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Title: Charge-separated atmospheric neutrino-induced muons in the MINOS far detector

Abstract

We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector, which has an acceptance for neutrino-induced muons of 6.91x10{sup 6} cm{sup 2} sr. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios, R, is R=0.65{sub -0.12}{sup +0.15}(stat){+-}0.09(syst), a result that is consistent with an oscillation signal. A fit to the data for the oscillation parameters sin{sup 2}2{theta}{sub 23} and {delta}m{sub 23}{sup 2} excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons into {mu}{sup -} and {mu}{sup +} in both the data and Monte Carlo events and found the ratio of the total number of {mu}{sup -} to {mu}{sup +} in both samples. The ratio of those ratios, R-circumflex{sub CPT}, is a test of CPT conservation. The result R-circumflex{sub CPT}=0.72{sub -0.18}{sup +0.24}(stat){sub -0.04}{sup +0.08}(syst) is consistent with CPT conservation.

Authors:
 [1];  [2]; ; ; ; ; ;  [3]; ; ; ; ; ; ; ; ; ; ; ; more »;  [4] « less
  1. Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)
  2. (United Kingdom)
  3. Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)
  4. University of Minnesota, Minneapolis, Minnesota 55455 (United States) (and others)
Publication Date:
OSTI Identifier:
21020460
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 9; Other Information: DOI: 10.1103/PhysRevD.75.092003; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; MONTE CARLO METHOD; MULTIPARTICLE SPECTROMETERS; MUON DETECTION; MUONS MINUS; MUONS PLUS; NEUTRINO DETECTION; NEUTRINO OSCILLATION; NEUTRINO REACTIONS; NEUTRINOS; PARTICLE DISCRIMINATION; STANDARD MODEL; WEINBERG ANGLE

Citation Formats

Adamson, P., Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, Andreopoulos, C., Belias, A., Durkin, T., Hartnell, J., Nicholls, T. C., Pearce, G. F., Arms, K. E., Becker, B. R., Border, P. M., Gogos, J., Heller, K., Kasahara, S. M. S., Kumaratunga, S., Litchfield, P. J., Marshak, M. L., Meier, J. R., Miller, W. H., Peterson, E. A., and Petyt, D. A.. Charge-separated atmospheric neutrino-induced muons in the MINOS far detector. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.092003.
Adamson, P., Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, Andreopoulos, C., Belias, A., Durkin, T., Hartnell, J., Nicholls, T. C., Pearce, G. F., Arms, K. E., Becker, B. R., Border, P. M., Gogos, J., Heller, K., Kasahara, S. M. S., Kumaratunga, S., Litchfield, P. J., Marshak, M. L., Meier, J. R., Miller, W. H., Peterson, E. A., & Petyt, D. A.. Charge-separated atmospheric neutrino-induced muons in the MINOS far detector. United States. doi:10.1103/PHYSREVD.75.092003.
Adamson, P., Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, Andreopoulos, C., Belias, A., Durkin, T., Hartnell, J., Nicholls, T. C., Pearce, G. F., Arms, K. E., Becker, B. R., Border, P. M., Gogos, J., Heller, K., Kasahara, S. M. S., Kumaratunga, S., Litchfield, P. J., Marshak, M. L., Meier, J. R., Miller, W. H., Peterson, E. A., and Petyt, D. A.. Tue . "Charge-separated atmospheric neutrino-induced muons in the MINOS far detector". United States. doi:10.1103/PHYSREVD.75.092003.
@article{osti_21020460,
title = {Charge-separated atmospheric neutrino-induced muons in the MINOS far detector},
author = {Adamson, P. and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT and Andreopoulos, C. and Belias, A. and Durkin, T. and Hartnell, J. and Nicholls, T. C. and Pearce, G. F. and Arms, K. E. and Becker, B. R. and Border, P. M. and Gogos, J. and Heller, K. and Kasahara, S. M. S. and Kumaratunga, S. and Litchfield, P. J. and Marshak, M. L. and Meier, J. R. and Miller, W. H. and Peterson, E. A. and Petyt, D. A.},
abstractNote = {We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector, which has an acceptance for neutrino-induced muons of 6.91x10{sup 6} cm{sup 2} sr. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios, R, is R=0.65{sub -0.12}{sup +0.15}(stat){+-}0.09(syst), a result that is consistent with an oscillation signal. A fit to the data for the oscillation parameters sin{sup 2}2{theta}{sub 23} and {delta}m{sub 23}{sup 2} excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons into {mu}{sup -} and {mu}{sup +} in both the data and Monte Carlo events and found the ratio of the total number of {mu}{sup -} to {mu}{sup +} in both samples. The ratio of those ratios, R-circumflex{sub CPT}, is a test of CPT conservation. The result R-circumflex{sub CPT}=0.72{sub -0.18}{sup +0.24}(stat){sub -0.04}{sup +0.08}(syst) is consistent with CPT conservation.},
doi = {10.1103/PHYSREVD.75.092003},
journal = {Physical Review. D, Particles Fields},
number = 9,
volume = 75,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector, which has an acceptance for neutrino-induced muons of 6.91 x 10{sup 6} cm{sup 2} sr. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios, R, is R = 0.65{sub 0.12}{sup +0.15}(stat) {+-} 0.09(syst), a result that is consistent withmore » an oscillation signal. A fit to the data for the oscillation parameters sin{sup 2} 2{theta}{sub 23} and {Delta}m{sub 23}{sup 2} excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons into {mu}{sup -} and {mu}{sup +} in both the data and Monte Carlo events and found the ratio of the total number of {mu}{sup -} to {mu}{sup +} in both samples. The ratio of those ratios, {cflx R}{sub CPT}, is a test of CPT conservation. The result {cflx R}{sub CPT} = 0.72{sub -0.18}{sup +0.24}(stat){sub -0.04}{sup +0.08}(syst), is consistent with CPT conservation.« less
  • The Main Injector Neutrino Oscillation Search (MINOS) is a long baseline neutrino oscillation experiment. The MINOS Far Detector, located in the Soudan Underground Laboratory in Soudan MN, has been collecting data since August 2003. The scope of this dissertation involves identifying the atmospheric neutrino induced muons that are created by the neutrinos interacting with the rock surrounding the detector cavern, performing a neutrino oscillation search by measuring the oscillation parameter values of Δmmore » $$2\atop{23}$$ and sin 223, and searching for CPT violation by measuring the charge ratio for the atmospheric neutrino induced muons. A series of selection cuts are applied to the data set in order to extract the neutrino induced muons. As a result, a total of 148 candidate events are selected. The oscillation search is performed by measuring the low to high muon momentum ratio in the data sample and comparing it to the same ratio in the Monte Carlo simulation in the absence of neutrino oscillation. The measured double ratios for the ''all events'' (A) and high resolution (HR) samples are R A = R$$data\atop{low/high}$$/R$$MC\atop{low/high}$$ = 0.60$$+0.11\atop{-0.10}$$(stat) ± 0.08(syst) and R HR = R$$data\atop{low/high}$$/R$$MC\atop{low/high}$$ = 0.58$$+0.14\atop{-0.11}$$(stat) ± 0.05(syst), respectively. Both event samples show a significant deviation from unity giving a strong indication of neutrino oscillation. A combined momentum and zenith angle oscillation fit is performed using the method of maximum log-likelihood with a grid search in the parameter space of Δm 2 and sin 2 2θ. The best fit point for both event samples occurs at Δm$$2\atop{23}$$ = 1.3 x 10 -3 eV 2, and sin 223 = 1. This result is compatible with previous measurements from the Super Kamiokande experiment and Soudan 2 experiments. The MINOS Far Detector is the first underground neutrino detector to be able to distinguish the charge of the muons. The measured charge is used to test the rate of the neutrino to the anti-neutrino oscillations by measuring the neutrino induced muon charge ratio. Using the high resolution sample, the μ + to μ - double charge ratio has been determined to be R CPT = R$$data\atop{μ-/μ+}$$/R$$MC\atop{μ-/μ+}$$ = 0.90$$+0.24\atop{-0.18}$$(stat) ± 0.09(syst). With the uncertainties added in quadrature, the CPT double ratio is consistent with unity showing no indication for CPT violation.« less
  • The MINOS (Main Injector Neutrino Oscillation Search) experiment has observed muon neutrino disappearance consistent with the oscillation hypothesis tested by Super-Kamiokande and K2K. The survival probability for v μ is given approximately by 1 - sin2 2θ 23sin 2(1.27Δmmore » $$2\atop{32}$$L/E), whereθ 23 and Δm$$2\atop{32}$$ are the mixing angle and difference in mass squared in eV 2/c 4 between the mass eigenstates v 3 and v 2, L is the distance traveled in km, and E is the neutrino energy in GeV. In the Near Detector at Fermilab, a measurement of the energy spectrum of the NuMI neutrino beam is made 1 km from the beam target. The neutrinos travel to the Far Detector in the Soudan Underground Laboratory, where another measurement of the energy spectrum is made 735 km from the target. MINOS measures |Δm$$2\atop{32}$$| and sin 223 by comparing the ND and FD neutrino energy spectra. In this dissertation, a n alternate method is presented that utilizes rock muons, a class of events that occur when a v μ interaction takes place in the rock surrounding the FD. Many muons that result from these interactions penetrate the rock and reach the detector. Muon events from v μ interactions in the non-fiducial volume of the FD are also used in this analysis. The distribution of reconstructed muon momentum and direction relative to the beam is predicted by Monte Carlo simulation, normalized by the measured v μ energy spectrum at the ND. In the first year of NuMI running (an exposure of 1.27x10 20 protons on target) 117 selected events are observed below 3.0 GeV/c, where 150.2±16.1 events are expected. When a fit is performed to events below 10.0 GeV/c, the null (no disappearance) hypothesis is ruled out at significance level α = 4.2 x 10 -3. The data are consistent with the oscillation hypothesis given parameter values |Δm$$2\atop{32}$$| = 2.32 ±$$1.06\atop{0.75}$$x 10 -3 eV 2/c 4 (stat+sys) and sin 223> 0.48 (68% CL) which is in agreement with the published MINOS result |Δm$$2\atop{32}$$| = 2.74 ±$$0.44\atop{0.26}$$ x 10 -3 eV 2/c 4 (stat+sys) and sin 223 > 0.87 (68% CL).« less
  • The Main Injector Neutrino Oscillation Search (MINOS) is an experiment designed to probe the phenomenon of neutrino oscillations. When MINOS is completed it will consist of a neutrino beam and two detectors, which are separated by a distance of 735 km. The near detector measures the energy distribution and ux of a beam of muon neutrinos produced at Fermilab, while the far detector, located in Soudan, MN, measures these same neutrino properties 735 km away. The signal for a detection of neutrino oscillations is a de cit of neutrinos at the far detector compared to expectations based on the nearmore » detector measurements. In addition to measuring beam neutrinos, the far detector can be used to measure neutrinos produced in cosmic ray interactions in the atmosphere. While waiting for the beam to begin running, the far detector was used in this mode. Several previous experiments, such as Super-K and MACRO, have suggested that the atmospheric neutrinos oscillate between di erent avor states. This dissertation looks for an oscillation signal in the atmospheric neutrinos by using muons resulting from the interaction of the atmospheric neutrinos in the rock surrounding the MINOS far detector.« less