| dc.description.abstract | Due to excess gravitational force in the observable universe, it is estimated that 85% of the matter in the universe does not interact with electromagnetic, or light, waves. This matter has been dubbed “Dark Matter:”, and the search for how to detect these particles has been the focus of many scientists for decades. One hypothesis is that dark matter is a WIMP (weakly interacting massive particle). These particles rarely interact with normal matter, so it is necessary to make extremely low-energy sensitive detectors to distinguish minute differences in closely residing energy peaks. One form of detection is through scintillators which take high energy electromagnetic waves (gamma rays) and through the intrinsic properties of the CsI(Tl) crystal transform them into visible light rays. These light rays are able to be detected through a photomultiplier tube (PMT). Once the gamma ray is transformed, the light ray must be reflected into the photocathode of the PMT which calls for a completely reflective material to be wrapped around the crystal to ensure that the highest percentage of transformed electromagnetic waves enter into the PMT to be detected, or in other words, a high light yield. To increase the ability of CsI(Tl) scintillator detectors to do so, a new wrapping material will be used on the innermost layer of the detector. The new wrapping material is a 3Mᵀᴹ Enhanced Specular Reflector (ESR) material which is hypothesized to produce a higher light yield with better resolution than the original wrapping of plumber’s tape due to its high reflectivity. Two different types of measurements were carried out to test this hypothesis. First, a source of ⁶⁰Co was used to test the difference between the wrappings. The test was run an hour for the original and the new wrapping. We observe a 35% increase in the ADC count for each ⁶⁰Co energy peak and 15% decrease in the value of the standard deviation around those peaks. Secondly, a source of ²⁴¹Am was used to test the low-energy capabilities of the new material. Here also we see a significant increase in the ADC count for the two energy peaks of the ²⁴¹Am source. Due to the high photon reflectivity capability of the new ESR film, our detector is more capable of collecting photons created by even low-energy interactions. As we know Dark Matter produces very low-energy recoils, while interacting with the detector target material, so the ability to contain a maximum number of photons within the detector volume will help us move one step closer to finding the rare interaction. Because of this significant increase in light yield and general decrease in standard deviation, it is clear that the ESR material has a greater ability to gather higher resolution data than its predecessor. This could lead to a greater understanding of low-energy particles, which in turn could help us understand what Dark Matter really is. | |
