8,545 research outputs found
Spin Filtering of Stored (Anti)Protons: from FILTEX to COSY to AD to FAIR
We review the theory of spin filtering of stored (anti)protons by multiple
passage through the polarized internal target (PIT). Implications for the
antiproton polarization buildup in the proposed PAX experiment at FAIR GSI are
discussed.Comment: 4 pages, 1 figure, Presented at the 17th Intl. Spin Physics
Symposium, SPIN2006, Kyoto, Japan, October 2-7, 200
Radiation spectra and polarization in magnetar bursts
We present Monte Carlo simulations of radiative transfer in magnetar
atmospheres. We include the effects of vacuum polarization, electron and proton
scattering, and free-free absorption. Simulations are performed for the
atmosphere model with the magnetic field perpendicular and also tilted with
respect to the neutron star surface, and we show that the average spectrum does
not strongly depend on the orientation of the magnetic field. We investigate
the region of the parameter space where the vacuum absorption-like feature
appears in the spectrum and we analyze the shape of the proton cyclotron line.
Our results indicate that the existence of the vacuum polarization feature
should be a general attribute of soft gamma-ray repeaters burst spectra,
provided that the energy release takes place at the sufficiently dense region,
and the atmosphere scaleheight is large enough. We discuss the existence of
such a feature in recent observational data on these sources.Comment: submitted to Ap
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