Operation of shaped charges with copper hemispherical liners of degressive (decreasing from top to bottom) thickness is experimentally studied. The velocity of the head of generated shaped-charge ...jets is determined along with how deep they penetrate a type-setting target made of steel disks and the sizes of holes made in the disks. The experimental data on an increase in the velocity and a decrease in the mass of the heads of shaped-charge jets, which occur with an increase in the difference in the thicknesses of the hemispherical liner at the apex and at the base are in good agreement with the results of numerical simulation carried out within the framework of a two-dimensional axisymmetric problem of continuous mechanics. According to the experimental results, the effect of technological manufacturing errors on the operation of these charges becomes stronger, which eliminates or significantly limits the increase in the penetrating action. In one of the versions of liners of degressive thickness, the depth of penetration of a target, which is average in two tests, increases by 7.5% as compared to the liner of constant thickness.
A new stage of the collider experiments at the maximum energy of protons and nuclei at the LHC may lead to the discovery of new phenomena, as well as to confirm the effects previously observed only ...at very high energies in cosmic rays. A specific program of the experiments is so-called "forward" physics, i.e. the study of low-angle processes. Of the most interesting phenomena can be noted the detection in cosmic rays events called Centauro, which could be explained as the strangelets production. Centauro represent events with small multiplicity and with a strong suppression of electromagnetic component. Since the energy of the beams at the collider and kinematic parameters of the forward detectors CASTOR (CMS), TOTEM, LHCf and the ADA and ADC (ALICE) are close to the parameters and energies of abnormal events in cosmic rays, it is possible to reproduce and investigate in details these events in the laboratory.
Tests of FARICH prototype with precise photon position detection Barnyakov, A.Yu; Barnyakov, M.Yu; Basok, I.Yu ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Volume:
766
Journal Article
Peer reviewed
In June 2012 a FARICH prototype from Philips Digital Photon Counting (PDPC) based on a photon camera with dimensions of 200200 mm has been tested at CERN. Remarkable particle separation has been ...achieved with a 4-layer aerogel sample: the pi /K separation at a 6 GeV/c momentum is 3.5 sigma , the mu / pi mu / pi separation is 5.3 sigma at 1 GeV/c. The analysis of the data has shown that the main contribution to the accuracy of the ring radius measurement comes from aerogel. The development of focusing aerogels is proceeding in two main directions: tuning of production technology of multilayer blocks and development of a new production method with continuous density (refractive index) gradient along the block depth. The beam test was carried out in December 2012-January 2013 at the electron beam test facility at the VEPP-4 M e super(+)e super(-) collider. The goal of this test was to measure different single layer and focusing aerogel samples, both multilayer and gradient. Aerogel samples were tested with a PDPC FARICH prototype. A part of DPC SPADs in each pixel was disabled to form an active area of 11 mm super(2). The collected data proved that gradient aerogel samples focus Cherenkov light.
Thanks to its multi-TeV LHC proton and lead beams, the LHC complex allows one to perform the most energetic fixed-target experiments ever and to study with high precision pp, pd and pA collisions at ...sNN=115GeV and Pbp and PbA collisions at sNN=72GeV. We present a selection of feasibility studies for the production of quarkonia, open heavy-flavor mesons as well as light-flavor hadrons in pA and PbA collisions using the LHCb and ALICE detectors in a fixed-target mode.
Luminosity Measurement and Control at NICA Igamkulov, Z.; Cruceru, M.; Kurepin, A. B. ...
Physics of particles and nuclei letters,
11/2019, Volume:
16, Issue:
6
Journal Article
Peer reviewed
A detector for measuring the luminosity at beam crossing points at the NICA collider is proposed. This small detector is based on scintillation counters and may be used both independently and as part ...of the base NICA detectors. Estimates of the count rate demonstrate that the number of useful counts per minute exceeds 10
4
for
pp
and Au–Au collisions. A detector calibration algorithm based on van der Meer scans is also proposed. Such calibration measurements take no more than 1 h at NICA. The distribution of interaction vertices is calculated for the NICA parameters.
The Projectile Spectator Detector (PSD) is a segmented hadron calorimeter used in NA61 experiment (CERN) to determine a collision centrality as well as an event plane orientation in nucleus-nucleus ...collisions. The main goal of the experiment includes studying the onset of de-confinement and searching for the critical point of strongly interacting matter. It is of crucial importance to have a precise characterization of the event class with the PSD for the analysis of event-by-event observables. The PSD has been already used for centrality selection on trigger level in measurements of Be+Be and Ar+Sc reactions at beam energies 13 − 158 AGeV and Pb+Pb reaction at beam energy 30 AGeV. In 2016, the central modules of PSD have been equipped with new Hamamatsu MPPC silicon photo-detectors in order to extend dynamic range for studying Pb+Pb reaction at the full energy range 13 − 158 AGeV. Results of the PSD response on proton and lead beams are presented.
Relevance
. A mathematical model of the distribution of the leaf area of a cucumber plant has been developed. On this basis, it is possible to determine the area of the leaf surface of the plant ...without removing them from the plants. By measuring the minimum number of parameters: the length and width of the largest leaf and the number of leaves on the plant.
Methods
. We determined the area by two methods: using scales and by scanning the leaves in black-and-white image mode. We present here a step-by-step instruction on determining the area of the sheet in both cases: by weighing and by using graphic editor (program) for his scan file. The accuracy of determining the area is ± 2%.
Results.
We have developed and practically tested a system for mass determination of the area of cucumber leaves. It includes the development of a mathematical model of the distribution of leaf area by plants at the time of accounting. For practical use of the obtained formulas, it is enough to measure only three parameters on each plant: the number of leaves, the length and width of the largest typical leaf. A typicality criterion based on the ratio of the length and width of the sheet was proposed. The model coincides with the actual plant area with a typical distribution of ±5%. This allows two people to account for up to 500 plants in one working day. The proportion of plants with a typical leaf area distribution ranges from 90% at the beginning of the growing season to 80-85% at its end. This allows relatively accurate calculation of the total area in agrotechnical experiments at minimal cost. The leaves of the plant do not receive any impact and continue to grow at the same time.
Conclusion.
The developed method allows taking into account the area on the same plants repeatedly, at different phases of ontogenesis and in different periods of vegetation.
Relevance
. When growing cucumbers in a greenhouse not equipped with additional lighting, especially in winter, there is a shortage of solar energy. To obtain high yields of cucumber at this time, it ...is necessary to select the most resistant to low light hybrids. The selection of genotypes resistant to this trait is a very important stage in the selection of cucumber for winter-spring turnover.
The purpose of the study
: search for an easy-to-use method for early diagnosis of cucumber resistance to insufficient illumination.
Methods
. The research was carried out at the variety testing site in the Gavrish Breeding Center (Krymsk city) of the Scientific Research Institute of Vegetable Crop Breeding, in winter-spring turnover conditions, in greenhouses not equipped with artificial lighting. Seedlings were planted in a permanent place in the greenhouse during the period of the lowest arrival of solar radiation in the year on December 21. The measurement of the height of the main stem was carried out on 31 days after planting the plants in a permanent place.
Results
. Measuring the height of the main stem before fruiting showed a significant variation of this trait in different cucumber hybrids. Further study of the correlation of the height of the main stem and yield revealed their high dependence. This fact suggests that a fairly simple measurable parameter has been found for evaluating different cucumber genotypes on the basis of resistance to low light. Regression analysis made it possible to divide the variability of the studied genotypes by yield into a dependent part of the height of the main stem and an additional one, which makes up to 30% of the yield increase. Further analysis of the high-yielding group has a high breeding value.
Particle flows formed from shaped charges with a combined steel liner consisting of a hemisphere and a cylinder with a hemispherical part of degressive thickness (decreasing from top to bottom) were ...investigated by flash radiography. It has been found experimentally that the change from a constant to a degressive thickness of the hemispherical part increases the velocity of the head part of the liner jet formed during its compression, which is subsequently separated upon collapse of the cylindrical part. The maximum particle velocity obtained as a result of separation in the experiments was 8.6 km/s.
We present a new measurement of $J/\psi$ production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental ...conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the ($J/\psi$)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the ($J/\psi$)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.
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