.
The centrality determination for Au + Au collisions at 1.23
A
GeV, as measured with HADES at the GSI-SIS18, is described. In order to extract collision geometry related quantities, such as the ...average impact parameter or number of participating nucleons, a Glauber Monte Carlo approach is employed. For the application of this model to collisions at this relatively low centre-of-mass energy of
s
NN
=
2
.
42
GeV special investigations were performed. As a result a well defined procedure to determine centrality classes for ongoing analyses of heavy-ion data is established.
We present measurements of the spectral distribution of transition radiation generated by electrons of momentum 1–10
GeV/
c in different radiator types. We investigate periodic foil radiators and ...irregular foam and fiber materials. The transition radiation photons are detected by prototypes of the drift chambers to be used in the Transition Radiation Detector (TRD) of the ALICE experiment at CERN, which are filled with a Xe, CO
2 (15%) mixture. The measurements are compared to simulations in order to enhance the quantitative understanding of transition radiation production, in particular the momentum dependence of the transition radiation yield.
The work is related to the removal of residual salts in hybrid structures formed as a result of silicon wires arrays combining with a nanomaterial of natural origin – bacterial ferritin-like ...protein Dps. The study of the morphology and composition of the surface and the bulk part of the hybrid structure as a result of combination and subsequent washing in water was carried out. The method of metal-assisted wet chemical etching was used to obtain silicon wires arrays. To obtain recombinant protein, Escherichia coli BL21*(DE3) cells with chromatographic purification were used as producers. The combination of silicon wires with protein molecules was carried out by layering them in laboratory conditions, followed by drying. The residual salt found earlier in the hybrid material was removed by washing in water. The resulting hybrid material was studied by scanning electron microscopy and X-ray photoelectron spectroscopy. A well-proven complementary combination of scanning electron microscopy and X-ray photoelectron spectroscopy together with ion etching was used to study the morphology of the hybrid material “silicon wires – bacterial protein Dps” and the composition with physico-chemical state respectively. In arrays of silicon wires with a wire diameter of about 100 nm and a distance between them from submicron to nanometer sizes, protein was found as a result of layering and after treatment in water. At the same time, the amount of residual NaCl salt is minimized on the surface of the hybrid structure and in its volume. The obtained data can be used in the development of coating technology for the silicon wires developed surface available for functionalization with controlled delivery of biohybrid material.
We present the first observation of K^{-} and ϕ absorption within nuclear matter by means of π^{-}-induced reactions on C and W targets at an incident beam momentum of 1.7 GeV/c studied with HADES ...at SIS18/GSI. The double ratio (K^{-}/K^{+})_{W}/(K^{-}/K^{+})_{C} is found to be 0.319±0.009(stat)_{-0.012}^{+0.014}(syst) indicating a larger absorption of K^{-} in heavier targets as compared to lighter ones. The measured ϕ/K^{-} ratios in π^{-}+C and π^{-}+W reactions within the HADES acceptance are found to be equal to 0.55±0.04(stat)_{-0.07}^{+0.06}(syst) and to 0.63±0.06(stat)_{-0.11}^{+0.11}(syst), respectively. The similar ratios measured in the two different reactions demonstrate for the first time experimentally that the dynamics of the ϕ meson in nuclear medium is strongly coupled to the K^{-} dynamics. The large difference in the ϕ production off C and W nuclei is discussed in terms of a strong ϕN in-medium coupling. These results are relevant for the description of heavy-ion collisions and the structure of neutron stars.
Increasing the service life of electrochemical devices is an important task, the solution of which will ensure their competitiveness and commercial attractiveness. One of the methods of protecting ...device elements from corrosion is the application of coatings of various compositions. Various methods are used, both chemical and physical. Recently, plasma methods, especially magnetron sputtering, have attracted increasing attention. Control of the plasma parameters allows the deposition of crystalline and amorphous coatings and films of different thicknesses (even very thin ones) having the required composition, structure, stoichiometry, density, and porosity. A detailed description and analysis of nanometer coatings and island films of noble metals (Pt, Au, Ir, Pd), which are traditionally used for protective coatings, is presented. We also describe promising nanostructured coatings from carbides and nitrides of transition metals of Groups IV–VI (Ti, Zr, V, Nb, Ta, Mo, W) and carbon-based nanostructured films (amorphous carbon, diamond-like, graphite). They are synthesized under various modes and conditions of magnetron sputtering using plasma- and heat-treatment methods. Tests under conditions close to real ones show their high efficiency in extending the service life of devices. The magnetron-sputtering method is a promising technology with a wide range of applications for coating electrochemical devices, which is confirmed by the references. The optimization of application modes and conditions will make it possible to achieve the greater efficiency and stability of nanostructured coatings.
Two forms were found in the NMR spectra of N
-substituted 2-chloroadenosines. The proportion of the mini-form was 11-32% of the main form. It was characterized by a separate set of signals in COSY,
...N-HMBC and other NMR spectra. We assumed that the mini-form arises due to the formation of an intramolecular hydrogen bond between the N7 atom of purine and the N
-CH proton of the substituent. The
H,
N-HMBC spectrum confirmed the presence of a hydrogen bond in the mini-form of the nucleoside and its absence in the main form. Compounds incapable of forming such a hydrogen bond were synthesized. In these compounds, either the N7 atom of the purine or the N
-CH proton of the substituent was absent. The mini-form was not found in the NMR spectra of these nucleosides, confirming the importance of the intramolecular hydrogen bond in its formation.
Two forms were found in the NMR spectra of Nsup.6-substituted 2-chloroadenosines. The proportion of the mini-form was 11-32% of the main form. It was characterized by a separate set of signals in ...COSY, sup.15N-HMBC and other NMR spectra. We assumed that the mini-form arises due to the formation of an intramolecular hydrogen bond between the N7 atom of purine and the Nsup.6-CH proton of the substituent. The sup.1H,sup.15N-HMBC spectrum confirmed the presence of a hydrogen bond in the mini-form of the nucleoside and its absence in the main form. Compounds incapable of forming such a hydrogen bond were synthesized. In these compounds, either the N7 atom of the purine or the Nsup.6-CH proton of the substituent was absent. The mini-form was not found in the NMR spectra of these nucleosides, confirming the importance of the intramolecular hydrogen bond in its formation.
MPD TPC Status Averyanov, A.; Balashov, I.; Bazhazhin, A. ...
Physics of atomic nuclei,
10/2023, Letnik:
86, Številka:
5
Journal Article
Recenzirano
In the framework of the JINR scientific program on study of hot and dense baryonic matter a new accelerator complex Ion Collider fAcility (NICA) based on the Nuclotron-M is under realization. It will ...operate at a luminosity up to
cm
s
for ions up to Au79+. Two interaction points are foreseen at NICA for two detectors which will operate simultaneously. One of these detectors, the Multi-Purpose Detector (MPD), is optimized for investigations of heavy-ion collisions. The Time-Projection Chamber (TPC) is a well-known detector for 3-dimensional tracking and particle identification for high multiplicity events. The conceptual layout of MPD, TPC design and its parameters, the current status of the readout based on multiwire proportional chamber (MWPC) and readout electronics based on SAMPA chip as well as the status of TPC subsystems are presented.
The Nuclotron-based Ion Collider fAcility (NICA) is under construction at the Joint Institute for Nuclear Research (JINR), with commissioning of the facility expected in late 2022. The Multi-Purpose ...Detector (MPD) has been designed to operate at NICA and its components are currently in production. The detector is expected to be ready for data taking with the first beams from NICA. This document provides an overview of the landscape of the investigation of the QCD phase diagram in the region of maximum baryonic density, where NICA and MPD will be able to provide significant and unique input. It also provides a detailed description of the MPD set-up, including its various subsystems as well as its support and computing infrastructures. Selected performance studies for particular physics measurements at MPD are presented and discussed in the context of existing data and theoretical expectations.
A feasibility study has been performed in order to investigate the performance of the HADES detector to measure the electromagnetic decays of the hyperon resonances
Σ
(
1385
)
0
,
Λ
(
1405
)
and
...Λ
(
1520
)
as well as the production of double strange baryon systems
Ξ
-
and
Λ
Λ
in p + p reactions at a beam kinetic energy of
4.5
GeV
. The existing HADES detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized.
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