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Splitting the Atom and Creating Solar Technology
Published in Wolfgang Palz, The Triumph of the Sun in 2000–2020, 2019
New Zealand-born Ernest Rutherford at the University of Manchester in England was the one who explained for the first time that all atoms are structured along a planetary geometry, with the nucleus in the centre and the electrons on shells around—an obvious difference being also that our Sun’s planets move approximately in one plane, while electrons move on shells. All space in between the tiny nucleus and the shells is virtually empty. Rutherford concluded his findings from the analysis of the spectral lines of hydrogen in 1911. Until then one had thought that the interior of the atom is composed of a soup of positive and electric charges, the plum pudding model. Here we encounter again the enigmatic and colossal force keeping all positive protons together in the nucleus. We discussed it in the context of the interpretation of the Sun’s energy. It is at the origin of those energies liberated when an atomic bomb explodes.
Splitting the Atom and Creating Solar Technology
Published in Wolfgang Palz, The Triumph of the Sun, 2018
New Zealand-born Ernest Rutherford at the University of Manchester in England was the one who explained for the first time that all atoms are structured along a planetary geometry, with the nucleus in the centre and the electrons on shells around—an obvious difference being also that our Sun’s planets move approximately in one plane, while electrons move on shells. All space in between the tiny nucleus and the shells is virtually empty. Rutherford concluded his findings from the analysis of the spectral lines of hydrogen in 1911. Until then one had thought that the interior of the atom is composed of a soup of positive and electric charges, the plum pudding model. Here we encounter again the enigmatic and colossal force keeping all positive protons together in the nucleus. We discussed it in the context of the interpretation of the Sun’s energy. It is at the origin of those energies liberated when an atomic bomb explodes.
Origins
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Noted in Millikan’s book Electricity, Sound and Light [1908], there were certain aspects of the atom not clearly understood. For instance, as Millikan deduced, because electrons possess negative electricity and atoms themselves are neutral, then there must be some form of positive charge within the atomic structure to cancel the negative charge of the electron. J.J. Thomson proposed an atomic model, later disproved, in which the atomic nucleus consisted of positive electricity (now known as protons) about which, or within which, the negative electrons were rotating. This model is often referred to as the “plum pudding model,” with the pudding being the positive stuff and the electrons the plums. In 1909, Ernest Rutherford performed an important experiment that proved the plum pudding model wrong. In his experiment, Rutherford collimated alpha particles from a Po sample into an ultra-thin sheet of Au foil, using the alpha particles as a method to probe the atomic structure of Au. If Thomson was correct and the Au atoms resembled the plum pudding model, then the alpha particles should just pass through the Au foil with hardly any deflection. Although Rutherford found that many alpha particles did actually pass directly through the Au foil, he also found that a small fraction were strongly deflected, and some scattered in the backwards direction. He concluded that such strong interactions could only happen if the positively charged alpha particles came into the close vicinity of another small but heavy positive mass, unlike the small deflections expected from the large neutralized atomic core suggested by Thomson. From his findings, Rutherford postulated the following: Most of the atomic mass and positive charge are contained in a small core called the nucleus.5Most of the volume of the atom is empty space about which the negative electrons are dispersed.Within the atom, the number of negatively charged electrons and the number of positively charged particles (protons) are equal.
The size of the helium nucleus: then and now
Published in Journal of the Royal Society of New Zealand, 2021
At the start of the twentieth century, the prevailing model for the atom was the Thomson ‘plum pudding’ model. In this model, the charges are distributed over the size of the atom, which was known to be in the order of Ångstroms ( m). To investigate whether this model was correct, and in collaboration with Rutherford, Hans Geiger and Ernest Marsden performed an experiment, in which they scattered highly energetic α-particles (now known to be nuclei of the helium atom) off a gold foil. It was found that the α-particles could be deflected over a large range of angles, including some that were scattered back towards the source. On the other hand, most α-particles went through without being deflected at all.
Nucleus-nucleus scattering and the Rutherford experiment
Published in Journal of the Royal Society of New Zealand, 2021
The structure of atoms was of interest at the time. One of the well-known models is the one proposed by Thomson (1904) soon after his discovery of the electron. This model tried to explain that electrons are negatively charged particles and that atoms have no net electric charge. This ‘plum pudding’ model has electrons surrounded by a volume of positive charge. Rutherford did not refer to Thomson’s results in his paper, but he concluded that his results are consistent with the electronic theory of matter ie Tomson picture.
Evolution of detectors for particle physics
Published in Radiation Effects and Defects in Solids, 2022
At the time the atomic conception of matter, revived already in 1803 by John Dalton for chemical motivations, had been further elaborated by J.J. Thomson (1906) with an atomic model (commonly called ‘Plum Pudding Model’) where positively (and uniformly) charged volumes were embedded with negatively charged corpuscles (electrons) that Thomson had discovered in 1897.