DNA and Bessel functions

I was reading a book on the history of the discovery of the structure of DNA [1] and was surprised by a few passing references to Bessel functions. According to Claude, When X-rays are diffracted by a helical structure, the resulting diffraction pattern breaks into a series of horizontal “layer lines.” Cochran, Crick, and Vand showed mathematically that the diffracted amplitude on the n-th layer line is proportional to a Bessel function of the first kind, order n: Jn(2π r R) where r is the radius of the helix and R is the distance out from the center (the meridian) in the diffraction pattern. The citation for this paragraph is a paper from 1952 [2] that amazingly is behind a paywall. Related posts Mr. Bessel’s eponymous functions From Kepler to Bessel Bessel zero spacing [1] Watson and Crick didn’t “discover DNA” as is commonly said. DNA was discovered in 1878. Watson and Crick discovered the structure of DNA in 1953. [2] Cochran, W., Crick, F. H. C., & Vand, V. (1952). “The Structure…