Atomic electron motion for Møller polarimetry in a double-arm mode

We analyse an effect of electron Fermi motion at atomic shells on the accuracy of electron beam polarization measurements with a M\"oller polarimeter operating in a double--arm mode. It is demonstrated that the effect can result in either {\it increase} or {\it decrease} of the measured polarization depending on the detector positions. The effect is simulated for the M\"oller polarimeter to be installed at CEBAF Hall A

Millimeter-wave study of London penetration depth temperature dependence in Ba(Fe0.926Co0.074)2As2 single crystal

In-plane surface Ka-band microwave impedance of optimally doped single crystals of the Fe-based superconductor Ba(Fe0.926Co0.074)2As2 (Tc= 22.8K) was measured. Sensitive sapphire disk quasi-optical resonator with high-Tc cuprate conducting endplates was developed specially for Fe-pnictide superconductors. It allowed finding temperature variation of London penetration depth in a form of power law, namely \Delta \lambda (T)~ Tn with n = 2.8 from low temperatures up to at least 0.6Tc consisted with radio-frequency measurements. This exponent points towards nodeless state with pairbreaking scattering, which can support one of the extended s-pairing symmetries. The dependence \lambda(T) at low temperatures is well described by one superconducting small-gap (\Delta \cong 0.75 in kTc units, where k is Boltzman coefficient) exponential dependence.Comment: 6 pages, 2 figures, to be published in Low Temperature Physics,vol.37, August 201

Møllerov polarimetar za elektrone u dvorani A u JLabu

As part of the spin-physics program at Jefferson Laboratory (JLab), a Moller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for Moller scattering is obtained using a series of three quadrupole magnets which provide an angular selection, and a dipole magnet for energy analysis. The design, commissioning and the first results of the polarization measurements of this polarimeter will be presented as well as future plans to use its small scattering angle capabilities to investigate physics in very low Q2 regime.Kao dio programa istraživanja spinske fizike, u Jeffersonovom se laboratoriju sagradio Møllerov polarimetar radi mjerenja polarizacije elektrona energije 0,8 do 5,0 GeV. Jedinstven signal za Møllerovo raspršenje se postiže nizom od tri kvadrupolna magneta koji određuju kut, te dipolnim magnetom za analizu impulsa elektrona. Opis, preuzimanje i prva mjerenja s tim polarimetrom se izlažu, kao i planovi za buduću upotrebu mogućnosti sustava za mjerenja na malim kutovima raspršenja radi istraživanja fizike za vrlo male Q2

Møllerov polarimetar za elektrone u dvorani A u JLabu

As part of the spin-physics program at Jefferson Laboratory (JLab), a Moller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for Moller scattering is obtained using a series of three quadrupole magnets which provide an angular selection, and a dipole magnet for energy analysis. The design, commissioning and the first results of the polarization measurements of this polarimeter will be presented as well as future plans to use its small scattering angle capabilities to investigate physics in very low Q2 regime.Kao dio programa istraživanja spinske fizike, u Jeffersonovom se laboratoriju sagradio Møllerov polarimetar radi mjerenja polarizacije elektrona energije 0,8 do 5,0 GeV. Jedinstven signal za Møllerovo raspršenje se postiže nizom od tri kvadrupolna magneta koji određuju kut, te dipolnim magnetom za analizu impulsa elektrona. Opis, preuzimanje i prva mjerenja s tim polarimetrom se izlažu, kao i planovi za buduću upotrebu mogućnosti sustava za mjerenja na malim kutovima raspršenja radi istraživanja fizike za vrlo male Q2

Preliminary Results from Integrating Compton Photon Polarimetry in Hall A of Jefferson Lab

A wide range of nucleon and nuclear structure experiments in Jefferson Lab's Hall A require precise, continuous measurements of the polarization of the electron beam. In our Compton polarimeter, electrons are scattered off photons in a Fabry-Perot cavity; by measuring an asymmetry in the integrated signal of the scattered photons detected in a GSO crystal, we can make non-invasive, continuous measurements of the beam polarization. Our goal is to achieve 1% statistical error within two hours of running. We discuss the design and commissioning of an upgrade to this apparatus, and report preliminary results for experiments conducted at beam energies from 3.5 to 5.9 GeV and photon rates from 5 to 100 kHz.Comment: 6 pages, 7 figures. To appear in the Proceedings of the International Nuclear Physics Conference (INPC 2010), July 4-9 2010, Vancouver, Canada (Journal of Physics: Conference Series

A New Measurement of the π0\pi^0 Radiative Decay Width

High precision measurements of the differential cross sections for $\pi^0$ photoproduction at forward angles for two nuclei, $^{12}$C and $^{208}$Pb, have been performed for incident photon energies of 4.9 - 5.5 GeV to extract the ${\pi^0 \to \gamma\gamma}$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${\pi^0 \to \gamma\gamma}$ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is $\Gamma{(\pi^0 \to \gamma\gamma)} = 7.82 \pm 0.14 ~({\rm stat.}) \pm 0.17 ~({\rm syst.}) ~{\rm eV}$. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current PDG average of this fundamental quantity and it is consistent with current theoretical predictions.Comment: 4 pages, 5 figure

ИССЛЕДОВАНИЕ ПЕРЕНОСИМОСТИ КОМПЛЕКСНОГО ПРОТИВОПАРАЗИТАРНОГО ПРЕПАРАТА «ИНСПЕКТОР ОШЕЙНИК»

Objective of research: To evaluate the tolerability of the drug, “Inspector Collar” based on Fipronil, Pyriproxyfen and Ivermectin in dogs and cats applied at a therapeutic dose and double increased therapeutic doses.Materials and methods: Research was conducted at the shelter for dogs and cats «Bano Eco» (Moscow). Effect of drug “Inspector Collar” was studied on 15 clinically healthy outbreed dogs between 2 and 6 years with the body mass of 10–14 kg and 15 clinically healthy outbreed cats between 2 and 4 years with the body mass of 2–3,5 kg, receiving complete and balanced nutrition. Animals were divided into six groups (three groups of dogs and three of cats) five animals in each group. Dogs and cats from the first experimental group had put on one collar (equivalent of single therapeutic dose) for 45 days. The second experimental group had put two collars (double therapeutic dose) for 45 days. Animals from the third (control) group did not carry collars. During the experiment, daily supervision of animals was conducted; their general health status, behavior, appetite were observed, body mass and temperature estimated. Before and 15 and 30 days after the beginning of drug application, blood and urine tests were performed to study morphological and biochemical parameters. Statistical processing of data were carried out using Student’s t-test.Results and discussion: The research results showed that the drug “Inspector Collar” is well tolerated even at double therapeutic dose. All observed indicators remained within the physiological norm.Цель исследований — изучить переносимость препарата «Инспектор ошейник» на основе фипронила, пирипроксифена и ивермектина на собаках и кошках в терапевтической и двукратно увеличенной терапевтической дозах.Материалы и методы. Исследования проводили в приюте для собак и кошек «Бано Эко» (Москва). Влияние препарата на организм изучали на 15 клинически здоровых беспородных собаках 2–6-летнего возраста массой тела 10–14 кг и на 15 клинически здоровых беспородных кошках 2–4-летнего возраста массой тела 2–3,5 кг, содержащихся на стандартном полнорационном кормлении. Животных по принципу аналогов разделили на шесть групп (три группы собак и три группы кошек) по пять животных в каждой. Собакам и кошкам первой опытной группы надевали один ошейник (что соответствует терапевтической дозе препарата) на срок 45 суток. Второй опытной группе надевали два ошейника (двукратно увеличенная терапевтическая доза) на 45 суток. Третьей группе (контрольной) ошейник не надевали. В течение опыта за животными вели ежедневное наблюдение, отмечая их общее состояние, поведение, аппетит, контролировали их массу, температуру тела. До начала опыта, а также через 15 и 30 суток после начала применения препарата брали кровь и мочу для исследования морфологических и биохимических показателей. Статистическую обработку полученных данных проводили с использованием критерия Стьюдента.Результаты и обсуждение. Препарат «Инспектор ошейник» обладает хорошей переносимостью даже в двукратно увеличенной терапевтической дозе. Все наблюдаемые показатели оставались в пределах физиологической нормы