Physics: Theses
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- ItemA PARITY VIOLATION TRANSMISSION EXPERIMENT FOR UNDERGRADUATE LABORATORIES(Houghton University, 2024-05-03) Kennel, LeviBecause there are currently no published weak interaction parity violation experiments specifically for undergraduate laboratories, a simple parity violation experiment is being developed using circularly polarized gamma rays. A 60Co source will be placed on one side of an electromagnet, so that the circularly polarized gamma rays emitted opposite the beta particles will pass through the electromagnet. A NaI detector detects the number of gamma rays that pass through the electromagnet, and a silicon detector detects in coincidence beta particles opposite the gamma rays. The number of 𝛾𝛽 coincidence events will be measured when the electromagnet is polarized both parallel and antiparallel to the gamma rays — an asymmetry between the number of coincidence events for each orientation would show that parity is violated.
- ItemX-RAY DIFFRACTOMETER FOR THIN FILM ANALYSIS AT HOUGHTON UNIVERSITY(Houghton University, 2024-05-03) Davie, Nathaniel T.A Bragg-Brentano theta-2 theta x-ray Diffractometer was advanced towards completion in construction at Houghton University as a means to measure the lattice structure and sub-atomic spacing of thin films and small crystals. The x-ray Diffractometer (XRD) uses angles of diffracted characteristic x-rays to analyze the space between cells. The XRD is dependent on the derivation and application of the mathematical equation denoted by Bragg’s Law, stating the angle of large quantities of x-rays being delayed by integer multiples such that the wavefronts are lined up in shape, called constructive interference. The Houghton XRD machine was inherited from previous students ranging back 14 years. Preliminary tests using a Silicon thin film and a single Sodium-Iodide lab-grown crystal have been conducted, and further, intensive tests are aimed to be conducted in the fall of 2024. The analysis conducted at Houghton University by the XRD can offer a range of data regarding the mechanical, physical, and electrodynamic properties of thin films, resulting in optimized application of the thin films themselves.
- ItemTHE EFFECTS OF RADIATION ESCAPE ON ACCURACY AND PRECISION IN ISOTOPIC COMPOSITION DETERMINATION OF URANIUM AND PLUTONIUM WITH DECAY ENERGY SPECTROSCOPY(Houghton University, 2024-05-03) Ockrin, Timothy R.Decay Energy Spectroscopy (DES) results in high energy resolution (1-5 keV @ 5 MeV) spectra of decay energies where the energy of each decay is measured as a single event as opposed to individual measurements of each decay particle. In order to accomplish this, the measured source is not external to the absorber, but embedded within it. DES can be used for nuclear safeguards, metrology, and medical isotope development, but measurements are affected by incomplete energy capture occurring when decay particles escape the absorber. In order to reduce escape likelihood, absorbers can be capped with a layer of gold. Geant4, a Monte-Carlo simulation software capable of handling energy transport between particles, is used to simulate DES measurements with varying thicknesses of absorber cap. Analysis of these spectra shows that the biggest benefit of capping can be realized by adding 5 μm of gold to all dimensions, reducing the escape of most alpha-decaying uranium and plutonium radionuclides by an order of magnitude.
- ItemDESIGN AND SIMULATION OF STRONG FOCUSING POLE TIPS FOR THE HOUGHTON UNIVERSITY CYCLOTRON(Houghton University, 2024-05-03) Hotchkiss, Andrew W.The Houghton University cyclotron accelerates ions inside of a 17 cm inner diameter evacuated aluminum chamber placed between the poles of a 1.2 T electromagnet. Two hollow “dee” electrodes, one grounded and one oscillating between a positive and negative potential, apply an electric force that, with the magnetic field, accelerates the ions. Previously, weak magnetic focusing, which requires the magnetic field to decrease with larger radius, was used to force the ions back toward the central plane between dees. For large numbers of orbits, however, this made the ions get out of phase with the oscillating electric field. Strong focusing can fix this problem by creating a restoring force while keeping the cyclotron frequency the same. Mathematica and Radia, a 3D magnetic field modeling software package, were used to model the magnetic field of a strong-focusing sector pole tip and calculate resulting ion orbits. In simulations, the original weak focusing pole tips allowed an ion orbit radius of 3.7 cm to be reached. Using newly designed strong focusing pole tips a radius of 4.9 cm corresponding to 165 keV for protons was achieved. The theoretical maximum radius achievable is 7.2 cm resulting in 360 keV of proton energy.
- ItemDEPOSITION SYSTEM FOR THIN LITHIUM NUCLEAR TARGETS(Houghton University, 2024-05-03) Lei, ChunsunA system was developed to create Sn or Ag coated Li nuclear targets for ICF simulation and Target Normal Sheath Acceleration (TNSA) experiments. The purpose of these experiments is to develop ways to measure low energy light-ion cross sections using high-power, ultra-fast lasers. The Li targets were designed to have a ~50 nm thick coating over a 2 μm thick Li film to prevent the Li from reacting with air and water vapor. The films were produced in a ~10−5 Torr evacuated deposition chamber. Approximate 15 A flowing one way through a diode circuit heated a stainless-steel boat holding a Li pellet to a thermocouple-measured temperature of nearly 400°C, evaporating the Li onto a 25 μm thick stainless-steel substrate. A current of up to 60 A flowing the opposite direction through another diode heated a molybdenum boat holding a Sn or Ag pellet, evaporating the metal and forming the thin coating over the Li. The film thicknesses were measured using Rutherford backscattering, a magnetic adhesion tester, and a home-made profilometer. To allow Li metal to be weighed and inserted onto the boat without oxidization, an Ar-filled glove box was constructed around the deposition chamber.