Search results for "strah"
showing 10 items of 123 documents
Strong effect of the electron spin on bremsstrahlung observed in the relativistic regime
2015
We have studied bremsstrahlung produced by polarized 2.1 MeV electrons colliding with a thin gold target. We have observed a strong correlation between the orientation of the electron spin and the angle of x-ray linear polarization at the x-ray high energy tip region. This indicates a dominance of the spin-orbit interaction in bremsstrahlung.
Vector polarimetry at MaMi – Measurements of tensor correlation coefficients in e−bremsstrahlungs processes
2011
Electron/photon tensor-correlation coefficients may allow to design a polarimeter that can measure all components of beam polarization simultaneously—a so-called vector polarimeter. Besides its purpose as a beam diagnostic device this vector polarimeter would also allow to test theoretical predictions for the electron-photon polarization correlations at energies between 1 MeV and 3.5 MeV. As a first step we have set up a measurement of the helicity transfer to the photon as a function of energy which is based on the Compton absorption method.
Does the plasma composition affect the long term evolution of relativistic jets?
2001
We study the influence of the matter content of extragalactic jets on their morphology, dynamics and emission properties. For this purpose we consider jets of extremely different compositions including pure leptonic and baryonic plasmas. Our work is based on two-dimensional relativistic hydrodynamic simulations of the long-term evolution of powerful extragalactic jets propagating into a homogeneous environment. The equation of state used in the simulations accounts for an arbitrary mixture of electrons, protons and electron-positron pairs. Using the hydrodynamic models we have also computed synthetic radio maps and the thermal Bremsstrahlung X-ray emission from their cavities. Although ther…
Plasma Electron Kinetics and Distribution Functions in Laser Fields
2010
A concise review of the properties of electron distribution functions in a fully ionized plasma in the presence of a high-frequency laser field is presented. In detail is discussed the physical origin of most of the reported results in the case of strong fields. The presence of a laser field, through the inverse bremsstrahlung absorption, alters dynamically the roles of and the interplay between electron-ion and electron-electron collisions shaping the distribution function. Special attention is paid to the role of e-e collisions in the process of laser-plasma interaction.
Line Features in Psds of X-Ray Binaries
1994
There is a great deal of evidence that the X-ray emission from High Mass X-Ray Binaries (HMXRB) is often associated with the accretion of matter from a “normal” companion to a degenerate (neutron) star. Provided the magnetic field in these systems is very high (B ~ 1012 — 1013 G), the accretion should occur via the formation of discrete “blobs” which should emit through bremsstrahlung process due to the sudden stop near the surface of the neutron star[2, 3, 5]. There are a number of detections of non-Poissonian aperiodic variations in the intensity of emitted radiation (often referred to as “flickering”) with a characteristic Power Spectrum Density (PSD) broad band feature (red noise)[4, 1]…
Nonlinear inverse bremsstrahlung and highly anisotropic electron distributions
1996
A procedure is proposed to deal with the approximate solution of the kinetic equation for the velocity distribution function of electrons in a fully ionized plasma in the presence of strong, high frequency radiation. The Legendre polynomial expansion is applied after the kinetic equation has been written in an oscillating frame, where some directions are appropriately scaled, with the aim of making approximately isotropic, on the average, distributions that are otherwise anisotropic. The equations are derived for the isotropic part of the electron distribution in the scaled frame and for the scaling factor. The procedure is meant to display its potential in cases where the electron distribu…
Enhancement of the linear polarization of coherent bremsstrahlung by collimation of the photon beam
1998
A method is described to precisely predict the relative intensities and degrees of linear polarization of coherent bremsstrahlung from diamond crystals, taking into account the collimation of the photon beam and the lateral distribution and angular divergence of the electron beam in addition to the properties of the crystal. It is confirmed that the increase of the degree of linear polarization through collimation of the photon beam is a sizable effect. Compared to previous approaches considerable progress has been made in reproducing the experimentally observed relative intensities of collimated coherent bremsstrahlung, by taking into account the angular distribution of coherent bremsstrah…
Precision measurement of the ratio BR(KS→π+π−e+e−)/BR(KL→π+π−πD0)
2011
Abstract The K S → π + π − e + e − decay mode was investigated using the data collected in 2002 by the NA48/1 Collaboration. With about 23 k K S → π + π − e + e − events and 59 k K L → π + π − π D 0 normalization decays, the K S → π + π − e + e − branching ratio relative to the K L → π + π − π D 0 one was determined to be BR ( K S → π + π − e + e − ) / BR ( K L → π + π − π D 0 ) = ( 3.28 ± 0.06 stat ± 0.04 syst ) × 10 − 2 . This result was used to set the upper limit | g E1 / g BR | 3.0 at 90% CL on the presence, in the decay amplitude, of an E1 direct emission ( g E1 ) term relative to the dominant inner bremsstrahlung ( g BR ) term. The CP-violating asymmetry A ϕ in the sin ϕ cos ϕ distri…
Time Evolution of High-Energy Bremsstrahlung and Argon Ion Production in Electron Cyclotron Resonance Ion-Source Plasma
2009
Bremsstrahlung radiation measurement is one of the most commonly used plasma-diagnostics methods. Most of the bremsstrahlung measurements with electron cyclotron resonance ion sources (ECRISs) have been performed in continuous-operation mode yielding information only on the steady-state bremsstrahlung emission. This paper describes results of bremsstrahlung and argon ion-current measurements with the JYFL 14-GHz ECRIS operated in a pulsed mode. The bremsstrahlung radiation was studied as a function of neutral-gas pressure and radio frequency power. The timescale of ECRIS bremsstrahlung production is compared to ion-production timescale for different charge states of argon for the first time…
The effect of magnetic field strength on the time evolution of high energy bremsstrahlung radiation created by an electron cyclotron resonance ion so…
2009
Abstract An electron cyclotron resonance (ECR) ion source is one of the most used ion source types for high charge state heavy ion production. In ECR plasma the electrons are heated by radio frequency microwaves in order to provide ionization of neutral gases. As a consequence, ECR heating also generates very high electron energies (up to MeV region) which can produce a vast amount of bremsstrahlung radiation causing problems with radiation shielding and heating superconducting cryostat of an ECR ion source. To gain information about the time evolution of the electron energies in ECR plasma radial bremsstrahlung measurements were performed. JYFL 14 GHz ECR ion source was operated in pulsed …