696 research outputs found
High-Sensitivity Measurement of 3He-4He Isotopic Ratios for Ultracold Neutron Experiments
Research efforts ranging from studies of solid helium to searches for a
neutron electric dipole moment require isotopically purified helium with a
ratio of 3He to 4He at levels below that which can be measured using
traditional mass spectroscopy techniques. We demonstrate an approach to such a
measurement using accelerator mass spectroscopy, reaching the 10e-14 level of
sensitivity, several orders of magnitude more sensitive than other techniques.
Measurements of 3He/4He in samples relevant to the measurement of the neutron
lifetime indicate the need for substantial corrections. We also argue that
there is a clear path forward to sensitivity increases of at least another
order of magnitude.Comment: 11 pages, 10 figure
AI ATAC 1: An Evaluation of Prominent Commercial Malware Detectors
This work presents an evaluation of six prominent commercial endpoint malware
detectors, a network malware detector, and a file-conviction algorithm from a
cyber technology vendor. The evaluation was administered as the first of the
Artificial Intelligence Applications to Autonomous Cybersecurity (AI ATAC)
prize challenges, funded by / completed in service of the US Navy. The
experiment employed 100K files (50/50% benign/malicious) with a stratified
distribution of file types, including ~1K zero-day program executables
(increasing experiment size two orders of magnitude over previous work). We
present an evaluation process of delivering a file to a fresh virtual machine
donning the detection technology, waiting 90s to allow static detection, then
executing the file and waiting another period for dynamic detection; this
allows greater fidelity in the observational data than previous experiments, in
particular, resource and time-to-detection statistics. To execute all 800K
trials (100K files 8 tools), a software framework is designed to
choreographed the experiment into a completely automated, time-synced, and
reproducible workflow with substantial parallelization. A cost-benefit model
was configured to integrate the tools' recall, precision, time to detection,
and resource requirements into a single comparable quantity by simulating costs
of use. This provides a ranking methodology for cyber competitions and a lens
through which to reason about the varied statistical viewpoints of the results.
These statistical and cost-model results provide insights on state of
commercial malware detection
Beyond the Hype: A Real-World Evaluation of the Impact and Cost of Machine Learning-Based Malware Detection
There is a lack of scientific testing of commercially available malware
detectors, especially those that boast accurate classification of
never-before-seen (i.e., zero-day) files using machine learning (ML). The
result is that the efficacy and gaps among the available approaches are opaque,
inhibiting end users from making informed network security decisions and
researchers from targeting gaps in current detectors. In this paper, we present
a scientific evaluation of four market-leading malware detection tools to
assist an organization with two primary questions: (Q1) To what extent do
ML-based tools accurately classify never-before-seen files without sacrificing
detection ability on known files? (Q2) Is it worth purchasing a network-level
malware detector to complement host-based detection? We tested each tool
against 3,536 total files (2,554 or 72% malicious, 982 or 28% benign) including
over 400 zero-day malware, and tested with a variety of file types and
protocols for delivery. We present statistical results on detection time and
accuracy, consider complementary analysis (using multiple tools together), and
provide two novel applications of a recent cost-benefit evaluation procedure by
Iannaconne & Bridges that incorporates all the above metrics into a single
quantifiable cost. While the ML-based tools are more effective at detecting
zero-day files and executables, the signature-based tool may still be an
overall better option. Both network-based tools provide substantial (simulated)
savings when paired with either host tool, yet both show poor detection rates
on protocols other than HTTP or SMTP. Our results show that all four tools have
near-perfect precision but alarmingly low recall, especially on file types
other than executables and office files -- 37% of malware tested, including all
polyglot files, were undetected.Comment: Includes Actionable Takeaways for SOC
High-sensitivity measurement of ^3He−^4He isotopic ratios for ultracold neutron experiments
Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of ^3He to ^4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10^(−14) level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of ^3He/^4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude
Supernova / Acceleration Probe: A Satellite Experiment to Study the Nature of the Dark Energy
The Supernova / Acceleration Probe (SNAP) is a proposed space-based
experiment designed to study the dark energy and alternative explanations of
the acceleration of the Universe's expansion by performing a series of
complementary systematics-controlled measurements. We describe a
self-consistent reference mission design for building a Type Ia supernova
Hubble diagram and for performing a wide-area weak gravitational lensing study.
A 2-m wide-field telescope feeds a focal plane consisting of a 0.7
square-degree imager tiled with equal areas of optical CCDs and near infrared
sensors, and a high-efficiency low-resolution integral field spectrograph. The
SNAP mission will obtain high-signal-to-noise calibrated light-curves and
spectra for several thousand supernovae at redshifts between z=0.1 and 1.7. A
wide-field survey covering one thousand square degrees resolves ~100 galaxies
per square arcminute. If we assume we live in a cosmological-constant-dominated
Universe, the matter density, dark energy density, and flatness of space can
all be measured with SNAP supernova and weak-lensing measurements to a
systematics-limited accuracy of 1%. For a flat universe, the
density-to-pressure ratio of dark energy can be similarly measured to 5% for
the present value w0 and ~0.1 for the time variation w'. The large survey area,
depth, spatial resolution, time-sampling, and nine-band optical to NIR
photometry will support additional independent and/or complementary dark-energy
measurement approaches as well as a broad range of auxiliary science programs.
(Abridged)Comment: 40 pages, 18 figures, submitted to PASP, http://snap.lbl.go
A Slow Neutron Polarimeter for the Measurement of Parity-Odd Neutron Rotary Power
We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutronoptical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable ofmeasuring a neutron rotary power of dϕ/dz = 1 × 10−7 rad/m
New Precision Orbits of Bright Double-Lined Spectroscopic Binaries. I: RR Lyncis, 12 Bootis, and HR 6169
Radial velocities from the 2.1 m telescope at McDonald Observatory
supplemented with radial velocities from the coude' feed telescope at KPNO
provide new precise orbits for the double-lined spectroscopic binaries RR Lyn
(A3/A8/A6), 12 Boo (F8IV), and HR 6169 (A2V). We derive orbital dimensions and
minimum masses with accuracies of 0.06 to 0.9 %. The three systems, which have
V magnitudes of 5.54, 4.83, and 6.42, respectively, are all sufficiently bright
that they are easily within the grasp of modern optical interferometers and so
afford the prospect, when our spectroscopic observations are complemented by
interferometric observations, of fully-determined orbits, precise masses, and
distances. In the case of RR Lyn, which is also a detached eclipsing binary
with a well-determined orbital inclination, we are able to determine the
semimajor axis of the relative orbit, a = 29.32 +/- 0.04 Rsun, primary and
secondary radii of 2.57 +/- 0.02 Rsun and 1.59 +/- 0.03 Rsun, respectively; and
primary and secondary masses of 1.927 +/- 0.008 Msun and 1.507 +/- 0.004 Msun,
respectively. Comparison of our new systemic velocity determination, gamma =
-12.03 +/- 0.04 km/s, with an earlier one, gamma = -11.61 +/- 0.30 km/s, shows
no evidence of any change in the systemic velocity in the 40 years separating
the two measurements, a null result that neither confirms nor contradicts the
presence of the low-mass third component proposed by Khaliullin & Khaliullina
(2002). Our spectroscopic orbit of 12 Boo is more precise that that of Boden et
al. (2005), but confirms their results about this system. Our analysis of HR
6169 has produced a major improvement in its orbital elements. The minimum
masses of the primary and secondary are 2.20 +/- 0.01 and 1.64 +/- 0.02 Msun,
respectively.Comment: To appear in the May A
A Slow Neutron Polarimeter for the Measurement of Parity-Odd Neutron Rotary Power
We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of dϕ/dz = 1 × 10−7 rad/m
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