Super Cryogenic Dark Subject Search: Surveying Muons/Muon Lots & Neutron Benchmarking in Ultra-Low Experience John Greavu
Mentor: Priscilla Cushman, PhD
October 7, 2013
Although it accocunts for over a one fourth of the universe, dark matter—and its composition—is yet being adequately understood. The University of Mn, among different institutions, can be heavily affiliated with the Extremely Cryogenic Dark Matter Search (SuperCDMS), the most sensitive dark matter search to date. SuperCDMS aims to detect dark matter in the form of weakly interacting massive particles (" WIMPs”), half a mile underneath the Earth's area at a converted straightener mine clinical in Soudan, MN. Ultra-low background/rare event searches just like SuperCDMS require an extremely precise analysis with the environment by which they are done. Of principal concern with this experiment can be understanding the ungeladenes nukleon backgrounds brought on by muons that penetrate profound underground.
Cosmic ray communications in the upper atmosphere promote a plethora of highly energetic muons. The muons that are able to penetrate deep enough into the my very own and connect to the dense surrounding rock will create a hadronic bathtub of particles—including many neutrons. The other particles produced in the shower are easily able to be distinguished inside the data; however , neutrons will be virtually indistinguishable from WIMPs and are difficult to detect due to their lack of fee. Therefore , data from a muon-tracking detector installed within a cavern near by, along with dedicated ungeladenes nukleon detectors, may be used to establish the amount and circulation of this kind of neutrons. The muon system can also provide new information about the muons themselves, including rare occasions such as muon bundles (multiple synchronous muons with high-energy).
Trial and error, technological, and physical improvements made throughout this experiment will have significant effects for foreseeable future ultra-low background searches—searches that happen to be vital pertaining to understanding the character and origins of darker matter, in addition to the universe in general. This research will also provide a window in high-energy muon interactions subterranean, an interesting examine by itself.
The prior occupant of the Soudan Underground Laboratory Western world Hall (adjacent to the SuperCDMS experiment) was your Soudan two Proton Corrosion experiment. If the calorimeter was removed, their muon divieto system was left set up. Over the last 10 years, it has been refurbished and supplied with a new custom electronics and a LabView-based data purchase system. The muon veto shield is usually constructed from energy of proportional tubes, which completely collection the threshold and surfaces. Each component is extruded aluminum created into 8 hexagonal line chambers, which are arranged as with a honeycomb-esque double part as shown in Determine 1 . Each tube contains a gold wire put down the middle, which is linked in series to the three other cables from the different tubes inside the same level. Most tubes are eight meters very long and further dimensions are displayed below in Figure 1 )
Figure 1 ) Cross-section of just one module. Measurements are in centimeters.
The tubes are filled with 90% Ar/10% LASER at 1 ) 12 pub. Very quite simply, the gas allow for an entering particle, such as a muon, to ionize a molecule of the inert gas. This cascades of electrons happen to be accelerated towards the positively recharged wire and create a heartbeat, which is in that case recorded inside the data acquisition.
Determine 2 . The Soudan Low Background Keeping track of Facility (on left). Muon veto shields line them and threshold. Diagram showing actual (vertically stacked) set up of themes (right).
The muon divieto shield paths muons that had enough energy to feed 710 meters of mountain. Comparing the timestamps (using absolute time obtained from GPS) from the muon shield and the timestamps from your two on-site neutron sensors allows for advancements in the precision of the physics in the Bosque Carlo...