Display of variability of bilateral features in taiga ticks in contrast conditions of habitation

The current research is aimed at studying the changes in a ratio of symmetrical to asymmetrical forms based on the counting bilateral characters in Ixodes persulcatus samples in various living conditions. Phenotypic variation was described with the following indices: (of) for a dispersion of the number of bristles at the left and right side; (Sa) for actual and (St) for theoretical number of symmetrical specimens with the supposition of an independent manifestation of such characters at the both sides of a body; and the difference between Sa and St. 4 bilateral characters were studied on the coxae of the fourth leg of the ticks collected by dragging off the plants outside Irkutsk (299 specimens) and Bratsk (156 specimens). The both territories are characterized by an excess of Sa and St. The σd2 value was proved to be higher among the ticks outside Bratsk where they live in a difficult environment. Given that no differences were revealed in the average values of «Sa-St» index, being characteristic of a subdivision of samples, the observed difference in of values may be considered as a prove of an increased instability during ontogeny under adverse circumstances

Experimental study of the radiation emitted by 180-GeV/c electrons and positrons volume-reflected in a bent crystal

The radiation emitted by 180-GeV/c volume-reflected electrons and positrons impinging on a bent crystal has been measured by the H8RD22 Collaboration on the H8 beamline at the CERN SPS. A dedicated spectrometer has been developed to measure high-energy photon spectra (up to similar to 100 GeV) under volume reflection: photon and charged particle beams have been separated by a bending magnet and leptons were detected and tagged by microstrip silicon detectors and a Pb-scintillator sampling calorimeter. A comparison between the experimental and analytical data for the amorphous and volume-reflection cases is presented and the differences are discussed

Experimental study of the radiation emitted by 180-GeV/c electrons and positrons volume-reflected in a bent crystal

The radiation emitted by 180-GeV/c volume-reflected electrons and positrons impinging on a bent crystal has been measured by the H8RD22 Collaboration on the H8 beamline at the CERN SPS. A dedicated spectrometer has been developed to measure high-energy photon spectra (up to similar to 100 GeV) under volume reflection: photon and charged particle beams have been separated by a bending magnet and leptons were detected and tagged by microstrip silicon detectors and a Pb-scintillator sampling calorimeter. A comparison between the experimental and analytical data for the amorphous and volume-reflection cases is presented and the differences are discussed

High-efficiency deflection of high energy protons due to channeling along the (110) axis of a bent silicon crystal

A deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110) planes it is about 25%. High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles

Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

In ideal two-stage collimation systems, the secondary collimator–absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator–absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator–absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber

Observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy negative particles

Multiple volume reflection by different planes passing through the axis in a bent silicon crystal was observed for the first time for 150 GeV/c negative particles, pi(-) mesons, at one of the secondary beams of the CERN SPS. The beam of pi(-) mesons was deflected opposite to the crystal bend by an angle of about 48 mu rad, which is 4.6 times larger than in a single volume reflection by the (110) bent planes. The one-side deflection efficiency was about 65\%. Multiple volume reflection transforms to a single volume reflection when the orientation angle of the axis relative to the beam direction is increased. Copyright (c) EPLA, 201

Multiple volume reflections of high-energy protons in a sequence of bent silicon crystals assisted by volume capture

Multiple volume reflections of the 400 GeV/c proton beam by the sequence of fourteen bent silicon strips has been studied at the CERN SPS. The sequence is close to be parallel that is the spread of the strip orientation angles is much smaller than their bend angle and eleven strips working coherently in the regime of volume reflections deflected the beam by 110 mu rad with the efficiency 88%, which is significantly larger than the estimation based on independent reflections. The mechanism giving the efficiency increase has been studied by simulation. It appears that many particles volume captured in one of the strips take part in volume reflections in the subsequent ones. Such a crystal multi reflector can be successfully used as a primary collimator for the beam halo collimation of high-energy accelerators

First observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy protons

Multiple volume reflection by different planes in a bent silicon crystal with its axis orientation close to the beam direction was observed for the first time for 400 GeV/c protons at the CERN SPS. The proton beam was deflected to the side opposite to the crystal bend by an angle of about 67 urad, which is five times larger than in a single volume reflection by the (110) bent planes. The registered efficiency of one side deflection was about 84%. It was shown that multiple volume reflection transforms to a single volume reflection when the orientation angle of the axis relative to the beam direction is increased