New Particles

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.

Cloud Chamber Observation of Photo-alpha Particles Produced by 17 MeV Gamma Rays

1946 ◽  
Vol 1 (1) ◽  
pp. 24-25
Author(s):  
Bunsaku Arakatsu ◽  
Sakae Shimizu ◽  
Terukazu Hanatani ◽  
Jiro Muto
Keyword(s):  
Gamma Rays ◽  
Alpha Particles ◽  
Cloud Chamber

Nuclear Electrons and Nuclear Structure

2018 ◽  
Author(s):  
Roger H. Stuewer
Keyword(s):  
Nuclear Structure ◽  
Beta Decay ◽  
Gamma Rays ◽  
Alpha Particle ◽  
Continuous Distribution ◽  
Alpha Particles ◽  
Light Nuclei ◽  
Coincidence Method ◽  
Wolfgang Pauli ◽  
Beta Particles

Serious contradictions to the existence of electrons in nuclei impinged in one way or another on the theory of beta decay and became acute when Charles Ellis and William Wooster proved, in an experimental tour de force in 1927, that beta particles are emitted from a radioactive nucleus with a continuous distribution of energies. Bohr concluded that energy is not conserved in the nucleus, an idea that Wolfgang Pauli vigorously opposed. Another puzzle arose in alpha-particle experiments. Walther Bothe and his co-workers used his coincidence method in 1928–30 and concluded that energetic gamma rays are produced when polonium alpha particles bombard beryllium and other light nuclei. That stimulated Frédéric Joliot and Irène Curie to carry out related experiments. These experimental results were thoroughly discussed at a conference that Enrico Fermi organized in Rome in October 1931, whose proceedings included the first publication of Pauli’s neutrino hypothesis.

Electron Capture by Alpha Particles Incident on Atomic Hydrogen

1967 ◽  
Vol 163 (1) ◽  
pp. 8-12 ◽  
Author(s):  
D. Basu ◽  
D. M. Bhattacharya ◽  
G. Chatterjee
Keyword(s):  
Electron Capture ◽  
Atomic Hydrogen ◽  
Alpha Particles

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

2000 ◽  
Vol 54 (2) ◽  
pp. 249-258 ◽  
Author(s):  
W. Schröder ◽  
K-. H. Wiederkehr
Keyword(s):  
Nuclear Physics ◽  
Cloud Chamber ◽  
Physical Explanation ◽  
Dust Clouds

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.

scholarly journals Dimethylamine and ammonia measurements with ion chromatography during the CLOUD4 campaign

2012 ◽  
Vol 5 (9) ◽  
pp. 2161-2167 ◽  
Author(s):  
A. P. Praplan ◽  
F. Bianchi ◽  
J. Dommen ◽  
U. Baltensperger
Keyword(s):  
Cosmic Rays ◽  
Sulphuric Acid ◽  
Ion Chromatography ◽  
Galactic Cosmic Rays ◽  
Cloud Chamber ◽  
Sampling Efficiency ◽  
Environmental Chamber ◽  
Mixing Ratios ◽  
Sampling Line ◽  
New Particles

Abstract. The CLOUD project investigates the influence of galactic cosmic rays on the nucleation of new particles in an environmental chamber at CERN. Dimethylamine (DMA) was injected intentionally into the CLOUD chamber to reach atmospherically relevant levels away from sources (up to 100 pptv) in order to study its effect on nucleation with sulphuric acid and water at 278 K. Quantification of DMA and also background ammonia (NH3) was performed with ion chromatography (IC). The IC method used together with the sampling line developed for CLOUD in order to measure NH3 and DMA at low pptv levels is described; the overall sampling efficiency of the method is discussed; and, finally, mixing ratios of NH3 and DMA measured during CLOUD4 are reported.

2. Productive ambiguity

2020 ◽  
pp. 22-39
Author(s):  
J. L. Heilbron
Keyword(s):  
English Translation ◽  
Alpha Particles ◽  
Mechanical Instability ◽  
Ernest Rutherford ◽  
Electron Theory ◽  
Nuclear Atom ◽  
Insight Into

‘Productive ambiguity’ begins with Bohr’s move to Cambridge in 1911 to work with J. J. Thompson on the electron theory and to publish an English translation of his thesis. He did not flourish in Cambridge, however, and moved to Manchester in early 1912 to study under Ernest Rutherford. He soon took an interest in the work of another researcher in the laboratory, Charles Galton Darwin, who was wrestling with the problem of how electrons in a nuclear atom interact with passing alpha particles. Consideration of Darwin’s problem prompted Bohr to discover the radical mechanical instability of the nuclear atom, a result for which his thesis and his philosophy had prepared him. He exploited the instability to develop his quantum atom. His several attempts to ground his invention in existing physics give a precious insight into his mind at work, into his way of entertaining several contradictory formulations of his thought at the same time.

1. The fly in the cathedral

2015 ◽  
Author(s):  
Frank Close
Keyword(s):  
Internal Structure ◽  
Nuclear Physics ◽  
Positive Charge ◽  
X Rays ◽  
Ernest Rutherford ◽  
Nuclear Atom ◽  
Positively Charged

‘The fly in the cathedral’ charts the discovery of the nuclear atom and the start of modern atomic and nuclear physics. It began in 1895 with the discovery of X-rays by Wilhelm Roentgen and radioactivity by Henri Becquerel. In 1897, J.J. Thomson discovered the electron and realised they were common to all atoms, which implied that atoms have an internal structure. Negatively-charged electrons are bound to positively-charged entities within the atom, but what carries this positive charge and how is it distributed? It was Ernest Rutherford, in 1911, who announced his solution: all of an atom’s positive charge and most of its mass are contained in a compact nucleus at the centre.

Sign in / Sign up

Export Citation Format

Share Document