Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHard bremsstrahlung from a high-voltage atmospheric discharge and its anisotropy
122
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The results of the experiments on recording hard gamma radiation and measurements of its angular distribution at the initial stage of a laboratory high-voltage atmospheric discharge are presented. The experiments were performed on an ERG installation at a voltage of $sim 1$ MV, an atmospheric discharge current of up to 12 kA, and a gap of 0.55 m. The duration of the voltage pulse was about 1~$mu$s with a pulse rise time of 150-200 ns. The radiation was recorded by an assembly of 10 identical scintillation detectors installed each 10$^circ$ around the circumference of a quarter of a circle with a curvature of 1 m. In order to separate the radiation with energies from 20 keV to 1.5 MeV, Al and Pb filters of different thicknesses were used. The obtained results show that, as a rule, a multi-beam radiation pattern and several bursts of radiation (each with a directional pattern) are recorded in each shot. In a considerable number of shots, hard radiation with photon energies comparable to or exceeding the maximum electron energy corresponding to the applied voltage is recorded. In these cases, a needle-like radiation pattern is observed, including at large angles to the axis of the discharge. This may indicate the acceleration of electrons in different plasma channels.
rate research
Read More
The new results concerning neutron emission detection from a laboratory high-voltage discharge in the air are presented. Data were obtained with a combination of plastic scintillation detectors and $^3$He filled counters of thermal neutrons. Strong dependence of the hard x-ray and neutron radiation appearance on the field strength near electrodes, which is determined by their form, was found. We have revealed a more sophisticated temporal structure of the neutron bursts observed during of electric discharge. This may indicate different mechanisms for generating penetrating radiation at the time formation and development of the atmospheric discharge.
A lightning surge generator generates a high voltage surge with 1.2 microsec. rise time. The generator fed a spark gap of two pointed electrodes at 0.7 to 1.2 m distances. Gap breakdown occurred between 0.1 and 3 microsec. after the maximum generator voltage of approximately 850 kV. Various scintillator detectors with different response time recorded bursts of hard radiation in nearly all surges. The bursts were detected over the time span between approximately half of the maximum surge voltage and full gap breakdown. The consistent timing of the bursts with the high-voltage surge excluded background radiation as source for the high intensity pulses. In spite of the symmetry of the gap, negative surges produced more intense radiation than positive. This has been attributed to additional positive discharges from the measurement cabinet which occurred for negative surges. Some hard radiation signals were equivalent to several MeV. Pile-up occurs of lesser energy X-ray quanta, but still with a large fraction of these with an energy of the order of 100 keV. The bursts occurred within the 4 nanosec. time resolution of the fastest detector. The relation between the energy of the X-ray quanta and the signal from the scintillation detector is quite complicated, as shown by the measurements.
Nanoparticles grown in a plasma are used to visualize the process of film deposition in a pulsed radio-frequency (rf) atmospheric pressure glow discharge. Modulating the plasma makes it possible to successfully prepare porous TiO2 films. We study the trapping of the particles in the sheath during the plasma-on phase and compare it with numerical simulations. During the plasma-off phase, the particles are driven to the substrate by the electric field generated by residual ions, leading to the formation of porous TiO2 film. Using video microscopy, the collective dynamics of particles in the whole process is revealed at the most fundamental kinetic level.
A precise measurement of the atmospheric mass-squared splitting |Delta m^2_{mumu}| is crucial to establish the three-flavor paradigm and to constrain the neutrino mass models. In addition, a precise value of |Delta m^2_{mumu}| will significantly enhance the hierarchy reach of future medium-baseline reactor experiments like JUNO and RENO-50. In this work, we explore the precision in |Delta m^2_{mumu}| that will be available after the full runs of T2K and NOvA. We find that the combined data will be able to improve the precision in |Delta m^2_{mumu}| to sub-percent level for maximal 2-3 mixing. Depending on the true value of sin^2theta_{23} in the currently-allowed 3 sigma range, the precision in |Delta m^2_{mumu}| will vary from 0.87% to 1.24%. We further demonstrate that this is a robust measurement as it remains almost unaffected by the present uncertainties in theta_{13}, delta_{CP}, the choice of mass hierarchy, and the systematic errors.
The Ra EDM experiment uses a pair of high voltage electrodes to measure the atomic electric dipole moment of $^{225}$Ra. We use identical, plane-parallel electrodes with a primary high gradient surface of 200 mm$^2$ to generate reversible DC electric fields. Our statistical sensitivity is linearly proportional to the electric field strength in the electrode gap. We adapted surface decontamination and processing techniques from accelerator physics literature to chemical polish and clean a suite of newly fabricated large-grain niobium and grade-2 titanium electrodes. Three pairs of niobium electrodes and one pair of titanium electrodes were discharge-conditioned with a custom high voltage test station at electric field strengths as high as $+52.5$ kV/mm and $- 51.5$ kV/mm over electrode gap sizes ranging from 0.4 mm to 2.5 mm. One pair of large-grain niobium electrodes was discharge-conditioned and validated to operate at $pm 20$ kV/mm with steady-state leakage current $leq 25$ pA ($1sigma$) and a polarity-averaged $98 pm 19$ discharges per hour. These electrodes were installed in the Ra EDM experimental apparatus, replacing a copper electrode pair, and were revalidated to $pm 20$ kV/mm. The niobium electrodes perform at an electric field strength 3.1 times larger than the legacy copper electrodes and are ultimately limited by the maximum output of our 30 kV bipolar power supply.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
