Search results for "Acceleration"
showing 10 items of 345 documents
Linking gamma-ray spectra of supernova remnants to the cosmic ray injection properties in the aftermath of supernovae
2017
The acceleration times of the highest-energy particles which emit gamma-rays in young and middle-age SNRs are comparable with SNR age. If the number of particles starting acceleration was varying during early times after the supernova explosion then this variation should be reflected in the shape of the gamma-ray spectrum. We use the solution of the non-stationary equation for particle acceleration in order to analyze this effect. As a test case, we apply our method to describe gamma-rays from IC443. As a proxy of the IC443 parent supernova we consider SN1987A. First, we infer the time dependence of injection efficiency from evolution of the radio spectral index in SN1987A. Then, we use the…
PRODUCTION CHARACTERISTICS OF K-0 AND LIGHT MESON RESONANCES IN HADRONIC DECAYS OF THE Z(0)
1995
An analysis of inclusive production of K0and the meson resonances K*±(892), Ï0(770), f0(975) and f2(1270) in hadronic decays of the Z0is presented, based on about 973,000 multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. Overall multiplicities have been determined as 1.962±0.060 K0mesons, 0.712±0.067 K*±(892) and 1.21±0.15Ï0(770) per hadronic Z0decay. The average multiplicities of f0(975) for scaled momentum, xp, in the range 0.05â¤xpâ¤0.6 and of f2(1270) for 0.05â¤xpâ¤1.0 are 0.098±0.016 and 0.170±0.043 respectively. The f0(975) and Ï0(770)xp-spectra have similar shapes. The f2(1270)/Ï0(770) ratio increases with xp. The average multiplicities…
MEASUREMENT OF THE GAMMA(B-B-OVER-BAR)/GAMMA(HAD) BRANCHING RATIO OF THE Z BY DOUBLE HEMISPHERE TAGGING
1995
Two measurements of {Mathematical expression} are presented. Both measurements use 250000 Z decays taken with the DELPHI detector in 1991 and rely mainly on the precision of the microvertex detector. One tagging method is as simple as possible so that background rates can be reliably predicted by simulation. The other one uses a more involved tagging technique and reduces the dependence on simulation as much as possible. Combining both results, {Mathematical expression} is found to be 0.2209±0.0041(stat.)±0.0042(syst.)±0.0018 {Mathematical expression}. © 1995 Springer-Verlag.
Sensitivity of alanine dosimeters with gadolinium exposed to 6 MV photons at clinical doses.
2011
In this study we analyzed the ESR signal of alanine dosimeters with gadolinium exposed to 6 MV linear accelerator photons. We observed that the addition of gadolinium brings about an improvement in the sensitivity to photons because of its high atomic number. The experimental data indicated that the addition of gadolinium increases the sensitivity of the alanine to 6 MV photons. This enhancement was better observed at high gadolinium concentrations for which the tissue equivalence is heavily reduced. However, information about the irradiation setup and of the radiation beam features allows one to correct for this difference. Monte Carlo simulations were carried out to obtain information on …
Analysis on the Time and Frequency Domains of the Acceleration in Front Crawl Stroke
2012
Analysis on the Time and Frequency Domains of the Acceleration in Front Crawl Stroke The swimming involves accelerations and decelerations in the swimmer's body. Thus, the main objective of this study is to make a temporal and frequency analysis of the acceleration in front crawl swimming, regarding the gender and the performance. The sample was composed by 31 male swimmers (15 of high-level and 16 of low-level) and 20 female swimmers (11 of high-level and 9 of low-level). The acceleration was registered from the third complete cycle during eight seconds in a 25 meters maximum velocity test. A position transducer (200Hz) was used to collect the data, and it was synchronized to an aquatic ca…
A superconducting CW-LINAC for heavy ion acceleration at GSI
2017
The European physical journal / Web of Conferences 138, 01026 (2017). doi:10.1051/epjconf/201713801026
Elektrische Registrierung der Druckanstiegsbeschleunigung und ihre Beziehung zur isometrischen Kontraktion des linken Herzventrikels
1967
Aus der zweimaligen Differentiation der Ventrikeldruckkurve nach der Zeit ergibt sich die Druckanstiegsbeschleunigung. Dieser Parameter wurde mittels RC-Glieder bei der Kontraktion des linken Ventrikels der Katze registriert. Sein Maximum lag in der Phase der isometrischen Kontraktion. Die maximale Druckanstiegsbeschleunigung nahm bei Erhohung der isometrischen Kontraktion starker zu als die maximale Druckanstiegsgeschwindigkeit. Es wird gefolgert, das zwischen der Kraft der isometrischen Kontraktion und der maximalen Druckanstiegsbeschleunigung eine Proportionalitat besteht.
Different acute effects of single-axis and multi-axis hand-arm vibration.
1996
Under laboratory conditions the effects of single-axis and multi-axis hand-arm vibration exposure on several strain parameters were tested in up to 20 male subjects. As parameters of these acute effects, the biodynamic vibration behavior of the hand-arm system, the electrical activity of the most affected muscle groups, the skin temperature, the vibration sensitivity of the fingertips, and the subjective vibration sensation were measured. When comparing simulated three-axis vibration exposure with single-axis vibration exposure, synergistic effects in the form of an increasing reaction could be found. It could be proven that the vector sum of the frequency-weighted acceleration in the three…
Probing the effects of hadronic acceleration at the SN 1006 shock front
2014
AbstractSupernova remnant shocks are strong candidates for being the source of energetic cosmic rays and hadron acceleration is expected to increase the shock compression ratio, providing higher post-shock densities. We exploited the deep observations of the XMM-Newton Large Program on SN 1006 to verify this prediction. Spatially resolved spectral analysis led us to detect X-ray emission from the shocked ambient medium in SN 1006 and to find that its density significantly increases in regions where particle acceleration is efficient. Our results provide evidence for the effects of acceleration of cosmic ray hadrons on the post-shock plasma in supernova remnants.
Observational Constraints on Undulant Cosmologies
2005
In an undulant universe, cosmic expansion is characterized by alternating periods of acceleration and deceleration. We examine cosmologies in which the dark-energy equation of state varies periodically with the number of e-foldings of the scale factor of the universe, and use observations to constrain the frequency of oscillation. We find a tension between a forceful response to the cosmic coincidence problem and the standard treatment of structure formation.