We present the results of the theoretical analysis and numerical simulations of the Weibel instability in two counterstreaming hot relativistic plasma flows, for instance the flows of electron-proton ...plasmas with rest-mass densities , Lorentz factors , and proper temperatures . The instability growth rate and the filament size at the linear stage are found analytically and are in qualitative agreement with the results of three-dimensional particle-in-cell simulations. In the simulations, incoherent synchrotron emission and pair photoproduction in electromagnetic fields are taken into account. If the plasma flows are dense, fast, and hot enough, the overall energy of the synchrotron photons can be much higher than the energy of the generated electromagnetic fields. Furthermore, a sizable number of positrons can be produced due to the pair photoproduction in the generated magnetic field. We propose a rough criterion to judge copious pair production and considerable synchrotron losses. By means of this criterion, we conclude that the incoherent synchrotron emission and the pair production during the Weibel instability can have implications for the collapsar model of gamma-ray bursts.
The NA61/SHINE experiment at the CERN SPS is undergoing a major upgrade during the CERN Long Shutdown 2 period (2019-2021). The upgrade is essential to fulfill the requirements of the new open charm ...and neutrino programs. In these programs the NA61/SHINE will operate with the data acquisition rate increased by a factor of 10, which requires an upgrade of current Beam Position Detectors (BPDs). New detectors should monitor beam particle positions with a frequency up to 10
5
Hz.
This paper presents an overview of the new BPD design, as well as discusses current state of development and prototype production of BPD, including: mechanical design, front-end electronics design and integration with experiment’s data aquisition system.
The collapse of a spherical microcavity in a plasma target under symmetrical irradiation by intense laser pulses has been numerically investigated. Configurations with 2, 4, and 8 laser pulses are ...considered. The formation of a strong quasi-static electric field at the cavity center as a result of the collapse is demonstrated. It is shown that the 8-pulse configuration is optimal from the point of view of increasing the ion density in the central bunch and increasing the electric field amplitude, while the transition from the 2-pulse to the 8-pulse configuration increases the field amplitude by a factor of 1.5, preserving the total laser pulse energy. Estimates show that, for the XCELS parameters in the 8-pulse configuration, one would expect the maximum electric field amplitude of 1.61 × 10
14
V/cm, or 1.2% of the Schwinger field.
Highly efficient scintillation Lu
2
SiO
5 ‒
z
:Y
3+
:Ce
3+
:Ca
2+
crystals are grown from 20 to 85% of the initial melt using the Czochralski method. Crystallization of less than 50% of the melt ...residues in the iridium crucible leads to its deformation and short operating time. Optimized parameters of the growth process and the composition of the initial melt make it possible to grow crystalline boules with a diameter of 75‒80 mm. The scintillation properties of elements measuring 3 × 3 × 20 mm for time-of-flight positron emission tomography (TOF PET), made of the upper and lower parts of a boule weighing 5 kg, are studied.
The NA61/SHINE experiment at the CERN SPS is undergoing a major upgrade during the LHC Long Shutdown 2 period (2019-2021). The upgrade is essential to fulfil the requirements of the new open charm ...measurement program. In this program detector will operate at a beam intensity increased by a factor of 10, which requires an upgrade of current Beam Position Detectors (BPDs). New BPDs should monitor lead and proton beam intensities with up to 105 Hz rate. In this paper, progress on design and development of the new BPDs based on Si strip detectors, its front-end and readout electronics, as well as integration with the NA61/SHINE DAQ is presented.
Abstract
The article is devoted to the broadband vibrodiagnostics of jet engines. The material discusses the main causes that affect the level of vibration of the engine. Using the methods for ...controlling vibrations in a wide frequency band, an analysis was made of the criteria that cause defects and their manifestations in a wide frequency band of vibrations. The author has studied the effect of defects in parts and assembly units on vibration levels in a wide range. Based on the data obtained, it was found that the results allow to determine the bottlenecks of the gas turbine engine with accuracy to the details of the assembly units.
The Compressed Baryonic Matter (CBM) experiment at FAIR needs a detector to measure the nucleus-nucleus collision centrality and orientation of the reaction plane. The Projectile Spectator Detector ...(PSD) as a sampling lead/scintillator forward hadron calorimeter with transverse and longitudinal segmentation will be used for this purpose. The PSD consist of 44 modules with 10 longitudinal sections in each. Electronics of PSD consist of MPPCs boards mounted directly on detector and readout ADC interface with ADC FPGA board installed into crate distanced on 50m from detector part. ADC has 14-bit resolution and 125MHz digitization rate, Kintex-7 FPGA is placed on the board. Concept of PSD Front End Electronics (FEE) is already designed and most crucial parts including ADC FPGA board already tested and confirmed to be operational. One PSD module ("mini PSD" or mPSD) has been installed into the "mini CBM" (mCBM) assembled at SIS18 accelerator in GSI, Darmstadt, Germany in the framework of the FAIR Phase-0 program. ADC FPGA readout board has been integrated into common DAQ experiment and tested. Details of the mPSD FEE design and test results are shown.
Forward Diffractive Detector control system for Run 3 in the ALICE experiment Mejía Camacho, J.M.; Rodríguez Ramírez, S.A.; Cabanillas Noris, J.C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2023, Letnik:
1050
Journal Article
Recenzirano
The ALICE experiment went through major upgrades in preparation for Runs 3 and 4 at the CERN LHC, which foresee a significant increase in the data stream rate. To cope with it, a new Computing System ...Online–Offline (O2) was developed by ALICE and several detectors were upgraded. One of these upgrades corresponded to the ALICE Diffractive (AD) detector, which was replaced by the new Forward Diffractive Detector (FDD). A fundamental system that allows for recording of data as well as for the stable and safe operation of the experimental setup is the Detector Control System (DCS). The DCS controls, monitors, and configures detectors’ hardware and their subsystems among which are commercial hardware and specific custom equipment. In this work, we describe the implementation of the DCS of FDD, which was designed and developed using the SCADA commercial software WinCC Open Architecture (WinCC-OA®) and the Joint Controls Project (JCOP) Framework. We also describe the modeling of FDD-DCS as a finite state machine to be integrated into the ALICE Central DCS, and to be operated by DCS shifters in the run control center and, remotely, by detector experts. This new DCS was developed to comply with the new LHC operational standards that allow for processing the increased luminosity due to collisions at a higher energy, and for fulfilling the specific requirements of the ALICE experiment, in order to address the scientific challenges of its physics program.
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