David Petyt

Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of $7.25 \times 10^{20}$ protons on target. A fit to neutrino oscillations yields values of $|Δm^2| = (2.32^{+0.12}_{-0.08})\times10^{-3}$\,eV$^2$ for the atmospheric mass splitting and $\rm \sin^2\!(2θ) > 0.90$ (90%\,C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.

The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 ± 0.19−0.07+0.05 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown not to produce low values of the ratio.

We report a measurement of the atmospheric neutrino flavor ratio, R, using a sample of quasi-elastic neutrino interactions occurring in an iron medium. The flavor ratio (tracks/showers) of atmospheric neutrinos in a 3.9 fiducial kiloton-year exposure of Soudan 2 is 0.64±0.11(stat.)±0.06(syst.) of that expected. Important aspects of our main analysis have been checked by carrying out two independent, alternative analyses; one is based upon automated scanning, the other uses a multivariate approach for background subtraction. Similar results are found by all three approaches.

Results are reported from a search for active to sterile neutrino oscillations in the MINOS longbaseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07 × 10 20 protons on target.A total of 802 neutralcurrent event candidates is observed in the Far Detector, compared to an expected number of 754 ± 28(stat) ± 37(syst) for oscillations among three active flavors.The fraction fs of disappearing νµ that may transition to νs is found to be less than 22% at the 90% C.L.

The effects of oscillations of atmospheric ν µ are observed in the 5.90 fiducial kiloton-year exposure of the Soudan 2 detector.An unbinned maximum likelihood analysis of the neutrino L/E distribution has been carried out using the Feldman-Cousins prescription.The probability of the no oscillation hypothesis is 5.8 × 10 -4 .The 90% confidence allowed region in the sin 2 2θ, ∆m 2 plane is presented.

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 an exposure of 1.71 × 10²⁰ protons on target. In the Far Detector, 97 charged current ν(μ) events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The 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). The MINOS ν(μ) and ν(μ) measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

Upward-going stopping muons initiated by atmospheric νμ and ν¯μ interactions in the rock below the Soudan 2 detector have been isolated, together with a companion sample of neutrino-induced single muons, created within the detector, which travel downwards and exit. The downward-going sample is consistent with the atmospheric-neutrino flux prediction, but the upward-going sample exhibits a sizable depletion. Both are consistent with previously reported Soudan 2 neutrino-oscillation results. Inclusion of the two samples in an all-event likelihood analysis, using recent 3D-atmospheric-neutrino-flux calculations, reduces both the allowed oscillation parameter region and the probability of the no-oscillation hypothesis.7 MoreReceived 15 July 2005DOI:https://doi.org/10.1103/PhysRevD.72.052005©2005 American Physical Society

We have searched for neutron-antineutron oscillations using the 5.56 fiducial kiloton-year exposure of the Soudan 2 iron tracking calorimeter. We require candidate nn̄ occurrences to have >~4 prongs (tracks and showers) and to have kinematics compatible with n̄N annihilation within a nucleus. We observe five candidate events, with an estimated background from atmospheric neutrino and cosmic ray induced events of 4.5±1.2 events. Previous experiments with smaller exposures observed no candidates, with estimated background rates similar to this experiment. We set a lifetime lower limit at 90% C.L. for the nn̄ oscillation time in iron: TA(Fe)>7.2×1031yr. The corresponding lower limit for oscillation of free neutrons is τnn̄>1.3×108sec. Received 29 May 2002DOI:https://doi.org/10.1103/PhysRevD.66.032004©2002 American Physical Society

This paper describes the MINOS calibration detector (CalDet) and the procedure used to calibrate it. The CalDet, a scaled-down but functionally equivalent model of the MINOS Far and Near detectors, was exposed to test beams in the CERN PS East Area during 2001–2003 to establish the response of the MINOS calorimeters to hadrons, electrons and muons in the range 0.2–10 GeV/c. The CalDet measurements are used to fix the energy scale and constrain Monte Carlo simulations of MINOS.

Anomalous large signals are observed in the CMS Electromagnetic Calorimeter during proton-proton collisions at the Large Hadron Collider. They are ascribed to direct energy deposition by particles in the Avalanche Photodiodes (APDs) used for the light readout. Laboratory and test beam studies, as well as Monte Carlo simulations, have been used to understand their origin. The methods that have been employed to reject these signals in the online trigger of CMS and in the reconstruction of physics data are also presented.

Anomalous large signals are observed in the CMS Electromagnetic Calorimeter during proton–proton collisions at the Large Hadron Collider. They are ascribed to direct energy deposition by particles in the Avalanche Photodiodes (APDs) used for the light readout. Laboratory and test beam studies, as well as Monte Carlo simulations, have been used to understand their origin. The methods that have been employed to reject these signals in the online trigger of CMS and in the reconstruction of physics data are also presented.

MINOS is a long baseline neutrino oscillation experiment that uses two detectors separated by 734 km. The readout systems used for the two detectors are different and have to be independently calibrated. To verify and make a direct comparison of the calibrated response of the two readout systems, test beam data were acquired using a smaller calibration detector. This detector was simultaneously instrumented with both readout systems and exposed to the CERN PS T7 test beam. Differences in the calibrated response of the two systems are shown to arise from differences in response non-linearity, photomultiplier crosstalk, and threshold effects at the few percent level. These differences are reproduced by the Monte Carlo (MC) simulation to better than 1% and a scheme that corrects for these differences by calibrating the MC to match the data in each detector separately is presented. The overall difference in calorimetric response between the two readout systems is shown to be consistent with zero to a precision of 1.3% in data and 0.3% in MC with no significant energy dependence.

We describe the observation and mitigation of anomalous, large signals, observed in the barrel part of the CMS Electromagnetic Calorimeter during proton collisions at LHC. Laboratory and beam tests, as well as simulations, have been used to understand their origin. They are ascribed to direct energy deposition by particles in the avalanche photodiodes used for light readout. A reprogramming of the front-end electronics has allowed a majority of these anomalous signals to be identified and rejected at the first (hardware) trigger level with minimum impact on physics performance. Further rejection is performed in the high-level software trigger and offline analyses.

A shadow of the Moon, with a statistical significance of $5\ensuremath{\sigma},$ has been observed in the underground muon flux at a depth of 2090 mwe using the Soudan 2 detector. The angular resolution of the detector is well described by a Gaussian with a sigma $<~0.3\ifmmode^\circ\else\textdegree\fi{}.$ The position of the shadow confirms that the alignment of the detector is known to better than $0.15\ifmmode^\circ\else\textdegree\fi{}$ and has remained stable during ten years of data taking.

We have searched for the proton decay mode proton to neutrino K+ using the one-kiloton Soudan 2 high resolution calorimeter. Contained events obtained from a 3.56 kiloton-year fiducial exposure through June 1997 are examined for occurrence of a visible K+ track which decays at rest into mu+ nu or pi+ pi0. We found one candidate event consistent with background, yielding a limit, tau/B > 4.3 10^{31} years at 90% CL with no background subtraction.

We have searched for nucleon decay into five two-body final states using a 4.4 kiloton-year fiducial exposure of the Soudan 2 iron tracking calorimeter. For proton decay into the fully visible final states μ+η0 and e+η0, we observe zero and one event, respectively, that satisfy our search criteria for nucleon decay. The lifetime lower limits (τ/B) thus implied are 89×1030years and 81×1030years at 90% confidence level. For neutron decay into ν¯η0, we obtain the lifetime lower limit 71×1030years. Limits are also reported for neutron decay into ν¯π0, and for proton decay into ν¯π+. Received 7 January 2000DOI:https://doi.org/10.1103/PhysRevD.62.092003©2000 American Physical Society

We measure the horizontal (|cos(θz)|<0.14 corresponding to a slant depth cut 14 kmwe) neutrino-induced muon flux (Eμ>1.8 GeV) in Soudan 2 to be 4.01 ± 0.50 ± 0.30 × 10−13 cm−2 sr−1 s−1. From the absence of horizontal muons with large energy loss, we set a limit on the flux of muon neutrinos from active galactic nuclei.

This paper reports on an analysis of a 5.14 fiducial kiloton year exposure of atmospheric neutrinos in the Soudan 2 detector. The atmospheric neutrino flavour ratio is measured to be 0.68±0.11(stat)±0.06(syst) and a fit to neutrino oscillations in the mode νμ → ντ yields best fit parameters Δm2 = 8.9 × 10−3 eV2 and sin2 2θ = 0.94. The 90% C.L allowed region in parameter space is in good agreement with Super-Kamiokande and MACRO.

A search for nucleon decay into two-body final states containing K0 mesons has been conducted using the 963 metric ton Soudan 2 iron tracking calorimeter. The topologies, ionizations, and kinematics of contained events recorded in a 5.52 kiloton-year total exposure (4.41 kton-year fiducial volume exposure) are examined for compatibility with nucleon decays in an iron medium. For proton decay into the fully visible final states μ+KS0 and e+KS0, zero and one event candidates are observed respectively. The lifetime lower limits (τ/B) thus implied are 1.5×1032yr and 1.2×1032yr, respectively. Lifetime lower limits are also reported for proton decay into l+Kl0, and for neutron decay into νKS0. Received 7 June 1999DOI:https://doi.org/10.1103/PhysRevD.61.072004©2000 American Physical Society

NO A, LBNE, and T2HK experiments. The theory of the three flavor paradigm is explained and the methods to use these theoretical predictions to design long baseline neutrino experiments are described. The sensitivity to the oscillation parameters for each experiment is presented with a particular focus on the search for CP violation and the measurement of the neutrino mass hierarchy. The variations of these sensitivities with statistical considerations and experimental design optimizations taken into account are explored. The effects of systematic uncertainties in the neutrino flux, interaction, and detection predictions are also considered by incorporating more advanced simulations inputs from the LBNE experiment.

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons recorded after the closure of CMS in late 2008 are described. The overall status of the 75848 channels corresponding to the crystal barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented. The status of the barrel, endcap and preshower detectors following additional cosmic-ray muon tests in 2009 is also summarised.

The electromagnetic calorimeter (ECAL) of the Compact Muon Solenoid Experiment (CMS) is operating at the Large Hadron Collider (LHC) with proton-proton collisions at 13 TeV center-of-mass energy and at a bunch spacing of 25 ns. Upgrades are necessary for the High-Luminosity upgrade of the LHC (HL-LHC). We review the design and R&amp;D studies for the CMS ECAL crystal calorimeter upgrade. We present test beam results of hadron irradiated PbWO 4 crystals up to fluences expected at the HL-LHC. We also report on the R&amp;D for the new readout and trigger electronics, which must be upgraded due to the increased trigger and latency requirements at the HL-LHC.