Johann Kiessling, the Krakatoa event and the development of atmosheric optics after 1883

Johann Kiessling studied the sensational twilights that followed the eruption of Krakatoa (1883) and looked for their physical explanation. He believed that the cause of the extraordinary optical appearances essentially lay in diffraction through particles in the condensation and dust clouds which, following the eruption of the volcano, reached high strata in the atmosphere and travelled around the globe. Research concerning the generation of fog in the atmosphere was greatly forwarded by Kiessling's ideas and experiments. The studies of C.T.R. Wilson, F.R.S., which led to the construction of his cloud chamber and its use in nuclear physics, were strongly influenced by Kiessling's work.

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New Particles

10.1093/oso/9780198827870.003.0007 ◽

2018 ◽

Author(s):

Roger H. Stuewer

Keyword(s):

Gamma Rays ◽

Atomic Hydrogen ◽

Nuclear Physics ◽

Hydrogen Isotope ◽

Alpha Particles ◽

Cloud Chamber ◽

Ernest Rutherford ◽

James Chadwick ◽

Theoretical Foundations ◽

New Particles

In December 1931, Harold Urey discovered deuterium (and its nucleus, the deuteron) by spectroscopically detecting the faint companion lines in the Balmer spectrum of atomic hydrogen that were produced by the heavy hydrogen isotope. In February 1932, James Chadwick, stimulated by the claim of the wife-and-husband team of Irène Curie and Frédéric Joliot that polonium alpha particles cause the emission of energetic gamma rays from beryllium, proved experimentally that not gamma rays but neutrons are emitted, thereby discovering the particle whose existence had been predicted a dozen years earlier by Chadwick’s mentor, Ernest Rutherford. In August 1932, Carl Anderson took a cloud-chamber photograph of a positron traversing a lead plate, unaware that Paul Dirac had predicted the existence of the anti-electron in 1931. These three new particles, the deuteron, neutron, and positron, were immediately incorporated into the experimental and theoretical foundations of nuclear physics.

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Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

International Astronomical Union Colloquium ◽

10.1017/s0252921100080520 ◽

1976 ◽

Vol 32 ◽

pp. 169-182

Author(s):

B. Kuchowicz

Keyword(s):

Nuclear Physics ◽

Nuclear Reactions ◽

Chemical Elements ◽

Fission Products ◽

Abundance Pattern ◽

Isotopic Shifts ◽

Processed Material ◽

R Process ◽

Ap Stars ◽

Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

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