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.
This paper considers approaches to modeling defects in a semiconductor material using computer calculations, in particular, within the framework of applications that implement density functional ...theory (DFT). An approach is proposed to study the vacancy mechanism of the mobility of dopant atoms based on the dependence of the binding energy on the impurity fraction. The thermodynamic stability of a semiconductor was studied using the cubic phase of silicon carbide 3C-SiC as an example.
Abstract
The authors consider heterostructures of silicon carbide obtained during endotaxy on silicon substrates. The question is raised in connection with the description of the endotaxy process ...itself at the structural level. Authors focus on the technological aspects of the formation of a stable β-SiC/Si heterostructure by endotaxy in relation to the evolution of point defects of various nature and their probable association models with the participation of a radionuclide impurity at the micro-alloying level: 1) the growth of the SiC*/Si thin layer with C-14 atoms in the doping process; 2) physical properties of defects formation; 3) some interface between properties and efficiency.
The 3C-SiC Silicon Carbide phase doped by P, Ga, and N atoms was analyzed in the framework of Density Functional Theory. The physical parameters, changing with time due to N concentration increase, ...were calculated. Crucial statements about the existence of the deepest level were checked. Calculations of band structures were performed using the software applications VASP and Siesta. The plane wave basis was used in the first case and the orbital basis in the frame of the virtual crystal approach in the second one.
The aim of the study is to consider the features of the physico–chemical processes in the near-contact region of the semiconductor SiC phase doped with radionuclide by solid-phase diffusion of
C ...atoms, generation of nonequilibrium carriers and the semiconductor phase distinctive characteristic features. The DFT approach in this paper is aimed at obtaining evidence of the vacancy mechanism of diffusion during the formation of the SiC phase in the Si wafer. Radionuclide and silicon atoms counter-diffuse through a growing layer of silicon carbide, forming layers by solid-phase chemical transformation of silicon of
- or
-type conductivity into heterostructures of anisotypic or isotypic type of conductivity relative to the SiC phase, with superstecheometric alloying with conservation of the valence and the type of impurity conductivity, forming, depending on the phase, effects energetically manifested as the effect of ‘‘the inner sun,’’ which is the source of electrons and electron–hole pairs at ionization losses. This is due to interactions with the electrons of the shells of neighboring atoms, leading to the formation of electrons and holes in the region of spatial charge and carrying by built-in electric fields. The purpose of the study is due to an increase in the efficiency of separation of electron–hole pairs.
Silicon-carbide (SiC) nanowire structures 40–50 nm in diameter are produced by the high-temperature carbonization of porous silicon and silicon nanowires. The SiC nanowires are studied by scanning ...electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and infrared reflectance spectroscopy. The X-ray structural and Raman data suggest that the cubic 3
C
-SiC polytype is dominant in the samples under study. The shape of the infrared reflectance spectrum in the region of the reststrahlen band 800–900 cm
–1
is indicative of the presence of free charge carriers. The possibility of using SiC nanowires in microelectronic, photonic, and gas-sensing devices is discussed.
We tested whether internal transcribed spacer (ITS) rDNA sequence differences are correlated with sexual compatibility in the Sellaphora pupula complex, a model system for investigations of the ...species concept and speciation in diatoms. The phylogenetic relationships among the demes and the systematic position of the genus within the raphid diatoms were also investigated. The division of clones of S. pupula and S. laevissima into groups, based on sequence similarities and phylogenetic analyses, resembled groupings based on sexual compatibility: A high ITS sequence divergence, making full alignment difficult or impossible, was found among clones whose gametangia do not interact, whereas there was little sequence divergence among interfertile clones. This is clearly consistent with the idea that 'Z clades' exhibit less intraclade than interclade variation in ITS and, as comparisons of secondary structure models for the RECT and PSEUDOCAP clones showed, that there is an equivalence of 'CBC' and Z clades in the rectangular and pseudocapitate demes of S. pupula, as earlier hypothesized for chlorophytes. Intraclonal, presumably intraindividual, variation in ITS was found in S. pupula, though with a degree of variation less than that found within a single Z clade; it was too minor to affect the interclonal relationships in the ITS phylogeny. Sellaphora, which appears monophyletic in 18S phylogenies, with Pinnularia and 'Navicula'pelliculosa as its closest allies, may also include some species currently classified in Eolimna. The S. pupula-S. laevissima group began to diversify in or before the Miocene.
Within the framework of the scientific program for the study of hot and dense nuclear matter in the Veksler and Baldin Laboratory of High Energy Physics of the Joint Institute of Nuclear Research, ...Dubna (JINR), the NICA megaproject (Nuclotron-based Ion Collider fAcility) based on the Nuclotron-M accelerator is implemented. The new accelerator facility will make it possible to research the properties of dense baryonic matter in the collision of heavy ions in a wide range of atomic masses from
p
–
p
collisions in the energy range √
S
pp
= 12–27 GeV/
n
and
d
+
d
collisions with energies of √
S
NN
= 4–13.8 GeV/n with the average luminosity
L
= 10
32
cm
–2
s
–1
up to Au
+79
+ Au
+79
collisions in the energy range √S
NN
= 4–11 GeV/
n
with the average luminosity
L
= 10
27
cm
–2
s
–1
(Au
+79
). A collider provides two points of intersection of beams, in one of which the multipurpose detector (Multi-Purpose Detector, MPD) will be installed. The time-projection gas chamber (TPC) is the main tracking detector and the particle identifier of the Multi-Purpose Detector. The article considers the structure of the MPD, the design and the main working parameters of TPC and its subsystems. The front-end electronics (FEE), as well as the procedure for assembling and integrating the TPC into the MPD are discussed.
The features of the manufacturing process, as well as the results of studies on the morphology, electrophysical, and photoelectric properties of photosensitive structures based on silicon containing ...siliconcarbide and porous silicon layers, are considered. A porous layer is created on the surface of a monocrystalline silicon substrate via electrolytic etching in fluorine-containing solutions. Wafers with a different surface microrelief such as a ground, polished, and textured one, has been used. The carbonization of the samples resulting in the formation of SiC/Si heterostructures has been carried out via gas transport endotaxy in a hydrogen flow using a vertical reactor with cold walls and a graphite container. The structure and composition of the manufactured SiC/Si heterostructures formed on different types of structured surfaces on polycrystalline and monocrystalline silicon, including the surface porous silicon layer, are investigated. It is shown that the process of endotaxy on all the types of surfaces leads to the formation of a single-crystal phase of silicon carbide by cubic modification. Using scanning and transmission electron microscopy, the morphology of the produced structures is investigated. Filiform entities with a different structure have been revealed on nonporous surfaces identified as silicon carbide, whereas the cylindrical or conical structures, whose nature is uncertain, have been observed on porous surfaces. The current-voltage and current-power curves are plotted for all types of manufactured structures, the general form of which indicates the presence of several potential barriers there. The photoelectric properties of the structures and the prospects of their use in photoelectric converters of solar cells are analyzed.
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