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The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay μ(+) → e(+)γ 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 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

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The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay μ + → e + γ by using one of the most intense continuous μ + 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.

Notch signaling plays an important role in cell-fate specification in multicellular organisms by regulating cell-cell communication. The Drosophila deltex gene encodes a modulator of the Notch pathway that has been shown to interact physically with the Ankyrin repeats of Notch. We isolated four distinct cDNAs corresponding to mouse homologs of deltex - mouse Deltex1 (MDTX1), mouse Deltex2 (MDTX2), mouse Deltex2DeltaE (MDTX2DeltaE), and mouse Deltex3 (MDTX3). Deduced amino acid sequences of these four cDNAs showed a high degree of similarity to Drosophila Deltex and its human homolog, DTX1 throughout their lengths, even though they possess distinct structural features. MDTX proteins formed homotypic and heterotypic multimers. We found that these genes were expressed in the central, peripheral nervous system and in the thymus, overlapping with those of mouse Notch1. In mammalian tissue culture cells, overexpression of any of the four mouse deltex homologs suppressed the transcriptional activity of E47, a basic helix-loop-helix (bHLH) protein, in a manner similar to suppression by an activated form of human Notch1 or human DTX1. In addition, overexpression of MDTX2 and MDTX2DeltaE in C2C12 cells under differentiation-inducing conditions suppressed the expression of myogenin, one of the myogenic transcriptional factors; this was also similar to a previously reported activity of constitutively activated Notch. Furthermore, misexpression of any of the MDTX genes in Xenopus embryos resulted in an expansion of the region expressing the neural cell adhesion molecule (N-CAM) gene, a marker for the neuroepithelium. Collectively, our results suggest that these mouse deltex homologs are involved in vertebrate Notch signaling and regulation of neurogenesis.

periods of the time, providing a new instrument for physics experiments. OCR Output conclude that such a detector can be built in large sizes and reliably operated over longThe in depth understanding of the basic physics aspects of the liquid Argon TPC allows us toThe data from radioactive sources are used to study the energy resolution in the MeV range. electron diffusion coefficient, the space resolution and the particle identification capability.following items: the electron drift velocity, the electron lifetime, the free electron yield, the detector. We present here the results obtained from the analysis of the cosmic rays data on the We have systematically investigated the performances and the physical parameters of the rays and from radioactive sources collected from June 1991 to June 1993.R&D programme for the ICARUS project. We report on the analysis of events from cosmicWe have constructed and operated a 3 ton liquid argon time projection chamber as part of the ABSTRACT Pooaeloaa

A high performance distillation system to remove krypton from xenon was constructed, and a purity level of Kr/Xe = ∼ 3 × 10 −12 was achieved. This development is crucial in facilitating high sensitivity low background experiments such as the search for dark matter in the universe.

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