Astroparticle physics with the MINOS Far Detector
- Univ. of Minnesota, Minneapolis, MN (United States)
Since August 2003, the MINOS Far Detector collected over 67 million underground muons at Soudan MN, USA. As the temperature of the atmosphere changes, the interaction height of incident cosmic rays changes, which affects the production of muons that are seen underground. A four percent peak-to-peak seasonal fl was seen over a period of four years, which was highly correlated to the measured temperature variations of the upper atmosphere over the same period. The coeffi relating changes in the muon rate to changes changes in atmospheric temperature, αT , was found to be: αT = 0.877 ± 0.010 (stat.) ±0.017 (syst.). A new model was developed to describe the observed effect, and is the fi to include the contribution from kaons. This model predicts αT = 0.865 ± 0.015. The fi measurements of charge separated seasonal variations were reported: αT (µ+) = 0.782 ± 0.056 (stat.) ± 0.02 (syst.), αT (µ-) = 0.788 ± 0.066 (stat.) ± 0.02 (syst.). The observed difference between the pion-only temperature coeffi and the kaon-inclusive temperature coeffi allowed a measurement of the atmospheric K/π ratio = 0.21 ± 0.08. A high signifi observation of two muon signals, the shadow of the sun and moon, have been seen. The shadow of the moon was observed at the 5 σ level, and the shadow of the sun was observed at the 4.3 σ level. The angular resolution of the detector was found to be 0.62° using dimuons, and the two dimensional shadowing distribution was used to quantify the absolute pointing of the detector 0.15 ± 0.10 . A cosmic ray point source search was performed, and no statistically signifi source was found. In the absence of a source, 95% fl limits were placed on cosmic ray sources. The minimum fl limit was -16 -2 -1 2.7 × 10 cm s , which is comparable to the previous best limit set by MACRO [1, 2]. Using the 239 Gamma Ray Bursts (GRBs) of the fi Swift catalog a search for space-time coincidence between neutrino induced muons and GRBs was performed. In the absence of a statistically signifi coincidence, 90% fl limits were placed on neutrino production in GRBs. Assuming a Waxman-Bahcall neutrino spectrum [3], the average 90% fl limit was found to be 1.7 × 10 GeVcm -2s-1 . This new limit is slightly better than the MACRO [4] and AMANDA [5] limits as well as the theoretical limit set by cosmic rays [6, 7], but does not constrain the model.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1415813
- Report Number(s):
- AAT-3321901; FERMILAB-THESIS-2008-06; PROQUEST-1579688341; 785112
- Country of Publication:
- United States
- Language:
- English
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