Towards Neutron Transformation Searches

To probe the origins of the baryon asymmetry, baryon number violation, the last unconfirmed Sakharov condition, must be definitively observed experimentally. Similarly, the nature of dark matter is currently unknown, and calls out for new candidates to be investigated. Each of these issues can be considered through the study of neutron transformations. Some rare baryon number violating processes, such as neutron-antineutron transformations, are expected to probe baryogenesis. Here, I show progress on this discovery target through construction of more accurate Monte Carlo models, the design of future detectors, creation of more complete atmospheric neutrino background simulations, and use of automated analysis techniques within the the NNBAR/HIBEAM experimental program at the European Spallation Source (ESS) and the Deep Underground Neutrino Experiment (DUNE). First simulation-based sensitivities for these experiments will be discussed. Modeling of rare neutron-antineutron transformation and subsequent annihilation will be discussed at length for multiple nuclei useful to these and other collaborations. To go along with this work, more comprehensive lepton-scattering nuclear models must be integrated into neutrino event generators for proper atmospheric neutrino background simulations. I discuss the first furnishing of these backgrounds for DUNE, and I highlight a potential path forward for the community in this vein using precision electron scattering modeling as a facsimile. Aspects of other potentially related neutron--mirror-neutron oscillations pertinent to dark matter and the neutron lifetime anomaly will also be considered for the ESS HIBEAM experiment. Here, I will present the first experimental sensitivity calculations for a broad range of modular experimental setups which will serve as research and design stepping stones toward NNBAR while producing a multitude of physics results over short time scales

Snowmass Early Career: The Key Initiatives Organization

In April 2020, the 2019 and 2020 American Physical Society's Division of Particles and Fields (APS DPF) Early Career Executive Committee (ECEC) members were tasked with organizing the formation of a representative body for High-Energy Physics (HEP) early career members for the Snowmass process by the DPF Executive Committee. Here, we outline the structure we developed and the process we followed to help provide context and guidance for future early career Snowmass efforts. Our organization was composed of a cross-frontier branch with committees on Inreach, Diversity Equity and Inclusion, Survey, and Long Term Organizational Planning; in addition to the Frontier Coordination branch, formed by committees responsible for liaising with each Frontier. Throughout this document, the authors reflect on the triumphs and pitfalls of a program created from nothing over a very short period of time, by people with good intentions, who had no prior experience in building such an organization. Through this exercise of reflecting, we sometimes find that we would recommend a different path to our future selves. Insomuch as there are things to find fault with, it is in the robustness of the systems we built and refined.Comment: contribution to Snowmass 2021, 16 pages, 0 figure

Dispersal direction, geographic location and river discharge all influence juvenile growth of a freshwater fish

Seeking out appropriate habitat or food resources is one of the key reasons why animals move. Despite the benefits of movement, some individuals in a population remain resident or express alternative movement phenotypes. Movement, however, is energetically costly and can result in resources being diverted away from growth and reproduction. The presence of multiple movement phenotypes within populations suggests that each can have commensurate levels of performance depending on the underlying environmental conditions. Here we explore the context-dependent costs and benefits of upstream and downstream juvenile dispersal in a large river system. We expect that if the energetic costs of moving (upstream against a current or downstream with a current) exceed any benefits to growth, then residents (who do not move) will have faster growth. Alternatively, movement costs may be offset if individuals move to more favourable environments, resulting in dispersers benefiting with faster growth. We used biological information naturally archived in the otoliths of a potamodromous fish, golden perch Macquaria ambigua, to quantify how movement phenotypes affect growth across individuals exposed to spatiotemporally varying environmental conditions. We found that juvenile growth differed considerably among dispersal phenotypes (resident, upstream, downstream, stocked): in general, surviving wild-spawned downstream and upstream dispersers and hatchery-stocked fish all grew faster than individuals that remained resident within their natal reach. Further, juvenile growth was sensitive to local environmental conditions and had carryover effects from an individual's natal-year. Juvenile growth of all dispersal phenotypes was higher in years with below average natal-year summer discharge (when fish are ~2–3 months old), likely because of increased concentrations of food resources. In contrast, the effects of natal-year spring discharge (around the time individuals were spawned) were dependent on dispersal direction, with positive effects for downstream dispersers and upstream dispersers, and negative effects for resident individuals. Our results suggest that an individual's growth can benefit from early-life movement, although the magnitude of this effect depends on local environmental conditions and the direction travelled. Our study reinforces the importance of heterogeneous and connected riverscapes that foster a diversity of individual growth responses

Paying for Performance: The Education Impacts of a Community College Scholarship Program for Low-Income Adults

We evaluate the effect of performance-based incentive programs on educational outcomes for community college students from a random assignment experiment at three campuses. Incentive payments over two semesters were tied to meeting two conditions¿enrolling at least half time and maintaining a ¿C¿ or better grade point average. Eligibility increased the likelihood of enrolling in the second semester after random assignment and total number of credits earned. Over two years, program group students completed nearly 40 percent more credits. We find little evidence that program eligibility changed types of courses taken but some evidence of increased academic performance and effort

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference