Radioactive isotopes are present at some level in all materials in our environment. Detection of these isotopes by conventional means can be difficult if they decay very slowly (have a long half-life). Accelerator Mass Spectrometry (AMS) systems are actually designed to measure extremely low levels or such isotopes. Such measurements are often useful for dating geological processes and archaeological artifacts or tracing chemical pathways through complex systems. In the search for very rare processes such as neutrinoless double beta decay, the presence of very low levels of radioactive material can interfere with the measurement process. Therefore, materials used to build the experimental equipment have to contain as few radioactive isotopes as possible.
Neutrinoless double beta decay (NDBD) is of interest for understanding whether the neutrinos are Dirac or Majorana particles. SNO+ and nEXO are among the experiments at SNO Lab, located in Sudbury, Canada for the detection of neutrinos and other extremely weak physical processes.
The SNO+ detector is a large 12m diameter spherical scintillation counter which will be able to study low energy solar, geo- and reactor neutrinos, as well as being able to conduct supernova searches. This detector was built with materials with very low radioactivity such as the organic liquid, Linear Alkyl Benzene (LAB), the scintillation fluid in which the radioactivity was measured in earlier scintillation detectors. For NSBD measurements, the SNO+ experiment will add tellurium-130 to the LAB; In order to fully mix the 130Te into the LAB, the liquid 1, 2 Butanediol has been selected as a chelating agent to which the atoms of 130Te can be added. This project describes the measurement of the 14C content of the 1, 2 Butanediol which confirmed its suitability for use in the NDBD experiment.
nEXO is the next in a series of experiments dedicated to the search for NDBD in Xenon-136. The nEXO detector is a time projection chamber (TPC) filled with 5000 kg of liquid Xe.
One major source of reduction in sensitivity of this detector is the radioactive decay of trace amounts of uranium and thorium isotopes naturally present the construction materials. In order to assess the quantity of these isotopes in the copper used to make the electrodes in the TPC, samples of the copper to be used in the chamber were analyzed using AMS. In this measurement, a better source of copper was found.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/38236 |
| Date | 03 October 2018 |
| Creators | Alsubaie, MONA |
| Contributors | Kieser, William |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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