C. Sharp Cook

A High Resolution Nuclear Spectrometer

A magnetic spectrometer for the measurement of beta‐ and gamma‐ray energies has been constructed. By using an inhomogeneous field varying radially in the proper manner, it is possible to bring electrons which leave the source with an extremely wide spread in angle to essentially a perfect focus in 180°. It has thus been possible to use a large mean radius of curvature of 40 cm in order to obtain high resolution combined with a reasonable transmission of about 0.1 percent of the total solid angle. Under operating conditions, with a 0.4‐cm wide source, the full width at half maximum for an internal conversion line is 0.5 percent. Scattering and background effects are negligible.

A Course in Electromagnetic Radiation for Seniors

The course described replaces the optics course in the undergraduate curriculum. It is believed that the course described provides the student with a more interesting approach to the subject of optics, allows a better understanding of the relationship optics plays to the other fields of physics, and above all, gives a much better knowledge of the fundamental principles of the subject.

The Capture of Orbital Electrons by Nuclei (K-Capture)

The paper presents a review of recent work on it-capture of orbital electrons by nuclei, including a simple outline of the underlying theory and a discussion of the conditions under which the phenomenon occurs. A brief description is given of the instruments and methods used to observe K-capture.

Suggestion Regarding the Introduction of the Concept of Phase Change for Reflected Radiation

In the study of radiation reflected from a surface, the concept of phase change appears to many students as some sort of “black magic” when introduced following the derivation of the Fresnel equations. This, however, is the point at which the concept is first considered by many texts. It seems that by appropriate introduction of phase change into the derivation of the Fresnel equations, a clearer understanding of this concept may be gained.