Some problems of flash tubs operation

A review has been made of the development of the neon flash tube, from its introduction by Conversi in 1955, up to the present day. Particular attention is paid to the problems which arose from attempts to use flash tube arrays on accelerator experiments, namely the long sensitive and recovery times of the tubes, and the loss of efficiency at high event rates, caused by internal clearing fields. The problems arising from attempts to describe analytically the flash tube discharge mechanism are also discussed. An investigation of the decay mechanisn of the internal clearing fields has been made, which indicated that the effect may be overcome by decreasing the surface resistance of the outer wall of the flash tube. A description of a gamma ray detector, utilising flash tubes as the detecting elements, interspersed with lead absorber, is included. The energy and spatial resolutions are found to compare favourably with those of more complex and expensive detectors. The problems arising from the use of this detector in the e(^+) test beam at the Daresbury Laboratory are discussed

Neutrino Detection using Lead Perchlorate

We discuss the possibility of using lead perchlorate as a neutrino detector. The primary neutrino interactions are given along with some relevant properties of the material.Comment: 2 pages, 2 figures, TAUP-99, TEX fil

Background Studies for the Neutral Current Detector Array in the Sudbury Neutrino Observatory

An array of 3He-filled proportional counters will be used in the Sudbury Neutrino Observatory to measure the neutral-current interaction of neutrinos and deuterium. We describe the backgrounds to this detection method.Comment: Accepted for publication in the proceedings of TAUP99. 2 page

Solubility, Light Output and Energy Resolution Studies of Molybdenum-Loaded Liquid Scintillators

The search for neutrinoless double-beta decay is an important part of the global neutrino physics program. One double-beta decay isotope currently under investigation is 100Mo. In this article, we discuss the results of a feasibility study investigating the use of molybdenum-loaded liquid scintillator. A large, molybdenum-loaded liquid scintillator detector is one potential design for a low-background, internal-source neutrinoless double-beta decay search with 100Mo. The program outlined in this article included the selection of a solute containing molybdenum, a scintillating solvent and the evaluation of the mixture's performance as a radiation detector.Comment: 8 pages, 3 figure

Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector

The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the MAJORANA Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure

The Majorana Neutrinoless Double-Beta Decay Experiment

The proposed Majorana double-beta decay experiment is based on an array of segmented intrinsic Ge detectors with a total mass of 500 kg of Ge isotopically enriched to 86% in 76Ge. A discussion is given of background reduction by: material selection, detector segmentation, pulse shape analysis, and electro-formation of copper parts and granularity. Predictions of the experimental sensitivity are given. For an experimental running time of 10 years over the construction and operation of Majorana, a half-life sensitivity of ~4x10^27 y (neutrinoless) is predicted. This corresponds to an effective Majorana mass of the electron neutrino of ~0.03-0.04 eV, according to recent QRPA and RQRPA matrix element calculations.Comment: 10 pages, 7 figure

Dead layer on silicon p–i–n diode charged-particle detectors

Semiconductor detectors in general have a dead layer at their surfaces that is either a result of natural or induced passivation, or is formed during the process of making a contact. Charged particles passing through this region produce ionization that is incompletely collected and recorded, which leads to departures from the ideal in both energy deposition and resolution. The silicon p-i-n diode used in the KATRIN neutrinomass experiment has such a dead layer. We have constructed a detailed Monte Carlo model for the passage of electrons from vacuum into a silicon detector, and compared the measured energy spectra to the predicted ones for a range of energies from 12 to 20 keV. The comparison provides experimental evidence that a substantial fraction of the ionization produced in the "dead" layer evidently escapes by diffusion, with 46% being collected in the depletion zone and the balance being neutralized at the contact or by bulk recombination. The most elementary model of a thinner dead layer from which no charge is collected is strongly disfavored

The mammalian gene function resource: The International Knockout Mouse Consortium

In 2007, the International Knockout Mouse Consortium (IKMC) made the ambitious promise to generate mutations in virtually every protein-coding gene of the mouse genome in a concerted worldwide action. Now, 5 years later, the IKMC members have developed highthroughput gene trapping and, in particular, gene-targeting pipelines and generated more than 17,400 mutant murine embryonic stem (ES) cell clones and more than 1,700 mutant mouse strains, most of them conditional. A common IKMC web portal (www.knockoutmouse.org) has been established, allowing easy access to this unparalleled biological resource. The IKMC materials considerably enhance functional gene annotation of the mammalian genome and will have a major impact on future biomedical research

Gamma-induced background in the KATRIN main spectrometer

International audienceThe KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β -particles from tritium β -decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background