R. J. Nichol
A5028598053- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Cryospheric studies and observations
- Particle accelerators and beam dynamics
- Gamma-ray bursts and supernovae
- Plasma Diagnostics and Applications
- Noncommutative and Quantum Gravity Theories
- Aerospace Engineering and Energy Systems
- Arctic and Antarctic ice dynamics
- Planetary Science and Exploration
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Scientific Research and Discoveries
- High-Energy Particle Collisions Research
- Nuclear Physics and Applications
- CCD and CMOS Imaging Sensors
- Quantum Chromodynamics and Particle Interactions
- Methane Hydrates and Related Phenomena
- Calibration and Measurement Techniques
University College London
2016-2025
RWTH Aachen University
2021
The Ohio State University
2005-2018
UCL Australia
2007-2011
Université Paris Cité
2008-2009
Délégation Paris 7
2008-2009
National and Kapodistrian University of Athens
2008-2009
California Institute of Technology
2008
Southwest Bahia State University
2007
University of California, Irvine
2006
We report the results of a search for ${\ensuremath{\nu}}_{e}$ appearance in ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ beam MINOS long-baseline neutrino experiment. With an improved analysis and increased exposure $8.2\ifmmode\times\else\texttimes\fi{}{10}^{20}$ protons on NuMI target at Fermilab, we find that $2{sin}^{2}({\ensuremath{\theta}}_{23}){sin}^{2}(2{\ensuremath{\theta}}_{13})<0.12(0.20)$ 90% confidence level $\ensuremath{\delta}=0$ normal (inverted) mass hierarchy, with best-fit...
Measurements of neutrino oscillations using the disappearance muon neutrinos from Fermilab NuMI beam as observed by two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample exposure 7.25×10(20) protons on target. A fit yields values |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) mixing angle. Pure decay quantum decoherence hypotheses excluded at 7 9 standard deviations, respectively.
We report measurements of oscillation parameters from ν(μ) and disappearance using beam atmospheric data MINOS. The comprise exposures 10.71×10(20) protons on target in the ν(μ)-dominated beam, 3.36×10(20) ν(μ)-enhanced 37.88 kton yr neutrinos. Assuming identical ν parameters, we measure |Δm2| = (2.41(-0.10)(+0.09))×10(-3) eV2 sin2(2θ) 0.950(-0.036)(+0.035). Allowing independent oscillations, antineutrino (2.50(-0.25)(+0.23))×10(-3) 0.97(-0.08)(+0.03), with minimal change to neutrino parameters.
We report on a new analysis of neutrino oscillations in MINOS using the complete set accelerator and atmospheric data. The combines $\nu_{\mu}$ disappearance $\nu_{e}$ appearance data three-flavor formalism. measure $|\Delta m^{2}_{32}|=[2.28-2.46]\times10^{-3}\mbox{\,eV}^{2}$ (68% C.L.) $\sin^{2}\theta_{23}=0.35-0.65$ (90% normal hierarchy, m^{2}_{32}|=[2.32-2.53]\times10^{-3}\mbox{\,eV}^{2}$ $\sin^{2}\theta_{23}=0.34-0.67$ inverted hierarchy. also constrain $\delta_{CP}$, $\theta_{23}$...
We report on ν(e) and appearance in ν(μ) beams using the full MINOS data sample. The comparison of these at a 735 km baseline with θ13 measurements by reactor experiments probes δ, θ23 octant degeneracy, mass hierarchy. This analysis is first use this technique includes accelerator long-baseline search for → ν(e). Our disfavor 31% (5%) three-parameter space defined θ23, hierarchy 68% (90%) C.L. measure value 2sin(2)(2θ13)sin(2)(θ23) that consistent experiments.
A search for mixing between active neutrinos and light sterile has been performed by looking muon neutrino disappearance in two detectors at baselines of 1.04 735 km, using a combined MINOS MINOS+ exposure 16.36×10^{20} protons on target. simultaneous fit to the charged-current neutral-current energy spectra yields no evidence 3+1 model. The most stringent limit date is set parameter sin^{2}θ_{24} values mass splitting Δm_{41}^{2}>10^{-4} eV^{2}.
The Antarctic Impulsive Transient Antenna (ANITA) completed its second long-duration balloon flight in January 2009, with 31 days aloft (28.5 live days) over Antarctica. ANITA searches for impulsive coherent radio Cherenkov emission from 200 to 1200 MHz, arising the Askaryan charge excess ultra-high energy neutrino-induced cascades within ice. This included significant improvements first payload sensitivity, efficiency, and a trajectory deeper Analysis of in-flight calibration pulses surface...
We report new limits on cosmic neutrino fluxes from the test flight of Antarctic Impulsive Transient Antenna (ANITA) experiment, which completed an 18.4 day a prototype long-duration balloon payload, called ANITA-lite, in early 2004. search for impulsive events that could be associated with ultrahigh energy interactions ice and derive constrain several models rule out long-standing -burst model.
We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation Askaryan effect As part complete validation process for ANITA experiment, we performed an experiment at Stanford Linear Accelerator Center June 2006 using a 7.5 metric ton ice target. measure time large-scale angular dependence pattern, major factor determining solid-angle acceptance ultrahigh-energy neutrino detectors.
Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on observation of neutral-current interactions, an exposure NuMI beam 7.07×1020 protons target. A total 802 event candidates is observed Far Detector, compared expected number 754±28(stat)±37(syst) among three flavors. The fraction fs disappearing νμ that may transition νs found be less than 22% at 90% C.L.Received 19 April...
We report the observation of 16 cosmic ray events with a mean energy $1.5\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$ via radio pulses originating from interaction air shower Antarctic geomagnetic field, process known as geosynchrotron emission. present measurements in 300--900 MHz range, which are first self-triggered, ultrawide band, far-field, and highest sample collected technique. Their properties inconsistent current ground-based models. The emission is 100%...
Ultrahigh energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultrahigh processes in the Universe. These particles, with energies above ${10}^{16}\text{ }\text{ }\mathrm{eV}$, interact very rarely. Therefore, detectors that instrument several gigatons of matter needed to discover them. The ARA detector is currently being constructed at South Pole. It designed use Askaryan effect, emission radio waves from neutrino-induced...
We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of were previously identified as stratospheric CR air showers during ANITA-I flight. A third was detected ANITA-II Here we characteristics these three unusual events, which develop nearly horizontally, 20-30~km above surface Earth. In addition, fourth steeply upward-pointing radio event has consistent primary...
The energy dependence of the neutrino-iron and antineutrino-iron inclusive charged-current cross sections their ratio have been measured using a high-statistics sample with MINOS Near Detector exposed to NuMI beam from Main Injector at Fermilab. Neutrino antineutrino fluxes were determined low hadronic subsample events. We report measurements neutrino-Fe (antineutrinoFe) section in range 3-50 GeV (5-50 GeV) precision 2-8% (3-9%) which is 2-8%. data set spans region energy, where accurate are...
We report on an upward traveling, radio-detected cosmic-ray-like impulsive event with characteristics closely matching extensive air shower. This event, observed in the third flight of Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload, is consistent similar reported previous flight. These events could be produced by atmospheric decay upward-propagating τ lepton ν_{τ} interaction, although their relatively steep arrival angles create tension...
The ANtarctic Impulsive Transient Antenna (ANITA) NASA long-duration balloon payload completed its fourth flight in December 2016, after 28 days of time. ANITA is sensitive to impulsive broadband radio emission from interactions ultrahigh-energy neutrinos polar ice (Askaryan emission). We present the results two separate blind analyses searching for signals Askaryan data ANITA. more analysis, with a better expected limit, has background estimate ${0.64}_{\ensuremath{-}0.45}^{+0.69}$ and an...
The Payload for Ultrahigh Energy Observations (PUEO) long-duration balloon experiment is designed to have world-leading sensitivity ultrahigh-energy neutrinos at energies above 1 EeV. Probing this energy region essential understanding the extreme-energy universe all distance scales. PUEO leverages experience from and supersedes successful Antarctic Impulsive Transient Antenna (ANITA) program, with an improved design that drastically improves by more than order of magnitude below 30 will...
We report initial results of the first flight Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence a diffuse flux cosmic neutrinos above energies E(nu) approximately 3 x 10(18) eV. ANITA-1 flew 35 days looking radio impulses due to Askaryan effect in neutrino-induced electromagnetic showers within ice sheets. here on our analysis, was performed as blind search data. No neutrino candidates are seen, with no detected physics...
A search for depletion of the combined flux active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by MINOS detectors in NuMI beam. Such not expected according to conventional interpretations oscillation involving three known flavors. would be signature oscillations or decay postulated noninteracting sterile neutrinos, scenarios ruled out existing data. From an exposure 3.18×1020 protons on target which neutrinos energies between ∼500 MeV...
We report results of a search for oscillations involving light sterile neutrino over distances 1.04 and 735 km in ν_{μ}-dominated beam with peak energy 3 GeV. The data, from an exposure 10.56×10^{20} protons on target, are analyzed using phenomenological model one neutrino. constrain the mixing parameters θ_{24} Δm_{41}^{2} set limits four-dimensional Pontecorvo-Maki-Nakagawa-Sakata matrix, |U_{μ4}|^{2} |U_{τ4}|^{2}, under assumption that between ν_{e} ν_{s} is negligible (|U_{e4}|^{2}=0)....
This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν(μ) production, accumulating exposure 1.71 × 10²⁰ protons on target. In Far Detector, 97 charged current events are observed. no-oscillation hypothesis predicts 156 and is excluded at 6.3σ. best fit to oscillation yields |Δm²| = [3.36(-0.40)(+0.46)(stat) ± 0.06(syst)] 10⁻³ eV², sin²(2θ) 0.86(-0.12)(+0.11)(stat) 0.01(syst)....
We report an improved measurement of ν(μ) disappearance over a distance 735 km using the MINOS detectors and Fermilab Main Injector neutrino beam in ν(μ)-enhanced configuration. From total exposure 2.95×10(20) protons on target, which 42% have not been previously analyzed, we make most precise Δm2=[2.62(-0.28)(+0.31)(stat)±0.09(syst)]×10(-3) eV2 constrain mixing angle sin2(2θ)>0.75 (90% C.L.). These values are agreement with Δm2 sin2(2θ) measured for ν(μ), removing tension reported [P....
We have searched for sidereal variations in the rate of antineutrino interactions MINOS Near Detector. Using antineutrinos produced by NuMI beam, we find no statistically significant modulation rate. When this result is placed context Standard Model Extension theory are able to place upper limits on coefficients defining theory. These used combination with results from an earlier analysis neutrino data further constrain coefficients.