36 research outputs found
Status of direct searches for WIMP dark matter
Astrophysical observations indicate that about 23% of the energy density of
the universe is in the form of non-baryonic particles beyond the standard model
of particle physics. One exciting and well motivated candidate is the lightest
supersymmetric partner particle (LSP), which could be a weakly interacting
massive particle (WIMP) left over from the Big Bang. To determine that the LSP
is the dark matter, it is necessary both to measure the particle's properties
at an accelerator and to detect the particle in the galaxy directly (or
indirectly). Direct detection of these particles requires sophisticated
detectors to defeat much higher-rate backgrounds due to radioactivity and other
sources. Promising techniques identify individual interactions in shielded
fiducial volumes and distinguish nuclear-recoil signal events from
electron-recoil backgrounds, based on the timing, energy density, and/or the
division of the energy into signals of ionization, scintillation, or phonons. I
review the techniques of the dozens of experiments searching for WIMPs and
summarize the most interesting results and prospects for detection.Comment: 8 pages, 3 figures, to appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Supporting Capabilities For Underground Facilities
The 2021 particle physics community study, known as "Snowmass 2021", has
brought together particle physicists around the world to create a unified
vision for the field over the next decade. One of the areas of focus is the
Underground Facilities (UF) frontier, which addresses underground
infrastructure and the scientific programs and goals of underground-based
experiments. To this effect, the UF Supporting Capabilities topical group
created two surveys for the community to identify potential gaps between the
supporting capabilities of facilities and those needed by current and future
experiments. Capabilities surveyed are discussed in this report and include
underground cleanroom space size and specifications, radon-reduced space needs
and availability, the assay need and other underground space needs as well
timeline for future experiments. Results indicate that future, larger
experiments will increasingly require underground assembly in larger, cleaner
cleanrooms, often with better radon-reduction systems and increased monitoring
capability for ambient contaminants. Most assay needs may be met by existing
worldwide capabilities with organized cooperation between facilities and
experiments. Improved assay sensitivity is needed for assays of bulk and
surface radioactivity for some materials for some experiments, and would be
highly beneficial for radon emanation
The Formation of Low-Mass Binary Star Systems Via Turbulent Fragmentation
We characterize the infall rate onto protostellar systems forming in
self-gravitating radiation-hydrodynamic simulations. Using two dimensionless
parameters to determine disks' susceptability to gravitational fragmentation,
we infer limits on protostellar system multiplicity and the mechanism of binary
formation. We show that these parameters give robust predictions even in the
case of marginally resolved protostellar disks. We find that protostellar
systems with radiation feedback predominately form binaries via turbulent
fragmentation, not disk instability, and we predict turbulent fragmentation is
the dominant channel for binary formation for low-mass stars. We clearly
demonstrate that systems forming in simulations including radiative feedback
have fundamentally different parameters than those in purely hydrodynamic
simulations.Comment: 11 pages, 10 figures, accepted to Ap
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
Burden of disease from inadequate water, sanitation and hygiene for selected adverse health outcomes: An updated analysis with a focus on low- and middle-income countries
Background
To develop updated estimates in response to new exposure and exposure-response data of the burden of diarrhoea, respiratory infections, malnutrition, schistosomiasis, malaria, soil-transmitted helminth infections and trachoma from exposure to inadequate drinking-water, sanitation and hygiene behaviours (WASH) with a focus on low- and middle-income countries.
Methods
For each of the analysed diseases, exposure levels with both sufficient global exposure data for 2016 and a matching exposure-response relationship were combined into population-attributable fractions. Attributable deaths and disability-adjusted life years (DALYs) were estimated for each disease and, for most of the diseases, by country, age and sex group separately for inadequate water, sanitation and hygiene behaviours and for the cluster of risk factors. Uncertainty estimates were computed on the basis of uncertainty surrounding exposure estimates and relative risks.
Findings
An estimated 829,000 WASH-attributable deaths and 49.8 million DALYs occurred from diarrhoeal diseases in 2016, equivalent to 60% of all diarrhoeal deaths. In children under 5 years, 297,000 WASH-attributable diarrhoea deaths occurred, representing 5.3% of all deaths in this age group. If the global disease burden from different diseases and several counterfactual exposure distributions was combined it would amount to 1.6 million deaths, representing 2.8% of all deaths, and 104.6 million DALYs in 2016.
Conclusions
Despite recent declines in attributable mortality, inadequate WASH remains an important determinant of global disease burden, especially among young children. These estimates contribute to global monitoring such as for the Sustainable Development Goal indicator on mortality from inadequate WASH
Demonstration of surface electron rejection with interleaved germanium detectors for dark matter searches
The following article appeared in Applied Physics Letters 103.16 (2013): 164105 and may be found at http://scitation.aip.org/content/aip/journal/apl/100/26/10.1063/1.4729825The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two 210 Pb sources producing ∼130 beta decays/hr. In ∼800 live hours, no events leaked into the 8–115 keV signal region, giving upper limit leakage fraction 1.7 × 10−5 at 90% C.L., corresponding to < 0.6 surface event background in the future 200-kg SuperCDMS SNOLAB experiment.This work is supported in part by the National Science Foundation (Grant Nos. AST-9978911, NSF-0847342, PHY-1102795,NSF-1151869, PHY-0542066, PHY-0503729, PHY-0503629, PHY-0503641, PHY-0504224, PHY-0705052,PHY-0801708, PHY-0801712, PHY-0802575, PHY-0847342, PHY-0855299, PHY-0855525, and PHY-1205898), by the Department of Energy (Contract Nos. DE-AC03-76SF00098, DE-FG02-92ER40701, DE-FG02-94ER40823,DE-FG03-90ER40569, DE-FG03-91ER40618, and DESC0004022),by NSERC Canada (Grant Nos. SAPIN 341314 and SAPPJ 386399), and by MULTIDARK CSD2009-00064 and FPA2012-34694. Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359, while SLAC is operated under Contract No. DE-AC02-76SF00515 with the United States Department of
Energy
Evaluation of the effect of sodium–glucose co‐transporter 2 inhibition with empagliflozin on morbidity and mortality of patients with chronic heart failure and a reduced ejection fraction: rationale for and design of the EMPEROR‐Reduced trial
Drugs that inhibit the sodium–glucose co‐transporter 2 (SGLT2) have been shown to reduce the risk of hospitalizations for heart failure in patients with type 2 diabetes. In populations that largely did not have heart failure at the time of enrolment, empagliflozin, canagliflozin and dapagliflozin decreased the risk of serious new‐onset heart failure events by ≈30%. In addition, in the EMPA‐REG OUTCOME trial, empagliflozin reduced the risk of both pump failure and sudden deaths, the two most common modes of death among patients with heart failure. In none of the three trials could the benefits of SGLT2 inhibitors on heart failure be explained by the actions of these drugs as diuretics or anti‐hyperglycaemic agents. These observations raise the possibility that SGLT2 inhibitors could reduce morbidity and mortality in patients with established heart failure, including those without diabetes. The EMPEROR‐Reduced trial is enrolling ≈3600 patients with heart failure and a reduced left ventricular ejection fraction (≤ 40%), half of whom are expected not to have diabetes. Patients are being randomized to placebo or empagliflozin 10 mg daily, which is added to all appropriate treatment with inhibitors of the renin–angiotensin system and neprilysin, beta‐blockers and mineralocorticoid receptor antagonists. The primary endpoint is the time‐to‐first event analysis of the combined risk of cardiovascular death and hospitalization for heart failure, but the trial will also evaluate the effects of empagliflozin on renal function, cardiovascular death, all‐cause mortality, and recurrent hospitalization events. By adjusting eligibility based on natriuretic peptide levels to the baseline ejection fraction, the trial will preferentially enrol high‐risk patients. A large proportion of the participants is expected to have an ejection fraction < 30%, and the estimated annual event rate is expected to be at least 15%. The EMPEROR‐Reduced trial is well‐positioned to determine if the addition of empagliflozin can add meaningfully to current approaches that have established benefits in the treatment of chronic heart failure with left ventricular systolic dysfunction