BOTHE, W.

Über eine neue Sekundärstrahlung der Röntgenstrahlen. II. Mitteilung.

Berlin, Julius Springer, 1923. 8vo. In contemporary half cloth with gilt lettering. In "Zeitschrift für Physik" Bd. 20, 1923. Entire issue offered. Stamp to front free end paper, otherwise a fine and clean copy. Pp. 237-255. [Entire volume: V, (1) 426 pp.].

First appearance of Bothe's early paper on the Compton effect which, together with his later paper (in Bd 32, Zeitschrift für Physik), awarded him the Nobel Prize in Physics "for the coincidence method and his discoveries made therewith".

"Among the topics that Bothe studied in 1924 was the ejection of electrons by X rays, and it was in connection with this phenomenon that he and Geiger performed an important experiment. In an effort to reconcile the particulate and wavelike properties of radiation, Bohr, Kramers, and Slater in 1924 formulated a new quantum theory of radiation. According to their hypothesis, momentum and energy-are conserved only statistically in interactions between radiation and matter. Bothe and Geiger suggested that this could be tested experimentally by examining individual Compton collisions. Bothe introduced a modification into the Geiger counter that made it appropriate for use in coincidence experiments (a very novel procedure in 1924). Using two counters, they studied the coincidences between the scattered X ray and the recoiling electron. Correlating photons with electrons, Bothe and Geiger found a coincidence rate of one in eleven; since the chance coincidence rate for the situation was 10?5, the experimental results contradicted the theoretical predictions and indicated small-scale conservation of energy and momentum." (DSB)

Order-nr.: 48977