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Elastic and nonelastic scattering cross sections from 42-MeV alpha particles interacting with helium isotopes.
Scientific Study from the year 2019 in the subject Physics - Nuclear Physics, Molecular Physics, Solid State Physics, grade: 0.82, University of Manchester (The University of Manchester), language: English, abstract: Alpha particles, or Helium nuclei, are projected by a radioactive isotope source into a vacuum chamber filled by varying thicknesses of either metallic foils (aluminium, nickel) or gases (helium, nitrogen, argon). A Silicon detector, placed at the opposite end of the chamber, detects the final energies of the alpha particles as they penetrate through the media. It is theorised by the Bethe-Bloch equation that the greater the thickness of the medium in the vacuum chamber, the lower the final energies. Through comparison between the Bethe-Bloch equation and experimental data, the ionisation values for the various elements used can be found. Our preliminary results for one such element, aluminium, demonstrate an ionisation value of I=141.2eV.
In this work the photographic emulsion technique has been applied to the study of the long range particles given off during neutron irradiation of uranium. Alvarez first observed these particles with an ion chamber and linear amplifier. Segre, et al (LA-87) studied these particles with an ion chamber which gave coincidences between these particles and fission. They found them to be coincident with fission within the time constant of their circuit (approx 5u sec). They were also able to identify these particles as alpha particles from the density of ionization near the end of the tracks. Hughes has observed a number of these alpha particles in the cloud chamber, but his setup did not permit him to observe the associated fission track. The cloud chamber or photographic emulsion technique permits information to be obtained about the alpha particles and their association with the fission process that cannot be got by the ion chamber method. The photographic emulsion technique has been used in this case because it lends itself very well to a study of rare events of this type.