scholarly journals 1,000,000 Giant Pulses from the Crab Pulsar

2017 ◽  
Vol 13 (S337) ◽  
pp. 380-381
Author(s):  
Mitchell B. Mickaliger ◽  
Ben W. Stappers ◽  
Cees G. Bassa ◽  
Aldus G. Fletcher
Keyword(s):  
Single Pulse ◽  
High Energy ◽  
Daily Basis ◽  
Large Set ◽  
Crab Pulsar ◽  
Energy Distributions ◽  
Giant Pulses ◽  
High Energy Tail ◽  
Insight Into ◽  
Shed Light

AbstractThe Crab pulsar was first detected soon after the discovery of pulsars, and has long been studied for its unique traits. One of these traits, giant pulses that can be upwards of 1000 times brighter than the average pulse, was key to the Crab’s initial detection. Giant pulses are only seen in a few pulsars, and their energy distributions distinguish them from normal pulsed emission. There have been many studies over a period of decades to measure the power-law slope of these energy distributions, which provide insight into the possible emission mechanism of these giant pulses.The 42-foot telescope at Jodrell Bank Observatory monitors the Crab pulsar on a daily basis. We have single-pulse data dating back to 2012, containing roughly 1,000,000 giant pulses, the largest sample of Crab giant pulses to date. This large set of giant pulses allows us to do a range of science, including pulse-width studies and in-depth studies of giant-pulse energy distributions. The latter are particularly interesting, as close inspection of the high-energy tail of the energy distribution allows us to investigate the detectability of extragalactic giant-pulsing pulsars. Also, by calculating rates from these energy distributions, we may be able to shed light on a possible link between Fast Radio Bursts and giant pulses.

Observation of Hot Electron Field Emission

2000 ◽  
Vol 621 ◽  
Author(s):  
Jonathan Shaw
Keyword(s):  
High Energy ◽  
Metallic State ◽  
Hot Electron ◽  
Many Body ◽  
Energy Distributions ◽  
Field Emitter Arrays ◽  
High Energy Tail ◽  
Electron Field ◽  
Gap States

ABSTRACTWe report energy distributions of silicon Field Emitter Arrays coated with 50A of ZnO. The distributions reflect changes in the ZnO conductivity induced by annealing in vacuum, temperature, and annealing in hydrogen. An additional coating of titanium performed in-situ produced large additional changes. Emission from the ZnO at energies near the Fermi level increased with gate voltage only after hydrogen annealing, when hot, and after Ti coating. In those same cases the emission distribution contained a tail at energies above EF. The highenergy emission tail is due to a many-body or Auger process whereby holes injected below EF create hot electrons. Although emission from ZnO occurred at energies up to 8eV below EF, no high-energy tail was observed in the normal case. Thus emission appears to occur from isolated electrons in ZnO gap states in cases where the distribution lacks a high-energy tail. Conversely, emission above EF suggests that emission occurred from a metallic state such as an accumulated conduction band.

scholarly journals Advances in Two-Dimensional MXenes for Nitrogen Electrocatalytic Reduction to Ammonia

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Lan-lan Yu ◽  
Jiang-zhou Qin ◽  
Wen-jun Zhao ◽  
Zhi-guang Zhang ◽  
Jun Ke ◽  
...  
Keyword(s):  
High Energy ◽  
Raw Material ◽  
Synthesis Methods ◽  
Two Dimensional ◽  
Catalytic Material ◽  
Temperature And Pressure ◽  
Negative Impacts ◽  
High Energy Consumption ◽  
Insight Into ◽  
Shed Light

As an important chemical raw material, ammonia is mainly produced by the traditional Haber-Bosch process, which has certain limitations such as high energy consumption, high safety responsibility, and severe pollution, thereby having negative impacts on ecosystem. The synthesis of ammonia from dinitrogen at ambient temperature and pressure is one of the most attractive topics in the field of chemistry. As a new two-dimensional nanomaterial, MXene has excellent electrochemical properties and is a potential catalytic material for electrocatalytic nitrogen fixation. In this review, we firstly introduce the crystal, electronic structures of two-dimensional MXenes and summarize the synthesis methods, N2 reduction, and simulation computation, as well as have insight into the challenges of MXenes, which shed light on the development of highly efficient MXene-based electrocatalysts in the reduction of N2 to ammonia.

ENERGY AND ANGULAR DISTRIBUTIONS OF PHOTONEUTRONS PRODUCED BY 70-MEV. X-RAYS

1955 ◽  
Vol 33 (12) ◽  
pp. 785-796 ◽  
Author(s):  
W. R. Dixon
Keyword(s):  
High Energy ◽  
Zinc Sulphide ◽  
Angular Distributions ◽  
X Rays ◽  
Evaporation Process ◽  
Light Elements ◽  
Energy Distributions ◽  
High Energy Tail ◽  
Nuclear Temperature ◽  
Energy And Angular Distributions

The angular distributions of the photoneutrons produced by 70-Mev. X-rays in seven elements have been measured with a zinc sulphide – lucite scintillation detector. For the heavy elements the distributions are essentially isotropic, indicating the predominance of the evaporation process, while for the light elements there is also an anisotropic component peaked at 90°. The energy distributions of the photoneutrons produced in copper and lead targets have been determined with nuclear emulsions. It is shown that most of the neutrons can be attributed to an evaporation process which is governed by a constant nuclear temperature, the temperature found for copper being 1.2 Mev., and for lead being 1.0 Mev. A high-energy tail on the energy distributions is attributed to direct interactions.

scholarly journals Development of ion recoil energy distributions in the Coulomb explosion of argon clusters resolved by charge-state selective ion energy spectroscopy

2021 ◽  
Author(s):  
D. Komar ◽  
L. Kazak ◽  
K-H. Meiwes-Broer ◽  
J. Tiggesbäumker
Keyword(s):  
High Energy ◽  
Coulomb Explosion ◽  
Energy Spectra ◽  
Recoil Energy ◽  
Energy Distributions ◽  
Ion Energy ◽  
Argon Clusters ◽  
High Energy Tail ◽  
Charge States ◽  
The Individual

AbstractThe laser intensity dependence of the recoil energies from the Coulomb explosion of small argon clusters has been investigated by resolving the contributions of the individual charge states to the ion recoil energy spectra. Between $$10^{14}$$ 10 14 and $$10^{15}$$ 10 15 W/cm$$^2$$ 2 , the high-energy tail of the ion energy spectra changes its shape and develops into the well-known knee feature, which results from the cluster size distribution, laser focal averaging, and ionization saturation. Resolving the contributions of the different charge states to the recoil energies, the experimental data reveal that the basic assumption of an exploding homogeneously charged sphere cannot be maintained in general. In fact, the energy spectra of the high-q show distinct gaps in the yields at low kinetic energies, which hints at more complex radial ion charge distributions developing during the laser pulse impact.

scholarly journals Non-Maxwellian rate coefficients for electron and ion collisions in Rydberg plasmas: implications for excitation and ionization

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
Daniel Vrinceanu ◽  
Roberto Onofrio ◽  
H. R. Sadeghpour
Keyword(s):  
Principal Quantum Number ◽  
Charged Particles ◽  
High Energy ◽  
Rate Coefficients ◽  
Hydrogen Atoms ◽  
Energy Distributions ◽  
Ion Collisions ◽  
Laboratory Plasmas ◽  
High Energy Tail ◽  
Collisional Rate Coefficients

Scattering phenomena between charged particles and highly excited Rydberg atoms are of critical importance in many processes in plasma physics and astrophysics. While a Maxwell–Boltzmann (MB) energy distribution for the charged particles is often assumed for calculations of collisional rate coefficients, in this contribution we relax this assumption and use two different energy distributions, a bimodal MB distribution and a $\unicode[STIX]{x1D705}$ -distribution. Both variants share a high-energy tails occurring with higher probability than the corresponding MB distribution. The high-energy tail may significantly affect rate coefficients for various processes. We focus the analysis to specific situations by showing the dependence of the rate coefficients on the principal quantum number of hydrogen atoms in $n$ -changing collisions with electrons in the excitation and ionization channels and in a temperature range relevant to the divertor region of a tokamak device. We finally discuss the implications for diagnostics of laboratory plasmas.

scholarly journals Effects of electron distribution anisotropy in spectroscopic diagnostics of solar flares

2018 ◽  
Vol 618 ◽  
pp. A176 ◽  
Author(s):  
E. Dzifčáková ◽  
M. Karlický
Keyword(s):  
Electron Distribution ◽  
High Energy ◽  
Maxwellian Distribution ◽  
Temperature Anisotropy ◽  
Energy Distributions ◽  
Ionization Equilibrium ◽  
Line Intensities ◽  
Relative Line ◽  
High Energy Tail ◽  
Temperature Diagnostics

Aims. We analyzed effects of the bi-Maxwellian electron distribution representing electron temperature anisotropy along and across the magnetic field on the ionization and excitation equilibrium with consequences on the temperature diagnostics of the flare plasma. Methods. The bi-Maxwellian energy distributions were calculated numerically. Synthetic X-ray line spectra of the bi-Maxwellian distributions were calculated using non-Maxwellian ionization, recombination, excitation and de-excitation rates. Results. We found that the anisotropic bi-Maxwellian velocity distributions transform to the nonthermal energy distributions with a high-energy tail. Their maximum is shifted to lower energies and contains a higher number of the low-energy particles in comparison with the Maxwellian one. Increasing the deviation of the parameter p = T∥/T⊥ from 1, changes the shape of bi-Maxwellian distributions and ionization equilibrium, and relative line intensities also increase. The effects are more significant for the bi-Maxwellian distribution with T∥ > T⊥. Moreover, considering different acceleration mechanisms and collisional isotropization it is possible that the bi-Maxwellian distributions with high deviations from the Maxwellian distribution are more probable for those with p >  1 than for those with p <  1. Therefore, distributions with p >  1 can be much more easily diagnosed than those with p <  1. Furthermore, we compared the effects of the bi-Maxwellian distributions on the ionization equilibrium and temperature diagnostics with those for the κ-distributions obtained previously. We found that they are similar and at the present state it is difficult to distinguish between the bi-Maxwellian and κ-distributions from the line ratios.

scholarly journals Statistics of VHE γ-rays in temporal association with radio giant pulses from the Crab pulsar

2020 ◽  
Vol 634 ◽  
pp. A25 ◽  
Author(s):  
◽  
M. L. Ahnen ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
C. Arcaro ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Gamma Ray ◽  
High Energy ◽  
Statistical Correlation ◽  
Temporal Association ◽  
Time Lags ◽  
Crab Pulsar ◽  
Giant Pulses ◽  
Upper Limits ◽  
Very High Energy

Aims. The aim of this study is to search for evidence of a common emission engine between radio giant pulses (GPs) and very-high-energy (VHE, E >  100 GeV) γ-rays from the Crab pulsar. Methods. We performed 16 h of simultaneous observations of the Crab pulsar at 1.4 GHz with the Effelsberg radio telescope and the Westerbork Synthesis Radio Telescope (WSRT), and at energies above 60 GeV we used the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We searched for a statistical correlation between the radio and VHE γ-ray emission with search windows of different lengths and different time lags to the arrival times of a radio GP. A dedicated search for an enhancement in the number of VHE γ-rays correlated with the occurrence of radio GPs was carried out separately for the P1 and P2 phase ranges, respectively. Results. In the radio data sample, 99444 radio GPs were detected. We find no significant correlation between the GPs and VHE photons in any of the search windows. Depending on phase cuts and the chosen search windows, we find upper limits at a 95% confidence level on an increase in VHE γ-ray events correlated with radio GPs between 7% and 61% of the average Crab pulsar VHE flux for the P1 and P2 phase ranges, respectively. This puts upper limits on the flux increase during a radio GP between 12% and 2900% of the pulsed VHE flux, depending on the search window duration and phase cuts. This is the most stringent upper limit on a correlation between γ-ray emission and radio GPs reported so far.

Sentence-Based Experience Logging in New Hearing Aid Users

2020 ◽  
Vol 29 (3S) ◽  
pp. 631-637
Author(s):  
Katja Lund ◽  
Rodrigo Ordoñez ◽  
Jens Bo Nielsen ◽  
Dorte Hammershøi
Keyword(s):  
Hearing Aid ◽  
Patient Experiences ◽  
Online Tool ◽  
Rehabilitation Process ◽  
Hearing Rehabilitation ◽  
Clinical Observations ◽  
Hearing Aid Use ◽  
Wide Range ◽  
Insight Into ◽  
Shed Light

Purpose The aim of this study was to develop a tool to gain insight into the daily experiences of new hearing aid users and to shed light on aspects of aided performance that may not be unveiled through standard questionnaires. Method The tool is developed based on clinical observations, patient experiences, expert involvement, and existing validated hearing rehabilitation questionnaires. Results An online tool for collecting data related to hearing aid use was developed. The tool is based on 453 prefabricated sentences representing experiences within 13 categories related to hearing aid use. Conclusions The tool has the potential to reflect a wide range of individual experiences with hearing aid use, including auditory and nonauditory aspects. These experiences may hold important knowledge for both the patient and the professional in the hearing rehabilitation process.

Aleksey Peshkov as an editor of Samarskaya Gazeta

2020 ◽  
pp. 128-138
Author(s):  
A. S. Bik-Bulatov
Keyword(s):  
Local History ◽  
Organizational Skills ◽  
First Time ◽  
New Evidence ◽  
Insight Into ◽  
Shed Light

The article uses little known letters of M. Gorky, many of which were published for the first time in 1997, as well as findings of Samara-based experts in local history to shed light on the writer’s work as editor-in-chief of the Samarskaya Gazeta newspaper in 1895. The researcher introduces hitherto unstudied reminiscences of the journalist D. Linyov (Dalin) about this period, which reference a letter by Gorky, now lost. The paper details a newly discovered episode of Gorky’s professional biography as a journalist: it concerns his campaign against a Samara ‘she-wolf,’ the madam of a local brothel A. Neucheva. Linyov’s reminiscences turn out to be an important and interesting source, offering an insight into the daily grind of the young editor Gorky, providing new evidence of his excellent organizational skills, and describing his moral and social stance. The author presents his work in the context of a recently initiated broader discussion about the need to map out all Russian periodicals for the period until 1917, as well as all research devoted to individual publications.

scholarly journals Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Miyoshi ◽  
K. Hosokawa ◽  
S. Kurita ◽  
S.-I. Oyama ◽  
Y. Ogawa ◽  
...  
Keyword(s):  
High Energy ◽  
Daily Basis ◽  
Maximum Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Mesospheric Ozone ◽  
Field Lines ◽  
Eiscat Radar

AbstractPulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

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