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showing 10 items of 1701 documents
The fast photon detection system of COMPASS RICH-1
2007
Abstract A fast photon detection system has been built for the upgrade of COMPASS RICH-1, the large size gaseous RICH detector in use at the COMPASS Experiment at the CERN SPS since 2001. The photon detectors of the central region have been replaced by a new system based on multi-anode photomultipliers coupled to individual fused silica lens telescopes and a fast readout electronics system, while in the outer region the existing MWPCs with CsI photocathodes have been equipped with a new readout system, based on the APV chip. RICH-1 has been successfully operated in its upgraded version during the 2006 run. We report on the upgrade design and construction, and on the preliminary characteriza…
Ontogenetic and phylogenetic diversification of the hooded staminode in Marantaceae
2010
The flowers of Marantaceae are known for their unique pollination mechanism mediated by an explosive style movement. The mechanism is based on the highly modified elements of the inner androecial whorl, i.e., the single half-fertile anther and the fleshy and hooded staminodes. We investigated 67 species across 24 genera to elucidate which parts of the hooded staminode are shared by all species, thus likely under strong selection pressure, and which are allowed to vary. We treated hooded staminodes as character syndromes and grouped them based on gross similarities. We identified characters underlying the similarity and investigated their diversity and developmental pathways. All hooded stam…
IL-23: a master regulator in Crohn disease
2007
Three studies should shift thinking about the causes of inflammatory bowel disease. It seems that researchers have been focusing on the wrong cytokine as a driving force.
Turnstile behaviour of the Cooper-pair pump
2003
We have experimentally studied the behaviour of the so-called Cooper pair pump (CPP) with three Josephson junctions, in the limit of small Josephson coupling EJ < EC. These experiments show that the CPP can be operated as a traditional turnstile device yielding a gate-induced current 2ef in the direction of the bias voltage, by applying an RF-signal with frequency f to the two gates in phase, while residing at the degeneracy node of the gate plane. Accuracy of the CPP during this kind of operation was about 3% and the fundamental Landau-Zener limit was observed to lie above 20 MHz. We have also measured the current pumped through the array by rotating around the degeneracy node in the ga…
A cylindrical GEM detector with analog readout for the BESIII experiment
2016
Abstract A cylindrical GEM detector with analog readout is under development for the upgrade of the Inner Tracker of the BESIII experiment at IHEP (Beijing). The new detector will match the requirements for momentum resolution ( σ pt / p t ~ 0.5 % at 1 GeV) and radial resolution ( σ xy ~ 120 μ m ) of the existing drift chamber and will improve significantly the spatial resolution along the beam direction ( σ z ~ 150 μ m ) with very small material budget (less than 1.5% of X 0 ). With respect to the state of the art the following innovations will be deployed: a lighter mechanical structure based on Rohacell, a new XV anode readout plane with jagged strip layout to reduce the parasitic capaci…
Recent results with lifetime enhanced microchannel-plate photomultipliers
2018
Abstract The favored photon sensors for the DIRC (detection of internally reflected Cherenkov light) detectors at the PANDA (Anti-proton Annihilation at Darmstadt) experiment at FAIR (Facility for anti-proton and ion research) are micro-channel-plate photomultipliers (MCP-PMTs). The main problem until a few years ago was the limited lifetime of the MCP-PMTs caused by a rapid decrease in quantum efficiency (QE) of the photo cathode (PC) with increasing integrated anode charge (IAC). These limitations are overcome by applying an atomic layer deposition (ALD) coating on the MCPs, as recently done by PHOTONIS and Hamamatsu. During the last years’ tests of lifetime enhanced MCP-PMTs were perform…
Improved lifetime of microchannel-plate PMTs
2014
Abstract The charged particle identification at the PANDA experiment will be mainly performed with DIRC detectors. Because of their advantageous properties the preferred photon sensors are MCP-PMTs. However, until recently these devices showed serious aging problems which resulted in a diminishing quantum efficiency (QE) of the photo cathode. By applying innovative countermeasures against the aging causes, the manufacturers recently succeeded in drastically improving the lifetime of MCP-PMTs. Especially the application of an ALD coating technique to seal the material of the micro-channels proves very powerful and results in a lifetime of ≈ 6 C / cm 2 integrated anode charge without a substa…
Characterisation and calibration of a scintillating fibre detector with > 4000 multi-anode photomultiplier channels
2012
In the Kaos spectrometer at the Mainz Microtron a high-resolution coordinate detector for high-energy particles is operated. It consists of scintillating fibres with diameters of 4000 multi-anode photomultiplier channels. It is one of the most modern focal-plane detectors for magnetic spectrometers world-wide. To correct variations in the detection efficiency, caused by the different gains and the different optical transmittances, a fully automated off-line calibration procedure has been developed. The process includes the positioning of a radioisotope source alongside the detector plane and the automated acquisition and analysis of the detector signals. It was possible to characterise and …
Front-End Electronics for the KAOS Spectrometer at MAMI
2009
A new front-end electronics system has been developed for the electron arm tracking detectors in the Kaos spectrometer at the Mainz microtron MAMI. The signals of multi-anode photomultipliers are collected by 96-channel front-end boards, digitized by double-threshold discriminators and the signal time is picked up by F1 TDC chips. The system was designed to process more than 4,000 channels and to cope with the high electron flux in the spectrometer and the high count rate requirement of the detectors. A subset of 288 channels was installed and successfully used in the 2008 data taking period of the Kaos spectrometer.
Fast photon detection for COMPASS RICH-1
2007
A fast photon detection system has been built and assembled for the upgrade of COMPASS RICH-1. The system is based on multianode photomultipliers coupled to fused silica lenses to collect the light from a larger surface and to guide it to the photocathode, preserving the position information. The emphasis is on the fast response and high rate capability of the detectors and the associated electronics. The photon detection system is now ready and it will be employed in the 2006 COMPASS data taking. We report about the system design and construction.