396,156 research outputs found

    The Magnetic Distortion Calibration System of the LHCb RICH1 Detector

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    The LHCb RICH1 detector uses hybrid photon detectors (HPDs) as its optical sensors. A calibration system has been constructed to provide corrections for distortions that are primarily due to external magnetic fields. We describe here the system design, construction, operation and performance.Comment: 9 pages, 14 figure

    Gaseous time projection chambers for rare event detection: Results from the T-REX project. II. Dark matter

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    As part of the T-REX project, a number of R&D and prototyping activities have been carried out during the last years to explore the applicability of Micromegas-read gaseous TPCs in rare event searches like double beta decay (DBD), axion research and low-mass WIMP searches. While in the companion paper we focus on DBD, in this paper we focus on the results regarding the search for dark matter candidates, both axions and WIMPs. Small ultra-low background Micromegas detectors are used to image the x-ray signal expected in axion helioscopes like CAST at CERN. Background levels as low as 0.8×1060.8\times 10^{-6} c keV1^{-1}cm2^{-2}s1^{-1} have already been achieved in CAST while values down to 107\sim10^{-7} c keV1^{-1}cm2^{-2}s1^{-1} have been obtained in a test bench placed underground in the Laboratorio Subterr\'aneo de Canfranc. Prospects to consolidate and further reduce these values down to 108\sim10^{-8} c keV1^{-1}cm2^{-2}s1^{-1}will be described. Such detectors, placed at the focal point of x-ray telescopes in the future IAXO experiment, would allow for 105^5 better signal-to-noise ratio than CAST, and search for solar axions with gaγg_{a\gamma} down to few 1012^{12} GeV1^{-1}, well into unexplored axion parameter space. In addition, a scaled-up version of these TPCs, properly shielded and placed underground, can be competitive in the search for low-mass WIMPs. The TREX-DM prototype, with \sim0.300 kg of Ar at 10 bar, or alternatively \sim0.160 kg of Ne at 10 bar, and energy threshold well below 1 keV, has been built to test this concept. We will describe the main technical solutions developed, as well as the results from the commissioning phase on surface. The anticipated sensitivity of this technique might reach 1044\sim10^{-44} cm2^2 for low mass (<10<10 GeV) WIMPs, well beyond current experimental limits in this mass range.Comment: Published in JCAP. New version with erratum incorporated (new figure 14

    A modulation property of time-frequency derivatives of filtered phase and its application to aperiodicity and fo estimation

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    We introduce a simple and linear SNR (strictly speaking, periodic to random power ratio) estimator (0dB to 80dB without additional calibration/linearization) for providing reliable descriptions of aperiodicity in speech corpus. The main idea of this method is to estimate the background random noise level without directly extracting the background noise. The proposed method is applicable to a wide variety of time windowing functions with very low sidelobe levels. The estimate combines the frequency derivative and the time-frequency derivative of the mapping from filter center frequency to the output instantaneous frequency. This procedure can replace the periodicity detection and aperiodicity estimation subsystems of recently introduced open source vocoder, YANG vocoder. Source code of MATLAB implementation of this method will also be open sourced.Comment: 8 pages 9 figures, Submitted and accepted in Interspeech201

    Use of Carbon Arc Lamps as Solar Simulation in Environmental Testing

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    This report covers work done by the authors on the solar simulator for the six-foot diameter space simulator presently in use at JPL. The space simulator was made by modifying an existent vacuum chamber and uses carbon arc lamps for solar simulation. All Ranger vehicles flown to date have been tested in this facility. The report also contains a series of appendixes covering various aspects of space-simulation design and use. Some of these appendixes contain detailed analyses of space-simulator design criteria. Others cover the techniques used in studying carbon-arc lamps and in applying them as solar simulation

    Developing Future UK Energy Performance Standards: The St Nicholas Court project, Final Report

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    The St Nicholas Court Project was set up to explore the implications of an enhanced energy performance standard for new housing for the design, construction and performance of timber framed dwellings. The energy performance standard, EPS08, is modelled on proposals made by the DETR in June 2000 for a possible review of Part L of the Building Regulations in the second half of the present decade. The overall goal of the project was to support the next revision of Part L through an enhanced body of qualitative and quantitative evidence on options and impacts. The seeds of the project were contained in a report – Towards Sustainable Housing - commissioned by Joseph Rowntree Foundation at the start of the last review of this part of the Building Regulations. The project itself has been based on the St Nicholas Court Development which involves the design and construction of a group of 18 low energy and affordable dwellings on a brown field site in York (see site plan below). The research project was established in two stages. Initial funding was provided by the Joseph Rowntree Foundation in the spring of 1999. This ensured the involvement of the research team from the outset of the development process. Additional funding was provided from late 2000 by the Housing Corporation and by the DETR through the Partners in Innovation programme (responsibility for which now lies with the DTI). The research project was originally divided into five phases – project definition, design, construction, occupation, and communication and dissemination. Delays in site acquisition initially allowed the design phase to be extended, but ultimately forced the abandonment of the construction and occupation phases, and the scaling down of the communication and dissemination phase. Despite the delays, the development itself will now go ahead, with construction starting in mid-2003
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