SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution - Survey description and compact source catalogue

We present the first release of the data and compact-source catalogue for the JCMT Large Program SCUBA-2 Continuum Observations of Pre-protostellar Evolution (SCOPE). SCOPE consists of 850 μm continuum observations of 1235 Planck Galactic Cold Clumps (PGCCs) made with the Submillimetre Common-User Bolometer Array 2 on the James Clerk Maxwell Telescope. These data are at an angular resolution of 14.4 arcsec, significantly improving upon the 353 GHz resolution of Planck at 5 arcmin, and allowing for a catalogue of 3528 compact sources in 558 PGCCs. We find that the detected PGCCs have significant sub-structure, with 61 per cent of detected PGCCs having three or more compact sources, with filamentary structure also prevalent within the sample. A detection rate of 45 per cent is found across the survey, which is 95 per cent complete to Planck column densities of NH2 > 5 × 1021 cm−2. By positionally associating the SCOPE compact sources with young stellar objects, the star formation efficiency, as measured by the ratio of luminosity to mass, in nearby clouds is found to be similar to that in the more distant Galactic Plane, with the column density distributions also indistinguishable from each other

X-ray polarimetry - A novel application of CCDs

A new method of X-ray polarimetry based on measuring the photoelectron emission direction in a finely segmented MOS CCD has been established using monochromatic synchrotron radiation and planar channeling radiation. For the smallest pixel dimensions (6.8 × 6.8 μm2) available today in commercial optical CCD cameras an analyzing power for linear polarization in the order of 10% has been measured at energies above 10 keV. A strong rise with energy is observed in accord with expectations from Monte Carlo simulations. In addition to events due to the photoeffect in the thin depleted front layer of the CCD, also diffusion spread events resulting from much more abundant conversions deeper inside the chip were found to be very useful for simultaneous measurements of polarization, energy and position

X-ray polarimetry - A novel application of CCDs

A new method of X-ray polarimetry based on measuring the photoelectron emission direction in a finely segmented MOS CCD has been established using monochromatic synchrotron radiation and planar channeling radiation. For the smallest pixel dimensions (6.8 × 6.8 μm2) available today in commercial optical CCD cameras an analyzing power for linear polarization in the order of 10% has been measured at energies above 10 keV. A strong rise with energy is observed in accord with expectations from Monte Carlo simulations. In addition to events due to the photoeffect in the thin depleted front layer of the CCD, also diffusion spread events resulting from much more abundant conversions deeper inside the chip were found to be very useful for simultaneous measurements of polarization, energy and position

X-ray detection with submicron impact accuracy

Utilizing a commercial optical CCD camera with the smallest pixel size presently available (6.8 × 6.8 μm2) we have measured impact accuracies of 0.9 μm (rms) for 15 keV synchrotron radiation in direct photon counting mode. Of crucial importance was diffusion spreading of the deposited charge such that by centroid reconstruction interpolation between discrete pixel coordinates was possible

X-ray polarimetry and position measurement using the photoeffect and charge diffusion in a CCD

A new method of X-ray polarimetry based on the photoeffect in a highly segmented silicon charge coupled device (CCD) has been established using monochromatic synchrotron radiation and planar channeling radiation. For the smallest pixel dimensions (6.8 × 6.8 μm2) available today in commercial optical CCD cameras an analyzing power for linear polarization in the order of 10% has been measured at energies above 10 keV. A strong energy dependence is observed in the energy range from 15 to 40 keV. In addition to events due to the photoeffect in the thin depleted front layer of the CCD, also diffusion spread events resulting from far more abundant conversions deeper inside the chip were found to be very useful for simultaneous measurements of polarization, energy and position with sub-pixel, submicron impact accuracy (0.9 μm rms at 15 keV). The spatial accuracy is in accord with expectations from Monte-Carlo simulations