Bevalac calibration of the SOFIE range and hodoscope detectors

The scintillating optical fiber isotope experiment (SOFIE) is a Cerenkov-dE/dx-Range experiment which was developed initially for balloon flight to study the isotopic composition of cosmic rays in the iron region. The electronic range and hodoscope detectors use scintillating optical fibers to image the tracks of stopping charged particles and to determine their trajectory. The particle range is determined and used together with a Cerenkov measurement to determine the mass of the stopping particle. Preliminary results of a Bevalac calibration performed in August, 1984 with a prototype of the balloon flight instrument, to study the measurement precision in range and trajectory which could be attained with this detector are described

Time-frequency analysis of ship wave patterns in shallow water: modelling and experiments

A spectrogram of a ship wake is a heat map that visualises the time-dependent frequency spectrum of surface height measurements taken at a single point as the ship travels by. Spectrograms are easy to compute and, if properly interpreted, have the potential to provide crucial information about various properties of the ship in question. Here we use geometrical arguments and analysis of an idealised mathematical model to identify features of spectrograms, concentrating on the effects of a finite-depth channel. Our results depend heavily on whether the flow regime is subcritical or supercritical. To support our theoretical predictions, we compare with data taken from experiments we conducted in a model test basin using a variety of realistic ship hulls. Finally, we note that vessels with a high aspect ratio appear to produce spectrogram data that contains periodic patterns. We can reproduce this behaviour in our mathematical model by using a so-called two-point wavemaker. These results highlight the role of wave interference effects in spectrograms of ship wakes.Comment: 14 pages, 7 figure

Basic Research on the Composition of Heavy Cosmic Rays: The Trans-Iron Galactic Element Recorder Experiment (TIGER)

Among the most fundamental astrophysical problems is understanding the mechanism by which particles are accelerated to the enormous energies observed in the cosmic rays. That problem can be conveniently divided into two questions: (1) What is the source of the energy and the mechanism for converting the energy of that source into the energy of individual cosmic-ray nuclei, and (2) what is the source of the material that is accelerated and the mechanism for injecting that material into the cosmic-ray accelerator? There is a general consensus that the answer to the first of these questions, for nuclei with energy eV, is that the source of their energy is almost certainly from supernova explosions (e.g., Ginzburg & Syrovatskii, 1964). The answer to the second question is still uncertain, although evidence in favor of a superbubble origin of cosmic rays is becoming quite significant (Higdon et al, 2203 and Binns, 2005 (Submitted to ApJ). There are several ways of interpreting available data that lead to quite different models for the source of the material and its injection mechanism. With the The Trans-Iron Galactic Element Recorder Experiment (TIGER) instrument we have obtained data that will help to distinguish among these possible models. In the report, the TIGER flights, the instrument itself, results, and a publication list as a result of the work are presented

Large area pulse ionization chamber for measurement of extremely heavy cosmic rays

Parallel plate ionization chamber for identifying relativistic cosmic ray nucle

Observation of VH and VVH cosmic rays with an ionization-Cerenkov detector system

Heavy and ultraheavy nuclei observations of cosmic rays using ionization chamber-Cerenkov counter syste

The Need for Sensemaking in Networked Privacy and Algorithmic Responsibility

This paper proposes that two significant and emerging problems facing our connected, data-driven society may be more effectively solved by being framed as sensemaking challenges. The first is in empowering individuals to take control of their privacy, in device-rich information environments where personal information is fed transparently to complex networks of information brokers. Although sensemaking is often framed as an analytical activity undertaken by experts, due to the fact that non-specialist end-users are now being forced to make expert-like decisions in complex information environments, we argue that it is both appropriate and important to consider sensemaking challenges in this context. The second is in supporting human-in-the-loop algorithmic decision-making, in which important decisions bringing direct consequences for individuals, or indirect consequences for groups, are made with the support of data-driven algorithmic systems. In both privacy and algorithmic decision-making, framing the problems as sensemaking challenges acknowledges complex and illdefined problem structures, and affords the opportunity to view these activities as both building up relevant expertise schemas over time, and being driven potentially by recognition-primed decision making

The Isotopic Composition of Cosmic Ray Nuclei Beyond the Iron Peak

Isotope measurements of cosmic ray nuclei beyond the Fe peak are considered, using the charge region from Z=29 to Z∼40 as an example. Such studies can address a number of important questions that bear on cosmic ray origin, acceleration, and propagation. One possible approach for measuring isotopes with Z≥30 is based on large‐area arrays of silicon solid state detectors combined with scintillating optical fiber trajectory detectors optical fiber trajectory detectors

Energy spectra of elements with 18 or = Z or = 28 between 10 and 300 GeV/amu

The HEAO-3 Heavy Nuclei Experiment is composed of ionization chambers above and below a plastic Cerenkov counter. The energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 at very high energies where they are rare and thus need the large area x time are measured. The measurements of the Danish-French HEAO-3 experiment (Englemann,, et al., 1983) are extended to higher energies, using the relativistic rise of ionization signal as a measure of energy. Source abundances for Ar and Ca were determined

Flicker Sensitivity in Normal Aging-Monocular Tests of Retinal Function at Photopic and Mesopic Light Levels

Purpose: Aging can affect many aspects of visual performance. In general, the effects become more significant in those older than 40 to 50 years, with increased intersubject variability and stronger dependence on ambient illumination. This study aimed to establish how healthy aging of the retina affects the detection of 15-Hz flicker under photopic and mesopic lighting. Methods: We investigated 71 participants aged 20 to 75 years. Thresholds were measured for detection of 15-Hz flicker at the fovea (0°) and at an eccentricity of 4° in each of the four quadrants. The background luminance ranged from 0.6 to 60 cd/m2 and pupil size was measured continuously. Participants were excluded if they had signs/history of ocular disease, substantial interocular differences in flicker thresholds, or were unable to detect 100% flicker modulation in the high mesopic range. Results: Mesopic and photopic flicker thresholds were used to calculate an index, the health of the retina index, to determine the limits of flicker sensitivity in healthy aging. Log flicker thresholds changed bilinearly with age; they remained stable until 40 to 50 years, with a linear decline with increasing age. This bilinear pattern of the change in flicker thresholds with age is consistent across photopic and mesopic light levels. Conclusions: The health of the retina index captures the lowest threshold, usually obtained under photopic conditions, as well as the loss of flicker sensitivity with decreasing light level. The established limits of healthy aging may benefit from future studies in patients with ocular hypertension and/or glaucoma that are known to experience loss of flicker sensitivity