Gas dynamics in high-luminosity polarized He-3 targets using diffusion and convection

The dynamics of the movement of gas is discussed for two-chambered polarized He-3 target cells of the sort that have been used successfully for many electron scattering experiments. A detailed analysis is presented showing that diffusion is a limiting factor in target performance, particularly as these targets are run at increasingly high luminosities. Measurements are presented on a new prototype polarized He-3 target cell in which the movement of gas is due largely to convection instead of diffusion. NMR tagging techniques have been used to visualize the gas flow, showing velocities along a cylindrically-shaped target of between 5-80 cm/min. The new target design addresses one of the principle obstacles to running polarized He-3 targets at substantially higher luminosities while simultaneously providing new flexibility in target geometry.Comment: First revision: 14 pages, 9 figures, submitted to Phys. Rev. C. We have shortened our discussion of the limitations inherent in various historical He-3 targets, and we have added a discussion exploring the optimal performance that can be expected from a suitably modified target based on diffusion-based mixing. A reference (Jones et. al.) was added. The results we present have not change

The Power of Environmental Observatories for Advancing Multidisciplinary Research, Outreach, and Decision Support: The Case of the Minnesota River Basin

An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union.Observatory‐scale data collection efforts allow unprecedented opportunities for integrative, multidisciplinary investigations in large, complex watersheds, which can affect management decisions and policy. Through the National Science Foundation‐funded REACH (REsilience under Accelerated CHange) project, in collaboration with the Intensively Managed Landscapes‐Critical Zone Observatory, we have collected a series of multidisciplinary data sets throughout the Minnesota River Basin in south‐central Minnesota, USA, a 43,400‐km2 tributary to the Upper Mississippi River. Postglacial incision within the Minnesota River valley created an erosional landscape highly responsive to hydrologic change, allowing for transdisciplinary research into the complex cascade of environmental changes that occur due to hydrology and land use alterations from intensive agricultural management and climate change. Data sets collected include water chemistry and biogeochemical data, geochemical fingerprinting of major sediment sources, high‐resolution monitoring of river bluff erosion, and repeat channel cross‐sectional and bathymetry data following major floods. The data collection efforts led to development of a series of integrative reduced complexity models that provide deeper insight into how water, sediment, and nutrients route and transform through a large channel network and respond to change. These models represent the culmination of efforts to integrate interdisciplinary data sets and science to gain new insights into watershed‐scale processes in order to advance management and decision making. The purpose of this paper is to present a synthesis of the data sets and models, disseminate them to the community for further research, and identify mechanisms used to expand the temporal and spatial extent of short‐term observatory‐scale data collection efforts

The Power of Environmental Observatories for Advancing Multidisciplinary Research, Outreach, and Decision Support: The Case of the Minnesota River Basin

Observatory‐scale data collection efforts allow unprecedented opportunities for integrative, multidisciplinary investigations in large, complex watersheds, which can affect management decisions and policy. Through the National Science Foundation‐funded REACH (REsilience under Accelerated CHange) project, in collaboration with the Intensively Managed Landscapes‐Critical Zone Observatory, we have collected a series of multidisciplinary data sets throughout the Minnesota River Basin in south‐central Minnesota, USA, a 43,400‐km2 tributary to the Upper Mississippi River. Postglacial incision within the Minnesota River valley created an erosional landscape highly responsive to hydrologic change, allowing for transdisciplinary research into the complex cascade of environmental changes that occur due to hydrology and land use alterations from intensive agricultural management and climate change. Data sets collected include water chemistry and biogeochemical data, geochemical fingerprinting of major sediment sources, high‐resolution monitoring of river bluff erosion, and repeat channel cross‐sectional and bathymetry data following major floods. The data collection efforts led to development of a series of integrative reduced complexity models that provide deeper insight into how water, sediment, and nutrients route and transform through a large channel network and respond to change. These models represent the culmination of efforts to integrate interdisciplinary data sets and science to gain new insights into watershed‐scale processes in order to advance management and decision making. The purpose of this paper is to present a synthesis of the data sets and models, disseminate them to the community for further research, and identify mechanisms used to expand the temporal and spatial extent of short‐term observatory‐scale data collection efforts

Single Spin Asymmetries of Inclusive Hadrons Produced in Electron Scattering from a Transversely Polarized 3^3He Target

We report the first measurement of target single-spin asymmetries (A$_N$) in the inclusive hadron production reaction, $e~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a transversely polarized $^3$He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons ($\pi^{\pm}$, $\text{K}^{\pm}$ and proton) were detected in the transverse hadron momentum range 0.54 $<p_T<$ 0.74 GeV/c. The range of $x_F$ for pions was -0.29 $<x_F<$ -0.23 and for kaons -0.25 $<x_F<$-0.18. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for $\pi^+$ and $\text{K}^+$. A negative asymmetry is observed for $\pi^{-}$. The magnitudes of the asymmetries follow $|A^{\pi^-}| < |A^{\pi^+}| < |A^{K^+}|$. The K$^{-}$ and proton asymmetries are consistent with zero within the experimental uncertainties. The $\pi^{+}$ and $\pi^{-}$ asymmetries measured for the $^3$He target and extracted for neutrons are opposite in sign with a small increase observed as a function of $p_T$.Comment: Updated version, submitted to Phys. Rev.

Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized 3^3He target

An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized $^3$He target was performed at Jefferson Lab in the kinematic region of $0.16<x<0.35$ and $1.4<Q^2<2.7$ ${\rm GeV^2}$. The pretzelosity asymmetries on $^3$He, which can be expressed as the convolution of the $h^\perp_{1T}$ transverse momentum dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Using the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured $^3$He asymmetries and cross-section ratios between the proton and $^3$He. Our results show that for both $\pi^{\pm}$ on $^3$He and on the neutron the pretzelosity asymmetries are consistent with zero within experimental uncertainties.Comment: 6 pages, 3 figures; enlarged the legends in Fig.3; added 3 citation

Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp

The electric form factor of the neutron was determined from studies of the reaction He3(e,e'n)pp in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2-range over which it is known, we find GEn = 0.0225 +/- 0.0017 (stat) +/- 0.0024 (syst), 0.0200 +/- 0.0023 +/- 0.0018, and 0.0142 +/- 0.0019 +/- 0.0013 for Q2 = 1.72, 2.48, and 3.41 GeV2, respectively.Comment: submitted to PR

Double Spin Asymmetries of Inclusive Hadron Electroproductions from a Transversely Polarized 3He^3\rm{He} Target

We report the measurement of beam-target double-spin asymmetries ($A_\text{LT}$) in the inclusive production of identified hadrons, $\vec{e}~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized $^3\rm{He}$ target. Hadrons ($\pi^{\pm}$, $K^{\pm}$ and proton) were detected at 16$^{\circ}$ with an average momentum $$=2.35 GeV/c and a transverse momentum ($p_{T}$) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the $^3\text{He}$ target were observed to be non-zero for $\pi^{\pm}$ production when the target was polarized transversely in the horizontal plane. The $\pi^{+}$ and $\pi^{-}$ asymmetries have opposite signs, analogous to the behavior of $A_\text{LT}$ in semi-inclusive deep-inelastic scattering.Comment: Published in PRC (92.015207), nuclear experiment, high-energy experimen