REGENER, ERICH RUDOLPH ALEXANDER

(b. Schleussenau, near Bromberg, Germany [now Bydgoszcz, Poland], 12 November 1881; d. Stuttgart, Germany, 27 February 1955)physics.

Regener studied physics at the University of Berlin. His doctoral dissertation, begun under Emil Warburg and concluded under Paul Drude, concerned the influence of shortwave light on the oxygen-ozone equilibrium, a subject to which he returned thirty years later in his research on stratospheric physics. Yet he considered his real teacher to be Heinrich Rubens, whom he assisted in Berlin. Regener turned to the new field of nuclear physics at Berlin and qualified as a university lecturer in 1909 with an outstanding Habilitationsschrift on the determination of the elementary electric charge by means of scintillation and charge measurements.

In 1913 he became professor of physics at the agricultural college in Berlin, and in 1920 he accepted a position at the Technische Hochschule in Stuttgart, from which he was dismissed in 1937 because his wife was Jewish. She then emigrated along with both their children. A son, Victor, was also a physicist, and a daughter was married to a physicist. About the time of his dismissal, the Kaiser-Wilhelm-Gesellschaft built for him a research station for stratospheric physics at Friedrichshafen on Lake Constance. In 1944 the facility was transferred to Weissenau, and in 1953 it was elevated by the Max-Planek-Gesellschaft to the status of an institute for stratospheric physics. Regener served as its director until his death. Also, after the war he again held a post at the Technische Hochschule in Stuttgart.

Regener furnished the first convincing proof of his skill as an experimentalist at Berlin in 1909, when he determined, through the use of a radiation, the elementary electric charge. He based his work on the procedure developed by Rutherford and Geiger—a combination of measuring the charge of a number of a particles and counting these particles by means of the number of points of light (scintillations) they produced as they struck a zinc sulfide screen, which consisted of pulverized zinc sulfide on a base-plate spread with an adhesive material. But this arrangement allowed some a particles to pass between the granules of zinc sulfide and thus escape being counted. Accordingly, Regener sought to find scintillating materials not possessing a granular structure; he settled upon thin layers of yellow diamond. These had the additional advantage of permitting the investigator to count points of light on the reverse side. He obtained the result e = 4.79.l0^-10 electrostatic units, which differs from the presently accepted figure of 4.802 by only two parts per thousand. At the beginning of his stay in Stuttgart, Regener and his co-workers attempted to find out why, when Millikan’s oil-drop method was used to determine the elementary charge, there also appeared smaller charges, the so-called subelectrons. They were able to show that the reason was that the masses of the drops had been incorrectly determined through a failure to take into account the rate of vaporization.

Regener’s contributions to cosmic radiation were of special importance. He recognized that the intensity of the rays had to be measured at the highest possible altitudes and at the greatest possible depths (in his case, in Lake Constance). For this purpose balloons equipped with measurement chambers were sent aloft and high-pressure chambers outfitted with ionization chambers, Geiger counters, and spectroscopes were lowered into Lake Constance. Regener developed appropriate recording devices in his own house. The balloon coverings were at first thin sheets of rubber glued together and later cellophane. The balloons reached altitudes as great as thirty kilometers. The measurements revealed that the intensity of the cosmic rays decreased at a height of twenty kilometers, which suggested that the greater ionic density in the layer below the incoming radiation must originate from secondary effects. (Today it is known that the effect is due to nuclear processes.) Regener also made a sensational finding from data gathered during an ascent conducted in March 1933. On this occasion he was able to link an unusually strong ionization with an eruption on the solar surface, thereby demonstrating that events occurring on the fixed stars are a source of cosmic radiation.

In his later years Regener investigated the formation of ice directly from the vapor state at low temperatures. He was especially interested in research on the nuclei around which freezing commences.

BIBLIOGRAPHY

I. Original Works. An early work is “Über Zahlung der a-Teilchen durch die Szintillation und Über die Grosse des elektrischen Elementarquantums,” in Sitzungsberchte der Preussischen Akademie der Wissenschaften zu Berlin (1909), 948–965. Memoirs on cosmic rays published in Physikalische Zeitschrift include “Über die durchdringende Komponente der Ultrastrahlung,” 31 (1930), 1018–1019; “Die Absorptionskurve der Ultrastrahlung und ihre Deutung,” 34 (1933), 306–323; “Weitere Messungen der Ultrastrahlung in der Stratosphare,” ibid., 820–823, 880; and the series of short articles in 35 (1934), 779–793. See also the following, in Zeitschrift fur Physik : “Über das Spektrum der Ultrastrahlung,” 74 (1932), 433–454; “Die Energiestrom der Ultrastrahlung,” 80 (1933), 666–669; “Über Ultrastrahlungsmessungen in grossen Wassertiefen und Über die Radioaktivitat von Trocken-batterien,” 100 (1936), 286; and “Über die Schauer der kosmischen Ultrastrahlung in der Stratosphere,” 111 (1938–1939), 501–507, written with A. Ehmert; a series of brief communications in Naturwissenschaften, 19–33 (1931–1946); and “Erforschungen und Ergebnisse mit Registrierballonen und Registrierapparaten in der Stratosphere,” in Beiträge zur Physik der freien Atmosphäre, 22 (1935), 249–260.

Regener’s writings are listed in Poggendorff, V , I , 1031; VI, 2138 2139; and Vlla, pt. 3, 696–697.

II. Secondary Literature. See Regener’s Festschrift: W. Bothe and O. Hahn, “Zum 70. Geburtstag,” in Zeitschrift fur Naturforschtng, 6a (1951), 565 ff., with portrait. Obituaries include A. Ehmert and E. Schopper, in Naturwissenschaften, 43 (1956), 69–71; W. Gerlach, in Jahrbuch der bayerischen Akademie der Wissenschaften (1956), 222–229, with portrait; O. Hahn, in Reden und Aufsdtze der Technische Hochschule Stuttgart, 21 (1956), 37; and L. Weikmann, in Meteorohgische Rundschau, 8 (1955), 41.

F. Fraunberger