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Dielectric breakdown is an example of a natural phenomenon that occurs on very short time scales, making it incredibly difficult to capture optical images of the process. Event initiation jitter is one of the primary challenges, as even a microsecond of jitter time can cause the imaging attempt to fail. Initial attempts to capture images of dielectric breakdown with a gigahertz frame rate camera and an exploding bridge wire initiation were stymied by high initiation jitter. Subsequently, a novel optical delay line apparatus was developed in order to effectively circumvent the jitter and reliably image dielectric breakdown. The design and performance of the optical delay line apparatus are presented. The optical delay line increased the image capture success rate from 25% to 94% while also permitting enhanced temporal resolution and has applications for use in imaging other high-jitter, extremely fast phenomena., Comment: 11 pages, 6 figures, accepted manuscript

Neutrons are encountered in many different fields, including condensed matter physics, space exploration, nuclear power, and healthcare. Neutrons interacting with a biological target produce secondary charged particles that are damaging to human health. The most effective way to shield neutrons is to slow them to thermal energies and then capture the thermalized neutrons. These factors lead us to consider potential materials solutions for neutron shields that maximize the protection of humans while minimizing the shield mass, and which adapt well to modern additive manufacturing techniques. Using hexagonal boron nitride (hBN) as a capture medium and high-density polyethylene (HDPE) as a thermalization medium, we aim to design the optimal internal structure of h$^{10}$BN/HDPE composites by minimizing the effective dose, which is a measure of the estimated radiation damage exposure for a human. Through Monte Carlo simulations in Geant4, we find that the optimal structure reduces the effective dose up to a factor of 72x over aluminum (Al) and 4x over HDPE; this is a significant improvement in shielding effectiveness that could dramatically reduce the radiation exposure of occupational workers.

We present the first proof-of-concept simulations of detectors using biomaterials to detect particle interactions. The essential idea behind a "DNA detector" involves the attachment of a forest of precisely-sequenced single or double-stranded nucleic acids from a thin holding layer made of a high-density material. Incoming particles break a series of strands along a roughly co-linear chain of interaction sites and the severed segments then fall to a collection area. Since the sequences of base pairs in nucleic acid molecules can be precisely amplified and measured using polymerase chain reaction (PCR), the original spatial position of each broken strand inside the detector can be reconstructed with nm precision. Motivated by the potential use as a low-energy directional particle tracker, we perform the first Monte Carlo simulations of particle interactions inside a DNA detector. We compare the track topology as a function of incoming direction, energy, and particle type for a range of ionising particles. While particle identification and energy reconstruction might be challenging without a significant scale-up, the excellent potential angular and spatial resolution ($\lesssim 25^\circ$ axial resolution for a keV-scale particles and nm-scale track segments) are clear advantages of this concept. We conclude that a DNA detector could be a cost-effective, portable, and powerful new particle detection technology. We outline the outstanding experimental challenges, and suggest directions for future laboratory tests., Comment: 17+3 pages, 9+3 figures

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band., Comment: Astro2020 APC White Paper Updated to make small change to author list in metadata

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions., Comment: 14 pages including 3 figures

Since 1990, high school students in Washington have had the choice of earning college credit through the Running Start program. Running start is a dual enrollment and dual credit program that allows eleventh and twelfth grade high school students to take college courses at any of Washington's 34 community and technical colleges, Central Washington University, Eastern Washington University, Northwest Indian College, Washington State University and The Evergreen State College. Participants receive high school and college credit while taking classes located on the campus of participating colleges. Running Start gives high school juniors and seniors the option to attend college on either full-time or part-time basis while concurrently earning high school and college credit. During the 2012-2013 academic year, 17,704 students participated in the Running Start program. In its 24th year, there are concerns of access for traditionally underrepresented minority groups and low-income students. In 2012-2013, African-Americans, Hispanic/Latino, Native-American and Pacific Islanders comprised 23.7% of enrolled 11th and 12th grade students but only made up 12.5% of Running Start students. While 46.1% of all students in Washington qualify for free or reduced lunch only 28% of Running Start participants qualify. This report will explore policy barriers that potentially limit the participation of underrepresented minority and low-income students in the Running Start program. Specifically this report will provide an overview of national practices and policies in other states for potential solutions to increasing the participation of underrepresented populations in the Running Start program.

The natural neutron background influences the maximum achievable sensitivity in most deep underground nuclear, astroparticle and double-beta decay physics experiments. Reliable neutron flux numbers are an important ingredient in the design of the shielding of new large-scale experiments as well as in the analysis of experimental data. Using a portable setup of He-3 counters we measured the thermal neutron flux at the Kimballton Underground Research Facility, the Soudan Underground Laboratory, on the 4100 ft and the 4850 ft levels of the Sanford Underground Research Facility, at the Waste Isolation Pilot Plant and at the Gran Sasso National Laboratory. Absolute neutron fluxes at these laboratories are presented., Comment: Preparation version for submission

Today's engineering graduates will solve tomorrow's problems in a world that is advancing faster and facing more critical challenges than ever before. This situation creates significant demand for engineering education to evolve in order to effectively prepare a diverse community of engineers for these challenges. Such concerns have led to the publication of visionary reports that help orient the work of those committed to the success of engineering education. Research in engineering education is central to "all" of these visions. Research on the student experience is fundamental to informing the evolution of engineering education. A broad understanding of the engineering student experience involves thinking about diverse academic pathways, navigation of these pathways, and decision points--how students choose engineering programs, navigate through their programs, and then move on to jobs and careers. Further, looking at students' experiences broadly entails not just thinking about their learning (i.e., skill and knowledge development in both technical and professional areas) but also their motivation, their identification with engineering, their confidence, and their choices after graduation. However, an understanding of the engineering student experience is clearly not enough to create innovation in engineering education. Educators who are capable of using the research on the student experience are needed. This involves not only preparing tomorrow's educators with conceptions of teaching that enable innovation but also understanding how today's educators make teaching decisions. The nation also needs to be concerned about creating the capacity to do such research--in short, more researchers are needed. One promising approach is to work with educators who are interested in engaging in research, supporting them as they negotiate the space between their current activities and their new work in engineering education research. To fully support this process, the nation must also investigate what is required for educators to engage in such a path. The Center for the Advancement of Engineering Education (CAEE) began research in January 2003 as one of two national higher-education Centers for Teaching and Learning funded by the National Science Foundation that year. Originally funded for 2003-2007, supplementary funds from the Engineering Directorate allowed additional analysis and dissemination to continue through 2010. This report describes the work of CAEE. The authors summarize CAEE's findings and outcomes, followed by highlights from their efforts to disseminate the results, including a set of research instruments and other materials that are available for use by others. The authors conclude with a look ahead at next steps and some questions for future research. Appended are: (1) References and Cumulative Bibliography; (2) Cumulative Team List and Advisory Board Members; (3) APS Headlines; (4) Local Inquiry Questions; (5) Looking Ahead: Ideas for Future Research. (Contains 26 figures and 10 tables.)

We show that when an electron or photon propagates in a cylindrically symmetric waveguide, it experiences both a zitterbewegung effect and a spin-orbit interaction leading to identical propagation dynamics for both particles. Applying a unified perturbative approach to both particles simultaneously, we find that to first-order in perturbation theory their Hamiltonians each contain identical Darwin (zitterbewegung) and spin-orbit terms, resulting in the unification of their dynamics. The presence of the zitterbewegung effect may be interpreted physically as the delocalization of the electron on the scale of its Compton wavelength, or the delocalization of the photon on the scale of its wavelength in the waveguide. The presence of the spin-orbit interaction leads to the prediction of several rotational effects: the spatial or time evolution of either particle's spin/polarization vector is controlled by the sign of its orbital angular momentum quantum number, or conversely, its spatial wave function is controlled by its spin angular momentum., Comment: 13 pages, 2 figures

The research area of nuclear astrophysics is characterized by a need for information published in tens of journals in several fields and an extremely dilute distribution of researchers. For these reasons it is difficult for researchers, especially students, to be adequately informed of the relevant published research. For example, the commonly employed journal club is inefficient for a group consisting of a professor and his two students. In an attempt to address this problem, we have developed a virtual journal (VJ), a process for collecting and distributing a weekly compendium of articles of interest to researchers in nuclear astrophysics. Subscribers are notified of each VJ issue using an email-list server or an RSS feed. The VJ data base is searchable by topics assigned by the editors, or by keywords. There are two related VJs: the Virtual Journal of Nuclear Astrophysics (JINA VJ), and the SEGUE Virtual Journal (SEGUE VJ). The JINA VJ also serves as a source of new experimental and theoretical information for the JINA REACLIB reaction rate database. References to review articles and popular level articles provide an introduction to the literature for students. The VJs and support information are available at http://groups.nscl.msu.edu/jina/journals, Comment: submitted, 9 pages, 5 figures, 1 table. http://groups.nscl.msu.edu/jina/journals

Current concerns over reforming engineering education have focused attention on helping students develop skills and an adaptive expertise. Phenomenological guidelines for instruction along these lines can be understood as arising out of an emerging theory of thinking and learning built on results in the neural, cognitive, and behavioral sciences. We outline this framework and consider some of its implications for one example: developing a more detailed understanding of the specific skill of using mathematics in modeling physical situations. This approach provides theoretical underpinnings for some best-practice instructional methods designed to help students develop this skill and providesguidance for further research in the area., Comment: 20 pages

First steps have been taken in a more comprehensive study of the dependence of observables in Type I X-ray bursts on uncertain (p,gamma) reaction rates along the rp-process path. We use the multizone hydrodynamics code KEPLER which implicitly couples a full nuclear reaction network of more than 1000 isotopes, as needed, to follow structure and evolution of the X-ray burst layer and its ashes. This allows us to incorporate the full rp-process network, including all relevant nuclear reactions, and individually study changes in the X-ray burst light curves when modifying selected key nuclear reaction rates. In this work we considered all possible proton captures to nuclei with 10 < Z < 28 and N <= Z. When varying individual reaction rates within a symmetric full width uncertainty of a factor of 10000, early results for some rates show changes in the burst light curve as large as 10 percent of peak luminosity. This is very large compared to the current sensitivity of X-ray observations. More precise reaction rates are therefore needed to test current X-ray burst models, particularly of the burst rise, with observational data and to constrain astrophysical parameters., Comment: 6 pages, 2 figures, Nuclei in the Cosmos IX - poster 068