Hard photodisintegration of a proton pair

We present a Study of high energy photodisintegration of proton-pairs through the gamma + (3)He -\u3e p + p + n channel. Photon energies, E(gamma), from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s(-11) scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photoclisintegration. For E(gamma) below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration. (C) 2010 Elsevier B.V. All rights reserved

Moments of the neutron g(2) structure function at intermediate Q(2)

We present new experimental results for the He-3 spin structure function g(2) in the resonance region atQ 2 values between 1.2 and 3.0 (GeV/c)(2). Spin dependent moments of the neutron were extracted. Our main result, the inelastic contribution to the neutron d(2) matrix element, was found to be small at \u3c Q(2)\u3e = 2.4 (GeV/c)(2) and in agreement with the lattice QCD calculation. The Burkhardt-Cottingham sum rule for He-3 and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region

E00-110 experiment at Jefferson Lab Hall A: Deeply virtual Compton scattering off the proton at 6 GeV

We present final results on the photon electroproduction ((e) over right arrowp - \u3e ep gamma) cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region from Jefferson Lab experiment E00-110. Results from an analysis of a subset of these data were published before, but the analysis has been improved, which is described here at length, together with details on the experimental setup. Furthermore, additional data have been analyzed, resulting in photon electroproduction cross sections at new kinematic settings for a total of 588 experimental bins. Results of the Q(2) and x(B) dependencies of both the helicity-dependent and the helicity-independent cross sections are discussed. The Q(2) dependence illustrates the dominance of the twist-2 handbag amplitude in the kinematics of the experiment, as previously noted. Thanks to the excellent accuracy of this high-luminosity experiment, it becomes clear that the unpolarized cross section shows a significant deviation from the Bethe-Heitler process in our kinematics, compatible with a large contribution from the leading twist-

Exclusive neutral pion electroproduction in the deeply virtual regime

We present measurements of the ep -\u3e ep pi(0) cross section extracted at two values of four-momentum transfer Q(2) = 1.9 GeV(2) and Q(2) = 2.3 GeV(2) at Jefferson Lab Hall A. The kinematic range allows one to study the evolution of the extracted cross section as a function of Q(2) and W. Results are confronted with Regge-inspired calculations and GPD predictions. An intepretation of our data within the framework of semi-inclusive deep inelastic scattering is also discussed

Polarization observables in deuteron photodisintegration below 360 MeV

High precision measurements of induced and transferred recoil proton polarization in d((gamma) over right arrow, (p) over right arrow )n have been performed for photon energies of 277-357 MeV and theta(cm) = 20 degrees-120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used. (C) 2011 Elsevier B.V. All rights reserved

Hard Two-Body Photodisintegration of He-3

We have measured cross sections for the gamma He-3 -\u3e pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90 degrees. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron

Spectroscopy of Li-9(Lambda) by electroproduction

Background: In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei provides information on the details of the effective hyperon-nucleon interaction. Purpose: To obtain a high-resolution binding-energy spectrum for the Be-9(e, e\u27 K+) Li-9(Lambda) reaction. Method: Electroproduction of the hypernucleus Li-9(Lambda) has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a Be-9 target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a ring imaging Cherenkov detector were added to the Hall A standard equipment. Results: The cross section to low-lying states of Li-9(Lambda) is concentrated within 3 MeV of the ground state and can be fit with four peaks. The positions of the doublets agree with theory while a disagreement could exist with respect to the relative strengths of the peaks in the doublets. The Lambda separation energy, B-Lambda, of 8.36 +/- 0.08 (stat.) +/- 0.08 (syst.) MeV was measured, in agreement with an earlier experiment

Community Perspectives on the Impact of Climate Change on Health in Nunavut, Canada

The purpose of this study was to explore community perspectives on the most important ways that climate change is affecting the health of northern peoples. The study was conducted in Iqaluit, Nunavut, using a participatory action approach and the photovoice research method. Participants identified themes and patterns in the data and developed a visual model of the relationships between the themes identified. Five themes emerged from the data: the direct impacts of climate change on the health of individuals and communities, the transition from past climates to future climates, necessary adaptation to the changing climate in the North, the call to action (individual, regional, and national), and reflection on the past and changing knowledge systems. A climate change and health model was developed to illustrate the relationships between the themes. Participants in this study conceptualized health and climate change broadly. Participants believed that by engaging in a process of ongoing reflection, and by continually incorporating new knowledge and experiences into traditional knowledge systems, communities may be better able to adapt and cope with the challenges to health posed by climate change.L’objectif de cette étude consistait à explorer diverses perspectives communautaires quant aux manières les plus importantes dont le changement climatique a des incidences sur la santé des gens du Nord. L’étude a été réalisée à Iqaluit, au Nunavut, au moyen d’une méthode d’action et de recherche participative faisant appel à la « photovoice ». Les participants ont déterminé les thèmes de même que les tendances caractérisant les données, puis ont abouti à un modèle visuel pour établir des relations entre les thèmes ainsi déterminés. Les données ont donné lieu à la formulation de cinq thèmes, soit les incidences directes du changement climatique sur la santé des gens et des collectivités; la transition des anciens climats aux nouveaux climats; l’adaptation nécessaire au climat changeant dans le Nord; un appel à l’action (individuel, régional et national); et une réflexion sur les systèmes de savoir du passé qui sont en pleine évolution. Ensuite, un modèle de changement climatique et de santé a été élaboré dans le but d’illustrer les liens existant entre les divers thèmes. Les participants à cette étude ont conceptualisé le changement climatique et ses incidences sur la santé à grande échelle. Ils croyaient qu’en s’adonnant à un processus de réflexion continue et qu’en intégrant constamment de nouvelles connaissances et expériences aux systèmes de savoir traditionnel, les collectivités pourraient être mieux placées pour s’adapter et relever les défis posés par le changement climatique en matière de santé

Topological Phases near a Triple Degeneracy

We study the pattern of three state topological phases that appear in systems with real Hamiltonians and wave functions. We give a simple geometric construction for representing these phases. We then apply our results to understand previous work on three state phases. We point out that the ``mirror symmetry'' of wave functions noticed in microwave experiments can be simply understood in our framework.Comment: 4 pages, 1 figure, to appear in Phys. Rev. Let