Novel diagnostic for precise measurement of the modulation frequency of Seeded Self-Modulation via Coherent Transition Radiation in AWAKE

We present the set-up and test-measurements of a waveguide-integrated heterodyne diagnostic for coherent transition radiation (CTR) in the AWAKE experiment. The goal of the proof-of-principle experiment AWAKE is to accelerate a witness electron bunch in the plasma wakefield of a long proton bunch that is transformed by Seeded Self-Modulation (SSM) into a train of proton micro-bunches. The CTR pulse of the self-modulated proton bunch is expected to have a frequency in the range of 90-300 GHz and a duration of 300-700 ps. The diagnostic set-up, which is designed to precisely measure the frequency and shape of this CTR-pulse, consists of two waveguide-integrated receivers that are able to measure simultaneously. They cover a significant fraction of the available plasma frequencies: the bandwidth 90-140 GHz as well as the bandwidth 255-270 GHz or 170-260 GHz in an earlier or a latter version of the set-up, respectively. The two mixers convert the CTR into a signal in the range of 5-20 GHz that is measured on a fast oscilloscope, with a high spectral resolution of 1-3 GHz dominated by the pulse length. In this contribution, we will describe the measurement principle, the experimental set-up and a benchmarking of the diagnostic in AWAKE.Comment: Conference proceedings to 3rd European Advanced Accelerator Concepts Worksho

Predicting the optical observables for nucleon scattering on even-even actinides

Previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on $^{232}$Th and $^{238}$U nuclei is extended to describe scattering on even-even actinides with $Z=$90--98. A soft-rotator-model (SRM) description of the low-lying nuclear structure is used, where SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions (mixed in $K$ quantum number) have been used to calculate coupling matrix elements of the generalized optical model. The "effective" deformations that define inter-band couplings are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential leading to additional couplings between rotational bands. Fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizs\"acker-Skyrme global mass model (WS4), allowing to use the latter to predict cross section for nuclei without experimental data. A good description of scarce "optical" experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from the one calculated with rigid-rotor potentials coupling the ground-state rotational band. Derived parameters can be used to describe both neutron and proton induced reactions.Comment: 6 pages, 4 figures, 5 table

Nucleon scattering on actinides using a dispersive optical model with extended couplings

Tamura coupling model has been extended to consider the coupling of additional low-lying rotational bands to the ground state band. Rotational bands are built on vibrational bandheads (even-even targets) or single particle bandheads (odd-$A$ targets) including both axial and non-axial deformations. These additional excitations are introduced as a perturbation to the underlying axially-symmetric rigid rotor structure of the ground state rotational band. Coupling matrix elements of the generalized optical model are derived for extended multi-band transitions in even-even and odd-$A$ nuclei. Isospin symmetric formulation of the optical model is employed. A coupled-channels optical model potential (OMP) containing a dispersive contribution is used to fit simultaneously all available optical experimental databases including neutron strength functions for nucleon scattering on $^{232}$Th, $^{233,235,238}$U and $^{239}$Pu nuclei and quasi-elastic ($p$,$n$) scattering data on $^{232}$Th and $^{238}$U. Lane consistent OMP is derived for all actinides if corresponding multi-band coupling schemes are defined. Calculations using the derived OMP potential reproduce measured total cross-section differences between several actinide pairs within experimental uncertainty for incident neutron energies from 50 keV up to 150MeV. Multi-band coupling is stronger in even-even targets due to the collective nature of the coupling; the impact of extended coupling on predicted compound-nucleus formation cross section reaches 5% below 3 MeV of incident neutron energy. Coupling of ground-state rotational band levels in odd-$A$ nuclei is sufficient for a good description of the compound-nucleus formation cross sections as long as the coupling is saturated (a minimum of 7 coupled levels are typically needed).Comment: 30 pages, 4 figures, 8 tables, 3 appendice

Reaction of cardiovascular and respiratory system of the first-year pupils to the various types of load during the school year

© Medwell Journals, 2016.Study of respiratory functions and functions of cardiovascular system of 8 years old pupils of the 1st grade of secondary school, in a state of relative rest, after the graduated dynamic and static load at the beginning, in the middle and at the end of school year was conducted. It was found that the static load caused no changes in the parameters of the cardiovascular system of the first graders. Only at the end of the year, the group of girls showed changes in the parameters of the cardiovascular system. Dynamic load in all stages of research led to changes in the parameters of cardiovascular system. At the beginning of the year, boys showed adverse reaction of the parameters of external respiration. By mid year, the adaptive capacity of the cardio-respiratory system of the 8 years old children was optimal. By spring, the local static load caused adverse changes in the respiratory system of the boys. By the end of the school year, the group of first grade girls showed an adverse reaction of the parameters of external respiration to both dynamic and static load

Dispersive optical model description of nucleon scattering on Pb-Bi isotopes

A recently derived dispersive optical model potential (DOMP) for $^{208}$Pb is extended to consider the non-locality in the real potential and the shell-gap in the definition of the nuclear imaginary potentials near the Fermi energy. The modified DOMP improves the simultaneous description of nucleon scattering on $^{208}$Pb and of the $^{208}$Pb particle-hole bound states. The new potential is shown to give a very good description of nucleon scattering data on near-magic targets $^{206,207}$Pb and $^{209}$Bi.Comment: 9 pages, 8 figure

Control of platelet CLEC-2-mediated activation by receptor clustering and tyrosine kinase signalling

Platelets are blood cells responsible for vascular integrity preservation. The activation of platelet receptor CLEC-2 could partially mediate the latter function. Although this receptor is considered to be of importance for hemostasis, the rate-limiting steps of CLEC-2 induced platelet activation are not clear. Here we aimed to investigate CLEC-2-induced platelet signal transduction using computational modelling in combination with experimental approaches. We developed a stochastic multicompartmental computational model of CLEC-2 signalling. The model described platelet activation beginning with CLEC-2 receptor clustering, followed by Syk and SFK phosphorylation, determined by the cluster size. Active Syk mediated LAT protein phosphorylation and membrane signalosome formation, which resulted in the activation of Btk, PLC and PI3K, calcium and phosphoinositide signalling. The model parameters were assessed from published experimental data. Flow cytometry, TIRF and confocal microscopy and western blotting quantification of the protein phosphorylation were used for the assessment of the experimental dynamics of CLEC-2-induced platelet activation. Analysis of the model revealed that the CLEC-2 receptor clustering leading to the membrane-based signalosome formation is a critical element required for the accurate description of the experimental data. Both receptor clustering and signalosome formation are among the rate-limiting steps of CLEC-2-mediated platelet activation. In agreement with these predictions, the CLEC-2 induced platelet activation, but not activation mediated by G-protein coupled receptors, was strongly dependent on temperature conditions and cholesterol depletion. Besides, the model predicted that CLEC-2 induced platelet activation results in cytosolic calcium spiking, which was confirmed by single platelet TIRF microscopy imaging. Our results suggest a refined picture of the platelet signal transduction network associated with CLEC-2. We show that the tyrosine kinases activation is not the only rate-limiting step in CLEC-2 induced activation of platelets. Translocation of receptor-agonist complexes to the signalling region and LAT-signalosome formation in this region are limiting CLEC-2-induced activation as well

Tailoring the oxidation state of cobalt through halide functionality in sol-gel silica

The functionality or oxidation state of cobalt within a silica matrix can be tailored through the use of cationic surfactants and their halide counter ions during the sol-gel synthesis. Simply by adding surfactant we could significantly increase the amount of cobalt existing as Co3O4 within the silica from 44% to 77%, without varying the cobalt precursor concentration. However, once the surfactant to cobalt ratio exceeded 1, further addition resulted in an inhibitory mechanism whereby the altered pyrolysis of the surfactant decreased Co3O4 production. These findings have significant implications for the production of cobalt/silica composites where maximizing the functional Co3O4 phase remains the goal for a broad range of catalytic, sensing and materials applications

Георадарные исследования для подготовки взлетно-посадочной полосы на морском льду в районе полевой базы Оазис Бангера, Восточная Антарктида

When one is carrying out logistic operations at Russian Antarctic stations, organization and safe operation of snow-runways play an important role. Nowadays six of the seven existing stations and field bases of the Russian Antarctic expedition (RAE) are provided with air communication, however, the Bunger Oasis field base is still outside the air transportation structure. The aim of the investigations described in this paper was to find a safe site for organizing a snow-runway in the area of the Bunger Oasis field base. Taking into account the location of the infrastructure objects of RAE within the Bunger Oasis, the central part of the epishelf Transcription Gulf, situated 7 km away from the base, was chosen as the most appropriate site. During the summer field season of the 64th RAE (2018/2019), a geophysical survey using the GPR (Ground-penetrating radar) method was carried out within the area to obtain data on the thickness of the bay ice. The GPR survey conducted shows that the sea ice thickness varies from 2.9 to 3.1 m. Moreover, no signs of discontinuities in the ice layer were found. The area investigated was identified as a safe site suitable for the landing of light and medium aircraft. However, due to the specificity of the relief of the oasis adjacent to the Bay, the weathering products of the rocks composing the hills migrated to the surface of the ice layer. The effect of solar radiation caused the thawing in the areas of such particles to increase, and this, in turn, led to the formation of cavities on the surface, the dimensions of which do not meet the requirements for runway coatings. As a result, in the area under study, the boundaries of the sites were determined that are suitable for the organization of runways for medium and small aircraft without preliminary rolling of the landing site.В настоящей работе представлены результаты исследований, выполненных в районе полевой базы Оазис Бангера в ходе полевого сезона 64-й РАЭ (2018/19 г.). Целью работ был поиск безопасной площадки для организации посадочной полосы для самолетов средней и малой авиации. Наиболее подходящим местом для возможного аэродрома был выбран покров залива Транскрипция, располагающегося на удалении 7 км от базы. В рамках исследований были выполнены геофизические инженерные изыскания методом георадиолокации для определения мощности льда залива и выявления нарушения целостности ледяного покрова. По результатам работ был найден безопасный участок для приема мало- и среднегабаритных самолетов на лыжных шасси