J.D. McCullough X-ray Facility

About

James Douglas McCullough was born in Oskaloosa, Iowa on May 17, 1905 and grew up in Seattle. After graduating from Seattle’s Lincoln High School in 1923, he went to work for the Standard Oil Company of California, first as a junior clerk and then in a service station in Los Angeles, a job that he used to help support himself while earning his A.B. degree in chemistry at UCLA. Upon graduation in February 1932 he was regarded, in the words of Professor W.C. Morgan, the first chairman of the Department of Chemistry, as “possibly the most outstanding man we have had in Department of Chemistry since we started giving instruction”. He was appointed to the UCLA teaching staff at once, first with a six-months’ temporary position and then with a series of one –year appointments as Associate (essentially a high-level teaching assistant) while he was earning his Ph.D. in physical chemistry at the California Institute of Technology under the guidance of A.O. Beckman and Linus Pauling. After receiving his Ph.D. in 1936, Dr. McCullough joined the UCLA faculty on a full time basis and remained at UCLA throughout his career. He retired in 1971 after 39 years of service, remaining active in research for another half dozen years, although his move to Orange County made coming into the laboratory less convenient. Professor McCullough established the first X-ray laboratory at UCLA in 1936, in the basement of the “old chemistry building” (now Haines Hall). He started with an old powder camera (which he converted into a camera for taking single-crystal rotation photographs), borrowed from Caltech, and a specially ordered cold-cathode gas-ion x-ray tube (see picture below). A decade later he received a grant to buy our first Weissenberg camera. From those modest beginnings grew the well equipped laboratory that you see around you today.

This photograph was taken about 1938 by a student (Nichols) in Professor McCullough’s Chemistry Class. The gas-ion X-ray generator tube is in the left and center foreground. The anode or target (interchangeable Cu or Mo) is to the left and is water cooled at ground potential. The cold Cathode is to the right and is air cooled at high potential. At the extreme right we have the high capacity vacuum pump which maintains a pressure in the 103 to 102 mm range. The desired operating pressure was maintained by admitting air through an adjustable slow leak made of coiled up, flattened silver tube. The pressure was not measured as such, but was adjusted to optimum X-ray emission. The rebuilt powder camera, now as oscillation camera, is in the left rear. Unfortunately, it does not show up very well, being obscured by the X-ray tube. The vertical black cylinder encloses the film and the oscillating single crystal. It also holds the beam collimator and the beam stop.