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.

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 GOhm·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 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 current in the event of rare spark discharges inside them caused by the registration of random highly ionizing particles.

We consider a mathematical model that predicts the electric conductivity of anodic resistive coatings in a charged particle detector and ensures the removal of electron charge in a time shorter than the electron avalanche period. The model is based on the equations for non-stationary electrical current in solids and implemented in COMSOL Multiphysics finite-element code. The model allowed us to establish a correlation between the duration of the avalanche time tau, the amplitude of the current pulse j(max), and the electrical conductivity sigma. The model predicted that for a thick gas elecrton multiplier detector with a standard gain about 10(4) order and a thickness of coating 100 nm, the conductivity s should be in the range (2...5)center dot 10(-7) S/m in order to ensure that current does not exceed the breakdown value that lies in the range similar to 1.5 mu A. This allowed us to define the most appropriate regime of charged particle detector functioning that combines a high rate of operation and resistance to coating erosion in a detector. The obtained results will be useful for the improvement of the time resolution of charged particles detection in well-type detectors.

The relationship between sp2/sp3-hybridizations ratio of atomic bonds in diamond-like carbon ( DLC --- Diamond-Like Carbon) 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 KDB-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 sp2-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 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 current in the event of rare spark discharges inside them caused by the registration of random highly ionizing particles. Keywords: ( DLC), electrical properties of thin films, hybridization of electronic orbitals, Raman scattering, I-V characteristic.

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.

Presented below are the results of the measurements of temperature of simulators of front-end electronic boards (62 pcs), heat sinks for electronic units, housing of the ROC chamber, and the pad plane of the TPC detector for the MPD facility to be operated at the NICA collider. The measurements were conducted for two coolant temperatures. Data of computer simulations, which are in good agreement with the measurements, are also presented. The results reported will be used to develop and optimize cooling and thermal stabilization systems for ROC chambers and front-end electronics.

The relationship between sp2/sp3 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 sp2 hybridization of electronic orbitals from 86 to 91

This paper describes carrier transport mechanisms in polyethylene terephthalate (PET) films and porous PET-based membranes (PMs) obtained by irradiating pristine PET film with swift heavy ions, with subsequent chemical etching in an alkali (NaOH) solution. The obtained PMs had through nanochannels (pores) with an average diameter of 720-750 nm. We observed that in the temperature range 240-300 K, the current-voltage characteristics I(V) of the initial Cu|PET|Cu structure obeyed the improved Mott--Gurney law, which is based on the Mark--Helfrich model for a space-charge-limited current (SCLC) mechanism for electron transport. It was found for the first time that creation of nanochannels in PMs resulted in a significant increase in the electric current density (by about three orders of magnitude) while maintaining the SCLC mechanism. The enhanced current density is explained by the formation of a highly conductive layer along the inner surface of the walls of the nanochannel that are covered with carboxyl end groups, which are created by alkaline hydrolysis. According to the model, the surface states formed by these groups enable the drift of additional electrons injected from the copper electrodes under the action of the bias voltage. Keywords: polyethylene terephthalate, electron transport, space-charge-limited current mechanism, Mark--Helfrich injection model.

A prototype of the Micromegas detector with 30 x 30 mm2 active area and the resistive anode was developed and produced at DLNP JINR using a bulk Micromegas technological process and a diamond-like carbon resistive layer on a polyimide substrate. The prototype is considered as an option for the future upgrade of the readout chambers for the Time Projection Chamber of the Multi-Purpose Detector experiment at the NICA collider. The performance of the prototype of the Micromegas detector was studied using a 55Fe radioactive source and an Ar:CO2 (90:10) gas mixture. The dependencies of the gas gain and the energy resolution on applied high voltage are obtained. The detector works stably up to the gas gain of 30,000. For the gas gain of 10,000 the resolution for the line 5.9 keV of the 55Fe source is 22%. The robustness of the detector prototype to electric discharges was demonstrated by accumulating about 10,000 discharge events at a gas gain of 40,000 without any visible impact on the operation of the prototype.

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.

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.

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.

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.

For the development of charged particle detectors based on straw tubes operating in vacuum, a special measurement technique is required for the evaluation of their mechanical properties. A summary of the known equations that govern straw behavior under internal pressure is provided, and a new experimental method of a strained pressurized straw tube study is presented in this paper. The Poisson’s ratio of the straw wall, which defines the stability conditions of a built-in tube, was measured for the NA62 spectrometer straw, and its minimum pre-tension was estimated.

A prototype of a 2D detector based on specially designed straw tubes with cathode data readout has been developed and tested. This detector exhibits comparable accuracies in measuring radial and longitudinal coordinates. Its rate capability is similar to the capabilities of traditional detectors whose tubes are smaller by half in diameter.

A device for fabricating thin-wall (straw) drift tubes using polyethylene terephthalate film 36 μm thick by ultrasonic welding is described together with the technique for controlling their quality. The joint width amounts to 0.4–1.0 mm. The joint breaking strength is 31.9 kg/mm 2 . The argon leakage from a tube of volume 188.6 cm 3 under a pressure gradient of 1.0 atm does not exceed 0.3 × 10 –3 cm 3 /min, which is mainly related to the absence of metallization in the joint vicinity. The high strength, the low tensile creep due to the absence of glued layers, the small value of gas leakage makes the new tubes capable of reliable and long-term operation in vacuum, which is confirmed by the operation of 7168 straw tubes for two years in the NA62 experiment.

Precise measurement of straw axial coordinate (along the anode wire) with accuracy compatible with straw radial coordinate determination by drift time measurement and increase of straw detector rate capability by using straw cathode readout instead of anode readout are presented.

The time-projection chamber (TPC) is the main tracking detector in the MPD/NICA. The information on charge-particle tracks in the TPC is registered by the MWPG with cathode pad readout. The frontend electronics (FEE) are developed with use of modern technologies such as application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), and data transfer to a concentrator via a fast optical interface. The main parameters of the FEE are as follows: total number of channels, ~95 000; data stream from the whole TPC, 5 GB/s; low power consumption, less than 100 mW/ch; signal to noise ratio (S/N), 30; equivalent noise charge (ENC), <1000e– (C in = 10–20 pF); and zero suppression (pad signal rejection ~90%). The article presents the status of the readout chamber construction and the data acquisition system. The results of testing FEE prototypes are presented.