658 research outputs found
The Beta-decay Paul Trap Mk IV: Design and commissioning
The Beta-decay Paul Trap is an open-geometry, linear trap used to measure the
decays of Li and B to search for a tensor contribution to the weak
interaction. In the latest Li measurement of Burkey et al. (2022),
scattering was the dominant experimental systematic uncertainty. The Beta-decay
Paul Trap Mk IV reduces the prevalence of scattering by a factor of 4
through a redesigned electrode geometry and the use of glassy carbon and
graphite as electrode materials. The trap has been constructed and successfully
commissioned with Li in a new data campaign that collected 2.6 million
triple coincidence events, an increase in statistics by 30% with 4 times less
scattering compared to the previous Li data set.Comment: 17 pages, 7 figure
All-sky search for periodic gravitational waves in the O1 LIGO data
We report on an all-sky search for periodic gravitational waves in the frequency band 20-475 Hz and with a frequency time derivative in the range of [-1.0,+0.1]×10-8 Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our galaxy. This search uses the data from Advanced LIGO\u27s first observational run, O1. No periodic gravitational wave signals were observed, and upper limits were placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude h0 are ∼4×10-25 near 170 Hz. For a circularly polarized source (most favorable orientation), the smallest upper limits obtained are ∼1.5×10-25. These upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest upper limits obtained for the strain amplitude are ∼2.5×10-25
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Negative priming and occasion setting in an appetitive Pavlovian procedure
Rats received training in which two auditory target stimuli, X and Y, were signaled by two visual stimuli, A and B, and followed by food (i.e., A→X1, B→Y+). The test consisted of presentations of X and Y preceded either by the same signal as during training (same trials: A→X, B→Y) or by the alternative signal (different trials: A→Y, B→X). After 8 training sessions, the animals responded less on same trials than on different trials; this effect was significantly reduced after 24 training sessions. In two additional experiments, animals that had also experienced presentations of A and B alone, either before or during training, showed the opposite pattern of results, responding more on same trials than on different trials. These results are interpreted as being due to the interaction between the effects of occasion setting andnegative priming (see Wagner, 1981)
Identification and mitigation of narrow spectral artifacts that degrade searches for persistent gravitational waves in the first two observing runs of Advanced LIGO
Searches are under way in Advanced LIGO and Virgo data for persistent
gravitational waves from continuous sources, e.g. rapidly rotating galactic
neutron stars, and stochastic sources, e.g. relic gravitational waves from the
Big Bang or superposition of distant astrophysical events such as mergers of
black holes or neutron stars. These searches can be degraded by the presence of
narrow spectral artifacts (lines) due to instrumental or environmental
disturbances. We describe a variety of methods used for finding, identifying
and mitigating these artifacts, illustrated with particular examples. Results
are provided in the form of lists of line artifacts that can safely be treated
as non-astrophysical. Such lists are used to improve the efficiencies and
sensitivities of continuous and stochastic gravitational wave searches by
allowing vetoes of false outliers and permitting data cleaning.Comment: 21 page
Quantum correlation measurements in interferometric gravitational-wave detectors
Quantum fluctuations in the phase and amplitude quadratures of light set limitations on the sensitivity of modern optical instruments. The sensitivity of the interferometric gravitational-wave detectors, such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), is limited by quantum shot noise, quantum radiation pressure noise, and a set of classical noises. We show how the quantum properties of light can be used to distinguish these noises using correlation techniques. Particularly, in the first part of the paper we show estimations of the coating thermal noise and gas phase noise, hidden below the quantum shot noise in the Advanced LIGO sensitivity curve. We also make projections on the observatory sensitivity during the next science runs. In the second part of the paper we discuss the correlation technique that reveals the quantum radiation pressure noise from the background of classical noises and shot noise. We apply this technique to the Advanced LIGO data, collected during the first science run, and experimentally estimate the quantum correlations and quantum radiation pressure noise in the interferometer.National Science Foundation (U.S.)Kavli Foundation (Kavli Foundation
Effects of Data Quality Vetoes on a Search for Compact Binary Coalescences in Advanced LIGO's First Observing Run
The first observing run of Advanced LIGO spanned 4 months, from September 12,
2015 to January 19, 2016, during which gravitational waves were directly
detected from two binary black hole systems, namely GW150914 and GW151226.
Confident detection of gravitational waves requires an understanding of
instrumental transients and artifacts that can reduce the sensitivity of a
search. Studies of the quality of the detector data yield insights into the
cause of instrumental artifacts and data quality vetoes specific to a search
are produced to mitigate the effects of problematic data. In this paper, the
systematic removal of noisy data from analysis time is shown to improve the
sensitivity of searches for compact binary coalescences. The output of the
PyCBC pipeline, which is a python-based code package used to search for
gravitational wave signals from compact binary coalescences, is used as a
metric for improvement. GW150914 was a loud enough signal that removing noisy
data did not improve its significance. However, the removal of data with excess
noise decreased the false alarm rate of GW151226 by more than two orders of
magnitude, from 1 in 770 years to less than 1 in 186000 years.Comment: 27 pages, 13 figures, published versio
Environmental Noise in Advanced LIGO Detectors
The sensitivity of the Advanced LIGO detectors to gravitational waves can be
affected by environmental disturbances external to the detectors themselves.
Since the transition from the former initial LIGO phase, many improvements have
been made to the equipment and techniques used to investigate these
environmental effects. These methods have aided in tracking down and mitigating
noise sources throughout the first three observing runs of the advanced
detector era, keeping the ambient contribution of environmental noise below the
background noise levels of the detectors. In this paper we describe the methods
used and how they have led to the mitigation of noise sources, the role that
environmental monitoring has played in the validation of gravitational wave
events, and plans for future observing runs
Sensitivity and performance of the Advanced LIGO detectors in the third observing run
On April 1st, 2019, the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO), joined by the Advanced Virgo detector, began the third observing run, a year-long dedicated search for gravitational radiation. The LIGO detectors have achieved a higher duty cycle and greater sensitivity to gravitational waves than ever before, with LIGO Hanford achieving angle-averaged sensitivity to binary neutron star coalescences to a distance of 111 Mpc, and LIGO Livingston to 134 Mpc with duty factors of 74.6% and 77.0% respectively. The improvement in sensitivity and stability is a result of several upgrades to the detectors, including doubled intracavity power, the addition of an in-vacuum optical parametric oscillator for squeezed-light injection, replacement of core optics and end reaction masses, and installation of acoustic mode dampers. This paper explores the purposes behind these upgrades, and explains to the best of our knowledge the noise currently limiting the sensitivity of each detector
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