. Wyckoff, Chief Radiation Physics Laboratory Studies of the interaction of electrons with matter. Current problems include depth dose in different atomic number materials and distribution of ionization in gases. 15. Positive Ion Tube (AEC Project 2910) and (Neutron Attenuation, AEC Project 2968) R, S, Caswell This instrument is presently being converted from a 0.5 ma 200 kv proton source to a high intensity neutron source. It will be used first to determine the attenuation of monoenergetic high energy neutrons in water. 16, Radiation Attenuation Studies (AEC Project 2909) H. O. Wyckoff Present problems include the attenuation of betatron radiation and the oblique attenuation of Cobalt-60, Cesium-137 and gold-198 gamma rays. Betatron Building 18, 50 Mev betatron, 180 Mev synchrotron, Studies of high energy X-ray interactions with matter. Personnel protection recommendations in new NCRP handbook for high energy electron accelerators, a. X-ray spectrometer measurements of the energies of high b. Calorimeter measurements of X-ray beam intensities. ce. Concrete attenuation studies. d. Energy dose rate measurements in water using anthracene energy X-ray photons. (H. W. Koch, Chief, Betatron Section) (J. McElhinney) scintillation crystals. (H. W. Koch) (H. W. Koch)