Isotopic quantum effects in the structure of liquid ethanol

2002 ◽  
Vol 80 (9) ◽  
pp. 1059-1068 ◽  
Author(s):  
B Tomberli ◽  
C J Benmore ◽  
J Neuefeind ◽  
P A Egelstaff
Keyword(s):  
Room Temperature ◽  
Gamma Ray ◽  
Ambient Pressure ◽  
High Energy ◽  
Radiation Scattering ◽  
Structure Factors ◽  
Structural Differences ◽  
Order Of Magnitude ◽  
Total Structure Factor ◽  
Total Structure

High-energy electromagnetic-radiation-scattering techniques have been used to measure the structural differences between five isotopic samples of ethanol (CH3CH2OH, CD3CD2OD, CD3CH2OH, CH3CH2OD, and CH3CD2OH) at room temperature and ambient pressure. The differences in the X-ray structure factors between several pairs of isotopes, ΔSX(Q), are shown to have maximum amplitudes that are on the order of a few percent compared to the total structure factor for CH3CH2OH. Our uncertainties are an order of magnitude smaller than those of early gamma-ray measurements on methanol (C.J. Benmore and P.A. Egelstaff. J. Phys. Condens. Matter, 8, 9429 (1996)). These studies have shown that isotopic structural differences in room-temperature ethanol vary as a function of substitution site and are in qualitative agreement with similar differences found in liquid methanol. PACS Nos.: 61.20-p, 61.25E, 61.10-E

scholarly journals Time-Domain Astronomy with Swift, Fermi and Lobster

2011 ◽  
Vol 7 (S285) ◽  
pp. 41-46 ◽  
Author(s):  
Neil Gehrels ◽  
Scott D. Barthelmy ◽  
John K. Cannizzo
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Tidal Disruption ◽  
X Ray ◽  
Order Of Magnitude ◽  
New Type ◽  
The Crab Nebula ◽  
High Energy Emission ◽  
Higher Sensitivity

AbstractThe dynamic transient gamma-ray sky is revealing many interesting results, largely due to findings by Fermi and Swift. The list includes new twists on gamma-ray bursts (GRBs), a GeV flare from a symbiotic star, GeV flares from the Crab Nebula, high-energy emission from novae and supernovae, and, within the last year, a new type of object discovered by Swift—a jetted tidal disruption event. In this review we present highlights of these exciting discoveries. A new mission concept called Lobster is also described; it would monitor the X-ray sky at order-of-magnitude higher sensitivity than current missions can.

Future prospects for y-ray astronomy

1981 ◽  
Vol 301 (1462) ◽  
pp. 693-701 ◽  
Keyword(s):  
Gamma Ray ◽  
Dynamic Pressure ◽  
High Energy ◽  
Compact Objects ◽  
Pressure Effects ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
High Energy Particles ◽  
Nuclear Processes ◽  
The Universe

As y-ray astronomy moves from the discovery to the exploratory phase, the promise of y-ray astrophysics noted by theorists in the late 1940s and 1950s is beginning to be realized. In the future, satellites should carry instruments that will have over an order of magnitude greater sensitivity than those flown thus far, and, for at least some portions of the y-ray energy range, these detectors will also have substantially improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance our knowledge of several astrophysical phenomena including the very energetic and nuclear processes associated with compact objects, astrophysical nucleosynthesis, solar particle acceleration, the chemical composition of the planets and other bodies of the Solar System, the structure of our Galaxy, the origin and dynamic pressure effects of the cosmic rays, high energy particles and energetic processes in other galaxies especially active ones, and the degree of matter-antimatter symmetry of the Universe. The y-ray results of the forthcoming programs such as Gamma-I, the Gamma Ray Observatory, the y-ray burst network, Solar Polar, and very high energy y-ray telescopes on the ground will almost certainly provide justification for more sophisticated telescopes. These advanced instruments might be placed on the Space Platform currently under study by N.A.S.A.

scholarly journals The Galactic Center Region Imaged by VERITAS from 2010{2012

2014 ◽  
Vol 1 (1) ◽  
pp. 227-230
Author(s):  
Matthias Beilicke
Keyword(s):  
Supernova Remnant ◽  
Gamma Ray ◽  
Galactic Center ◽  
Region Of Interest ◽  
High Energy ◽  
Central Black Hole ◽  
Potential Sources ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
Very High

The galactic center has long been a region of interest for high-energy and very-high-energy observations. Many potential sources of GeV/TeV gamma-ray emission are located in this region, e.g. the accretion of matter onto the central black hole, cosmic rays from a nearby shell-type supernova remnant, or the annihilation of dark matter. The galactic center has been detected at MeV/GeV energies by EGRET and recently by <em>Fermi</em>/LAT. At TeV energies, the galactic center was detected at the level of 4 standard deviations with the Whipple 10m telescope and with one order of magnitude better sensitivity by H.E.S.S. and MAGIC. We present the results from 3 years of VERITAS galactic center observations conducted at large zenith angles. The results are compared to astrophysical models.

scholarly journals Radiation GRMHD simulations of M87: Funnel properties and prospects for gap acceleration

2021 ◽  
Author(s):  
Philippe Z Yao ◽  
Jason Dexter ◽  
Alexander Y Chen ◽  
Benjamin R Ryan ◽  
George N Wong
Keyword(s):  
Black Hole ◽  
Radiation Field ◽  
Gamma Ray ◽  
Theoretical Models ◽  
High Energy ◽  
Point Sources ◽  
Photon Momentum ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
General Relativistic

Abstract We use the public code ebhlight to carry out 3D radiative general relativistic magnetohydrodynamics (GRMHD) simulations of accretion on to the supermassive black hole in M87. The simulations self-consistently evolve a frequency-dependent Monte Carlo description of the radiation field produced by the accretion flow. We explore two limits of accumulated magnetic flux at the black hole (SANE and MAD), each coupled to several sub-grid prescriptions for electron heating that are motivated by models of turbulence and magnetic reconnection. We present convergence studies for the radiation field and study its properties. We find that the near-horizon photon energy density is an order of magnitude higher than is predicted by simple isotropic estimates from the observed luminosity. The radially dependent photon momentum distribution is anisotropic and can be modeled by a set of point-sources near the equatorial plane. We draw properties of the radiation and magnetic field from the simulation and feed them into an analytic model of gap acceleration to estimate the very high energy (VHE) gamma-ray luminosity from the magnetized jet funnel, assuming that a gap is able to form. We find luminosities of $\rm \sim 10^{41} \, erg \, s^{-1}$ for MAD models and $\rm \sim 2\times 10^{40} \, erg \, s^{-1}$ for SANE models, which are comparable to measurements of M87’s VHE flares. The time-dependence seen in our calculations is insufficient to explain the flaring behaviour. Our results provide a step towards bridging theoretical models of near-horizon properties seen in black hole images with the VHE activity of M87.

Study on TlBr Radioactive Detector

2017 ◽  
Author(s):  
He Li-xia ◽  
Hao Xiao-yong ◽  
He Gao-kui
Keyword(s):  
Room Temperature ◽  
High Energy Physics ◽  
Gamma Ray ◽  
Detection Efficiency ◽  
Nuclear Material ◽  
High Energy ◽  
High Detection ◽  
High Detection Efficiency ◽  
Excellent Energy Resolution ◽  
Energy Physics

TlBr is a kind of semiconductor material. Due to its promising physical properties and can be used at room temperature, it is continually studied as X and gamma ray detectors candidate material. Both of its atomic number and density are high. It also has large band-gap (B = 2.68eV) and low ionization energy. TlBr device exhibits high detection efficiency and excellent energy resolution. It can be easily fabricated or compacted in small housing. So it is a reasonable selection in the fields of nuclear material inspection and safeguards property, national security, spatial and high energy physics researches. The paper investigates the TlBr radioactive detector development and fabrication procedures. The processing detail information and signals collection are emphasized in different section. The prototype detectors were irradiated by Am-241 and corresponding spectrum was obtained. The photoelectric peak at 59.5keV is distinguished visible and the best resolution at 59.5keV is 4.15keV (7%).

scholarly journals A Large-Area Gas-Čerenkov Detector for High-Energy Gamma-Ray Astronomy

1971 ◽  
Vol 41 ◽  
pp. 75-76 ◽  
Author(s):  
J. Delvaille ◽  
K. Greisen ◽  
D. Koch ◽  
B. McBreen ◽  
G. Fazio ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Point Sources ◽  
Large Area ◽  
Cerenkov Detector ◽  
High Energy Gamma ◽  
Area 5 ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
Energy Gamma

Experimental upper limits of the high-energy gamma-ray flux (above 100 MeV) from point sources are about 10−5 cm−2 s−1, and realistic theoretical predictions for the strongest sources are an order of magnitude lower than this, while the diffuse background flux is about 4 × 10−5 cm−2 s−1 sr−1 in space, and 100 times higher at balloon altitudes. To meet the need for instrumental sensitivity and angular resolution adequate to measure the small but important gamma-ray source strengths, a telescope of large area (5 m2) and fine angular discrimination (0.5 deg at 300 MeV, 0.3 deg at energies above 1 GeV) has been developed.

scholarly journals Sources of the X-Ray Background: Temporal Stability

1980 ◽  
Vol 92 ◽  
pp. 227-228
Author(s):  
Elihu Boldt
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Temporal Stability ◽  
High Energy ◽  
Energy Limit ◽  
X Ray ◽  
New Class ◽  
Order Of Magnitude ◽  
X Ray Background ◽  
Einstein Observatory

The A2 experiment on HEAO-1 was especially developed to make systematics-free measurements of the extragalactic X-ray background (Boldt et al. 1979) over the band (up to 60 keV) of maximum flux. The spectrum observed has a remarkably simple thermal form (Marshall et al. 1980) with a mean photon energy of about 40 keV, an order of magnitude above the high-energy limit of the Einstein Observatory (HEAO-2) telescope. If most of this hard X-ray flux is not diffuse, then the main sources of this background could be 1) unresolved objects of known classification (e.g. BL Lac type, quasars, active galaxies) at high redshift, 2) redshifted (z > 1) gamma-ray bursts and/or 3) a new class of X-ray objects peculiar to high redshifts. If we assume that the number of such sources that are highly variable is less than 106, then our first-cut analysis of the temporal stability measured for the X-ray background indicates that 1) their contribution is less than 15% if they are variable on scales less than 104 seconds, and 2) their contribution is less than 60% if they are variable on scales less than a half-year.

scholarly journals Gamma-ray flux depressions of the Crab Nebula in the high-energy range

2020 ◽  
Vol 496 (4) ◽  
pp. 5227-5232
Author(s):  
M S Pshirkov ◽  
B A Nizamov ◽  
A M Bykov ◽  
Yu A Uvarov
Keyword(s):  
Energy Range ◽  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Synchrotron Emission ◽  
Pulsar Wind Nebulae ◽  
Average Value ◽  
Order Of Magnitude ◽  
Pulsar Wind ◽  
The Crab Nebula

ABSTRACT The giant gamma-ray flares of the Crab Nebula discovered by AGILE and Fermi observatories came as a surprise and have challenged the existing models of pulsar wind nebulae. We have carried out an analysis of 10.5 yr of Fermi-LAT observations (August 2008 to February 2019) and investigated variability of the Crab Nebula in the 100–300 MeV range. Besides the flares, we found several month long depressions of the gamma-ray flux and identified several cases of sharp flux drops, where during 1 week the flux decreased by an order of magnitude with respect to its average value. No statistically significant variations of the nebula flux in the E &gt; 10 GeV range were found in the data. We discuss possible implications of the observed gamma-ray flux depressions on the model of synchrotron emission of the Crab Nebula.

Synthesis of Cupric Oxide Films using Mass-Separated Low-Energy O+ Beams

1992 ◽  
Vol 268 ◽  
Author(s):  
R. Kita ◽  
T. Hase ◽  
R. Itti ◽  
M. Sasaki ◽  
T. Morishita
Keyword(s):  
Flux Density ◽  
Room Temperature ◽  
Oxygen Plasma ◽  
Cupric Oxide ◽  
Ambient Pressure ◽  
Ion Beams ◽  
Low Energy ◽  
Epitaxial Relationship ◽  
Order Of Magnitude ◽  
Relationship Of

ABSTRACTWe report the epitaxial growth of CuO thin films prepared by lowenergy and high-density O+ ion beams mass-separated from an oxygen plasma. We have successfully produced O+ beams of 50 μA/cm2 while maintaining an ambient pressure of 3×10−9 Torr during the growth. CuO grows on MgO(100) with epitaxial relationship of (111)CuO // (100)MgO and [110]CuO // [110]MgO at room temperature and even under conditions where the flux density of O+ beams is at least one order of magnitude lower than the minimum flux density of O2 required to form CuO.

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