89 research outputs found
MEG Upgrade Proposal
We propose the continuation of the MEG experiment to search for the charged
lepton flavour violating decay (cLFV) \mu \to e \gamma, based on an upgrade of
the experiment, which aims for a sensitivity enhancement of one order of
magnitude compared to the final MEG result, down to the
level. The key features of this new MEG upgrade are an increased rate
capability of all detectors to enable running at the intensity frontier and
improved energy, angular and timing resolutions, for both the positron and
photon arms of the detector. On the positron-side a new low-mass, single
volume, high granularity tracker is envisaged, in combination with a new highly
segmented, fast timing counter array, to track positron from a thinner stopping
target. The photon-arm, with the largest liquid xenon (LXe) detector in the
world, totalling 900 l, will also be improved by increasing the granularity at
the incident face, by replacing the current photomultiplier tubes (PMTs) with a
larger number of smaller photosensors and optimizing the photosensor layout
also on the lateral faces. A new DAQ scheme involving the implementation of a
new combined readout board capable of integrating the diverse functions of
digitization, trigger capability and splitter functionality into one condensed
unit, is also under development. We describe here the status of the MEG
experiment, the scientific merits of the upgrade and the experimental methods
we plan to use.Comment: A. M. Baldini and T. Mori Spokespersons. Research proposal submitted
to the Paul Scherrer Institute Research Committee for Particle Physics at the
Ring Cyclotron. 131 Page
New constraint on the existence of the mu+-> e+ gamma decay
The analysis of a combined data set, totaling 3.6 \times 10^14 stopped muons
on target, in the search for the lepton flavour violating decay mu^+ -> e^+
gamma is presented. The data collected by the MEG experiment at the Paul
Scherrer Institut show no excess of events compared to background expectations
and yield a new upper limit on the branching ratio of this decay of 5.7 \times
10^-13 (90% confidence level). This represents a four times more stringent
limit than the previous world best limit set by MEG.Comment: 5 pages, 3 figures, a version accepted in Phys. Rev. Let
Measurement of the radiative decay of polarized muons in the MEG experiment
We studied the radiative muon decay by
using for the first time an almost fully polarized muon source. We identified a
large sample (~13000) of these decays in a total sample of 1.8x10^14 positive
muon decays collected in the MEG experiment in the years 2009--2010 and
measured the branching ratio B() =
(6.03+-0.14(stat.)+-0.53(sys.))x10^-8 for E_e > 45 MeV and E_{\gamma} > 40 MeV,
consistent with the Standard Model prediction. The precise measurement of this
decay mode provides a basic tool for the timing calibration, a normalization
channel, and a strong quality check of the complete MEG experiment in the
search for process.Comment: 8 pages, 7 figures. Added an introduction to NLO calculation which
was recently calculated. Published versio
The MEG detector for decay search
The MEG (Mu to Electron Gamma) experiment has been running at the Paul
Scherrer Institut (PSI), Switzerland since 2008 to search for the decay \meg\
by using one of the most intense continuous beams in the world. This
paper presents the MEG components: the positron spectrometer, including a thin
target, a superconducting magnet, a set of drift chambers for measuring the
muon decay vertex and the positron momentum, a timing counter for measuring the
positron time, and a liquid xenon detector for measuring the photon energy,
position and time. The trigger system, the read-out electronics and the data
acquisition system are also presented in detail. The paper is completed with a
description of the equipment and techniques developed for the calibration in
time and energy and the simulation of the whole apparatus.Comment: 59 pages, 90 figure
Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.
Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter
We present a study of showers initiated by electrons, pions, kaons, and
protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE
scintillator-tungsten analogue hadronic calorimeter. The data were recorded at
the CERN Super Proton Synchrotron in 2011. The analysis includes measurements
of the calorimeter response to each particle type as well as measurements of
the energy resolution and studies of the longitudinal and radial shower
development for selected particles. The results are compared to Geant4
simulations (version 9.6.p02). In the study of the energy resolution we include
previously published data with beam momenta from 1 GeV to 10 GeV recorded at
the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table
Airâliquid interface cultures enhance the oxygen supply and trigger the structural and functional differentiation of intestinal porcine epithelial cells (IPEC)
The specific function of the epithelium as critical barrier between the intestinal lumen and the organismâs internal microenvironment is reflected by permanent maintenance of intercellular junctions and cellular polarity. The intestinal epithelial cells are responsible for absorption of nutritional components, facing mechanical stress and a changing oxygen supplementation via blood stream. Oxygen itself can regulate the barrier and the absorptive function of the epithelium. Therefore, we compared the dish cell culture, the transwell-like membrane culture and the oxygen enriched airâliquid interface (ALI) culture. We demonstrated strong influence of the different culture conditions on morphology and function of intestinal porcine epithelial cell lines in vitro. ALI culture resulted in a significant increase in cell number, epithelial cell layer thickness and expression as well as apical localisation of the microvilli-associated protein villin. Remarkable similarities regarding the morphological parameters were observed between ALI cultures and intestinal epithelial cells in vivo. Furthermore, the functional analysis of protein uptake and degradation by the epithelial cells demonstrated the necessity of sufficient oxygen supply as achieved in ALI cultures. Our study is the first report providing marked evidence that optimised oxygen supply using ALI cultures directly affects the morphological differentiation and functional properties of intestinal epithelial cells in vitro
Produtos quĂmicos e nĂșmero de pulverizaçÔes para o manejo do oĂdio do cajueiro.
Objetivou-se avaliar diferentes produtos quĂmicos e o nĂșmero de pulverizaçÔes para o manejo do oĂdio. Foram avaliados quatro produtos e trĂȘs nĂșmeros de pulverizaçÔes. Dois experimentos foram realizados em delineamento de blocos casualizados em esquema fatorial com quatro repetiçÔes, cujos tratamentos principais foram os produtos quĂmicos trifloxystrobina + tebuconazol, enxofre, calda sulfocĂĄlcica e calda viçosa em Pacajus, CE, e enxofre e calda sulfocĂĄlcica em Ribeira do Pombal, BA.bitstream/item/203995/1/BP-192.pd
Measurement of the radiative decay of polarized muons in the MEG experiment
We studied the radiative muon decay (Formula presented.) by using for the first time an almost fully polarized muon source. We identified a large sample ((Formula presented.) 13,000) of these decays in a total sample of (Formula presented.) positive muon decays collected in the MEG experiment in the years 2009â2010 and measured the branching ratio (Formula presented.) for (Formula presented.) and (Formula presented.) , consistent with the Standard Model prediction. The precise measurement of this decay mode provides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for (Formula presented.) process
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