Muon Reconstruction in the Daya Bay Water Pools

Muon reconstruction in the Daya Bay water pools would serve to verify the simulated muon fluxes and offer the possibility of studying cosmic muons in general. This reconstruction is, however, complicated by many optical obstacles and the small coverage of photomultiplier tubes (PMTs) as compared to other large water Cherenkov detectors. The PMTs' timing information is useful only in the case of direct, unreflected Cherenkov light. This requires PMTs to be added and removed as an hypothesized muon trajectory is iteratively improved, to account for the changing effects of obstacles and direction of light. Therefore, muon reconstruction in the Daya Bay water pools does not lend itself to a general fitting procedure employing smoothly varying functions with continuous derivatives. Here, an algorithm is described which overcomes these complications. It employs the method of Least Mean Squares to determine an hypothesized trajectory from the PMTs' charge-weighted positions. This initially hypothesized trajectory is then iteratively refined using the PMTs' timing information. Reconstructions with simulated data reproduce the simulated trajectory to within about 5 degrees in direction and about 45 cm in position at the pool surface, with a bias that tends to pull tracks away from the vertical by about 3 degrees.Comment: Supplementary materials available in the journal-published versio

UAS Integration in the NAS FY15 Annual Review

This presentation gives insight into the research activities and efforts being executed in order to integrate unmanned aircraft systems into the national airspace system. This briefing is to inform others of the UAS-NAS progress and future directions

“Evolving Homes, Not Revolving Doors”: Examining Lesbian, Gay, and Bisexual Foster Parents’ Discursive Construction and Negotiation of Identity Layers and Identity Gaps

The United States foster care system serves more than half a million children each year (U.S. Department of Health and Human Services [DHH], 2023). The purpose of this study was to examine how LGB foster parents discursively construct and navigate their identities in the fostering context. The researcher undertook in-depth interviews with 18 LGB people who were currently fostering or had previously fostered at least one child from the foster care system. The researcher analyzed the interview data using Braun and Clarke’s reflexive thematic analysis (2019). Consistent with the Communication Theory of Identity (Hecht, 1993; 2015; Hecht & Phillips, 2022), the researcher identified ten manifestations of identity for LGB foster parents across the four identity layers. The manifestation of identity layers indicated that LGB foster parents perceive their LGB identity to be salient in the foster care context, which can be perceived both negatively and positively, and the influence of multiple subsystems within the foster family. Further, participants described five sources of identity gaps (Jung & Hecht, 2004). Identity gaps were related to sexual orientation (communal-communal and communal-personal-relational) and being a foster parent (intralayer relational, personal-relational, enacted-relational, relational-communal, and person-communal). Participants described six discursive practices of identity work (labeling, ritualizing, integrating biological and foster families, redefining fostering expectations, seeking supportive agencies, and connecting to community) (Galvin, 2006, Miller-Ott, 2017). The identity gaps and discursive practices provide insight into the dialectical identity negotiation of LGB foster parents. The researcher discusses implications based on these findings. Theoretical implications include expanding the foster care square (Nelson, 2017) and examining the interdependence of identity gaps within foster families (Merrill & Afifi, 2017). Practical implications include LGB foster parents as a resource for LGBT+ foster children and LGBT+ competency training for social workers and foster care agencies. Future researchers should consider the influence of sexual orientation from multiple perspectives and the intersection of multiple identities in the fostering process. Advisors: Dawn O. Braithwaite & Jordan Soli

Observation of exotic meson production in the reaction π−p→η′π−p \pi^{-} p \to \eta^{\prime} \pi^- p at 18 GeV/c

An amplitude analysis of an exclusive sample of 5765 events from the reaction $\pi^{-} p \to \eta^{\prime} \pi^- p$ at 18 GeV/c is described. The $\eta^{\prime} \pi^-$ production is dominated by natural parity exchange and by three partial waves: those with $J^{PC} = 1^{-+}, 2^{++},$ and $4^{++}$. A mass-dependent analysis of the partial-wave amplitudes indicates the production of the $a_2(1320)$ meson as well as the $a_4(2040)$ meson, observed for the first time decaying to $\eta^{\prime}\pi^-$. The dominant, exotic (non-$q\bar{q})$ $1^{-+}$ partial wave is shown to be resonant with a mass of $1.597 \pm 0.010^{+0.045}_{-0.010}$ GeV/c^2 and a width of $0.340 \pm 0.040 \pm 0.050$ GeV/c^2 . This exotic state, the $\pi_1(1600)$, is produced with a $t$ dependence which is different from that of the $a_2(1320)$ meson, indicating differences between the production mechanisms for the two states.Comment: 5 pages with 4 figure

Partial-wave analysis of the eta pi+ pi- system produced in the reaction pi-p --> eta pi+ pi- n at 18 GeV/c

A partial-wave analysis of 9082 eta pi+ pi- n events produced in the reaction pi- p --> eta pi+ pi- n at 18.3 GeV/c has been carried out using data from experiment 852 at Brookhaven National Laboratory. The data are dominated by J^{PC} = 0^{-+} partial waves consistent with observation of the eta(1295) and the eta(1440). The mass and width of the eta(1295) were determined to be 1282 +- 5 MeV and 66 +- 13 Mev respectively while the eta(1440) was observed with a mass of 1404 +- 6 MeV and width of 80 +- 21 MeV. Other partial waves of importance include the 1++ and the 1+- waves. Results of the partial wave analysis are combined with results of other experiments to estimate f1(1285) branching fractions. These values are considerably different from current values determined without the aid of amplitude analyses.Comment: 22 pages, 8 figure

A partial wave analysis of the π0π0\pi ^0\pi ^0 system produced in π−p\pi ^-p charge exchange collisions

A partial wave analysis of the of the $\pi ^0\pi ^0$ system produced in the charge exchange reaction: $\pi ^-p\to \pi ^0\pi ^0n$ at an incident momentum of $18.3 GeV/c$ is presented as a function of ${\pi ^0\pi ^0}$ invariant mass, $m_{\pi^0\pi^0}$, and momentum transfer squared, $| {t} |$, from the incident $\pi^-$ to the outgoing ${\pi ^0\pi ^0}$ system.Comment: 24 pages total,8 pages text, 14 figures, 1 table. Submitted to Phys Rev

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments.

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Δm_{41}^{2}<13  eV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}<1.6 eV^{2}