152 research outputs found
Hybrid Teaching in Extension: Learning at the Crossroads
Extension clients\u27 learning preferences are changing, with many increasingly going online for educational content. In response, Oregon State University Extension pilot tested a training program for Extension educators to explore hybrid teaching—a methodology that could provide more flexible access to a wider audience. Hybrid teaching offers a powerful blend of online and face-to-face instruction that could attract Extension educators—and administrators—to this pedagogical approach. The pilot training revealed both the promises and challenges of hybrid teaching
Potential and limitations of nucleon transfer experiments with radioactive beams at REX-ISOLDE
As a tool for studying the structure of nuclei far off stability the
technique of gamma-ray spectroscopy after low-energy single-nucleon transfer
reactions with radioactive nuclear beams in inverse kinematics was
investigated. Modules of the MINIBALL germanium array and a thin
position-sensitive parallel plate avalanche counter (PPAC) to be employed in
future experiments at REX-ISOLDE were used in a test experiment performed with
a stable 36S beam on deuteron and 9Be targets. It is demonstrated that the
Doppler broadening of gamma lines detected by the MINIBALL modules is
considerably reduced by exploiting their segmentation, and that for beam
intensities up to 10^6 particles/s the PPAC positioned around zero degrees with
respect to the beam axis allows not only to significantly reduce the gamma
background by requiring coincidences with the transfer products but also to
control the beam and its intensity by single particle counting. The predicted
large neutron pickup cross sections of neutron-rich light nuclei on 2H and 9Be
targets at REX-ISOLDE energies of 2.2 MeV A are confirmed.Comment: 11 pages, 8 figure
Perturbed angular correlations for Gd in gadolinium: in-beam comparisons of relative magnetizations
Perturbed angular correlations were measured for Gd ions implanted into
gadolinium foils following Coulomb excitation with 40 MeV O-16 beams. A
technique for measuring the relative magnetizations of ferromagnetic gadolinium
hosts under in-beam conditions is described and discussed. The combined
electric-quadrupole and magnetic-dipole interaction is evaluated. The effect of
nuclei implanted onto damaged or non-substitutional sites is assessed, as is
the effect of misalignment between the internal hyperfine field and the
external polarizing field. Thermal effects due to beam heating are discussed.Comment: 37 pages, 15 figures, accepted for publication in NIM
Report on the Implementation of Work Package 7 “Dissemination of the Project Results” in the Framework of the IRNet Project
This article, prepared by an international team of researchers from different
scientific areas connected with ICT, e-learning, pedagogy, and other related
disciplines, focuses on the objectives and some results of the international project
IRNet (www.irnet.us.edu.pl). In particular, the article describes research tools,
methods, and a procedure of the Work Package 7 “Dissemination of the Project
Results,” that is, objectives, tasks, deliverables, publications, and implementation
of research trips in the context of the next stages and Work Packages of IRNet
project – International Research Network
LENDA, a Low Energy Neutron Detector Array for experiments with radioactive beams in inverse kinematics
The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight
(TOF) spectrometer developed at the National Superconducting Cyclotron Lab-
oratory (NSCL) for use in inverse kinematics experiments with rare isotope
beams. Its design has been motivated by the need to study the spin-isospin
response of unstable nuclei using (p, n) charge-exchange reactions at
intermediate energies (> 100 MeV/u). It can be used, however, for any reaction
study that involves emission of low energy neutrons (150 keV - 10 MeV). The
array consists of 24 plastic scintillator bars and is capable of registering
the recoiling neutron energy and angle with high detection efficiency. The
neutron energy is determined by the time-of-flight technique, while the
position of interaction is deduced using the timing and energy information from
the two photomultipliers of each bar. A simple test setup utilizing radioactive
sources has been used to characterize the array. Results of test measurements
are compared with simulations. A neutron energy threshold of < 150 keV, an
intrinsic time (position) resolution of \sim 400 ps (\sim 6 cm) and an
efficiency > 20 % for neutrons below 4 MeV have been obtained.Comment: Version accepted for publication in Nucl. Instr. Methods A. Revised
text, 2 new figures added (one in section 4 and one in section 7
Coulomb fragmentation and Coulomb fission of relativistic heavy-ions and related nuclear structure aspects
The Coulomb excitation of 208Pb projectiles has been studied at an
energy of 640 A MeV. Cross sections for the excitation of the two-phonon
giant dipole resonance were measured for different targets, and show clear
evidence for a two-step electromagnetic excitation mechanism. The experimental
cross sections exceed those calculated in the harmonic oscillator
approximation by a factor of 1.33 ± 0.16. The deduced 27-decay probability
is consistent with the expectation in the harmonic limit. Finally, the
excitation of the two-phonon giant dipole resonance in the deformed and
fissile nucleus 238U is discussed
Measurement and simulation of the neutron response of the Nordball liquid scintillator array
The response of the liquid scintillator array Nordball to neutrons in the
energy range 1.5 < T_n < 10 MeV has been measured by time of flight using a
252Cf fission source. Fission fragments were detected by means of a thin-film
plastic scintillator. The measured differential and integral neutron detection
efficiencies agree well with predictions of a Monte Carlo simulation of the
detector which models geometry accurately and incorporates the measured,
non-linear proton light output as a function of energy. The ability of the
model to provide systematic corrections to photoneutron cross sections,
measured by Nordball at low energy, is tested in a measurement of the two-body
deuteron photodisintegration cross section in the range E_gamma=14-18 MeV.
After correction the present 2H(gamma,n)p measurements agree well with a
published evaluation of the large body of 2H(gamma,p)n data.Comment: 20 pages 10 figures, submitted Nucl. Instr. Meth.
Invariant-mass and [gamma]-ray spectroscopy using secondary, radioactive ion beams
Coulomb excitation of secondary beams (5 < Z < 20) at energies
around 250 .1 MeV was explored at GSI. For low-lying states, 7-ray spectroscopy
was utilized, while high-lying excitations were investigated by
means of invariant-mass spectroscopy
- …