James Paton MacArthur

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We present an analysis of both the resolved X-ray emission-line profiles and the broadband X-ray spectrum of the O2 If∗ star HD 93129A, measured with the Chandra High Energy Transmission Grating Spectrometer (HETGS). This star is among the earliest and most massive stars in the Galaxy, and provides a test of the embedded wind-shock scenario in a very dense(More)
STRICKER, E. M. AND J. P. MACARTHUR. Physiological bases for different effects of extravascular colloid treatments on water and NaCI solution drinking by rats. PHYSIOL. BEHAV. 13(3) 389-394, 1974. Extravascular injections of colloidal solutions gradually promote the sequestration of isosmotic protein-free plasma fluid which has been extruded from local(More)
A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a(More)
We present a method for computing the net transmission of X-rays emitted by shock-heated plasma distributed throughout a partially optically thick stellar wind from a massive star. We find the transmission by an exact integration of the formal solution, assuming that the emitting plasma and absorbing plasma are mixed at a constant mass ratio above some(More)
We report the fabrication and first demonstration of an electron beam position monitor for a dielectric microaccelerator. This device is fabricated on a fused silica substrate using standard optical lithography techniques and uses the radiated optical wavelength to measure the electron beam position with a resolution of 10 μm, or 7% of the electron beam(More)
X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L(3,2)-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This(More)
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