292 research outputs found
Liquid Scintillator Time Projection Chamber Concept
Results are presented from a small-scale experiment to investigate the use of
room temperature organic liquid scintillators as the active medium for a time
projection chamber (TPC). The optical properties of liquid scintillators have
long been known, but their ability to transport charge has remained, until now,
largely untested. The idea of using room temperature liquids as an active
medium for an ionisation chamber was first presented in \cite{EnglerTMS}. Since
then the range of liquid scintillators available has been greatly developed. We
present successful transport of ionization charges in a selection of both, pure
organic liquid solvents and liquid scintillator cocktails over 20mm using a
variety of electric drift field strengths. The target of this research is to
offer a cost effective alternative to liquid noble gas detectors in neutrino
physics.Comment: 6 pages, 5 figures, submitted to Proceedings 12th Pisa Meeting on
Advanced Detectors, La Biodola, Isola d'Elba, Ital
A New Model-Independent Method for Extracting Spin-Dependent Cross Section Limits from Dark Matter Searches
A new method is proposed for extracting limits on spin-dependent WIMP-nucleon
interaction cross sections from direct detection dark matter experiments. The
new method has the advantage that the limits on individual WIMP-proton and
WIMP-neutron cross sections for a given WIMP mass can be combined in a simple
way to give a model-independent limit on the properties of WIMPs scattering
from both protons and neutrons in the target nucleus. Extension of the
technique to the case of a target material consisting of several different
species of nuclei is discussed.Comment: 15 pages, 6 Encapsulated Postscript figure
Implementation of a local principal curves algorithm for neutrino interaction reconstruction in a liquid argon volume
A local principal curve algorithm has been implemented in three dimensions
for automated track and shower reconstruction of neutrino interactions in a
liquid argon time projection chamber. We present details of the algorithm and
characterise its performance on simulated data sets.Comment: 14 pages, 17 figures; typing correction to Eq 5, the definition of
the local covariance matri
Calibrated in-vacuum quantum efficiency system for metallic and III-V thin-film photocathodes
The construction and calibration of a high vacuum system for thin film growth and in situ quantum efficiency (QE) measurement are described. Surface cleaning by in situ argon ion sputtering and annealing is supported. The QE measurement is based on an external 265 nm LED and in situ positively biased collector grid. The system is applied to two metallic and two semiconducting photocathodes: polycrystalline silver and copper, and single crystal InP and InSb. Surface cleaning protocols are shown to have a dramatic effect on the QE for all of these materials. The maximum QE values achieved for clean InSb and InP are around 8 × 10−5, for Cu 9 × 10−5 and for Ag 2 × 10−4
WIMP direct detection overview
This review on weakly interacting massive particle (WIMP) dark matter direct
detection focuses on experimental approaches and the corresponding physics
basics. The presentation is intended to provide a quick and concise
introduction for non-specialists to this fast evolving topic of astroparticle
physics.Comment: 13 pages, 6 figures, invited review for the Proc. XXth Int. Conf.
Neutrino Physics and Astrophysics, May 25-30, 2002, Munich, Germany; version
includes correction of typo in eqn.2; to appear in Nucl. Phys. B Proc. Supp
Searching for the Annual Modulation of Dark Matter signal with the GENIUS-TF experiment
The annual modulation of the recoil spectrum observed in an underground
detector is well known as the main signature of a possible WIMP signal. The
GENIUS-TF experiment, under construction in the Gran Sasso National Laboratory,
can search for the annual modulation of the Dark Matter signal using 40 kg of
naked-Ge detectors in liquid nitrogen. Starting from a set of data simulated
under the hypothesis of modulation and using different methods, we show the
potential of GENIUS-TF for extracting the modulated signal and the expected
WIMP mass and WIMP cross section.Comment: In press, Nuclear Instruments and Methods in Physics Research Section
A: Accelerators, Spectrometers, Detectors and Associated Equipment (2003) and
in Proc. of IDM2002, York Minster, England, 2-6 September, 2002, World
Scientific 200
Moving away from flat solar panels to PVtrees : exploring ideas and people's perceptions
Photovoltaic Trees (PVTrees) are artificial solar structures that look like sculptural trees and exist from small scale (size of a bonsai tree) to large scale (about the size of a wind turbine). The aesthetics of solar trees differ and they have been designed to provide different means of power to different urban and built environments. These range from powering mobile phones, electric cars, buildings and street lights covering small and large scale areas (one or a forest of PVTrees). This study brought together a research team of physicists and designers and to conduct focus groups with design based methods and prototyping (clustering of ideas, sketching and modelling) along with a computational 3D PVTree design tool. The focus groups consisted of capturing a) people's perception on PVTrees, idea generations and development of the 3D model and b) further discussion and evaluation of insights. A public exhibition followed to capture public perception on design concepts using 3D models, and a voting exercise. Overall it was found that PVTrees were received positively by the public with desires for them to be multifunctional by providing power yet also having a secondary function e.g. a shelter or seat. The paper details this, considerations for concept development, and the future direction of research in the area
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