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Marinas, C., & Vos, M. (2011). The Belle-II DEPFET pixel detector: A step forward in vertexing in the superKEKB flavour factory. Nucl. Instrum. Methods Phys. Res. A, 650(1), 59–63.
Abstract: An upgrade of the successful asymmetric e(+)e(-) collider in KEK (Tsukuba, Japan) is foreseen by the fall of 2013. This new Super Flavor Factory will deliver an increased instantaneous luminosity of up to L = 8 x 10(35) cm(-2) s(-1), 40 times larger than the current KEKB machine. To exploit these new conditions and provide high precision measurements of the decay vertex of the B meson systems, a new silicon vertex detector will be operated in Belle. This new detector will consist of two layers of DEPFET Active Pixel Sensors as close as possible to the interaction point. DEPFET is a field effect transistor, with an additional deep implant underneath the channel's gate, integrated on a completely depleted bulk. This technology offers detection and an in-pixel amplification stage, while keeping low the power consumption. Under these conditions, thin sensors with small pixel size and low intrinsic noise are possible. In this article, an overview of the full system will be described, including the sensor, the front-end electronics and both the mechanical and thermal proposed solutions as well as the expected performance.
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Prasad, V. et al, Lacasta, C., Marinas, C., Mazorra de Cos, J., & Molina-Bueno, L. (2027). Upgrade of the Belle II vertex detector with depleted monolithic CMOS active pixel sensors. Nucl. Instrum. Methods Phys. Res. A, 1093, 171963–5pp.
Abstract: The Belle II experiment, operating at the asymmetric SuperKEKB e+e-collider, is preparing an upgrade of its vertex detector to cope with an increased luminosity of 6 & times; 1035 cm-2s-1. The upgraded vertex detector (VTX) will consist of five or six layers of depleted monolithic active pixel sensors (DMAPS), with a total material budget of approximately 3% X/X0. The OBELIX chip, derived from the TJ-Monopix2 sensor and fabricated using Tower-Jazz Semiconductor 180 nm CMOS technology, is being developed for this upgrade. It features a 33 & micro;m pixel pitch with a time-stamping binning of 50-100 ns, along with a dedicated digital periphery compatible with the Belle II trigger system, supporting rates up to 30 kHz. The sensor is designed to operate under the high background conditions expected at the target luminosity, with radiation tolerance up to 5 & times;1014 neq/cm2 and 100 Mrad, while targeting a power density of about 200 mW/cm2. This corresponds to hit rates up to 120 MHz/cm2. Beam test and irradiation studies of TJ-Monopix2 demonstrate that the operating sensor temperature should stay below 40 degrees C after irradiation up to 5 & times; 1014 neq/cm2. This report reviews the proposed VTX concept, sensor performance, and ongoing R&D activities.
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Zornoza, J. D. (2021). Review on Indirect Dark Matter Searches with Neutrino Telescopes. Universe, 7(11), 415–10pp.
Abstract: The search for dark matter is one of the hottest topics in Physics today. The fact that about 80% of the matter of the Universe is of unknown nature has triggered an intense experimental activity to detect this kind of matter and a no less intense effort on the theory side to explain it. Given the fact that we do not know the properties of dark matter well, searches from different fronts are mandatory. Neutrino telescopes are part of this experimental quest and offer specific advantages. Among the targets to look for dark matter, the Sun and the Galactic Center are the most promising ones. Considering models of dark matter densities in the Sun, neutrino telescopes have put the best limits on spin-dependent cross section of proton-WIMP scattering. Moreover, they are competitive in the constraints on the thermally averaged annihilation cross-section for high WIMP masses when looking at the Galactic Centre. Other results are also reviewed.
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