865 research outputs found
Integral Matrix Gram Root and Lattice Gaussian Sampling without Floats
Many advanced lattice based cryptosystems require to sample lattice points from Gaussian distributions. On
A strained silicon cold electron bolometer using Schottky contacts
We describe optical characterisation of a strained silicon cold electron bolometer (CEB), operating on a 350 mK stage, designed for absorption of millimetre-wave radiation. The silicon cold electron bolometer utilises Schottky contacts between a superconductor and an n++ doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to 160 GHz and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of 50% for radiation coupled into the device by the planar antenna and an overall noise equivalent power, referred to absorbed optical power, of 1.1×10−16 W Hz−1/2 when the detector is observing a 300 K source through a 4 K throughput limiting aperture. Even though this optical system is not optimized, we measure a system noise equivalent temperature difference of 6 mK Hz−1/2. We measure the noise of the device using a cross-correlation of time stream data, measured simultaneously with two junction field-effect transistor amplifiers, with a base correlated noise level of 300 pV Hz−1/2 and find that the total noise is consistent with a combination of photon noise, current shot noise, and electron-phonon thermal noise
Torsion pairs and rigid objects in tubes
We classify the torsion pairs in a tube category and show that they are in
bijection with maximal rigid objects in the extension of the tube category
containing the Pruefer and adic modules. We show that the annulus geometric
model for the tube category can be extended to the larger category and
interpret torsion pairs, maximal rigid objects and the bijection between them
geometrically. We also give a similar geometric description in the case of the
linear orientation of a Dynkin quiver of type A.Comment: 25 pages, 13 figures. Paper shortened. Minor errors correcte
Effective mobilities in pseudomorphic Si/SiGe/Si p-channel metal-oxide-semiconductor field-effect transistors with thin silicon capping layers
The room-temperature effective mobilities of pseudomorphic Si/Si0.64Ge0.36/Si p-metal-oxidesemiconductor field effect transistors are reported. The peak mobility in the buried SiGe channel increases with silicon cap thickness. It is argued that SiO2/Si interface roughness is a major source of scattering in these devices, which is attenuated for thicker silicon caps. It is also suggested that segregated Ge in the silicon cap interferes with the oxidation process, leading to increased SiO2/Si interface roughness in the case of thin silicon caps
AGILE observation of a gamma-ray flare from the blazar 3C 279
Context. We report the detection by the AGILE satellite of an intense
gamma-ray flare from the gamma-ray source 3EG J1255-0549, associated to the
Flat Spectrum Radio Quasar 3C 279, during the AGILE pointings towards the Virgo
Region on 2007 July 9-13.
Aims. The simultaneous optical, X-ray and gamma-ray covering allows us to
study the spectral energy distribution (SED) and the theoretical models
relative to the flaring episode of mid-July.
Methods. AGILE observed the source during its Science Performance
Verification Phase with its two co-aligned imagers: the Gamma- Ray Imaging
Detector (GRID) and the hard X-ray imager (Super-AGILE) sensitive in the 30 MeV
- 50 GeV and 18 - 60 keV respectively. During the AGILE observation the source
was monitored simultaneously in optical band by the REM telescope and in the
X-ray band by the Swift satellite through 4 ToO observations.
Results. During 2007 July 9-13 July 2007, AGILE-GRID detected gamma-ray
emission from 3C 279, with the source at ~2 deg from the center of the Field of
View, with an average flux of (210+-38) 10^-8 ph cm^-2 s^-1 for energy above
100 MeV. No emission was detected by Super-AGILE, with a 3-sigma upper limit of
10 mCrab. During the observation lasted about 4 days no significative gamma-ray
flux variation was observed.
Conclusions. The Spectral Energy Distribution is modelled with a homogeneous
one-zone Synchrotron Self Compton emission plus the contributions by external
Compton scattering of direct disk radiation and, to a lesser extent, by
external Compton scattering of photons from the Broad Line Region.Comment: Accepted for publication in Astronomy and Astrophysic
Research to develop Spiritual Pedagogy, Awareness and Change
This is an Accepted Manuscript of an article published by Taylor & Francis in British Journal of Guidance and Counselling on 21-4-16, available online: http://dx.doi.org/10.1080/03069885.2016.1174976A co-operative inquiry group consisting of 8 counsellors met for 11 months to explore their experience of spirituality in their counselling training and in their work with clients (Swinton, 2010; 2015). The aim was to explore whether spirituality was absent from the process of counselling training, specifically to discover (1) how counsellors perceived and described their experience of spirituality in their training and (2) with a view to developing spiritual pedagogy; how spirituality could be incorporated into the training process of practitioner
First AGILE Catalog of High Confidence Gamma-Ray Sources
We present the first catalog of high-confidence gamma-ray sources detected by
the AGILE satellite during observations performed from July 9, 2007 to June 30,
2008. Catalogued sources are detected by merging all the available data over
the entire time period. AGILE, launched in April 2007, is an ASI mission
devoted to gamma-ray observations in the 30 MeV - 50 GeV energy range, with
simultaneous X-ray imaging capability in the 18-60 keV band. This catalog is
based on Gamma-Ray Imaging Detector (GRID) data for energies greater than 100
MeV. For the first AGILE catalog we adopted a conservative analysis, with a
high-quality event filter optimized to select gamma-ray events within the
central zone of the instrument Field of View (radius of 40 degrees). This is a
significance-limited (4 sigma) catalog, and it is not a complete flux-limited
sample due to the non-uniform first year AGILE sky coverage. The catalog
includes 47 sources, 21 of which are associated with confirmed or candidate
pulsars, 13 with Blazars (7 FSRQ, 4 BL Lacs, 2 unknown type), 2 with HMXRBs, 2
with SNRs, 1 with a colliding-wind binary system, 8 with unidentified sources.Comment: Revised version, 15 pages, 3 figures, 3 tables. To be published in
Astronomy and Astrophysics. Text improved and clarified. Refined analysis of
complex regions of the Galactic plane yields a new list of high-confidence
sources including 47 sources (compared with the 40 sources appearing in the
first version
A high-performance custom photodetection system to probe the light yield enhancement in oriented crystals
Scintillating homogeneous detectors represent the state of the art in
electromagnetic calorimetry. Moreover, the currently neglected crystalline
nature of the most common inorganic scintillators can be exploited to achieve
an outstanding performance boost in terms of compactness and energy resolution.
In fact, it was recently demonstrated by the AXIAL/ELIOT experiments that a
strong reduction in the radiation length inside PWO, and a subsequent
enhancement in the scintillation light emitted per unit thickness, are attained
when the incident particle trajectory is aligned with a crystal axis within
. A SiPM-based system has been developed to directly probe this
remarkable effect by measuring the scintillation light emitted by a PWO sample.
The same concept could be applied to full-scale detectors that would feature a
design significantly more compact than currently achievable and unparalleled
resolution in the range of interest for present and future experiments
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