Photodisintegration of He4 into p+t

The two-body photodisintegration of 4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid 4He target. This is the first measurement of the photodisintegration of 4He above 0.4 GeV. The differential cross sections for the γ4He→pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of 3He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV

Coherent photoproduction of π+ from 3He

We have measured the differential cross section for the γHe3→π+t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid 3He target. The differential cross sections for the γ3He→π+t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model

Photodisintegration of \u3csup\u3e4\u3c/sup\u3eHe into \u3ci\u3ep\u3c/i\u3e + \u3ci\u3et\u3c/i\u3e

The two-body photodisintegration of 4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid 4He target. This is the first measurement of the photodisintegration of 4He above 0.4 GeV. The differential cross sections for the γ 4He → pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.M. Laget. At 0.6–1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of 3He that demonstrated the great importance of three-body mechanisms in the energy region 0.5–0.8 GeV

Polarized structure function σLT′ for 1H(e→,e′K+)Λ in the nucleon resonance region

The first measurements of the polarized structure function σLT′ for the reaction 1H(e→,e′K+)Λ in the nucleon resonance region are reported. Measurements are included from threshold up to W=2.05 GeV for central values of Q2 of 0.65 and 1.00 GeV2, and nearly the entire kaon center-of-mass angular range. σLT′ is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and nonresonant processes. The results for σLT′ are comparable in magnitude to previously reported results from CLAS for σLT, the real part of the same response. An intriguing sign change in σLT′ is observed in the high Q2 data at W≈1.9 GeV. Comparisons to several existing model predictions are shown

Search for Medium Modifications of the ρ Meson

The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, ρ, ω, and ϕ, are observed via their decay to e+e−, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the ρ meson. The ρ mass spectrum is extracted from the data on various nuclei,2 H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the ρ meson

Chiral Symmetry in Nuclei -- Theoretical Expectations and Hard Facts

It is widely believed that chiral symmetry is restored not only at high temperatures, but also at high nuclear densities. The drop of the order parameter of the chiral phase transition, the chiral condensate, with density has indeed been calculated in various models and is as such a rather robust result. In this talk I point out that the connection of this property with actual observables is far less clear. For this task a good hadronic description of the primary production of hadrons, their propagation inside the nuclear medium, their decay and the propagation of the decay products through the medium to the detector all have to be treated with equal accuracy and weight. In this talk I illustrate with the examples of $\omega$ production and $\pi^0\pi^0$ production how important in particular final state interactions are.Comment: Invited Talk at Chiral07, Osaka, Japan, Nov. 13 - 16, 200

Coherent Photoproduction of \u3ci\u3eπ\u3c/i\u3e\u3csup\u3e+\u3c/sup\u3e from 3He

We have measured the differential cross section for the γ3He→ π+t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid 3He target. The differential cross sections for the γ3He→ π+t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model

Professionalism and dental education:in search of a shared understanding

Professionalism has profound historical origins; however, the current health care environment in the UK dental sphere is changing, which presents new professional dilemmas that require continued learning and debate. Professionalism is a key aspect of the education of dental students and the lifelong learning and development of dental practitioners. However, 'being' professional can be challenging because while it is recognised as a social good, there is much debate on what professionalism means and how best it can be learned and assessed. Since 2017, the UK Council for the Dental Teachers of Professionalism, consisting of educators from UK dental schools and dental therapy hygiene institutions, has been exploring and debating the role and place of professionalism, as well as sharing challenges and good practice within UK dental education. This paper includes a narrative overview of current thinking in the academic literature on professionalism to consider the use of a shared understanding of professionalism to facilitate conversations between various stakeholders

Coherent photoproduction of pi(+) from He-3

We have measured the differential cross section for the gamma He-3 -\u3e pi(+)t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid He-3 target. The differential cross sections for the gamma He-3 -\u3e pi(+)t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model