335 research outputs found
Using Formative Student Feedback: A Continuous Quality Improvement Approach for Online Course Development
The objective of this study was to examine the use of frequent, anonymous student course surveys as a tool in supporting continuous quality improvement (CQI) principles in online instruction. The study used a qualitative, multiple-case design involving four separate online courses. Analysis methods included pattern matching/explanation building, time series analysis, and thematic analysis. Findings suggested that instructors used student feedback to make course changes that alleviated technical difficulties, added and clarified content, and contributed to future course changes. Students and instructors responded positively to the opportunity to give and receive anonymous feedback and felt that it helped improve the course. It is uncertain, however, whether using CQI principles had an impact on end-of-semester teacher course quality ratings. An important finding from the research is that students like to be asked to help improve their learning experience, as long as the instructor listens and responds to their feedback. Evaluation is a valuable component of instructional design theories, which are based on the philosophy that the best designs result from an iterative process. Using a synergistic CQI approach, this study indicates that it is possible for changes to be made more quickly to a course when students are involved in the process. The combination of frequent student feedback with a willing and experienced instructor who can make expert course revision decisions allows the process of course improvement to be enhanced
SkyMapper Filter Set: Design and Fabrication of Large Scale Optical Filters
The SkyMapper Southern Sky Survey will be conducted from Siding Spring
Observatory with u, v, g, r, i and z filters that comprise glued glass
combination filters of dimension 309x309x15 mm. In this paper we discuss the
rationale for our bandpasses and physical characteristics of the filter set.
The u, v, g and z filters are entirely glass filters which provide highly
uniform band passes across the complete filter aperture. The i filter uses
glass with a short-wave pass coating, and the r filter is a complete dielectric
filter. We describe the process by which the filters were constructed,
including the processes used to obtain uniform dielectric coatings and
optimized narrow band anti-reflection coatings, as well as the technique of
gluing the large glass pieces together after coating using UV transparent epoxy
cement. The measured passbands including extinction and CCD QE are presented.Comment: 9 pages, 2 tables, 7 figure
The Planetary Nebulae Spectrograph: the green light for Galaxy Kinematics
Planetary nebulae are now well established as probes of galaxy dynamics and
as standard candles in distance determinations. Motivated by the need to
improve the efficiency of planetary nebulae searches and the speed with which
their radial velocities are determined, a dedicated instrument - the Planetary
Nebulae Spectrograph or PN.S - has been designed and commissioned at the 4.2m
William Herschel Telescope. The high optical efficiency of the spectrograph
results in the detection of typically ~ 150 PN in galaxies at the distance of
the Virgo cluster in one night of observations. In the same observation the
radial velocities are obtained with an accuracy of ~ 20 km/sComment: Accepted by PASP, to appear November 2002; the figures have been
degraded for archival purpose
Structure of Be probed via secondary beam reactions
The low-lying level structure of the unbound neutron-rich nucleus Be
has been investigated via breakup on a carbon target of secondary beams of
B at 35 MeV/nucleon. The coincident detection of the beam velocity
Be fragments and neutrons permitted the invariant mass of the
Be+ and Be++ systems to be reconstructed. In the case of
the breakup of B, a very narrow structure at threshold was observed in
the Be+ channel. Contrary to earlier stable beam fragmentation
studies which identified this as a strongly interacting -wave virtual state
in Be, analysis here of the Be++ events demonstrated that
this was an artifact resulting from the sequential-decay of the
Be(2) state. Single-proton removal from B was found to
populate a broad low-lying structure some 0.70 MeV above the neutron-decay
threshold in addition to a less prominent feature at around 2.4 MeV. Based on
the selectivity of the reaction and a comparison with (0-3)
shell-model calculations, the low-lying structure is concluded to most probably
arise from closely spaced J=1/2 and 5/2 resonances
(E=0.400.03 and 0.85 MeV), whilst the broad
higher-lying feature is a second 5/2 level (E=2.350.14 MeV). Taken
in conjunction with earlier studies, it would appear that the lowest 1/2
and 1/2 levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical
Review
Neutron-hole strength in the N = 81 isotones
The distribution of neutron-hole strength has been studied in the N 81 isotones 137Ba, 139Ce, 141Nd and 143Sm through the single-neutron removing reactions (p,d) and ( 3He,α), at energies of 23 and 34 MeV, respectively. Systematic cross section measurements were made at angles sensitive to the transferred angular momentum, and spectroscopic factors extracted through a distorted-wave Born approximation analysis. Application of the MacFarlane-French sum rules indicate an anomalously low summed g7/2 spectroscopic factor, most likely due to extensive fragmentation of the single-particle strength. Single-particle energies, based upon the centroids of observed strength, are presented. © Published under licence by IOP Publishing Ltd
A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector
We describe a compact, ultra-clean device used to deploy radioactive sources
along the vertical axis of the KamLAND liquid-scintillator neutrino detector
for purposes of calibration. The device worked by paying out and reeling in
precise lengths of a hanging, small-gauge wire rope (cable); an assortment of
interchangeable radioactive sources could be attached to a weight at the end of
the cable. All components exposed to the radiopure liquid scintillator were
made of chemically compatible UHV-cleaned materials, primarily stainless steel,
in order to avoid contaminating or degrading the scintillator. To prevent radon
intrusion, the apparatus was enclosed in a hermetically sealed housing inside a
glove box, and both volumes were regularly flushed with purified nitrogen gas.
An infrared camera attached to the side of the housing permitted real-time
visual monitoring of the cable's motion, and the system was controlled via a
graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements
to text, and revised reference
Search for extraterrestrial antineutrino sources with the KamLAND detector
We present the results of a search for extraterrestrial electron
antineutrinos ('s) in the energy range using the KamLAND detector. In an exposure of
4.53 kton-year, we identify 25 candidate events. All of the candidate events
can be attributed to background, most importantly neutral current atmospheric
neutrino interactions, setting an upper limit on the probability of B
solar 's converting into 's at
(90% C.L.), if we assume an undistorted shape. This limit
corresponds to a solar flux of or an event
rate of above the energy threshold
. The present data also allows us to set more
stringent limits on the diffuse supernova neutrino flux and on the annihilation
rates for light dark matter particles.Comment: 22 pages, 6 figure
7Be Solar Neutrino Measurement with KamLAND
We report a measurement of the neutrino-electron elastic scattering rate of
862 keV 7Be solar neutrinos based on a 165.4 kton-day exposure of KamLAND. The
observed rate is 582 +/- 90 (kton-day)^-1, which corresponds to a 862 keV 7Be
solar neutrino flux of (3.26 +/- 0.50) x 10^9 cm^-2s^-1, assuming a pure
electron flavor flux. Comparing this flux with the standard solar model
prediction and further assuming three flavor mixing, a nu_e survival
probability of 0.66 +/- 0.14 is determined from the KamLAND data. Utilizing a
global three flavor oscillation analysis, we obtain a total 7Be solar neutrino
flux of (5.82 +/- 0.98) x 10^9 cm^-2s^-1, which is consistent with the standard
solar model predictions.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector
We report a measurement of the neutrino-electron elastic scattering rate from
8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The
background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold
is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a
pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a
spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1.
The analysis threshold is driven by 208Tl present in the liquid scintillator,
and the main source of systematic uncertainty is due to background from
cosmogenic 11Be. The measured rate is consistent with existing measurements and
with Standard Solar Model predictions which include matter enhanced neutrino
oscillation.Comment: 6 pages, 3 figure
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