Search for sterile neutrino mixing in the MINOS long-baseline experiment

A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿µ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿µ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles ¿24 and ¿34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1×10-12¿¿s/eV at 90% C.L

Search for astronomical neutrinos from blazar TXS 0506+056 in super-kamiokande

We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7–9.3 × 10−10 [erg cm−2 s−1], respectively

First observations of separated atmospheric nu_mu and bar{nu-mu} events in the MINOS detector

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nuµ and [overline nu ]µ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving Rup/downdata/Rup/downMC=0.62-0.14+0.19(stat.)±0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nuµ and [overline nu ]µ interactions are separated. The ratio of [overline nu ]µ to nuµ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R[overline nu ][sub mu]/nu[sub mu]data/R[overline nu ][sub mu]/nu[sub mu]MC=0.96-0.27+0.38(stat.)±0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nuµ and [overline nu ]µ

Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6 x 10(20) protons on target

111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee comments111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee comments111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee commentsWe thank the J-PARC staff for superb accelerator performance and the CERN NA61/SHINE Collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC, NRC, and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; National Science Centre (NCN), Poland; RSF, RFBR and MES, Russia; MINECO and ERDF funds, Spain; SNSF and SER, Switzerland; STFC, UK; and the U. S. Deparment of Energy, USA. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, GridPP, UK, and the Emerald High Performance Computing facility in the Centre for Innovation, UK. In addition, participation of individual researchers and institutions has been further supported by funds from ERC (FP7), EU; JSPS, Japan; Royal Society, UK; and DOE Early Career program, USA

Measurement of the electron neutrino charged-current interaction rate on water with the T2K ND280 pi(0) detector

10 pages, 6 figures, Submitted to PRDhttp://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.112010© 2015 American Physical Society11 pages, 6 figures, as accepted to PRD11 pages, 6 figures, as accepted to PRD11 pages, 6 figures, as accepted to PR

Avaliação do efeito do eucaliptol nas convulsões induzidas por pentilenotetrazol em camundongos

The developmental process of epilepsies involves diverse mechanisms that culminate in the hyperactivity of a population of neurons, resulting in a pattern of repeated and rhythmic depolarizations. Antiepileptic drugs act by increasing GABAergic neurotransmission, reducing the effects of glutamate, or blocking ion channels, and are endowed with serious adverse effects that make it difficult for patients to adhere to treatment. This fact has encouraged the search for compounds of natural origin with potential anticonvulsant effect. Thus, the present study aimed to evaluate the effect of eucalyptol in seizures induced by pentylenetetrazole (PTZ). For this, male Swiss mice, orally treated with monotrepene, were used. The first protocol evaluated the toxicity and the estimated LD50 of the compound. Based on the value of LD50, the doses of terpene used in the behavioral and neurochemical tests were selected. For the behavioral tests, groups of mice were pretreated with saline (10 mL/kg, vol), diazepam (2 mg/kg, ip) and eucalyptol (100, 200 and 400 mg/kg, vol) and then with pentylenetetrazole 80 mg/kg, ip) and evaluated for the following parameters: seizure intensity, latency for first seizure and time of death. For neurochemical tests, groups of mice were pretreated with saline (10 mL/kg, v.o.) and eucalyptol (400 mg/kg, i.p.) and subsequently with pentylenetetrazole (80 mg/kg, i.p.); The determination of the concentration of neurotransmitters (monoamines - dopamine, noradrenaline and serotonin) and oxidative stress markers (nitrite and thiobarbituric acid reactive substances - TBARs) were the parameters evaluated. The results were analyzed by ANOVA or Kruskal-Wallis, followed by Student-Newman-Keuls, and Dunns, respectively. Values of p <0.05 were considered significant. The results showed that oral administration of eucalyptol had low toxicity and the estimated LD50 was greater than 2000 mg / kg. In the PTZ-induced seizure test, only the higher dose of monoterpene (400 mg/kg) significantly reduced seizure intensity by 60%, increased latency for onset of the first seizure by 85% and time of death of the animals in 75% in relation to the control. Similarly, treatment with eucalyptol (400 mg/kg) significantly reduced the concentration of noradrenaline, dopamine and serotonin by 50%, 33% and 70%, respectively, in relation to the PTZ-treated group (80 mg/kg). In addition, treatment with eucalyptol (400 mg/kg) significantly reduced the concentration of TBARs by 33%, but not nitrite, relative to the PTZ treated group (80 mg/kg). Taken together, the results show that the monoterpene studied has low oral toxicity and an important anticonvulsant effect, since its administration is capable of attenuating the convulsions chemically induced by pentylenetetrazol with consequent reduction of the concentration of monoamines and the reactive substances of thiobarbituric acid, elements whose increase is associated with the epileptogenesis phenomenon.O processo de desenvolvimento das epilepsias envolve mecanismos diversos que culminam na hiperatividade de uma população de neurônios, resultando em um padrão de despolarizações repetidas e rítmicas. Os fármacos antiepilépticos agem através do aumento da neurotransmissão GABAérgica, da redução dos efeitos do glutamato, ou do bloqueio de canais iônicos, sendo dotados de efeitos adversos sérios que dificultam a adesão do paciente ao tratamento. Este fato tem incentivado a busca por compostos de origem natural com potencial efeito anticonvulsivante. Desta forma, o presente trabalho teve como objetivo avaliar o efeito do eucaliptol nas convulsões induzidas por pentilenotetrazol (PTZ). Para tanto, foram utilizados camundongos Swiss machos, tratados oralmente com o monotrepeno. O primeiro protocolo realizado avaliou a toxicidade e a DL50 estimada do composto. Com base no valor da DL50, foram selecionadas as doses do terpeno utilizadas nos testes comportamentais e neuroqímicos. Para os testes comportamentais, grupos de camundongos foram previamente tratados com salina (10 mL/kg, v.o.), diazepam (2 mg/kg, i.p.) e eucaliptol (100, 200 e 400 mg/kg, v.o.) e posteriormente com pentilenotetrazol (80 mg/kg, i.p.) e avaliados quanto aos seguintes parâmetros: intensidade das convulsões, latência para primeira convulsão e tempo de morte. Para os testes neuroquímicos, grupos de camundongos foram previamente tratados com salina (10 mL/kg, v.o.) e eucaliptol (400 mg/kg, i.p.) e posteriormente com pentilenotetrazol (80 mg/kg, i.p.); a determinação da concentração de neurotransmissores (monoaminas – dopamina, noradrenalina e serotonina) e dos marcadores de estresse oxidativo (nitrito e substâncias reativas do ácido tiobarbitúrico – TBARs) foram os parâmetros avaliados. Os resultados foram analisados por ANOVA ou Kruskal-Wallis, seguido dos testes de Student-Newman-Keuls, e Dunns, respectivamente. Foram considerados significativos os valores de p < 0,05. Os resultados mostraram que a administração oral do eucaliptol apresentou baixa toxicidade e a DL50 estimada foi superior a 2000 mg/kg. No teste das convulsões induzidas por PTZ apenas a dose maior do monoterpeno (400 mg/kg) reduziu de forma significativa a intensidade das convulsões em 60%, aumentou a latência para aparecimento da primeira convulsão em 85% e o tempo de morte dos animais em 75% em relação ao controle. De forma semelhante, o tratamento com eucaliptol (400 mg/kg) reduziu de forma significativa a concentração de noradrenalina, dopamina e serotonina, em 50%, 33% e 70%, respectivamente, em relação ao grupo tratado com PTZ (80 mg/kg). Além disso, o tratamento com eucaliptol (400 mg/kg) reduziu de forma significativa a concentração de TBARs em 33%, mas não de nitrito, em relação ao grupo tratado com PTZ (80 mg/kg). Tomados em conjunto, os resultados mostram que o monoterpeno estudado apresenta baixa toxicidade oral e importante efeito anticonvulsivante, visto que sua administração é capaz de atenuar as convulsões quimicamente induzidas por pentilenotetrazol com consequente redução da concentração de monoaminas e das substâncias reativas do ácido tiobarbitúrico, elementos cujo aumento está associado ao fenômeno da epileptogênese

Measurement of proton, deuteron, triton, and alpha particle emission after nuclear muon capture on Al, Si, and Ti with the AlCap experiment

Background: Heavy charged particles after nuclear muon capture are an important nuclear physics background to the muon-to-electron conversion experiments Mu2e and COMET, which will search for charged lepton flavor violation at an unprecedented level of sensitivity. Purpose: The AlCap experiment aimed to measure the yield and energy spectra of protons, deuterons, tritons, and α particles emitted after the nuclear capture of muons stopped in Al, Si, and Ti in the low-energy range relevant for the muon-to-electron conversion experiments. Methods: Individual charged particle types were identified in layered silicon detector packages and their initial energy distributions were unfolded from the observed energy spectra. Results: The proton yields per muon capture were determined as Y p ( Al ) = 26.64 ( 28 stat. ) ( 77 syst. ) × 10 − 3 and Y p ( Ti ) = 26.48 ( 35 ) ( 80 ) × 10 − 3 in the energy range 3.5–20.0 MeV, and as Y p ( Si ) = 52.5 ( 6 ) ( 18 ) × 10 − 3 in the energy range 4.0–20.0 MeV. Detailed information on yields and energy spectra for all observed nuclei are presented in the paper. Conclusions: The yields in the candidate muon stopping targets, Al and Ti, are approximately half of that in Si, which was used in the past to estimate this background. The reduced background allows for less shielding and a better energy resolution in these experiments. It is anticipated that the comprehensive information presented in this paper will stimulate modern theoretical calculations of the rare process of muon capture with charged particle emission and inform the design of future muon-to-electron conversion experiments

Evaluation of gadolinium's action on water Cherenkov detector systems with EGADS

Used for both proton decay searches and neutrino physics, large water Cherenkov (WC) detectors have been very successful tools in particle physics. They are notable for their large masses and charged particle detection capabilities. While current WC detectors reconstruct charged particle tracks over a wide energy range, they cannot efficiently detect neutrons. Gadolinium (Gd) has the largest thermal neutron capture cross section of all stable nuclei and produces an 8 MeV gamma cascade that can be detected with high efficiency. Because of the many new physics opportunities that neutron tagging with a Gd salt dissolved in water would open up, a large-scale R&D program called EGADS was established to demonstrate this technique's feasibility. EGADS features all the components of a WC detector, chiefly a 200-ton stainless steel water tank furnished with 240 photo-detectors, DAQ, and a water system that removes all impurities in water while keeping Gd in solution. In this paper we discuss the milestones towards demonstrating the feasibility of this novel technique, and the features of EGADS in detail

Sensitivity of the T2K accelerator-based neutrino experiment with an Extended run to 20×102120\times10^{21} POT

18 pages, 4 figures18 pages, 4 figures18 pages, 4 figures18 pages, 4 figures18 pages, 4 figuresRecent measurements at the T2K experiment indicate that CP violation in neutrino mixing may be observed in the future by long-baseline neutrino oscillation experiments. We explore the physics program of an extension to the currently approved T2K running of $7.8\times 10^{21}$ protons-on-target to $20\times 10^{21}$ protons-on-target,aiming at initial observation of CP violation with 3$\,\sigma$ or higher significance for the case of maximum CP violation. With accelerator and beam line upgrades, as well as analysis improvements, this program would occur before the next generation of long-baseline neutrino oscillation experiments that are expected to start operation in 2026.We acknowledge the support of MEXT, Japan; NSERC (Grant No. SAPPJ-2014-00031), NRC and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; National Science Centre (NCN), Poland; RSF, RFBR and MES, Russia; MINECO and ERDF funds, Spain; SNSF and SERI, Switzerland; STFC, UK; and DOE, USA. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, and GridPP in the United Kingdom. In addition, participation of individual researchers and institutions has been further supported by funds from ERC (FP7), H2020 Grant No. RISE-GA644294-JENNIFER, EU; JSPS, Japan; Royal Society, UK; and the DOE Early Career program, USA. CNRS/IN2P3: Centre National de la Recherche ScientifiqueInstitut National de Physique Nucleaire et de Physique des Particules RSF: Russian Science Foundation MES: Ministry of Education and Science, Russia ERDF: European Regional Development Fund SNSF: Swiss National Science Foundation SER (should be SERI): State Secretariat for Education, Research and Innovatio

Limits on active to sterile neutrino oscillations from disappearance searches in the MINOS, Daya Bay, and bugey-3 experiments

Searches for a light sterile neutrino have been performed independently by the MINOS and the Daya Bay experiments using the muon (anti)neutrino and electron antineutrino disappearance channels, respectively. In this Letter, results from both experiments are combined with those from the Bugey-3 reactor neutrino experiment to constrain oscillations into light sterile neutrinos. The three experiments are sensitive to complementary regions of parameter space, enabling the combined analysis to probe regions allowed by the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE experiments in a minimally extended four-neutrino flavor framework. Stringent limits on sin^2 2θμe are set over 6 orders of magnitude in the sterile mass-squared splitting Δm^2 41. The sterile-neutrino mixing phase space allowed by the LSND and MiniBooNE experiments is excluded for Δm^2 41 < 0.8 eV^2 at 95% CLs