This review discusses the application of aerogel Cherenkov detectors in colliding beam experiments. Such detectors are used for charged particle identification at velocities at which other methods ...are ineffective. The paper examines aerogel production technology and how the aerogel optical parameters are measured. Data on threshold Cherenkov counters with direct light collection and on those using wavelength shifters are evaluated. Also presented are data on Ring Image Cherenkov detectors with single and multilayer focusing aerogel radiators.
We consider the two-bar charts packing problem generalizing the strongly NP-hard bin packing problem. We prove that the problem remains strongly NP-hard even if each two-bar chart has at least one ...bar higher than 1/2. If the first (or second) bar of each two-bar chart is higher than 1/2, we show that the O(n
2
)-time greedy algorithm with lexicographic ordering of two-bar charts constructs a packing of length at most OPT+1, where OPT is optimum, and present an O(n
2.5
)-time algorithm that constructs a packing of length at most 4/3 ・ OPT+2/3 in the NP-hard case where each two-bar chart has at least one bar higher than 1/2.
Loess deposits are widely spread all over Eastern Europe, extending as far south as the Sea of Azov and the northern Black Sea. For many decades these regions have been noted for series of key ...sections. However, despite prolonged investigations, a lack of absolute dating and detailed lithological data has left many unresolved problems in the correlation of the regional stratigraphic schemes. In this study, integrated studies were undertaken on the loess-paleosol sequence exposed on the northern coast of the Taman Peninsula, separating the Sea of Azov from the Black Sea. The exposure in the coastal scarp near Cape Pekla was sampled in detail for standard lithological and stratigraphic analyses, and for the first time, detailed data on the sediments lithology and petromagnetic properties were obtained, as well as the first optically stimulated luminescence age estimates. The data lead us to conclude that the formation of continental series exposed in the Pekla section started at the beginning of the Middle Pleistocene. There are five well pronounced buried soil complexes (PS 1–5) exposed in the sequence, covering sedimentation from the Middle Pleistocene to the present day. We attribute two lower paleosols (PS 4 and PS 5) to two main warm intervals of the Middle Pleistocene – MIS 9 and MIS 13, and the Kamenka interglacial paleosol, correlated with MIS 7 from other parts of the Azov loess area, is represented in the Pekla section by a sand layer formed at the time of the marine transgression dated to interval 220–280 ka (MIS 7). The upper soil horizons (PS1, PS2 and PS3) developed between 20 and 220 ka. The Pekla section contains a considerable proportion of sand fraction – presumably, due to active eolian processes that developed in immediate vicinities of sources of the material. The paleosol characteristics and the structure of loess horizons in the Pekla subaerial series differ considerably from the well described loess-paleosol series of the Northern Azov Sea coasts. In all probability, this region of the Taman Peninsula belongs to a specific province located south of the North Azov loess-soil province.
A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the
7Li(p,n)
7Be reaction as a ...neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine to be placed on high current IPPE proton accelerator KG-2.5. Results of calculation were experimentally tested and are in good agreement with measurements.
With global warming, snowmelt is occurring earlier and growing seasons are becoming longer around the Arctic. It has been suggested that this would lead to more uptake of carbon due to a lengthening ...of the period in which plants photosynthesize. To investigate this suggestion, 8 consecutive years of eddy covariance measurements at a northeastern Siberian graminoid tundra site were investigated for patterns in net ecosystem exchange, gross primary production (GPP) and ecosystem respiration (Reco). While GPP showed no clear increase with longer growing seasons, it was significantly increased in warmer summers. Due to these warmer temperatures however, the increase in uptake was mostly offset by an increase in Reco. Therefore, overall variability in net carbon uptake was low, and no relationship with growing season length was found. Furthermore, the highest net uptake of carbon occurred with the shortest and the coldest growing season. Low uptake of carbon mostly occurred with longer or warmer growing seasons. We thus conclude that the net carbon uptake of this ecosystem is more likely to decrease rather than to increase under a warmer climate. These results contradict previous research that has showed more net carbon uptake with longer growing seasons. We hypothesize that this difference is due to site‐specific differences, such as climate type and soil, and that changes in the carbon cycle with longer growing seasons will not be uniform around the Arctic.
Key Points
Longer growing seasons do not increase net carbon uptake
Highest uptake occurs in cold or short growing seasons
Greenhouse gas function of this tundra ecosystem is likely to diminish
The future
e
+
e
−
Super Charm-Tau Factory (SCTF) to be built at Novosibirsk will cover an energy range of 2 – 7 GeV. The projected record luminosity of 10
35
cm
−2
s
−1
and the longitudinal ...polarization of the electrons will enable a wide range of standard model precision tests and options for the discovery of flavor violating decays beyond the standard model. A 4
π
detector with excellent particle identification (PID) is required with challenging
μ
/
π
-separation in the range 0.2 – 1.2 GeV/c. This talk focuses on two new concepts and the first tests of novel Cherenkov detectors for SCTF, a focusing aerogel RICH (FARICH) and a focusing DIRC (fDIRC). Both require single-photon detection with good coordinate and timing resolution. The prototyping for both versions already started at BINP and Giessen. The tests include various photon detectors (MCP-PMT, SIPM, MPPC). The first results using cosmic muons at the Giessen Cosmic Station are presented.
We present the experimental results of our study of the formation and dynamics of chain structures by active Brownian particles in a DC glow discharge. The mechanism of active particle motion is ...associated with the conversion of laser radiation by particles into the energy of their own (nonthermal) motion. Through our analysis of the motion parameters (the trajectories, the root-mean-square displacement, the kinetic energy) as a function of the intensity of laser radiation incident on the particles, we have shown that the particles are active Brownian ones. It is possible to control their motion without changing the discharge parameters. It has been experimentally found that the formation of chain structures and their stable state are not violated under kinetic heating of the particles as their kinetic energy increases by more than an order of magnitude. This suggests the realization of a mechanism for the formation of chains with a strong coupling between the particles that is not explained by the simple (ion) wake behind the upstream particle.
Particle identification system based on Focusing Aerogel RICH (FARICH) detector is considered as an option for the future experiments at the Super Charm-Tau Factory (Russia). We present the progress ...of FARICH R&D at the Budker Institute of Nuclear Physics. New samples of focusing 4-layer aerogels with maximal refractive index 1.065 were produced in 2020–2021. First beam test results with relativistic electrons demonstrate single photon resolution (SPR) of 9÷10mrad. According to simulation results, the aerogels with such SPR are able to provide μ/π-separation at the level of more than 3 standard deviations for tracks with momentum 1.5 GeV/c. The first version of electronics to readout SiPM arrays based on TDC implemented on FPGA (FPGA-TDC) was developed and manufactured.
An integrated study of the loess–soil sequence in the coastal exposure near the settlement of Beglitsa (Rostov oblast) allowed us, for the first time, to reconstruct the landscape-climatic changes ...that occurred in the eastern Azov region over the course of the Late Pleistocene. In the south of the periglacial zone, considerable differences between intensity of the loess accumulation in the Early and Late Valdai Cryochrons were revealed. In the Early Valdai Epoch, which corresponds roughly to the end of Marine Isotope Stage (MIS) 5 and MIS 4, loess accumulation occurred after completion of development of the Mezin pedocomplex and before the beginning of the Bryansk stage of soil development, i.e., over more than 20 000 years. In the much shorter Late Valdai Cryochron MIS 2 (10 000–12 000 years), loess accumulation reached 5 m. The data evaluation shows that the loess accumulation rates in the Early Valdai Epoch (~0.07 mm/year) and the Late Valdai Epoch (~0.5 mm/year) differ from each other by an order of magnitude.
A new method for the synthesis of 2-acylamino glycal derivatives was developed, which helps to considerably simplify the preparation and increase the yield of the target compounds. For the first ...time, a method for the preparation of 2-amino-
D
-glucal derivative containing a 2,2,2-trichloroethoxycarbonyl
N
-protecting group was proposed.
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