Analysis of the \Lambda_{b}\rar \Lambda \ell^+\ell^- decay in QCD

Taking into account the $\Lambda$ baryon distribution amplitudes and the most general form of the interpolating current of the $\Lambda_{b}$, the semileptonic \Lambda_{b}\rar \Lambda \ell^+\ell^- transition is investigated in the framework of the light cone QCD sum rules. Sum rules for all twelve form factors responsible for the \Lambda_{b}\rar \Lambda \ell^+\ell^- decay are constructed. The obtained results for the form factors are used to compute the branching fraction. A comparison of the obtained results with the existing predictions of the heavy quark effective theory is presented. The results of the branching ratio shows the detectability of this channel at the LHCb in the near future is quite high.Comment: 18 Pages, 2 Figures and 9 Table

Measurement of D*+/- diffractive cross sections in photoproduction at HERA

The first measurement of D*+/- meson diffractive photoproduction cross sections has been performed with the ZEUS detector at the HERA $ep$ collider, using an integrated luminosity of 38 pb^-1. The measurement has been performed for photon--proton center-of-mass energies in the range 130 < W < 280 GeV and photon virtualities Q^2 < 1 GeV^2. D*+/- mesons have been reconstructed with p_T(D*)>2 GeV and -1.5 D^0 \pi^+_s with D^0 --> K-\pi^+ (+c.c.). The diffractive component has been selected with 0.001<x_Pom<0.018. The measured diffractive cross section in this kinematic range is: \sigma_(ep --> e'D*Xp') = 0.74 +/- 0.21 (stat.)^{+0.27}_{-0.18} (syst.) +/-0.16 (p. diss.) ~nb (ZEUS preliminary). Measured integrated and differential cross sections have been compared to theoretical expectations.Comment: LaTeX2e, 10 pages, 6 Postscript figures. Talk given at the Russian Academy of Science (RAS) Nuclear Physics 2000 Conference, Moscow, Russia, November 27-December 2, 2000. To be published in Rus. Nucl. Phys. (Ya.F.), Proceedings of RAS Nucl. Phys. 2000 Con

Enhanced Radiation Hardness and Faster Front Ends for the Beetle Readout Chip

This paper summarizes the recent progress in the development of the 128 channel pipelined readout chip Beetle, which is intended for the silicon vertex detector, the inner tracker, the pile-up veto trigger and the RICH detectors of LHCb. Deficiencies found in the front end of the Beetle Version 1.0 and 1.1 chips resulted in the submissions of BeetleFE 1.1 and BeetleFE 1.2, while BeetleSR 1.0 implements test circuits to provide future Beetle chips with logic circuits hardened against single event upset (SEU). Section I. motivates the development of new front ends for the Beetle chip, and section II. summarizes their concepts and construction. Section III. reports preliminary results from the BeetleFE 1.1 and BeetleFE 1.2 chips, while section IV. describes the BeetleSR 1.0 chip. An outlook on future test and development of the Beetle chip is given in section V

Performance of the Beetle readout chip for LHCb

Beetle is a 128-channel readout chip, which will be used in the silicon vertex detector, the pile-up veto counters and the silicon tracker of the LHCb experiment at CERN. A further application of the Beetle chip is the readout of the LHCb RICH, in case it is equipped with multi-anode PMTs. The scope of this paper is the design changes leading to the latest version 1.3 of the Beetle readout chip. In addition, measurements on earlier versions and simulation results driving these changes are shown

SEU Robustness, Total Dose Radiation Hardness and Analogue Performance of the Beetle Chip

The Beetle is a 128 channel readout chip for silicon strip detectors in LHCb. In addition to the pipelined readout path known from the RD20 architecture which can be used either in analogue or binary mode, the Beetle features an additional prompt binary readout path, used for the LHCb pile-up veto counters and a triple-redundant layout of the control logic. It is manufactured in commercial 0.25 µm CMOS technology using radiation hard design techniques. In addition to a total dose irradiation with X-rays, an SEU irradiation test with 65 MeV protons was performed with Beetle1.3. The results of this test are presented together with new results from the Beetle versions 1.3, 1.4 and 1.5, which were submitted in the Beetle ER engineering run in May 2004

The TORCH time-of-flight detector

AbstractThe TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10GeV/c momentum over a flight distance of 10m. TORCH is designed for large-area coverage, up to 30m2, and has a DIRC-like construction. The goal is to achieve a 15ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53mm2 Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40ps per photon and it will have a lifetime of up to at least 5Ccm−2 of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described

Glass-Coated Beryllium Mirrors for the LHCb RICH1 Detector

The design, manufacture and testing of lightweight glass-coated beryllium spherical converging mirrors for the RICH1 detector of LHCb are described. The mirrors need to be lightweight to minimize the material budget and fluorocarbon-compatible to avoid degradation in the RICH1 C4F10 gas radiator. Results of the optical measurements for the small-sized prototypes and for the first full-sized prototype mirror are reported

Test-beam and laboratory characterisation of the TORCH prototype detector

The TORCH time-of-flight (TOF) detector is being developed to provide particle identification up to a momentum of 10 GeV/c over a flight distance of 10 m. It has a DIRC-like construction with View the MathML source10mm thick synthetic amorphous fused-silica plates as a Cherenkov radiator. Photons propagate by total internal reflection to the plate periphery where they are focused onto an array of customised position-sensitive micro-channel plate (MCP) detectors. The goal is to achieve a 15 ps time-of-flight resolution per incident particle by combining arrival times from multiple photons. The MCPs have pixels of effective size 0.4 mm×6.6 mm2 in the vertical and horizontal directions, respectively, by incorporating a novel charge-sharing technique to improve the spatial resolution to better than the pitch of the readout anodes. Prototype photon detectors and readout electronics have been tested and calibrated in the laboratory. Preliminary results from testbeam measurements of a prototype TORCH detector are also presented