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K. Lang

Publications and source records attributed to K. Lang.

120 records · Page 7Linked to original sources
arXiv2010

Measurement of the two neutrino double beta decay half-life of Zr-96 with the NEMO-3 detector

Using 9.4 g of Zr-96 and 1221 days of data from the NEMO-3 detector corresponding to 0.031 kg yr, the obtained 2vbb decay half-life measurement is [2.35 +/- 0.14(stat) +/- 0.16(syst)] x 10^19 yr. Different characteristics of the final state electrons have been studied, such as the energy sum, individual electron energy, and angular distribution. The 2v nuclear matrix element is extracted using the measured 2vbb half-life and is 0.049 +/- 0.002. Constraints on 0vbb decay have also been set.

nucl-ex↗
arXiv2010

A Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector

We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the Standard-Model Extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of $20-510$ over the current best limits found using the MINOS near detector.

hep-ex↗
arXiv2010

Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils

The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in $^{208}$Tl and $^{214}$Bi for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 $m^2$ of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in $^{208}$Tl. After more than one year of background measurement, a surface activity of the scintillators of $\mathcal{A}$($^{208}$Tl) $=$ 1.5 $μ$Bq/m$^2$ is reported here. Given this level of background, a larger BiPo detector having 12 m$^2$ of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of $\mathcal{A}$($^{208}$Tl) $<$ 2 $μ$Bq/kg (90% C.L.) with a six month measurement.

physics.ins-det↗
arXiv2009

Measurement of the background in the NEMO 3 double beta decay experiment

In the double beta decay experiment NEMO~3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO~3 to evaluate the backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment.

nucl-ex↗
arXiv2003

A straw drift chamber spectrometer for studies of rare kaon decays

We describe the design, construction, readout, tests, and performance of planar drift chambers, based on 5 mm diameter copperized Mylar and Kapton straws, used in an experimental search for rare kaon decays. The experiment took place in the high-intensity neutral beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two analyzing dipoles, and redundant particle identification to remove backgrounds.

physics.ins-det↗
arXiv2003

Confirmation of solar-like oscillations in eta Bootis

We obtained time-series spectroscopy of the G0 subgiant eta Boo in an attempt to confirm the solar-like oscillations reported by Kjeldsen et al. (1995). We recorded 1843 spectra over six consecutive nights with the Nordic Optical Telescope, which we used to measure equivalent widths of strong temperature-sensitive lines. We also measured velocities from 1989 spectra obtained through an iodine reference cell at Lick Observatory over 56 nights that were badly affected by weather. Our analysis also included velocity measurements published by Brown et al. (1997) and the original equivalent-width measurements by Kjeldsen et al. (1995). All four data sets show power excesses consistent with oscillations, although with a range of amplitudes that presumably reflects the stochastic nature of the excitation. The highest peaks show regularity with a large separation of Delta nu = 40.4 microHz and we identify 21 oscillation frequencies from the combined data.

astro-ph↗
arXiv2002

Testing of Hamamatsu R5900-00-M64 Multi-Pixel PMTs for MINOS

The MINOS long baseline neutrino oscillation experiment is comprised of three calorimeters, a Near Detector at FNAL, a Far Detector at the Soudan mine in northern Minnesota, and a Calibration Detector in a test beam at CERN. The light produced in the interactions of neutrinos in the Near Detector at FNAL will be routed by optical fibres onto the pixels of Hamamatsu R5900-00-M64 multi-anode photomultiplier tubes. This article reports the measurements performed on 15 of these tubes to evaluate them for their use in MINOS.

hep-ex↗
arXiv2002

Confirmation of Solar-Like Oscillations in eta Bootis

We report observations of the G0 subgiant eta Boo made in 1998, in Balmer-line equivalent width with the 2.5-m Nordic Optical Telescope and in velocity with the 24-inch Lick CAT. In both data sets we see an excess in the power spectrum, with oscillation frequencies that confirm the earlier observations by Kjeldsen et al. (1995).

astro-ph↗
arXiv1998

A Technique of Direct Tension Measurement of a Strung Fine Wire

We present a new technique of direct measurement of wire tensions in wire chambers. A specially designed circuit plucks the wire using the Lorentz force and measures the frequency of damped transverse oscillations of the wire. The technique avoids the usual time-consuming necessity of tuning circuit parameter to a resonance. It allows a fast and convenient determination of tensions and is straightforward to implement.

hep-ex↗
arXiv1998

First Observation of the Rare Decay Mode K-long -> e+ e-

In an experiment designed to search for and study very rare two-body decay modes of the K-long, we have observed four examples of the decay K-long -> e+ e-, where the expected background is 0.17+-0.10 events. This observation translates into a branching fraction of 8.7^{+5.7}_{-4.1} X 10^{-12}, consistent with recent theoretical predictions. This result represents by far the smallest branching fraction yet measured in particle physics.

hep-ex↗
arXiv1998

A Compact Beam Stop for a Rare Kaon Decay Experiment

We describe the development and testing of a novel beam stop for use in a rare kaon decay experiment at the Brookhaven AGS. The beam stop is located inside a dipole spectrometer magnet in close proximity to straw drift chambers and intercepts a high-intensity neutral hadron beam. The design process, involving both Monte Carlo simulations and beam tests of alternative beam-stop shielding arrangements, had the goal of minimizing the leakage of particles from the beam stop and the resulting hit rates in detectors, while preserving maximum acceptance for events of interest. The beam tests consisted of measurements of rates in drift chambers, scintilation counter hodoscopes, a gas threshold Cherenkov counter, and a lead glass array. Measurements were also made with a set of specialized detectors which were sensitive to low-energy neutrons, photons, and charged particles. Comparisons are made between these measurements and a detailed Monte Carlo simulation.

hep-ex↗