2,305 research outputs found
Exploring low-energy neutrino physics with the Coherent Neutrino Nucleus Interaction Experiment
The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constraints on NSI from the CEνNS of antineutrinos from nuclear reactors.CONACYT - Consejo Nacional de Ciencias y TecnologĂaPROCIENCI
How to Reduce the Laparoscopic Colorectal Learning Curve
ProducciĂłn CientĂficaThe laparoscopic approach for colorectal pathologies is becoming more widely used, and surgeons have had to learn how to perform this new technique. The purpose of this work is to study the indicators of the learning curve for laparoscopic colectomy in a community hospital and to find when the group begins to improv
Estimation of water quality parameters using landsat 8 images: application to playa Colorada Bay, Sinaloa, Mexico
In this study, empirical models were generated to estimate water quality parameters, with the objective of showing the benefits of the satellite remote sensing application in the characterization of coastal waters. The study area was Playa Colorada Bay, located in the northwest of Mexico, in the eastern part of the Gulf of California. In two seasons of the year, on-site and laboratory characterizations were carried out to determine the spatial and temporal variation of phosphates (PO4), electrical conductivity (EC), total suspended solids (TSS), turbidity, and pH of water. Samplings were selected to match Landsat 8 satellite overpass in the study area. Radiometric and atmospheric corrections were applied to the images, prior to the generation of the models. The models were generated using the linear regression technique of successive steps; water quality parameters and their logarithms were used as dependent variables, and as independent variables were used corrected reflectance values of Landsat images. The results showed that the concentration of PO4 in the analyzed water samples were higher than those recommended in the Mexican ecological criteria of water quality, to protect the aquatic life of marine water in coastal areas. In autumn, PO4 was correlated with turbidity, T, pH, and TSS. The highest correlation coefficients were presented by TSS with PO4 (r = â 0.979) and pH (r = 0.958). The water quality models that were generated had coefficients of determination (R2) in the range of 0.637 to 0.955 and show the viability of the application of Landsat 8 images in the characterization of water quality parameters in Playa Colorada Bay. Models allowed the estimation of the distribution of water quality parameters over the whole bay instead of only at the sampling stations, favoring a better understanding of their spatial distribution
CAGIRE: a wide-field NIR imager for the COLIBRI 1.3 meter robotic telescope
The use of high energy transients such as Gamma Ray Bursts (GRBs) as probes
of the distant universe relies on the close collaboration between space and
ground facilities. In this context, the Sino-French mission SVOM has been
designed to combine a space and a ground segment and to make the most of their
synergy. On the ground, the 1.3 meter robotic telescope COLIBRI, jointly
developed by France and Mexico, will quickly point the sources detected by the
space hard X-ray imager ECLAIRs, in order to detect and localise their
visible/NIR counterpart and alert large telescopes in minutes. COLIBRI is
equipped with two visible cameras, called DDRAGO-blue and DDRAGO-red, and an
infrared camera, called CAGIRE, designed for the study of high redshift GRBs
candidates. Being a low-noise NIR camera mounted at the focus of an
alt-azimutal robotic telescope imposes specific requirements on CAGIRE. We
describe here the main characteristics of the camera: its optical, mechanical
and electronics architecture, the ALFA detector, and the operation of the
camera on the telescope. The instrument description is completed by three
sections presenting the calibration strategy, an image simulator incorporating
known detector effects, and the automatic reduction software for the ramps
acquired by the detector. This paper aims at providing an overview of the
instrument before its installation on the telescope.Comment: Accepted by Experimental Astronom
Exploring low-energy neutrino physics with the Coherent Neutrino Nucleus Interaction Experiment
The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) uses low-noise fully depleted charge-coupled devices (CCDs) with the goal of measuring low-energy recoils from coherent elastic scattering ( CE ν NS ) of reactor antineutrinos with silicon nuclei and testing nonstandard neutrino interactions (NSI). We report here the first results of the detector array deployed in 2016, considering an active mass 47.6 g (eight CCDs), which is operating at a distance of 30 m from the core of the Angra 2 nuclear reactor, with a thermal power of 3.8 GW. A search for neutrino events is performed by comparing data collected with the reactor on (2.1 kg-day) and reactor off (1.6 kg-day). The results show no excess in the reactor-on data, reaching the world record sensitivity down to recoil energies of about 1 keV (0.1 keV electron equivalent). A 95% confidence level limit for new physics is established at an event rate of 40 times the one expected from the standard model at this energy scale. The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constraints on NSI from the CEνNS of antineutrinos from nuclear reactors.Fil: Aguilar Arevalo, Alexis. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Bertou, Xavier Pierre Louis. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica. Centro AtĂłmico Bariloche; Argentina. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - Patagonia Norte; ArgentinaFil: Bonifazi, Carla Brenda. Universidade Federal do Rio de Janeiro; Brasil. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas; ArgentinaFil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados UnidosFil: CastaĂąeda, Alejandro. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Cervantes Vergara, Brenda. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Chavez, Claudio. Universidad Nacional de AsunciĂłn; ParaguayFil: DâOlivo, Juan C.. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Dos Anjos, JoĂŁo C.. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernandes Neto, Aldo R.. Centro Federal de EducacĂŁo TecnolĂłgica Celso Suckow Da Fonseca; BrasilFil: FernĂĄndez Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas; ArgentinaFil: Foguel, Ana. Universidade Federal do Rio de Janeiro; BrasilFil: Ford, Richard. Fermi National Accelerator Laboratory; Estados UnidosFil: Gonzalez Cuevas, Juan. Universidad Nacional de AsunciĂłn; ParaguayFil: HernĂĄndez, Pamela. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Hernandez, Susana. Fermi National Accelerator Laboratory; Estados UnidosFil: Izraelevitch, Federico HernĂĄn. ComisiĂłn Nacional de EnergĂa AtĂłmica; Argentina. Universidad Nacional de San MartĂn; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas; ArgentinaFil: Kavner, Alexander R.. University of Michigan; Estados UnidosFil: Kilminster, Ben. Universitat Zurich; SuizaFil: Kuk, Kevin. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima, H.P.. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Makler, MartĂn. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Molina, Jorge. Universidad Nacional de AsunciĂłn; ParaguayFil: Mota, Philipe. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Nasteva, Irina. Universidade Federal do Rio de Janeiro; BrasilFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca; ArgentinaFil: Romero, Carlos. Universidad Nacional de AsunciĂłn; ParaguayFil: Sarkis, Y.. Universidad Nacional AutĂłnoma de MĂŠxico; MĂŠxicoFil: Sofo Haro, Miguel Francisco. ComisiĂłn Nacional de EnergĂa AtĂłmica. Gerencia del Ărea de EnergĂa Nuclear. Instituto Balseiro; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica; Argentina. Universidad Nacional de Cuyo; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas. Centro CientĂfico Tecnol.conicet - Patagonia Norte. Unidad de Adm.territorial; ArgentinaFil: Souza, IruatĂŁ M. S.. Centro Brasileiro de Pesquisas FĂsicas; BrasilFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones CientĂficas y TĂŠcnicas; ArgentinaFil: Wagner, Stefan. Centro Brasileiro de Pesquisas FĂsicas; Brasil. PontifĂcia Universidade CatĂłlica do Rio de Janeiro; Brasi
Search for coherent elastic neutrino-nucleus scattering at a nuclear reactor with CONNIE 2019 data
The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) is taking data
at the Angra 2 nuclear reactor with the aim of detecting the coherent elastic
scattering of reactor antineutrinos with silicon nuclei using charge-coupled
devices (CCDs). In 2019 the experiment operated with a hardware binning applied
to the readout stage, leading to lower levels of readout noise and improving
the detection threshold down to 50 eV. The results of the analysis of 2019 data
are reported here, corresponding to the detector array of 8 CCDs with a
fiducial mass of 36.2 g and a total exposure of 2.2 kg-days. The difference
between the reactor-on and reactor-off spectra shows no excess at low energies
and yields upper limits at 95% confidence level for the neutrino interaction
rates. In the lowest-energy range, 50-180 eV, the expected limit stands at 34
(39) times the standard model prediction, while the observed limit is 66 (75)
times the standard model prediction with Sarkis (Chavarria) quenching factors.Comment: 23 pages, 14 figure
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy
A search for new physics is performed in events with two same-sign isolated
leptons, hadronic jets, and missing transverse energy in the final state. The
analysis is based on a data sample corresponding to an integrated luminosity of
4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of
7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of
140 increase in integrated luminosity over previously published results. The
observed yields agree with the standard model predictions and thus no evidence
for new physics is found. The observations are used to set upper limits on
possible new physics contributions and to constrain supersymmetric models. To
facilitate the interpretation of the data in a broader range of new physics
scenarios, information on the event selection, detector response, and
efficiencies is provided.Comment: Published in Physical Review Letter
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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