The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Josip Soln - One of the best experts on this subject based on the ideXlab platform.
-
The helical Cerenkov effect with a non-mono-energetic electron beam
Journal of Physics D, 1997Co-Authors: Josip SolnAbstract:The helical Cerenkov effect results from the helical electron motion in a medium caused by a magnetic field B. For B values of up to 100 T in strength helical Cerenkov radiation occurs in the visible spectrum for which an analytical expression for the number of emitted photons per Unit Path Length is derived. In general, however, for a non-mono-energetic beam at a fixed radiation angle and a fixed arbitrary frequency, one may have simultaneous contributions from the helical Cerenkov effect and radiation occurring below and above the threshold of the helical Cerenkov effect with the fundamental frequencies and their harmonics. When B increases we come to the asymptotic regions where the number of harmonics on both sides of the threshold first decreases towards the respective fundamental frequencies and, eventually, disappears altogether. Also, a general asymptotic limit, in which there is no radiation below and above the threshold of the helical Cerenkov effect and only the helical Cerenkov effect remains at any angle of radiation and for any medium, we argue, should occur at about T for the visible spectrum.
-
Nonmonoenergetic Beam With Helical Cerenkov Radiation: Possible Technique to Determine Magnetic Field in a Hostile Electromagnetic Environment.
1996Co-Authors: Josip SolnAbstract:Abstract : Modifications caused by the nonmonoenergetic beams to the recently described helical Carenkov radiation (resulting from electron helical motion in a medium under the influence of magnetic field) are studied in a visible portion of the spectrum. The analysis is greatly simplified by utilizing a new analytical approximate expression for the number of emitted photons per Unit Path Length for the usual 'monoenergetic' helical Carcknov radiator. The effect of the nonmonoenergetic beam is that simultaneously with the helical Carenkov radiation also the radiation into harmonics (above and below the helical Carenkov effect threshold) may occur at the same radiation angle and at the same visible frequency. Hence, harmonic radiators may enhance the usual helical Carenkov radiation. For the medium of silica aerogel with the index of refraction of 1.075 and the beam energy in the 2-3-MeV range interacting with the magnetic field of about 10 T, one estimates that in the visible portion of the spectrum an electron from a noumonoenergetic beam will generate between 1 and 2 photons at the end of the 10cm interaction Length. This shows the possibility of detecting a magnetic field coming from an electromagnetic treat wave form, which in turn, represents a hostile electromagnetic environmental The importance of detecting this magnetic field comes from the fact that in an environmental medium it can disrupt optical signals. Here we show the way for measuring and quantifying such disruptions. (AN)
-
Effect of the nonmonoenergetic beam on helical Cerenkov radiation
Intense Microwave Pulses III, 1995Co-Authors: Josip SolnAbstract:Modifications caused by the nonmonoenergetic beams to the recently described helical Cerenkov radiation (resulting from electron helical motion in a medium under the influence of magnetic field) are studied in a visible portion of the spectrum. The analysis is greatly simplified by utilizing a new analytical approximate expression for the number of emitted photons per Unit Path Length for the usual 'monoenergetic' helical Cerenkov radiator. The effect of the nonmonoenergetic beam on the helical Cerenkov radiation is that, for the same visible frequency and the same radiation angle, the radiation may occur, in addition to through the the usual helical Cerenkov effect, also through harmonic radiation above and below the helical Cerenkov threshold. Harmonic radiators may enhance the usual helical Cerenkov radiation. For the medium of silica aerogel with the index of refraction of 1.075 and the beam energy in the 2-3 MeV range interacting with the magnetic field of about 10 tesla, one estimates that in the visible portion of the spectrum an electron from a nonmonoenergetic beam will generate between one and two photons at the end of the 10 cm interaction Length.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
C G Duan - One of the best experts on this subject based on the ideXlab platform.
-
Energy loss effect of incoming gluons from J/ψ production in p-A collisions*
Chinese Physics, 2017Co-Authors: L H Song, C G DuanAbstract:The energy loss effect of incoming gluon from $J/\psi$ production in p-A (or d-A) collisions is investigated by means of the E866, RHIC and LHC experimental data. The gluon mean energy loss per Unit Path Length $dE/dL = 2.18\pm0.14$ GeV/fm is extracted by fitting the E866 experimental data for $J/\psi$ production cross section ratios $R_{W(Fe)/Be}(x_{F})$. The obtained result indicates that the incoming gluons lose more energy than the incident quarks. By comparing the theoretical results with E866, RHIC, and LHC experimental data, it is found that the nuclear suppression due to the incident gluon (quark) energy loss reduces (increases) with the increase of the kinematic variable $x_{F}$ (or $y$). The energy loss effect of incoming gluon plays an important role on the suppression of $J/\psi$ production in a wide energy range from $\sqrt{s}=38.7$ GeV to $\sqrt{s}=5.0$ TeV, and the influence of incident quark energy loss can be ignored for high energy(such as at RHIC and LHC energy).
-
$J/\psi $ suppression in p-A collisions from charm quark energy loss in cold nuclear matter
Journal of Physics G, 2015Co-Authors: L H Song, C G DuanAbstract:The energy loss effect of charm quarks in cold nuclear matter on suppression in p-A collisions is studied. By means of two parametrizations of quark energy loss, the leading-order computations for production cross section ratios are presented and compared with the selected E866 experimental data, with the remaining colored on its entire Path in the medium. It is found that the energy loss of the color octet is an important effect in suppression; however, whether it is linear or quadratic with the Path Length cannot be determined. The successful description of suppression in gives the charm quark mean energy loss per Unit Path Length /fm. Using the same quark energy loss model, we further give the phenomenological analysis at the leading order for production cross section ratios as a function of y for the Large Hadron Collider experimental data.
-
Systematic analysis of the incoming quark energy loss in cold nuclear matter
Physics Letters B, 2012Co-Authors: L H Song, C G DuanAbstract:Abstract The investigation into the fast parton energy loss in cold nuclear matter is crucial for a good understanding of the parton propagation in hot-dense medium. By means of four typical sets of nuclear parton distributions and three parametrizations of quark energy loss, the parameter values in quark energy loss expressions are determined from a leading order statistical analysis of the existing experimental data on nuclear Drell–Yan differential cross section ratio as a function of the quark momentum fraction. It is found that with independence on the nuclear modification of parton distributions, the available experimental data from lower incident beam energy rule out the incident-parton momentum fraction quark energy loss. Whether the quark energy loss is linear or quadratic with the Path Length is not discriminated. The global fit of all selected data gives the quark energy loss per Unit Path Length α = 1.21 ± 0.09 GeV / fm by using nuclear parton distribution functions determined only by means of the world data on nuclear structure function. Our result does not support the theoretical prediction: the energy loss of an outgoing quark is three times larger than that of an incoming quark approaching the nuclear medium. It is desirable that the present work can provide useful reference for the Fermilab E906/SeaQuest experiment.
L H Song - One of the best experts on this subject based on the ideXlab platform.
-
Energy loss effect of incoming gluons from J/ψ production in p-A collisions*
Chinese Physics, 2017Co-Authors: L H Song, C G DuanAbstract:The energy loss effect of incoming gluon from $J/\psi$ production in p-A (or d-A) collisions is investigated by means of the E866, RHIC and LHC experimental data. The gluon mean energy loss per Unit Path Length $dE/dL = 2.18\pm0.14$ GeV/fm is extracted by fitting the E866 experimental data for $J/\psi$ production cross section ratios $R_{W(Fe)/Be}(x_{F})$. The obtained result indicates that the incoming gluons lose more energy than the incident quarks. By comparing the theoretical results with E866, RHIC, and LHC experimental data, it is found that the nuclear suppression due to the incident gluon (quark) energy loss reduces (increases) with the increase of the kinematic variable $x_{F}$ (or $y$). The energy loss effect of incoming gluon plays an important role on the suppression of $J/\psi$ production in a wide energy range from $\sqrt{s}=38.7$ GeV to $\sqrt{s}=5.0$ TeV, and the influence of incident quark energy loss can be ignored for high energy(such as at RHIC and LHC energy).
-
$J/\psi $ suppression in p-A collisions from charm quark energy loss in cold nuclear matter
Journal of Physics G, 2015Co-Authors: L H Song, C G DuanAbstract:The energy loss effect of charm quarks in cold nuclear matter on suppression in p-A collisions is studied. By means of two parametrizations of quark energy loss, the leading-order computations for production cross section ratios are presented and compared with the selected E866 experimental data, with the remaining colored on its entire Path in the medium. It is found that the energy loss of the color octet is an important effect in suppression; however, whether it is linear or quadratic with the Path Length cannot be determined. The successful description of suppression in gives the charm quark mean energy loss per Unit Path Length /fm. Using the same quark energy loss model, we further give the phenomenological analysis at the leading order for production cross section ratios as a function of y for the Large Hadron Collider experimental data.
-
Systematic analysis of the incoming quark energy loss in cold nuclear matter
Physics Letters B, 2012Co-Authors: L H Song, C G DuanAbstract:Abstract The investigation into the fast parton energy loss in cold nuclear matter is crucial for a good understanding of the parton propagation in hot-dense medium. By means of four typical sets of nuclear parton distributions and three parametrizations of quark energy loss, the parameter values in quark energy loss expressions are determined from a leading order statistical analysis of the existing experimental data on nuclear Drell–Yan differential cross section ratio as a function of the quark momentum fraction. It is found that with independence on the nuclear modification of parton distributions, the available experimental data from lower incident beam energy rule out the incident-parton momentum fraction quark energy loss. Whether the quark energy loss is linear or quadratic with the Path Length is not discriminated. The global fit of all selected data gives the quark energy loss per Unit Path Length α = 1.21 ± 0.09 GeV / fm by using nuclear parton distribution functions determined only by means of the world data on nuclear structure function. Our result does not support the theoretical prediction: the energy loss of an outgoing quark is three times larger than that of an incoming quark approaching the nuclear medium. It is desirable that the present work can provide useful reference for the Fermilab E906/SeaQuest experiment.
Passage Maximilien-de-meuron - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of cw and pulsed operation with a TE-cooled quantum cascade infrared laser for detection of nitric oxide at 1900 cm −1
2020Co-Authors: Passage Maximilien-de-meuronAbstract:A quantum cascade laser operating near room tem- perature with thermoelectric (TE) cooling has been used in both continuous-wave (cw) mode (−9 ◦ C) and pulsed mode (+45 ◦ C) to detect atmospheric nitric oxide using spectral lines at 1900.07 cm −1 (5.3 µm). The totally non-cryogenic spectrom- eter integrates the laser with a 69-m astigmatic multi-pass cell and a TE-cooled infrared detector to enable operation for ex- tended time periods without operator attention. The pattern of reflections on the astigmatic cell mirrors has been designed to minimize optical interference fringes, which are substantially greater with cw mode than with pulsed operation. The detection method uses direct absorption with rapid- scan sweep integra- tion to achieve sub-second time response. Detection precision for NO in air of 0.5 parts in 10 9 Hz −1/2 (1σ) is obtained in pulsed mode with an Allan variance minimum corresponding to 0.1 parts in 10 9 after 30-s averaging time. The precision in cw mode improves to 0.1 parts in 10 9 Hz −1/2 and 0.03 parts in 10 9 after 30-s averaging, corresponding to an absorbance per Unit Path Length of 2 × 10 −10 cm −1 . The advantages and disadvan- tages of cw compared to pulsed operation are discussed.
J. Faist - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of cw and pulsed operation with a TE-cooled quantum cascade infrared laser for detection of nitric oxide at 1900 cm^-1
Applied Physics B, 2006Co-Authors: J.b. Mcmanus, D.d. Nelson, S.c. Herndon, J.h. Shorter, M.s. Zahniser, S. Blaser, L. Hvozdara, A. Muller, M. Giovannini, J. FaistAbstract:A quantum cascade laser operating near room temperature with thermoelectric (TE) cooling has been used in both continuous-wave (cw) mode (-9 °C) and pulsed mode (+45 °C) to detect atmospheric nitric oxide using spectral lines at 1900.07 cm^-1 (5.3 μm). The totally non-cryogenic spectrometer integrates the laser with a 69-m astigmatic multi-pass cell and a TE-cooled infrared detector to enable operation for extended time periods without operator attention. The pattern of reflections on the astigmatic cell mirrors has been designed to minimize optical interference fringes, which are substantially greater with cw mode than with pulsed operation. The detection method uses direct absorption with rapid- scan sweep integration to achieve sub-second time response. Detection precision for NO in air of 0.5 parts in 10^9 Hz^-1/2 (1σ) is obtained in pulsed mode with an Allan variance minimum corresponding to 0.1 parts in 10^9 after 30-s averaging time. The precision in cw mode improves to 0.1 parts in 10^9 Hz^-1/2 and 0.03 parts in 10^9 after 30-s averaging, corresponding to an absorbance per Unit Path Length of 2×10^-10 cm^-1. The advantages and disadvantages of cw compared to pulsed operation are discussed.
