7,543 research outputs found
Solar neutrino physics with low-threshold dark matter detectors
Dark matter detectors will soon be sensitive to Solar neutrinos via two
distinct channels: coherent neutrino-nucleus scattering and neutrino electron
elastic scattering. We establish an analysis method for extracting Solar model
properties and neutrino properties from these measurements, including the
possible effects of sterile neutrinos which have been hinted at by some reactor
experiments and cosmological measurements. Even including sterile neutrinos,
through the coherent scattering channel a 1 ton-year exposure with a
low-threshold Germanium detector could improve on the current measurement of
the normalization of the B Solar neutrino flux down to 3% or less.
Combining with the elastic scattering data will provide constraints on both the
high and low energy survival probability, and will improve on the uncertainty
on the active-to-sterile mixing angle by a factor of two. This sensitivity to
active-to-sterile transitions is competitive and complementary to forthcoming
dedicated short baseline sterile neutrino searches with nuclear decays.Comment: 12 pages, 4 figures, 3 table
Implication of neutrino backgrounds on the reach of next generation dark matter direct detection experiments
As direct dark matter experiments continue to increase in size, they will
become sensitive to neutrinos from astrophysical sources. For experiments that
do not have directional sensitivity, coherent neutrino scattering (CNS) from
several sources represents an important background to understand, as it can
almost perfectly mimic an authentic WIMP signal. Here we explore in detail the
effect of neutrino backgrounds on the discovery potential of WIMPs over the
entire mass range of 500 MeV to 10 TeV. We show that, given the theoretical and
measured uncertainties on the neutrino backgrounds, direct detection
experiments lose sensitivity to light (~10 GeV) and heavy (~100 GeV) WIMPs with
a spin-independent cross section below 10^{-45} cm^2 and 10^{-49} cm^2,
respectively.Comment: 15 pages, 12 figures, 7Be fluxes revised, conclusions unchange
Supersymmetric Kaluza-Klein reductions of M-waves and MKK-monopoles
We investigate the Kaluza-Klein reductions to ten dimensions of the purely
gravitational half-BPS M-theory backgrounds: the M-wave and the Kaluza-Klein
monopole. We determine the moduli space of smooth (supersymmetric) Kaluza-Klein
reductions by classifying the freely-acting spacelike Killing vectors which
preserve some Killing spinor. As a consequence we find a wealth of new
supersymmetric IIA configurations involving composite and/or bound-state
configurations of waves, D0 and D6-branes, Kaluza-Klein monopoles in type IIA
and flux/nullbranes, and some other new configurations. Some new features
raised by the geometry of the Taub-NUT space are discussed, namely the
existence of reductions with no continuous moduli. We also propose an
interpretation of the flux 5-brane in terms of the local description (close to
the branes) of a bound state of D6-branes and ten-dimensional Kaluza-Klein
monopoles.Comment: 36 pages (v2: Reference added, "draft" mode disabled; v3: two
singular reductions discarded, appendix on spin structures added, references
updated
Complementarity of dark matter detectors in light of the neutrino background
Direct detection dark matter experiments looking for WIMP-nucleus elastic
scattering will soon be sensitive to an irreducible background from neutrinos
which will drastically affect their discovery potential. Here we explore how
the neutrino background will affect future ton-scale experiments considering
both spin-dependent and spin-independent interactions. We show that combining
data from experiments using different targets can improve the dark matter
discovery potential due to target complementarity. We find that in the context
of spin-dependent interactions, combining results from several targets can
greatly enhance the subtraction of the neutrino background for WIMP masses
below 10 GeV/c and therefore probe dark matter models to lower
cross-sections. In the context of target complementarity, we also explore how
one can tune the relative exposures of different target materials to optimize
the WIMP discovery potential.Comment: 13 pages, 12 figures, 3 table
Groups and the Entropy Floor- XMM-Newton Observations of Two Groups
Using XMM-Newton spatially resolved X-ray imaging spectroscopy we obtain the
temperature, density, entropy, gas mass, and total mass profiles for two groups
of galaxies out to ~0.3 Rvir (Rvir, the virial radius). Our density profiles
agree well with those derived previously, and the temperature data are broadly
consistent with previous results but are considerably more precise. Both of
these groups are at the mass scale of 2x10^13 Msolar but have rather different
properties. They have considerably lower gas mass fractions at r<0.3 Rvir than
the rich clusters. NGC2563, one of the least luminous groups for its X-ray
temperature, has a very low gas mass fraction of ~0.004 inside 0.1 Rvir, which
rises with radius. NGC4325, one of the most luminous groups at the same average
temperature, has a higher gas mass fraction of 0.02. The entropy profiles and
the absolute values of the entropy as a function of virial radius also differ,
with NGC4325 having a value of ~100 keV cm-2 and NGC2563 a value of ~300 keV
cm-2 at r~0.1 Rvir. For both groups the profiles rise monotonically with radius
and there is no sign of an entropy "floor". These results are inconsistent with
pre-heating scenarios which have been developed to explain the entropy floor in
groups but are broadly consistent with models of structure formation which
include the effects of heating and/or the cooling of the gas. The total entropy
in these systems provides a strong constraint on all models of galaxy and group
formation, and on the poorly defined feedback process which controls the
transformation of gas into stars and thus the formation of structure in the
universe.Comment: 22 pages, 2 figure
The geometry of null rotation identifications
The geometry of flat spacetime modded out by a null rotation (boost+rotation)
is analysed. When embedding this quotient spacetime in String/M-theory, it
still preserves one half of the original supersymmetries. Its connection with
the BTZ black hole, supersymmetric dilatonic waves and one possible resolution
of its singularity in terms of nullbranes are also discussed.Comment: 1+18 pages, 5 figures. v2 references adde
An Intensive Pedestrian Archaeological Survey of the Salado Creek Greenway, Wetmore Avenue to Eisenhauer Road, San Antonio, Bexar County, Texas Phase II: N. E. Loop 410 to Wetmore Avenue
The Center for Archaeological Research (CAR) of The University of Texas at San Antonio conducted an intensive pedestrian archaeological survey of the Salado Creek Greenway project located in San Antonio, Bexar County, Texas to fulfill contract requirements with Adams Environmental, Inc. of San Antonio. The survey was conducted under the requirements of the City of San Antonio Unified Development Code Chapter 35, Section 106 of the National Historic Preservation Act (NHPA) of 1966, and the Texas Antiquities Code. The survey was performed under Texas Antiquities Permit No. 4561, with Dr. Raymond Mauldin, CAR Assistant Director, serving as Principal Investigator and Antonia L. Figueroa serving as the Project Archaeologist. The work was conducted in advance of construction of a multi-use greenway trail proposed by the Parks and Recreation Department of the City of San Antonio.
The project consists of development of a multi-use greenway trail running from Wetmore Avenue to Eisenhauer Road along the Salado Creek channel. The project area was surveyed in two phases with the first phase from N.E. Loop 410 to Eisenhauer Road completed in August 2007 (Munoz 2008) and the second phase from N.E. Loop 410 to Wetmore Avenue completed in February 2008. This report summarizes the results of the fieldwork from Phase II and provides recommendations regarding the management of cultural resources located on the project area.
The archaeological investigations conducted by CAR resulted in the identification and recording of three new sites (41BX1764, 41BX1765 and 41BX1766).A portion of site 41BX841 was revisited as part of the pedestrian survey. However, the proposed trail alignment will not impact the site. The CAR recommends that sites 41BX1765 and 41BX1766 are not eligible for nomination to the National Register of Historical Places (NRHP). Shovel testing at 41BX1764 suggests the site is potentially eligible for the NRHP under criterion D. Because the site is located on the proposed trail alignment, the CAR recommends eligibility testing of the 41BX1764.
All materials recovered during the investigations and all project related documents are curated at the Center for Archaeological Research
Archaeological Investigations of the City of San Antonio Nursery and San Antonio Zoo Eagle Railroad Tract Realignment Project, Bexar County, Texas
The Center for Archaeological Research (CAR) at The University of Texas at San Antonio (UTSA) conducted mechanical augering on land that was used for the former City of San Antonio Nursery and Parks and Maintenance Facility. Furthermore, a surface inspection of the San Antonio Zoo Eagle mini-track proposed re-alignment was also conducted. During investigations prehistoric site 41BX1773 was recorded in the northern section of the APE. Only one piece of fire-cracked rock and a railroad spike were collected during the surface inspection along the proposed San Antonio Zoo Eagle re-alignment. Archaeological investigations were conducted under Texas Antiquities Permit No. 4647.
CAR recommends that impacts to site 41BX1773 should be avoided and the re-alignment of the San Antonio Zoo Eagle train track may proceed as planned.
All materials recovered during the investigations and all project related documents are curated at the Center for Archaeological Research
- …