2,082 research outputs found

    Time Resolution of a Few Nanoseconds in Silicon Strip Detectors Using the APV25 Chip

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    The APV25 front-end chip for the CMS Silicon Tracker has a peaking time of 50 ns, but confines the signal to a single clock period (=bunch crossing) with its internal ‚Äúdeconvolution‚ÄĚ filter. This method requires a beam-synchronous clock and thus cannot be applied to a (quasi-) continuous beam. Nevertheless, using the multi-peak mode of the APV25, where 3 (or 6,9,12,...) consecutive shaper output samples are read out, the peak time can be reconstructed externally with high precision. Thus, offtime hits can be discarded which results in significant occupancy reduction. We will describe this method, results from beam tests and the intended implementation in an upgrade of the BELLE Silicon Vertex Detector

    Construction and Performance of a Double-Sided Silicon Detector Module Using the Origami Concept

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    The APV25 front-end chip with short shaping time will be used in the Belle II Silicon Vertex Detector (SVD) in order to achive low occupancy. Since fast amplifiers are more susceptible to noise caused by their capacitive input load, they have to be placed as close to the sensor as possible. On the other hand, material budget inside the active volume has to be kept low in order to constrain multiple scattering. We built a low mass sensor module with double-sided readout, where thinned APV25 chips are placed on a single flexible circuit glued onto one side of the sensor. The interconnection to the other side is done by Kapton fanouts, which are wrapped around the edge of the sensor, hence the name Origami. Since all front-end chips are aligned in a row on the top side of the module, cooling can be done by a single aluminum pipe. The performance of the Origami module was evaluated in a beam test at CERN in August 2009, of which first results are presented here

    Readout and Data Processing Electronics for the Belle-II Silicon Vertex Detector

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    A prototype readout system has been developed for the future Belle-II Silicon Vertex Detector at the Super-KEK-B factory in Tsukuba, Japan. It will receive raw data from double-sided sensors with a total of approximately 240,000 strips read out by APV25 chips at a trigger rate of up to 30kHz and perform strip reordering, pedestal subtraction, a two-pass common mode correction and zero suppression in FPGA firmware. Moreover, the APV25 will be operated in multi-peak mode, where (typically) six samples along the shaped waveform are used for precise hit-time reconstruction which will also be implemented in FPGAs using look-up tables

    The CMS Pixel FED

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    The innermost detector of the CMS Experiment consists of 66 million silicon pixels. The hit data has to be read out and must be digitized, synchronized, formatted and transferred over the S-Link to the CMS DAQ. The amount of data can only be handled because the readout chip (ROC) delivers zero-suppressed data above an adjustable threshold for every pixel. The Pixel FED 9U VME module receives an analog optical signal, which is subsequently digitized and processed. The position of the pixel on a module is transmitted with five symbols coded in six pulse height steps each. The data of 36 inputs build a final event data block. The data block from each detector module with either 16 or 24 ROCs differs in length and arrival time. Depending on the data length and trigger rate, there can be a skew of several events between any two inputs. That is possible because the ROC has a multievent time stamp memory and the readout bandwith is limited. Finally the information processed by the Pixel FED will be transferred over the S-Link to the CMS DAQ. Each module must be able to process a trigger rate of 100 kHz or, if in trouble, to send an alarm signal. The number of inputs is limited by the maximum data transmission rate of the S-Link (640 MB/s) for the expected high luminosity of LHC. The data flow on the module is continuously controlled. Errors are written in an error memory, included in the data stream and if critical sent to the general CMS readout control

    Repealing the √áatalh√∂y√ľk extractive metallurgy: The green, the fire and the ‚Äėslag‚Äô

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    The scholarly quest for the origins of metallurgy has focused on a broad region from the Balkans to Central Asia, with different scholars advocating a single origin and multiple origins, respectively. One particular find has been controversially discussed as the potentially earliest known example of copper smelting in western Eurasia, a copper ‚Äėslag‚Äô piece from the Late Neolithic to Chalcolithic site of √áatalh√∂y√ľk in central Turkey. Here we present a new assessment of metal making at √áatalh√∂y√ľk based on the re-analysis of minerals, mineral artefacts and high-temperature materials excavated in the 1960s by J. Mellaart and first analysed by Neuninger, Pittioni and Siegl in 1964. This paper focuses on copper-based minerals, the alleged piece of metallurgical slag, and copper metal beads, and their contextual relationship to each other. It is based on new microstructural, compositional and isotopic analyses, and a careful re-examination of the fieldwork documentation and analytical data related to the c. 8500 years old high-temperature debris at √áatalh√∂y√ľk. We re-interpret the sample identified earlier as metallurgical slag as incidentally fired green pigment, which was originally deposited in a burial and later affected by a destructive fire that also charred the bones of the interred body. We also re-confirm the contemporary metal beads as made from native metal. Our results provide a new and conclusive explanation of the previously contentious find, and reposition √áatalh√∂y√ľk in a new narrative of the multiple origins of metallurgy in the Old World.Qatar Foundation enabled the new study of this material through its generous funding of UCL Qatar as a joint centre of excellence for Museology, Conservation and Archaeolog

    The changing nature of labour regulation: the distinctiveness of the National Agreement for the Engineering Construction Industry

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    The article addresses the changing nature of labour regulation through analysis of the National Agreement for the Engineering Construction Industry, originating in 1981. It shows how multiple spatial regulatory scales, the changing coalitions of actors involved, employer and client engagement and labour agency have been critical to National Agreement for the Engineering Construction Industry's survival

    Latest Results from the Heidelberg-Moscow Double Beta Decay Experiment

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    New results for the double beta decay of 76Ge are presented. They are extracted from Data obtained with the HEIDELBERG-MOSCOW, which operates five enriched 76Ge detectors in an extreme low-level environment in the GRAN SASSO. The two neutrino accompanied double beta decay is evaluated for the first time for all five detectors with a statistical significance of 47.7 kg y resulting in a half life of (T_(1/2))^(2nu) = [1.55 +- 0.01 (stat) (+0.19) (-0.15) (syst)] x 10^(21) years. The lower limit on the half-life of the 0nu beta-beta decay obtained with pulse shape analysis is (T_(1/2))^(0_nu) > 1.9 x 10^(25) [3.1 x 10^(25)] years with 90% C.L. (68% C.L.) (with 35.5 kg y). This results in an upper limit of the effective Majorana neutrino mass of 0.35 eV (0.27 eV). No evidence for a Majoron emitting decay mode or for the neutrinoless mode is observed.Comment: 14 pages, revtex, 6 figures, Talk was presented at third International Conference ' Dark Matter in Astro and Particle Physics' - DARK2000, to be publ. in Proc. of DARK2000, Springer (2000). Please look into our HEIDELBERG Non-Accelerator Particle Physics group home page: http://www.mpi-hd.mpg.de/non_acc

    Measurement of the branching ratios of the decays Xi0 --> Sigma+ e- nubar and anti-Xi0 --> anti-Sigma+ e+ nu

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    From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi0 --> Sigma+ e- nubar candidates (with the subsequent Sigma+ --> p pi0 decay) and 555 anti-Xi0 --> anti-Sigma+ e+ nu candidates with background contamination of 215+-44 and 136+-8 events, respectively. From these samples, the branching ratios BR(Xi0 --> Sigma+ e- nubar)= (2.51+-0.03stat+-0.09syst)E(-4) and BR(anti-Xi0 --> anti-Sigma+ e+ nu)= (2.55+-0.14stat+-0.10syst)E(-4) were measured allowing the determination of the CKM matrix element |Vus| = 0.209+0.023-0.028. Using the Particle Data Group average for |Vus| obtained in semileptonic kaon decays, we measured the ratio g1/f1 = 1.20+-0.05 of the axial-vector to vector form factors.Comment: 16 pages, 11 figures Submitted to Phys.Lett.
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