Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1

An ensemble of multi-layer scintillators is discussed as an option of the high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic measurements of neutrino-less double beta decays. A prototype detector MOON-1, which consists of 6 layer plastic-scintillator plates, was built to study the sensitivity of the MOON-type detector. The scintillation photon collection and the energy resolution, which are key elements for the high-sensitivity experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region, respectively. The multi-layer plastic-scintillator structure with good energy resolution as well as good background suppression of beta-gamma rays is crucial for the MOON-type detector to achieve the inverted hierarchy neutrino mass sensitivity.Comment: 8 pages, 16 figures, submitted to Nucl.Instrum.Met

Measurement of the K+→μ+νμγK^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma} decay form factors in the OKA experiment

A precise measurement of the vector and axial-vector form factors difference $F_V-F_A$ in the $K^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma}$ decay is presented. About 95K events of $K^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma}$ are selected in the OKA experiment. The result is $F_V-F_A=0.134\pm0.021(stat)\pm0.027(syst)$. Both errors are smaller than in the previous $F_V-F_A$ measurements.Comment: 9 pages, 8 figure

Stability study and time resolution measurement of Straw Tube detectors

Straw tube detectors are single wire proportional counters that are widely used as a tracking device. We have carried out R$\&$D with a straw tube detector prototype. The motivation of this work is to study the stability of the performance in terms of gain and energy resolution of the straw tube detectors under high rate radiation. Two different methods are incorporated to perform this study. The gain and energy resolution of the detector are studied along with its variation with ambient temperature and pressure. X-ray from a radioactive source is used to irradiate the detector and the same source is also used to monitor the energy spectra simultaneously for calculation of gain. Variation of the gain and energy resolution of the straw tube detector under X-ray irradiation in Ar/CO$_2$ gas mixture is discussed in this article. We have also estimated the time resolution of the straw tube detectors that can be best achieved with cosmic rays as trigger for the same gas mixture. The details of the measurement process and the experimental results are presented in this article

THE TOOLS AND MONTE CARLO WORKING GROUP Summary Report from the Les Houches 2009 Workshop on TeV Colliders

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 "Tools and Monte Carlo" working group.Comment: 144 Pages. Workshop site http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skand

First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma

Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e- gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7 estimated background events. With K+- -> pi+- pi0D as normalisation channel, the branching ratio is determined in a model-independent way to be Br(K+- -> pi+- e+ e- gamma, m_eegamma > 260 MeV/c^2) = (1.19 +- 0.12_stat +- 0.04_syst) x 10^-8. This measured value and the spectrum of the e+ e- gamma invariant mass allow a comparison with predictions of Chiral Perturbation Theory.Comment: 13 pages, 3 figures. Accepted for publication in Phys.Lett.

Measurement of the branching ratio of the decay Ξ0→Σ+μ−νˉμ\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}

From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 $\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}$ candidates with a background contamination of $30.8 \pm 4.2$ events. From this sample, the BR($\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}$) is measured to be $(2.17 \pm 0.32_{\mathrm{stat}}\pm 0.17_{\mathrm{syst}})\times10^{-6}$

Empirical parameterization of the K+- -> pi+- pi0 pi0 decay Dalitz plot

As first observed by the NA48/2 experiment at the CERN SPS, the \p0p0 invariant mass (M00) distribution from \kcnn decay shows a cusp-like anomaly at M00=2m+, where m+ is the charged pion mass. An analysis to extract the pi pi scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively, has been recently reported. In the present work the Dalitz plot of this decay is fitted to a new empirical parameterization suitable for practical purposes, such as Monte Carlo simulations of K+- -> pi+- pi0 pi0 decays.Comment: 9 pages, 3 figures

Observation of the rare decay K_S -> pi^0mu^+mu^-

A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1 Collaboration at the CERN SPS accelerator. The data were collected during 2002 with a high-intensity K_S beam. Six events were found with a background expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit form factor, the measured branching ratio is B(K_S -> pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters