The direct reconstruction of pp elastic scattering amplitudes at the SPASCHARM experiment is discussed. The observables are expressed in terms of invariant amplitudes. These amplitudes are deduced ...analytically by solving bilinear relations. Monte-Carlo simulations of elastic scattering as well background reactions were carried out. Elastic and diffraction interactions of protons were simulated by using PYTHIA generator for 16 GeV incident protons, designed Setup geometry and the resolution of the detectors. The criteria to select elastic processes are discussed and presented. Two-dimensional distributions of the product of the tangents of the polar angles of the recoil particle and the scattered particle versus difference of the azimuth angles of these particles, were obtained. The estimated ratio of the signal to background S/(S+B) is about 0.99.
The altitudes of typical auroral forms observed on the polar and equatorial boundaries of the auroral oval are analyzed. Triangulation based on data from two pairs of cameras located in Apatity and ...Barentsburg is used. The cameras in pairs are separated by ~4 km. The energy of precipitating electrons is estimated in dynamics for different auroral structures.
We present a method for automatic search and parameterization of discrete elements of very low-frequency (VLF) chorus emissions. The method is based on the processing of dynamic spectrograms using a ...special scanning algorithm, which is intended for seeking the discrete elements of VLF chorus emissions and calculation of their parameters. We propose to create the optimal dynamic spectrograms for the scanning algorithm by using short-time Fourier transform. The paper gives general recommendations for calculation of spectrograms and their preprocessing. The scanning algorithm is based on processing of the dynamic-spectrogram images by using the methods of mathematical morphology. The developed method was tested for several cases of chorus emissions observed by the Van Allen Probes spacecraft. It is shown that the total errors related to “false positive” detection and missing the target are about 10% of the elements visible to the human eye when the optimal parameters of the scanning algorithm are used and intense discrete elements are processed. The method can be applied to both spacecraft and ground-based wave data. The results of using the method can be employed for verification of physical theories of the formation of chorus emissions and determining their statistical properties.
The intensive polar stratospheric vortex in the Arctic that shifted to northern Europe in the winter of 2019–2020 caused low temperatures and the frequent occurrence of polar stratospheric clouds ...followed by a significant decrease in the total ozone content. Polarimetry and multi-color photometry using all-sky cameras in Lovozero (Murmansk Region, Russia, 68.0°N, 35.1°E) together with a new method of cloud field separation against the twilight background allowed for finding the light scattering characteristics related to the particle size distribution of polar stratospheric clouds. The results are compared with lidar and balloon experiments. The conditions of the appearance of visually bright polar stratospheric clouds of type I are discussed.
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•Bright polar stratospheric clouds were registered by RGB and polarization all-sky cameras.•New method of cloud separation on the twilight background is developed.•Parameters of size distribution of polar stratospheric clouds particles are found with high accuracy.
The direct reconstruction of the pp elastic scattering amplitudes at the energy of 16 GeV is discussed. At the SPASCHARM experiment, the 19 different spin dependent observables will be measured in pp ...elastic scattering. The suggested selection of observables allows a complete analytical reconstruction of elastic scattering amplitudes as a solution of the system of bilinear equations. A set of physical observables, which are necessary for model independent reconstruction of all five complex elastic pp scattering amplitudes, is defined.
The results of the calculations of coordinate resolution and hadron rejection factor for a simple
е
/γ detector consisting of a lead converter followed by a hodoscope are presented. For the ...simulation of showers, initiated in the converter by electrons and hadrons with energies up to 1 TeV GEANT4 is used. It is shown that the best coordinate resolution for electrons is achieved when the converter thickness is closed to the position
t
max
of the shower maximum
.
For example, at 200 GeV with 2 mm strip width hodoscope it is equal to σ = 89 μm provided a “truncated mean” coordinate estimation is used. The optimal thickness of the converter for hadron rejection is also close to
t
max
. For 200 GeV beam of electrons and protons the rejection factor of 10
–4
for 0.9 electron detection efficiency can be reached using only data on charged particles multiplicities. Information on the spatial distribution of the shower particles after the converter allows to enhance further the rejection by several times.
A way of processing images to obtain information about ionospheric–magnetospheric plasma is described. Data from regular observations of auroras are used. Examples are given of triangulation using ...data from pairs of cameras with low (several kilometers) spatial diversity to determine the energy of precipitated electrons and numerically estimate the complexity of the spatial–temporal auroral dynamics.
The highly sensitive TUS telescope with high temporal resolution operated on board the
Lomonosov
satellite in 2016 and 2017. The detector measured UV pulsations in the auroral zone with a time ...resolution of 6.6 ms. Examples of joint observations by the TUS detector and all-sky cameras on the Kola Peninsula are analyzed. It is shown that the TUS field of view covered a wide region of pulsating auroras, and the fine temporal structure of pulsations is determined.
A system of imaging photometers with high temporal resolution (PAIPS, the Pulsating Aurora Imaging Photometers System) is being created at the observatories of the Polar Geophysical Institute on the ...Kola Peninsula in order to study the structure of pulsating auroras (PsA) in the near ultraviolet range (300–400 nm). Two PsA measurements using the PAIPS system in combination with all-sky cameras are described. A frequency analysis of the signal is performed for the first one. It is shown that pulsations occur within 1.5 h at a quasi-constant frequency of around 1 Hz. The ratio of intensities in lines 337 and 391 nm is measured for the second one. An analysis of simultaneous observations by the optical cameras in the spectrometer’s field of view shows that pulsations of radiation in the
on
phase are “greener” (i.e., they correspond to less energetic precipitating electrons). Stereometric observations using the camera at the Lovozero observatory yield the maxima of the coefficient of correlation for the time series of the cameras at altitudes of 145–150 and ~92 km.
A new photometer with spatial resolution was installed in addition to the all-sky camera at the Verkhnetulomsky observatory of the Polar Geophysical Institute, located inside the auroral zone, to ...study the fine space–time structure of the auroral luminescence. We describe the scientific equipment and the case of simultaneous observations of pulsating auroras with internal modulation in the hertz range.
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