The relationship between
sp
2
/
sp
3
hybridizations ratio of atomic bonds in diamond-like carbon (DLC) and its electrical resistivity for coatings with a thickness in the range 22–70 nm prepared by ...vacuum arc deposition on silicon substrate of the SHB-8 brand has been established. It is established, that an increase in the coating thickness from 22 to 70 nm is accompanied by a decrease in the specific transverse electrical resistance of samples from 17 to 2 GΩ m. This effect is explained by an increase in the proportion of carbon atoms with
sp
2
hybridization of electronic orbitals from 86 to 91%, which leads to the appearance of an additional number of π-bonds. A mathematical model describing the spatial distribution of current when measuring the transverse
I–V
characteristic, has been developed. The results obtained will be useful in creating resistive layers on the electrodes of gas-discharge detectors of charged particle to limit the amount of c-urrent in the event of rare spark discharges inside them caused by the registration of random highly ionizing pa-rticles.
The data acquisition system (DAQ) was designed for data taking from the TPC/MPD detector. The detector contains 95232 registration channels, includes 1488 Front-End Cards (FEC) and other modules ...grouped into 24 DAQ subsystems. Each FEC has an individual full-duplex few-gigabit communication channel with Readout and Control Unit (RCU). The RCU manages each FEC within the group, collects the data and then transmits them via a high-speed optical channel. Optical lines from each group of four RCUs are connected to the Local Data Concentrator (LDC) computer via a Data Concentrator Unit (DCU) module installed. Each of the six DCUs controls four RCUs, receives data from them and stores them into the LDC computer memory via the PCIe interface. The DAQ system is operating with a raw TPC event of the size up to 37 MB containing information up to 2000 tracks at the central collision and the event trigger rate of up to 7 kHz in zero suppression mode. The article presents the overall structure of the system and the realized functionality of its main components. Section 1 describes the arrangement of DAQ subsystems and modules inside MPD. Section 2 gives the function, structure and connections of DAQ subsystems. Section 3 describes in detail one of the 24 DAQ subsystems. Section 4 presents the scheme of the local storage of TPC data and communication with MPD DAQ. In Section 5, the system throughput is estimated. Section 6 summarizes the main performance indicators and key technologies used in the construction of the system.
Results of an electrical field simulation for various configurations of new 2D position-sensitive detectors based on the gas-filled multiwire electron multiplier (MWEM) are presented. In contrast to ...the multiwire proportional chambers (MWPCs), an avalanche multiplication of the primary charge in the MWEM occurs in between wires
1
, and high loading capability and counting rates with submillimeter spatial resolution can be achieved in this case.
Straw tubes with resistive cathode and cathode readout were successfully manufactured and tested. The straw tubes were manufactured by ultrasonic welding technique. The resistive cathode electrode ...was made of diamond like carbon (DLC). The possibility of cathode signal readout from external strip electrodes was successfully demonstrated. The event coordinate along the straw can be accurately determined by applying center of gravity method to the individual strip signals.
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.
Microscope investigations of new-type thin-wall tubes (straws) produced for NA62 drift chambers revealed that they are semitransparent and allow anode wires to be observed under illumination by ...visible light. In this work it is shown that positions of wires in straws and thus the anode spacing in the drift chambers can be directly determined with a high accuracy (~5–10µm) using a microscope mounted on a high-precision optical bench. These data are important for decreasing errors during reconstruction of charged particle track coordinates in the drift chambers. The proposed technique is much simpler than the X-ray or radioactive source methods.
The DLC/Kapton structures irradiated with
60
Co γ-rays at doses to 1 MGy have been studied by measuring transmission and attenuated total reflection (ATR) spectra. It has been shown that there are ...significant changes in the spectra in the ranges of vibrations of О–Н, CH
2
, and CH
3
bonds due to radiation-induced processes in the byproducts of polyimide synthesis and residual solvents. Significant differences were found in the radiation-induced processes occurring in the bulk and near-surface region of a polyimide film and DLC/polyimide structures. After irradiation, the bulk of polyimide exhibited bands due to asymmetric and symmetric vibrations of the CH
3
group. Bands associated with the vibrations of the CH
2
group were additionally observed in the near-surface region. The formation of CH
2
groups in the near-surface layer under irradiation was more pronounced in DLC/polyimide structures than in polyimide films; this was due to the additional supply of hydrogen from the DLC film.
A precision test of lepton flavour universality has been performed by measuring the ratio RK of kaon leptonic decay rates K+→e+ν and K+→μ+ν in a sample of 59 813 reconstructed K+→e+ν candidates with ...(8.71±0.24)% background contamination. The result RK=(2.487±0.013)×10−5 is in agreement with the Standard Model expectation.
A drift chamber with a new type of straws for operation in vacuum Azorskiy, N.; Glonti, L.; Gusakov, Yu ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
A 2150×2150mm2 registration area drift chamber capable of working in vacuum is presented. Thin-wall tubes (straws) of a new type are used in the chamber. A large share of these 9.80mm diameter drift ...tubes are made in Dubna from metalized 36µm Mylar film welded along the generatrix using an ultrasonic welding machine created at JINR. The main features of the chamber and some characteristics of the drift tubes are described. Four such chambers with the X, Y, U, V coordinates each, containing 7168 straws in total, are designed and produced at JINR and CERN. They are installed in the vacuum volume of the NA62 setup in order to study the ultra-rare decay K+→π+vv¯ and to search for and study rare meson decays. In autumn 2014 the chambers were used for the first time for the data taking in the experimental run of the NA62 at CERN׳s SPS.
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