408 research outputs found
The early history of radioactivity (1896-1904)
Imperial Users onl
Early Atomic Models - From Mechanical to Quantum (1904-1913)
A complete history of early atomic models would fill volumes, but a
reasonably coherent tale of the path from mechanical atoms to the quantum can
be told by focusing on the relevant work of three great contributors to atomic
physics, in the critically important years between 1904 and 1913: J. J.
Thomson, Ernest Rutherford and Niels Bohr. We first examine the origins of
Thomson's mechanical atomic models, from his ethereal vortex atoms in the early
1880's, to the myriad "corpuscular" atoms he proposed following the discovery
of the electron in 1897. Beyond predictions for the periodicity of the
elements, the application of Thomson's atoms to problems in scattering and
absorption led to quantitative predictions that were confirmed by experiments
with high-velocity electrons traversing thin sheets of metal. Still, the much
more massive and energetic {\alpha}-particles being studied by Rutherford were
better suited for exploring the interior of the atom, and careful measurements
on the angular dependence of their scattering eventually allowed him to infer
the existence of an atomic nucleus. Niels Bohr was particularly troubled by the
radiative instability inherent to any mechanical atom, and succeeded in 1913
where others had failed in the prediction of emission spectra, by making two
bold hypotheses that were in contradiction to the laws of classical physics,
but necessary in order to account for experimental facts.Comment: 58 Pages + References, 8 Figures. Accepted for publication in the
European Physical Journal H (Historical Perspectives on Contemporary
Physics). V2 - minor typos corrected and a footnote added to p.2
Development of a new Thomson parabola spectrometer for analysis of laser accelerated ions
This thesis details my work on developing a new Thomson parabola spectrometer for use at the
SCARLET Laser Facility at The Ohio State University. The SCARLET laser facility is a 300
TW laser reaching peak intensities exceeding 10 21 W/cm 2 . The laser is used to study laser-matter
interactions and plasma phenomena. The laser-matter interactions accelerate multiple types of
particles and to understand the interactions it is necessary to have diagnostic tools to characterize
the accelerated particles. In order to measure the charged particles a common device is a
Thomson parabola spectrometer. A Thomson parabola spectrometer uses parallel electric and
magnetic fields that are perpendicular to the incoming particles. This causes deflection of the
particles based on their charge-to-mass ratio and energy. Therefore, the Thomson parabola
spectrometer allows us to determine what particles are present and what their energy range is.
I designed a new spectrometer to replace the existing Thomson parabola spectrometer which had
problems during operation that reduced performance. Using a MATLAB code, I first modeled
the performance of the new design to determine physical dimensions and field strengths that
would allow for 1 MeV resolution of protons up to a maximum energy of 40 MeV. This resulted
in a 5 cm long magnetic field with a field strength of 0.12 T and 10 cm electrodes with a voltage
difference of 6 kV. These physical dimensions were used to create a SolidWorks model. As of
this writing, the newly designed Thomson parabola spectrometer has been built and is currently
being installed for use on future experiments.No embargoAcademic Major: Engineering Physic
An investigation of the mathematical formulation of quantum theory and its physical interpretation, 1900-1927
Imperial Users onl
The Centenary of the Electron, A European Exhibition : The Irish Dimension
Booklet of exhibition The Centenary of the Electron, hosted in Kevin Street College which came to Dublin after opening at Alencon, France the previous year
Electrical properties of thin metal films
Imperial Users onl
Volume 76 - Issue 2 - November, 1964
https://scholar.rose-hulman.edu/technic/1028/thumbnail.jp
Volume 47 - Issue 2 - November, 1937
https://scholar.rose-hulman.edu/technic/1230/thumbnail.jp
A Visualized Mathematical Model of Atomic Structure
A model of atomic structure is presented. Many questions that have baffled scientists
for the past decades may be answered by this visualized mathematical model. In particular, the
model mathematically relates the properties of the parabola to the atoms' shells and orbits. A
series of parabolas represents the atom shells (vertical sections along paraboloids) from outer to
inner part of the atom. A pair of electrons exists in a circular motion in each orbit. The orbits are
contained in the parabolic shells. Orbits in a shell equal to the square of shell number.
Furthermore, hydrogen atomic spectrum was simulated and a new relation was verified. The
frequencies of the visible spectra of the hydrogen atom were found to be related to the change in
the area enclosed by the first orbit in the second shell, 2s, when the electron is excited into the
inner concentric orbits. A proportionality constant equals 0.238725 femto-sec has been found to
satisfy that relatio
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