Novel semitransparent optical position sensors ("ALMY sensors") have been developed for the alignment monitoring systems of modern large-area tracking detectors. The high transmittance of up to 90% ...allows to align more than 10 sensors along a collimated laser beam. A position resolution of 1 /spl mu/m and an uncertainty in the deflection of the traversing laser beam of less than 3 /spl mu/rad have been achieved for sensitive areas of several square centimeters. For the thin-film amorphous silicon sensors, the required laser intensity could be minimized such that the performance is not deteriorated by aging effects.
The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor based on the reconstruction of beam-gas interaction vertices which is being developed as part of the High Luminosity LHC ...project. Tracks are identified using several planes of scintillating fibres, located outside the beam vacuum chamber and perpendicular to the beam axis. The gas pressure in the interaction volume is adjusted such as to provide an adequate trigger rate, without disturbing the beam. A BGV demonstrator monitoring one of the two LHC beams was fully installed and commissioned in 2016. First data and beam size measurements show that the complete detector and data acquisition system is operating as expected. The BGV operating parameters are now being optimised and the reconstruction algorithms developed to produce accurate and fast reconstruction on a CPU farm in order to provide real time beam profile measurements to the LHC operators.
The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor based on the reconstruction of beam-gas interaction vertices which is being developed as part of the High Luminosity LHC ...project. Tracks are identified using several planes of scintillating fibres, located outside the beam vacuum chamber and perpendicular to the beam axis. The gas pressure in the interaction volume is adjusted such as to provide an adequate trigger rate, without disturbing the beam. A BGV demonstrator monitoring one of the two LHC beams was fully installed and commissioned in 2016. First data and beam size measurements show that the complete detector and data acquisition system is operating as expected. The BGV operating parameters are now being optimised and the reconstruction algorithms developed to produce accurate and fast reconstruction on a CPU farm in order to provide real time beam profile measurements to the LHC operators.
We compare transition radiation (TR) and ionization energy loss distributions obtained from a Monte Carlo simulation based on Geant4 to electron and proton data. The data were taken with a prototype ...consisting of 20 layers of fleece radiator and straw tube proportional chambers, filled with Xe/CO
2, during a testbeam at CERN. We find impressive agreement for the simulation of TR for electrons and very good agreement for the ionization loss distributions for protons over a wide range of incident energies. The implications of slight deviations in the tails of the proton energy loss spectra on calculated proton suppression factors are studied briefly.
A silicon photomultiplier (SiPM) array has been developed at FBK-irst Piemonte C., Nucl. Instrum. Methods A,
568 (2006) 224; Piemonte C. et al., IEEE Trans. Nucl. Sci.,
54 (2007) 236 having 32 ...channels and a dimension of
8.0
×
1.1
mm
2
. Each 250 μm wide channel is subdivided into
5
×
22
rectangularly arranged pixels. These sensors are developed to read out a modular high resolution scintillating fiber tracker. Key properties like breakdown voltage, gain and photon detection efficiency (PDE) are found to be homogeneous over all 32 channels of an SiPM array. This could make scintillating fiber trackers with SiPM array readout a promising alternative to available tracker technologies, if noise properties and the PDE are improved.
A transition radiation detector for AMS Siedenburg, Th; Chung, C.H.; Fopp, S. ...
Nuclear physics. Section B, Proceedings supplement,
12/2002, Letnik:
113, Številka:
1
Journal Article
For cosmic particle spectroscopy on the International Space Station the AMS experiment will be equipped with a Transition Radiation Detector to improve proton background supression up to 300 GeV. The ...TRD has 20 layers of fleece radiator with Xe/CO2 proportional-mode straw-tube chambers. They are supported in a conically shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA analog multiplexers are used as front-end readout. A 20 layer prototype has achieved proton rejections above 100 at 90% electron efficiency for beam energies up to 250 GeV. The detector is under construction at RWTH Aachen, the gas system will be built at MIT, slow-control and DAQ at TH Karlsruhe.
The precise measurement of cosmic-ray antinuclei serves as an important means for identifying the nature of dark matter and other new astrophysical phenomena, and could be used with other cosmic-ray ...species to understand cosmic-ray production and propagation in the Galaxy. For instance, low-energy antideuterons would provide a "smoking gun" signature of dark matter annihilation or decay, essentially free of astrophysical background. Studies in recent years have emphasized that models for cosmic-ray antideuterons must be considered together with the abundant cosmic antiprotons and any potential observation of antihelium. Therefore, a second dedicated Antideuteron Workshop was organized at UCLA in March 2019, bringing together a community of theorists and experimentalists to review the status of current observations of cosmic-ray antinuclei, the theoretical work towards understanding these signatures, and the potential of upcoming measurements to illuminate ongoing controversies. This review aims to synthesize this recent work and present implications for the upcoming decade of antinuclei observations and searches. This includes discussion of a possible dark matter signature in the AMS-02 antiproton spectrum, the most recent limits from BESS Polar-II on the cosmic antideuteron flux, and reports of candidate antihelium events by AMS-02; recent collider and cosmic-ray measurements relevant for antinuclei production models; the state of cosmic-ray transport models in light of AMS-02 and Voyager data; and the prospects for upcoming experiments, such as GAPS. This provides a roadmap for progress on cosmic antinuclei signatures of dark matter in the coming years.
Charginos and neutralinos are searched for in the data collected by the ALEPH experiment at LEP for centre-of-mass energies up to 209 GeV. The negative result of these searches is combined with those ...from searches for sleptons and Higgs bosons to derive an absolute lower limit of 43.1 GeV/c2 on the mass of the lightest supersymmetric particle (LSP), assumed to be the lightest neutralino. This limit is obtained in the framework of the MSSM with R-parity conservation and with gaugino and sfermion mass unification at the GUT scale and assuming no mixing in the stau sector. The LSP limit degrades only slightly to 42.4 GeV/c2 if stau mixing is considered. Within the more constrained framework of minimal supergravity, the limit is 50 GeV/c2.
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