1,258 research outputs found
Mineral exploration in the Lower Palaeozoic rocks of south-west Cumbria. Part 1, regional surveys
The results of geochemical, geological and geophysical surveys over Lower Palaeozoic rocks in the
south-western part of Cumbria are given in two reports. This report (Part 1) describes the results of a
geochemical drainage survey and an examination of mineralised sites, and relates them to information
from new geological mapping and an assessment of regional geophysical data. Part 2 contains details
of follow-up surveys in the Black Combe inlier.
The geochemical drainage survey, involving the collection and analysis of heavy mineral concentrates
and stream sediment samples from 119 sites, found substantial antimony, arsenic, barium, bismuth,
copper, iron, lead, tin, tungsten and zinc anomalies. Gold was reported for the first time from this part
of the Lake District: small amounts were noted in panned concentrates from five sites. Other minerals
identified in panned concentrates included arsenopyrite, baryte, bismutite, bismuthinite, cassiterite,
chalcopyrite, cerussite, pyrite, pyromorphite, scheelite, sphalerite, stolzite and wolfram&e.
The examination of old workings and outcrops revealed many undocumented occurrences of quartzsulphide
vein-style mineralisation. The chemical analysis of samples taken from old workings and
other occurrences confirmed field observations that locally, particularly in the Black Combe area, this
mineralisation is polymetallic with variable amounts of arsenic, gold, bismuth, copper, lead, zinc and
in a few cases antimony, barium, cobalt, nickel, tungsten and tin. Iron mineralisation occurs both as
oxide (hematite) and sulphide deposits. Mercury was present in appreciable amounts in samples from
the High Brow pyrite mine.
The distribution of panned concentrate anomalies suggests that the vein-style mineralisation is
polyphase and that individual phases may be zoned. Highest zinc anomalies occur near Torver and the
highest lead on the west side of Black Combe. Tin and tungsten are restricted largely to the central
part of Black Combe, and the most prominent arsenic and bismuth anomalies are found in the same
area. Copper anomalies are widespread over the Skiddaw Group and the Borrowdale Volcanic Group.
Barium anomalies indicate that baryte mineralisation is weak and localised, occurring principally
within the Black Combe area and close to the Windermere Supergroup basal unconformity. Iron
oxides from host rocks and hematite mineralisation are responsible for local enrichments of iron,
antimony, arsenic and molybdenum in panned concentrates
Field trialling of a pulse airtightness tester in a range of UK homes
A new low pressure âquasi-steadyâ pulse technique for determining the airtightness of buildings has been developed further and compared with the standard blower-door technique for field-testing a range of typical UK homes. The reported low pressure air pulse unit (APU) has gone through several development stages related to optimizing the algorithm, pressure reference and system construction. The technique, which is compact, portable and easy to use, has been tested alongside the standard blower-door technique to measure the airtightness of a range of typical UK home types. Representative of the UK housing stock, the homes mostly have low levels of airtightness, resulting in poor energy performance, poor indoor air quality and poor thermal comfort. Some of these homes have been targeted for retrofitting and a quick, low cost and simple method for accurately determining their airtightness has clear advantages for correctly predicting the benefits of any improvements. A comparison between the results given by the two techniques is presented and the field trials indicate that the latest version of the pulse technique is reliable for determining building leakage at low pressure. Repeatability of multiple APU tests in the same house is found to be within +/-5% of the mean. A test where the leakage is increased by a known amount shows the APU is able to measure the change more accurately than the blower-door test. The APU also gives convenience in practical applications, due to being more compact and portable, plus it doesnât need to penetrate the building envelope. The field trials demonstrate the pulse test has the potential to be a feasible alternative to the standard blower-door test
How does the electromagnetic field couple to gravity, in particular to metric, nonmetricity, torsion, and curvature?
The coupling of the electromagnetic field to gravity is an age-old problem.
Presently, there is a resurgence of interest in it, mainly for two reasons: (i)
Experimental investigations are under way with ever increasing precision, be it
in the laboratory or by observing outer space. (ii) One desires to test out
alternatives to Einstein's gravitational theory, in particular those of a
gauge-theoretical nature, like Einstein-Cartan theory or metric-affine gravity.
A clean discussion requires a reflection on the foundations of electrodynamics.
If one bases electrodynamics on the conservation laws of electric charge and
magnetic flux, one finds Maxwell's equations expressed in terms of the
excitation H=(D,H) and the field strength F=(E,B) without any intervention of
the metric or the linear connection of spacetime. In other words, there is
still no coupling to gravity. Only the constitutive law H= functional(F)
mediates such a coupling. We discuss the different ways of how metric,
nonmetricity, torsion, and curvature can come into play here. Along the way, we
touch on non-local laws (Mashhoon), non-linear ones (Born-Infeld,
Heisenberg-Euler, Plebanski), linear ones, including the Abelian axion (Ni),
and find a method for deriving the metric from linear electrodynamics (Toupin,
Schoenberg). Finally, we discuss possible non-minimal coupling schemes.Comment: Latex2e, 26 pages. Contribution to "Testing Relativistic Gravity in
Space: Gyroscopes, Clocks, Interferometers ...", Proceedings of the 220th
Heraeus-Seminar, 22 - 27 August 1999 in Bad Honnef, C. Laemmerzahl et al.
(eds.). Springer, Berlin (2000) to be published (Revised version uses
Springer Latex macros; Sec. 6 substantially rewritten; appendices removed;
the list of references updated
Non-Equilibrium Bose-Einstein Condensates, Dynamical Scaling and Symmetric Evolution in large N Phi^4 theory
We analyze the non-equilibrium dynamics of the O(N) Phi^4 model in the large
N limit and for states of large energy density. The dynamics is dramatically
different when the energy density is above the top of the tree level potential
V_0 than when it is below it.When the energy density is below V_0, we find that
non-perturbative particle production through spinodal instabilities provides a
dynamical mechanism for the Maxwell construction. The asymptotic values of the
order parameter only depend on the initial energy density and all values
between the minima of the tree level potential are available, the asymptotic
dynamical `effective potential' is flat between the minima. When the energy
density is larger than V_0, the evolution samples ergodically the broken
symmetry states, as a consequence of non-perturbative particle production via
parametric amplification. Furthermore, we examine the quantum dynamics of phase
ordering into the broken symmetry phase and find novel scaling behavior of the
correlation function. There is a crossover in the dynamical correlation length
at a time scale t_s \sim \ln(1/lambda). For t < t_s the dynamical correlation
length \xi(t) \propto \sqrt{t} and the evolution is dominated by spinodal
instabilities, whereas for t>t_s the evolution is non-linear and dominated by
the onset of non-equilibrium Bose-Einstein condensation of long-wavelength
Goldstone bosons.In this regime a true scaling solution emerges with a non-
perturbative anomalous scaling length dimension z=1/2 and a dynamical
correlation length \xi(t) \propto (t-t_s). The equal time correlation function
in this scaling regime vanishes for r>2(t-t_s) by causality. For t > t_s the
equal time correlation function falls of as 1/r. A semiclassical but stochastic
description emerges for time scales t > t_s.Comment: Minor improvements, to appear in Phys. Rev. D. Latex file, 48 pages,
12 .ps figure
Effective Actions and Phase Fluctuations in d-wave Superconductors
We study effective actions for order parameter fluctuations at low
temperature in layered d-wave superconductors such as the cuprates. The order
parameter lives on the bonds of a square lattice and has two amplitude and two
phase modes associated with it. The low frequency spectral weights for
amplitude and relative phase fluctuations is determined and found to be
subdominant to quasiparticle contributions. The Goldstone phase mode and its
coupling to density fluctuations in charged systems is treated in a
gauge-invariant manner. The Gaussian phase action is used to study both the
-axis Josephson plasmon and the more conventional in-plane plasmon in the
cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum
XY model, which incorporates important cutoff effects overlooked in previous
studies. A variational analysis of this effective model shows that in the
cuprates, quantum effects of phase fluctuations are important in reducing the
zero temperature superfluid stiffness, but thermal effects are small for .Comment: Some numerical estimates corrected and figures changed. to appear in
PRB, Sept.1 (2000
Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c
We have searched for the K+ to pi+ gamma gamma decay in the kinematic region
with pi+ momentum close to the end point. No events were observed, and the 90%
confidence-level upper limit on the partial branching ratio was obtained, B(K+
to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral
perturbation theory including next-to-leading order ``unitarity'' corrections.
The same data were used to determine an upper limit on the K+ to pi+ gamma
branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for
publication in Physics Letters
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
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.
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