1,224 research outputs found
Estimating the efficiency turn-on curve for a constant-threshold trigger without a calibration dataset
Many particle physics experiments use constant threshold triggers, where the
trigger threshold is in an online estimator that can be calculated quickly by
the trigger module. Offline data analysis then calculates a more precise
offline estimator for the same quantity, for example the event energy. The
efficiency curve is a step function in the online estimator, but not in the
offline estimator.
One typically obtains the shape of the efficiency curve in the offline
estimator by way of a calibration dataset, where the true rate of events at
each value of the offline estimator is measured once and compared to the rate
observed in the physics dataset. For triggers with a fixed threshold condition,
it is sometimes possible to bootstrap the trigger efficiency curve without use
of a calibration dataset. This is useful to verify stability of a calibration
over time when calibration data cannot be taken often enough. It also makes it
possible to use datasets for which no calibration is available. This paper
describes the method and the conditions that must be met for it to be
applicable
Database support of detector operation and data analysis in the DEAP-3600 Dark Matter experiment
The DEAP-3600 detector searches for dark matter interactions on a 3.3 tonne
liquid argon target. Over nearly a decade, from start of detector construction
through the end of the data analysis phase, well over 200 scientists will have
contributed to the project. The DEAP-3600 detector will amass in excess of 900
TB of data representing more than 10 particle interactions, a few of
which could be from dark matter. At the same time, metadata exceeding 80 GB
will be generated. This metadata is crucial for organizing and interpreting the
dark matter search data and contains both structured and unstructured
information.
The scale of the data collected, the important role of metadata in
interpreting it, the number of people involved, and the long lifetime of the
project necessitate an industrialized approach to metadata management.
We describe how the CouchDB and the PostgreSQL database systems were
integrated into the DEAP detector operation and analysis workflows. This
integration provides unified, distributed access to both structured
(PostgreSQL) and unstructured (CouchDB) metadata at runtime of the data
analysis software. It also supports operational and reporting requirements
Polyethylene naphthalate film as a wavelength shifter in liquid argon detectors
Liquid argon-based scintillation detectors are important for dark matter
searches and neutrino physics. Argon scintillation light is in the vacuum
ultraviolet region, making it hard to be detected by conventional means.
Polyethylene naphthalate (PEN), an optically transparent thermoplastic
polyester commercially available as large area sheets or rolls, is proposed as
an alternative wavelength shifter to the commonly-used tetraphenyl butadiene
(TPB). By combining the existing literature data and spectrometer measurements
relative to TPB, we conclude that the fluorescence yield and timing of both
materials may be very close. The evidence collected suggests that PEN is a
suitable replacement for TPB in liquid argon neutrino detectors, and is also a
promising candidate for dark matter detectors. Advantages of PEN are discussed
in the context of scaling-up existing technologies to the next generation of
very large ktonne-scale detectors. Its simplicity has a potential to facilitate
such scale-ups, revolutionizing the field.Comment: 6 pages, 3 figure
Bosonic Integer Quantum Hall effect in an interacting lattice model
We study a bosonic model with correlated hopping on a honeycomb lattice, and
show that its ground state is a bosonic integer quantum Hall (BIQH) phase, a
prominent example of a symmetry protected topological (SPT) phase. By using the
infinite density matrix renormalization group method, we establish the
existence of the BIQH phase by providing clear numerical evidence: (i) a
quantized Hall conductance with (ii) two counter propagating
gapless edge modes. Our simple model is an example of a novel class of systems
that can stabilize SPT phases protected by a continuous symmetry on lattices
and opens up new possibilities for the experimental realization of these exotic
phases.Comment: 7 pages, 6 figure
Kagome chiral spin liquid as a gauged U(1) symmetry protected topological phase
While the existence of a chiral spin liquid (CSL) on a class of spin-1/2
kagome antiferromagnets is by now well-established numerically, a controlled
theoretical path from the lattice model leading to a low energy topological
field theory is still lacking. This we provide via an explicit construction,
starting from reformulating a microscopic model for a CSL as a lattice gauge
theory, and deriving the low-energy form of its continuum limit. A crucial
ingredient is the realisation that the bosonic spinons of the gauge theory
exhibit a symmetry-protected topological (SPT) phase, which upon
promoting its global symmetry to a local gauge structure ("gauging")
yields the CSL. We suggest that such an explicit lattice-based construction
involving gauging of an SPT phase can be applied more generally to understand
topological spin liquids.Comment: 5+3 pages, 3+4 figure
Fermionic quantum dimer and fully-packed loop models on the square lattice
We consider fermionic fully-packed loop and quantum dimer models which serve
as effective low-energy models for strongly correlated fermions on a
checkerboard lattice at half and quarter filling, respectively. We identify a
large number of fluctuationless states specific to each case, due to the
fermionic statistics. We discuss the symmetries and conserved quantities of the
system and show that for a class of fluctuating states in the half-filling
case, the fermionic sign problem can be gauged away. This claim is supported by
numerical evaluation of the low-lying states and can be understood by means of
an algebraic construction. The elimination of the sign problem then allows us
to analyze excitations at the Rokhsar-Kivelson point of the models using the
relation to the height model and its excitations, within the single-mode
approximation. We then discuss a mapping to a U(1) lattice gauge theory which
relates the considered low-energy model to the compact quantum electrodynamics
in 2+1 dimensions. Furthermore, we point out consequences and open questions in
the light of these results.Comment: 12 pages, 9 figure
Robust dynamic classes revealed by measuring the response function of a social system
We study the relaxation response of a social system after endogenous and
exogenous bursts of activity using the time-series of daily views for nearly 5
million videos on YouTube. We find that most activity can be described
accurately as a Poisson process. However, we also find hundreds of thousands of
examples in which a burst of activity is followed by an ubiquitous power-law
relaxation governing the timing of views. We find that these relaxation
exponents cluster into three distinct classes, and allow for the classification
of collective human dynamics. This is consistent with an epidemic model on a
social network containing two ingredients: A power law distribution of waiting
times between cause and action and an epidemic cascade of actions becoming the
cause of future actions. This model is a conceptual extension of the
fluctuation-dissipation theorem to social systems, and provides a unique
framework for the investigation of timing in complex systems.Comment: 5 pages, 5 figures, submitted to PNA
Task relevance modulates the cortical representation of feature conjunctions in the target template
AbstractLittle is known about the cortical regions involved in representing task-related content in preparation for visual task performance. Here we used representational similarity analysis (RSA) to investigate the BOLD response pattern similarity between task relevant and task irrelevant feature dimensions during conjunction viewing and target template maintenance prior to visual search. Subjects were cued to search for a spatial frequency (SF) or orientation of a Gabor grating and we measured BOLD signal during cue and delay periods before the onset of a search display. RSA of delay period activity revealed that widespread regions in frontal, posterior parietal, and occipitotemporal cortices showed general representational differences between task relevant and task irrelevant dimensions (e.g., orientation vs. SF). In contrast, RSA of cue period activity revealed sensory-related representational differences between cue images (regardless of task) at the occipital pole and additionally in the frontal pole. Our data show that task and sensory information are represented differently during viewing and during target template maintenance, and that task relevance modulates the representation of visual information across the cortex.</jats:p
How periodic driving heats a disordered quantum spin chain
We study the energy absorption in real time of a disordered quantum spin chain subjected to coherent monochromatic periodic driving. We determine characteristic fingerprints of the well-known ergodic (Floquet-Eigenstate thermalization hypothesis for slow driving/weak disorder) and many-body localized (Floquet-many-body localization for fast driving/strong disorder) phases. In addition, we identify an intermediate regime, where the energy density of the system-unlike the entanglement entropy a local and bounded observable-grows logarithmically slowly over a very large time window
Effects of Microbial Feed Additives on Performance of Starter and Growing-Finishing Pigs
Three trials were conducted to evaluate the effect of lactic acid-producing microbial feed additives (Probiotics) on performance of starting and growing-finishing pigs. Two commercially available probiotics, Probios (L. acidopbilus) and Feed-Mate 68 (Streptococcus faecium type Cernelle 68), were used. In the first of two starter trials, 192 crossbred pigs (initial weight 7 kg) were used in a 2 • 4 factorial arrangement of treatments, with Probios and antibiotics (ASP-250, lincomycin, tylosin) as the main effects
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