Date of Award

8-1-2021

Language

English

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College/School/Department

Department of Physics

Content Description

1 online resource (vii, 58 pages) : illustrations (chiefly color)

Dissertation/Thesis Chair

Cecilia Levy

Keywords

Dark matter (Astronomy), Nucleation, Particles (Nuclear physics)

Subject Categories

Physics

Abstract

Dark matter is non-baryonic, weakly interacting matter that makes up nearly 85% of the mass ofour universe, as seen through many different phenomena such as gravitational lensing and flat galactic rotation curves [48]. There are many experiments across the globe that are working to find these dark matter particles, but despite increasing levels of detector sensitivity, dark matter has been difficult to detect. Because of this, it is possible that dark matter has a lower mass than originally predicted. A new detector, the Snowball Chamber, could be used to aid in this search. By using the light molecule of water, it is possible to survey dark matter masses below 1 GeV/c2 . The Snowball Chamber is a completely new type of particle detector that was created at the University at Albany where supercooled water freezes when incident neutrons deposit energy. [54] Dark matter is expected to share similar kinematics with neutrons, namely elastic collisions with the nucleus of atoms [41]. This means that this new detector could indeed be used in the search for dark matter. Simulations of The Snowball Chamber that had been previously run using Californium-252 (Cf-252), Americium-Beryllium (AmBe) and Cesium-137 (Cs-137) were analyzed to answer four questions: Which incident particles are more likely to create events in the water, gammas or neutrons? Do these sources require lead (Pb) shielding? Are the sources strong enough to create events in the bulk and at the wall? And lastly, can incident particles undergo multiple scattering? Working from simulation data, it was found that gammas were twice as likely to create interactions in the water when compared to neutrons. Because each of the sources that were used emit neutrons as well as gammas, it is necessary to shield the detector with Pb to block these gammas and ensure interactions in the water are because of incident neutrons only. The amount of Pb required to reduce the transmission of these gammas for each of these sources was calculated and it was found that 9.5 cm of Pb would be required to shield 99% of all incident gamma radiation. It was also found that all of the sources used in the simulations could produce both wall and bulk events. Lastly, it was found that while multiple scattering is a possibility in the simulation, 88% of interactions in the water were single scatters. It was also shown that the neutron’s mean free path in water is five times larger than the container volume, which also suggests multiple scattering would be less likely but not impossible. The answers to these questions help set the foundation for better understanding the physics of this brand new particle detector.

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