It is known that vacuum polarization can modify the photon propagation modes in the atmospheric plasma of a strongly magnetized neutron star. A resonance occurs when the effect of vacuum polarization on the photon modes balances that of the plasma. We show that a photon (with energy E >∼ a few keV) propagating outward in the atmosphere can convert from one polarization mode into another as it t...

Recent discovery of the afterglow emission from short gamma-ray bursts suggests that binary neutron star or black hole-neutron star binary mergers are the likely progenitors of these short bursts. The accretion of neutron star material and its subsequent ejection by the central engine implies a neutron-rich outflow. We consider here a neutron-rich relativistic jet model of short bursts, and inv...

Neutron phase contrast imaging is a recently developmental technique which is based not only on the amplitude like in the projection imaging but also on the contribution of phase alteration of the neutron beam. With the additional contrast from the difference of neutron refraction index in the sample which mainly leads to edge enhancement, phase contrast imaging can show more details about the ...

We observed SAX J1808.4-3658 (1808), the first accreting millisecond pulsar, in deep quiescence with XMM-Newton and (near-simultaneously) Gemini-South. The X-ray spectrum of 1808 is similar to that observed in quiescence in 2001 and 2006, describable by an absorbed power-law with photon index 1.74 ± 0.11 and unabsorbed X-ray luminosity LX = 7.9 ± 0.7 × 10 31 ergs s, for NH = 1.3 × 10 21 cm. Fit...

Photon density and photon flux are widely used to model the measurable quantity in diffuse optical tomography problems. However, it is not these two quantities that are actually measured, but rather the radiance accepted by the detection system. We provide a theoretical analysis of the model deviations related to the choice of the measurable quantity-either photon density or flux. By using the ...

The Brookhaven Medical Research Reactor was a 5 mega-watt, light-water cooled and heavygraphite moderated research facility. It has two shutter-equipped treatment rooms, three horizontally extended thimble tubes, and an ex-core broad beam facility. The three experimental thimbles, or activation ports, external to the reactor tank were designed for several uses, including the investigations on d...

In this article we treat the non-adiabatic photon-to-axion resonant conversion of curvature radiation, synchrotron emission and inverse Compton scattering dominating spectral density function pulsars. First, introduce models benchmark observational data.vWe adopt a state-of-the-art profile that relieves tension with quantum electrodynamics vacuum polarization effect in highly magnetic stars, le...

A combined neutron imaging and neutron diffraction facility, IMAT, is currently being built at the pulsed neutron spallation source ISIS in the U.K. A supermirror neutron guide is required to combine imaging and diffraction modes at the sample position in order to obtain suitable time of flight resolutions for energy selective imaging and diffraction experiments. IMAT will make use of a straigh...

Aims. The purpose of this work is to search the Yangbajing neutron monitor data obtained between 1998 October and 2000 June for solar neutrons associated with solar flares. Methods. Using the onset times of 166 BATSE-detected flares with the GOES peak flux (1 – 8 Å) higher than 1.0 × 10−5 Wm−2, we prepare for each flare a light curve of the Yangbajing neutron monitor, spanning ± 1.5 hours from ...

introduction lead-based shields are the most widely used attenuators in x-ray and gamma ray fields. the heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. materials and methods the purpose of this study was to design multi-layered shields for protection against x-rays and gamma rays in diagnostic radiology and nuclear medicine. in this...