Doc Ewen: The Horn, HI, and Other Events in US Radio Astronomy

Slide 2: Detecting the Interstellar Hydrogen Line, 1951

The external beam machine installed in the Cyclotron, which consists of a beam scatterer, and the magnetic channel that accepts the scattered particles and directs them out of the cyclotron. The scatterer is shown in greater detail in the next slide.
Slide 3