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CMOS monolithic active pixel sensors (MAPS) constitute a novel technique for position sensitive charged particle detectors. Their development is driven by the requirements of vertex detectors for future high-energy and nuclear physics experiments as well as by those of biomedical applications, namely highly granular dosimetry. The radiation hardness of MAPS-detectors is subject to intensive studies. Their resistance against up to $\sim$10$^{12}$ n$_{eq}$/cm$^2$ was demonstrated [M. Deveaux, G. Claus, G. Deptuch,W. Dulinski, Y. Gornushkin, M. Winter, Nucl. Instr. and Meth. A 512 (2003) 71–76]. On the other hand, only poor data are available so far about their resistance against ionising doses. This paper summarises the results of radiation hardness studies on two different MAPS-detectors up to a dose of 1 MRad.
The low-energy electron detectors presented in this work have near theoretical electron signal gain at low energies measured down to 200 eV and high-speed response due to the following technological steps: (i) chemical vapor deposition (CVD) of boron layers (PureB layers) proven to form an ideal nm-deep p+n junction with the outstanding sensitivity to low-energy electrons [1], and (ii) defect-free, ultra-low doped, 40 μm thick n-- epitaxial layer which facilitates capacitance values as low as 3 pF/mm2. The fabricated detectors have been placed in SEMs and the resulting high-resolution images, robustness to the electron irradiation, and high scanning speeds make them promising candidates for the future solid-state backscatteredelectron (BSE) detectors.
The effect of quantum confinement on the direct bandgap of spherical Si nanocrystals has been modelled theoretically. We conclude that the energy of the direct bandgap at the $\Gamma$-point decreases with size reduction: quantum confinement enhances radiative recombination across the direct bandgap and introduces its "red" shift for smaller grains. We postulate to identify the frequently reported efficient blue emission (F-band) from Si nanocrystals with this zero-phonon recombination. In a dedicated experiment, we confirm the "red" shift of the F-band, supporting the proposed identification.
The elastic cross section for proton proton scattering at 11.75 GeV/c was measured at the Argonne ZGS using a 50% polarized target. In the range p[perpendicular]2=0.6 --> 2.2 (GeV/c)2 we obtained precise measurements of d[sigma]/dt(ij) for the [two upwards arrow] [two down arrows], and [up and down arrow]; initial spin states perpendicular to the scattering plane. We confirmed that the asymmetry parameter, A, decreases with energy in the diffraction peak, but is approximately energy-independent at large p[perpendicular]2. We found that the spin correlation parameter cnn acquires rather dramatic structure, and at large p[perpendicular]2 seems to grow with energy.
PCR procedures amplifying portions of the 16S rRNA and NADH oxidase genes of Brachyspira aalborgi and Serpulina pilosicoli were applied to DNA extracted from paraffin-embedded human colonic or rectal tissues from 30 Norwegian, Australian, and U.S. patients, 16 of whom had histologic evidence of intestinal spirochetosis (IS). B. aalborgi-specific sequences were identified by PCR in 10 of the IS patients (62.5%) but none of the others, while S. pilosicoli sequences were not detected in tissues from any patient. Direct sequencing of products from three of the positive samples provided further confirmation of the presence of B. aalborgi. B. aalborgi may be a more common cause of intestinal spirochetosis than has been previously thought.
The elastic cross section for proton proton scattering at 6 GeV/c was measured using a 70% polarized beam and a 75% polarized target at the Argonne ZGS. In the range P[perpendicular]2 = 0.5 --> 2.0(GeV/c)2 we obtained small error measurements for the [short up arrow][short up arrow], [downwards arrow][downwards arrow] and [short up arrow][downwards arrow] initial spin states perpendicular to the scattering plane. At P[perpendicular]2 = 0.5 we also measured the recoil spin and found that the 5 different cross sections were very unequal.
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