The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R_{2γ}, a direct measure of the contribution of hard two-photon ...exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb^{-1} was collected. In the extraction of R_{2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R_{2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
One hundred patients with ischemic heart disease and 70 healthy subjects were on unified regimen. Urine was collected with 4-h proportions during 3–5 days (72–120 h). Each portion of urine was ...analyzed for macro- (Na, K, P, Cl, Ca, Mg) and microelements (Fe, Cu, Zn, Cr, Cd, V). Temporal structure (biological and hydrometeorological indices) parameters have been estimated by nonlinear least squares method for sinusoidal rhythms and dispersion analysis for nonsinusoidal rhythms. Data of weather indices were received from the hydrometeorological service of the Republic of Armenia in 2015 at 3-h intervals. Statistically significant rhythms were observed in healthy subjects in 91% cases of 593 rhythmological investigations of water-mineral homeostasis. Acrophases of water-mineral homeostasis mostly had individual nature. Healthy subjects’ rhythms of water-mineral excretion were depending on rhythms of hydrometeorological indices and were characterized with significant correlative connections. Acrophases of indices of water-mineral homeostasis mostly were outstripping the acrophases of the rhythms of hydrometeorological indices. Chronostructure of water-mineral homeostasis in patients with ischemic heart disease was characterized with infradian and circadian fluctuations. In case of individuals with ischemic heart disease, statistically significant correlative connections between rhythms of water-mineral excretion and rhythms of hydrometeorological indices differ in comparison with the results of practically healthy individuals. In patients with ischemic heart disease, acrophases of biorhythms often were concurrent or delayed relative to the acrophases of the rhythms of hydrometeorological indices.
The article describes a new detector, a volume filled with hexane at low pressure (3 Torr), containing multi-wire proportional chambers and a silicon semiconductor detector. Using this setup, alpha ...particles emitted during the decay of the radioactive isotope
226
Ra were detected. The device has an energy resolution of ≤ 5% and allows measuring the ionization energy losses of alpha particles as well. Thus, the LPMWPC and SSD-based experimental setup is a good tool for studying both binary and ternary fission of heavy nuclei, in which the third fragment is a high-energy alpha particle.
In order to clarify the genesis of liquefaction folds (convolutions) developed at lithological boundaries in lacustrine sediments, such structures in three regions were compared. Folds in each region ...differ in morphology, composition of sediments, and the vertical gradient of their density and viscosity upon deformation. It is proposed to use the ratio of the widths of syn- and anticlinal folds in the convolution horizon (
K
s
) to analyze the latter, in which
K
s
> 1 corresponds to the normal viscosity gradient, and
K
s
< 1, to its inversion. Convolutions of the Baltic Shield and Yakutia from
K
s
≥ 1 are noted in the most liquefied sediments with unstable density stratification (sands-on-silts), which indicates the possibility of their spontaneous formation during lithogenesis. Folds with
K
s
≈ 1 are widespread in Yakutia, which indicates their cryogenic genesis. Convolutions in the Tien Shan were formed with stable sediment stratification in terms of density (silts-on-sands); low-fluidized coarse-grained sediments with viscosity inversion were also involved in deformation. These features indicate the seismic initiation of liquefaction processes. The results substantiate the lithogenic genesis of convolutions in lacustrine complexes of the Baltic Shield, cryogenic and lithogenic in Yakutia, and seismogenic in the Tien Shan. It is proposed to determine the scatter of the
K
s
value in the diagrams for diagnosing the genesis of convolutions. For lithogenic structures, this parameter is shifted to the region with
K
s
> 1, and for seismites, it is relatively symmetric with respect to
K
s
= 1.
Akchagyl deposits of Western Turkmenistan were studied in order to identify the spectrum of paleosecular variations in the geomagnetic field in Pliocene–Quaternary sediments. The detrital nature of ...remanent magnetization is established. The spectra of geomagnetic field variations in the Gauss direct polarity intervals (Zau section) and Matuyam reverse polarity intervals (Issu section) in Western Turkmenistan were studied. The spectrum of secular variations in the geomagnetic field is distinguished, in particular, by periods of 8–10, 25–30, and 45–50 ka. The selected periods are stable throughout the Pleistocene and agree well with the results obtained from corresponding deposits in Armenia and Azerbaijan. It should be noted that the revealed discrete series often differ for different elements of the field and different time intervals.
Owing to the growing interest in the low-energy nuclear physics, it becomes relevant to enhance the potential of the experimental facilities at Yerevan Physics Institute (YerPhI). The complex unit ...based on the linear electron accelerator LUE-75 (ARUS synchrotron injector) for applied and fundamental experiments with electron beams, the intensity and energy of which can vary in a wide range of 10
–18
–10
–5
А and 10–50 MeV, has been created. In recent years, the regimes developed at LUE-75 were applied to obtain the controllable electron beams of extremely low intensity used for calibration of detectors.
Based on the linear electron accelerator LUE-75 of the A.I. Alikhanyan National Scientific Laboratory a technique for obtaining controlled primary electron beams with an intensity of 10–20 electrons ...per second in the energy range 15–75 MeV for elementary particle detectors calibration was developed and used. Joint work with the V.P. Dzhelepov Laboratory of Nuclear Problems (JINR, Dubna, RF) showed the efficiency of the technique.
The effective sorption method for melanin isolation and purification from fermentation solutions of
Bacillus thuringiensis
serovar
galleriae
K1 has been elaborated, the principle process flowsheet is ...presented. The identification of obtained pigment with the samples of natural and synthetic melanin was done by IR-spectroscopy, and the intensity ratio of optical absorption at 650 and 500 nm allows to refer the isolated melanin to eumelanin class. By thermal treatment it was determined, that melanin’s amorphous sediment is steady at up to 120°C) the concentration of paramagnetic centers being changed from 0.053 × 10
18
spin/g (48°C) to 0.25 × 10
18
spin/g (120°C). The rising of the temperature of treatment up to 210°C brings to substantial increase of the concentration of unpaired electrons, and at 280°C its sharp growth is observed. At 350°C growth stops, then sharp decrease is observed. The obtained results were confirmed by methods of IR spectroscopy and derivatographic analysis.
An active target has been developed for studying the Hoyle like states in
16
O. It is a position and time sensitive detector system based on the Low-Pressure Multy-Wire Proportional Chamber (LPMWPC) ...technique and Si detectors. The few Torr pressure of methyl ((OCH
3
)
2
CH
2
) serves as a working gas for the LPMWPC operation, and the oxygen atoms of the methyl molecules serve as an experimental target. The main advantage of this new target-detector system is a high sensitivity to the low-energy, highly ionizing particles, produced after photodisintegration of
16
O, and the insensitivity to the γ-rays and low ionizing particles, which allows one to detect only the products of the nuclear reaction, which are studied. The threshold energies for detection of α particles and 12C nuclei are about 50 keV and 100 keV, respectively. Temporal and positional resolution of the LPMWPC modules was investigated with the use of the α-particle source. This paper discusses the architecture of the active target and the test results of the prototype MWPC detector. This installation has been constructed to study the cluster states at 15.1 MeV in
16
O using the proton beams from the Yerevan proton cyclotron and the Compton backscattered photon beams of the ELI-NP facility.