We report the measurement of the helicity asymmetry E for the pπ^{0} and nπ^{+} final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g.
View Article and Find Full Text PDFThe target asymmetry , recoil asymmetry , and beam-target double polarization observable were determined in exclusive and photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass.
View Article and Find Full Text PDFA precise measurement of the differential cross sections dσ/dΩ and the linearly polarized photon beam asymmetry Σ_{3} for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: α_{E1}=10.
View Article and Find Full Text PDFEur Phys J A Hadron Nucl
June 2021
The quasifree photon beam asymmetry, , has been measured at photon energies, , from 390 to 610Â MeV, corresponding to center of mass energy from 1.271 to 1.424Â GeV, for the first time.
View Article and Find Full Text PDFThe double-polarization observable E and helicity-dependent cross sections σ_{1/2}, σ_{3/2} have been measured for the photoproduction of π^{0} pairs off quasifree protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost 4π covering calorimeter.
View Article and Find Full Text PDFWe report a measurement of the spin polarization of the recoiling neutron in deuterium photodisintegration, utilizing a new large acceptance polarimeter within the Crystal Ball at MAMI. The measured photon energy range of 300-700 MeV provides the first measurement of recoil neutron polarization at photon energies where the quark substructure of the deuteron plays a role, thereby providing important new constraints on photodisintegration mechanisms. A very high neutron polarization in a narrow structure centered around E_{γ}∼570  MeV is observed, which is inconsistent with current theoretical predictions employing nucleon resonance degrees of freedom.
View Article and Find Full Text PDFIn this paper, we propose a theoretical study dedicated to the assessment of plasma current measurement in magnetic confinement fusion reactors using a polarization optical time-domain reflectometer (POTDR) setup with a low-birefringence fiber used as the sensing fiber. We consider the general case of a non-uniform magnetic-field distribution along the sensing fiber. The numerical simulations, based on Jones formalism taking into account the OTDR noise, provide the measurement error as a function of the plasma current.
View Article and Find Full Text PDFThe paper reports on the solution, principles, and application results related to a system for diagnosing main transformers in power plants via the radiofrequency method. The subject of the diagnostics is the occurrence of partial discharge activity in transformers. The technical solution of the system is characterized in the introductory section of the article.
View Article and Find Full Text PDFWe report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.
View Article and Find Full Text PDFThe photoproduction of η mesons off nucleons bound in 2H and 3He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility.
View Article and Find Full Text PDFPhys Rev Lett
September 2012
The first measurement is reported of the double-polarization observable G in the photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances.
View Article and Find Full Text PDFThis is a case study of Corey, a 9-year-old latency age boy living with two mothers and without an everyday father in the home. Corey presented with separation anxieties stemming from needle insertions he was forced to endure at the hands of one of his mothers, a licensed pediatrician. His anxieties were exacerbated by the unpredictable rages of his father, whom he began to see more frequently and for a longer duration starting at age 8.
View Article and Find Full Text PDFThe purpose of this study was to evaluate the surface hardness of a resin composite (TPH) polymerized with and without the use of a transparent light-curing cone. Twenty composite blocks were made on a Teflon mold with cylindrical holes of 3 mm depth and 6 mm radius, and were light cured following different procedures. Group 1: Ten samples were pressed with a glass slide and light cured for two 40-sec exposures without the plastic cone; Group 2: Ten samples were light cured using the transparent plastic cone which was pressed down into the composite until the tip was 1 mm from the floor of the cylindrical Teflon mold.
View Article and Find Full Text PDFBackground: Previously, we demonstrated that ketorolac, a nonsteroidal antiinflammatory drug (NSAID), prevented postoperative small bowel ileus in a rodent model. The aim of this study was to evaluate the effect of salsalate, an NSAID without antiplatelet effect, on postoperative ileus alone or in combination with morphine.
Methods: Forty-eight rats underwent placement of duodenal catheters and were then randomly assigned to one of eight groups (n = 6).
Objective: To determine how formulary changes, based on the recommendations of a clinical pharmacy specialist, affected outpatient nonsteroidal antiinflammatory drug (NSAID) prescribing patterns and drug costs in a Department of Veterans Affairs (VA) teaching hospital.
Design: Cost-benefit analysis.
Setting: VA teaching hospital.
One hundred one patients receiving enteral nutritional support (ENS) by tube feeding during a 5-month period were prospectively studied. Fifty patients were managed by a nutritional support team (T) and 51 patients were managed by the nonteam approach (NT). Demographics, primary diagnosis, chronic diseases, medical service, calculated basal energy expenditure (BEE), duration of ENS, and final patient disposition were recorded.
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