The LHCb experiment at the Large Hadron Collider (LHC) at CERN is aimed to study CP violation and to measure the rare decays of B-mesons with exceptionally high precision. A 4 Tm dipole magnet is required for particle separation and momentum measurements. The 1600 ton warm magnet with sloping poles was installed and fully commissioned by the end of 2004. It is the first detector magnet of the four LHC experiments to have been aligned and commissioned in its final position. In this paper, the magnet installation in the underground cavern of Point 8 and its alignment on the beam line are shortly reviewed. Results of a first magnetic field mapping in the region of the magnet poles and the fringe field in the location of the RICH detectors are presented. The mechanical equipment used for the automatic displacement of the Hall probe array is described, together with the precision of the measurements obtained which are compared with TOSCA finite element calculations

We present a C++ toolkit to do tracking and vertex reconstruction. The toolkit incorporates common fitting methods, as the Kalman Filter, a framework to define a detector setup, a general navigation and a simple simulation. Furthermore, the toolkit provides a collection of interfaces which facilitates the addition of new fitting methods, trajectory models, geometrical objects, pattern recognition logic, etc. Although the toolkit was originally developed to be used in High Energy Physics, it could be applied to other fields.

The NOMAD-STAR detector is a silicon vertex detector installed in the NOMAD spectrometer at the CERN SPS neutrino beam. It consists of four layers of a passive boron carbide target with a total mass of 45kg and five layers of 600 single-sided silicon microstrip detectors covering a total area of 1.14m2. About 11,500νμ charged current interactions were reconstructed in the fiducial volume of NOMAD-STAR from the neutrino run in 1998. The potential use of silicon detectors for νμ(νe)↔ντ oscillations depends on the observation of the τ candidates by the experimental signature of a large impact parameter, in the case of the one prong decay of the τ, or a double vertex, in the case of the three prong decay. The main aim of NOMAD-STAR is to measure the impact parameter and vertex distributions of charged current interactions, which constitute the main backgrounds for the oscillation signals, to understand the significance of a potential signal in a future experiment. The present paper describes the experience gained in the operation of this silicon vertex detector, and the performance achieved with it.

This article describes the application of Kalman filter techniques for the tracking and vertexing of particles inside the NOMAD-STAR detector, a silicon vertex detector installed in NOMAD, one of the neutrino oscillation experiments at the CERN-SPS. The use of the Kalman filter simplifies computationally the tracking and vertex procedure for NOMAD-STAR. The alignment of NOMAD-STAR is shown as an example of the application of the Kalman filter for tracking purposes. The accuracy of the method is such that one obtains alignment residuals between 9 and 12μm. Furthermore, a preliminary measure of the impact parameter (with an RMS ∼36μm) illustrates the vertexing capabilities of this technique.

The silicon tracker for the engineering model of the GLAST Large Area Telescope (LAT) to date represents the largest surface of silicon microstrip detectors assembled in a tracker (2.7m2). It demonstrates the feasibility of employing this technology for satellite based experiments, in which large effective areas and high reliability are required. This note gives an overview of the assembly of this silicon tracker and discusses in detail studies performed to track quality assurance: leakage current, mechanical alignment and production yields.

The silicon tracker for the engineering model of the GLAST Large-Area Telescope (LAT) has at least two unique features: it employs self-triggering readout electronics, dissipating less than 200 muW per channel and to date represents the largest surface of silicon microstrip detectors assembled in a tracker (2.7 m(2)). It demonstrates the feasibility of employing this technology for satellite based experiments, in which low power consumption, large effective areas and high reliability are required. This note describes the construction of this silicon tracker, which was installed in a beam test of positrons. hadrons and tagged photons at SLAG in December 1999 and January 2000. (C) 2001 Elsevier Science B.V. All rights reserved.

We present a measurement of the polarization of $\alam$ hyperons produced in $\nu_\mu$ charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same $\vo$ identification procedure and analysis method reported in a previous paper~\cite{NOMAD-polar} for the case of $\lam$ hyperons. The $\alam$ polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.

A beam test of GLAST (Gamma-ray Large Area Space Telescope) components was performed at the Stanford Linear Accelerator Center in October, 1997. These beam test components were simple versions of the planned light hardware. Results on the performance of the tracker, calorimeter, and anticoincidence charged particle veto are presented.

The Silicon Tracker/Converter of the Gamma-ray Large Area Space Telescope (GLAST) will have an active area of 80 m2, representing one of the largest planned applications of the silicon-strip detector technology. The large number of channels (1.3 million) to read out, together with the requirement that the tracker provide the trigger to the data acquisition, force the readout electronics to be of very low noise. Furthermore, to fit into the power constraints of the satellite environment, the electronics must have an ultra-low power consumption. To fulfill these requirements, plus others imposed by the space environment, such as redundancy, a mixed mode CMOS front-end readout chip and a digital readout controller chip have been designed and prototyped. In this article, we present the status of the readout electronics and the results from a test-beam study with a small GLAST tracker prototype.

This note describes the performance of modules assembled with up to 12 silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal-to-noise ratio of 19, a hit finding efficiency of 99.8% and a spatial resolution of 6.0μm. Laboratory measurements indicate that modules of twelve detectors exhibit a signal-to-noise ratio of the order of 16.

This note describes the construction of a target for neutrino interactions composed of passive boron carbide plates interleaved with silicon microstrip detectors. The target contains four layers of passive material with a total mass of 45 kg and 600 single-sided silicon microstrip detectors with a total surface of 1.14 m2 distributed over five layers. It is installed in the NOMAD spectrometer at the CERN SPS neutrino beam. During the 1997 run about 8000νμ charged current interactions were estimated to have occurred in the target. For these events it will be possible to perform a precise measurement of both vertex and kinematical variables. This will provide invaluable experience towards the construction of a future large-scale silicon tracker for neutrino oscillation experiments.

This note describes the performance of modules assembled with up to twelve silicon microstrip detectors. These modules were built for the instrumented Silicon Target (STAR) that has been installed in the NOMAD spectrometer. Laboratory and test beam results are compared with model predictions. For a module of nine detectors, test beam results indicate a signal{to{noise ratio of 19, a hit nding e ciency of 99.8% and a spatial resolution of 6.0 m. Laboratory measurements indicate that modules of twelve detectors exhibit a signal{to{noise ratio of the order of 16. a. University of Padua, Padua, Italy. b. CERN, Geneva, Switzerland. c. Harvard University, Cambridge, MA, USA. d. University of Sydney, Sydney, Australia. e. LAPP, Annecy, France. f . University of Valencia, Valencia, Spain. g. Joint Institute for Nuclear Research, Dubna, Russia. h. Dortmund University, Dortmund, Germany. i. University of Lausanne, Lausanne, Switzerland. j. Rudjer Bo skovi c Institute, Zagreb, Croatia. k. University of Urbino, Urbino and INFN, Florence, Italy. Submitted to Nuclear Instrumentation and Methods. Now at University of Geneva, Geneva, Switzerland. Now at University of California at Santa Cruz, California, USA. On leave of absence from Institute of Electron Technology, Warsaw, Poland.

A search for pair production of neutral heavy Higgs bosons decaying into\(b\bar b\) has been carried out in a study of hadronic decays of the Z boson into four jet final states using data taken by DELPHI in 1991 and 1992. The two production mechanisms present in the two Higgs doublets scheme, bremsstrahlung production of hZ* and associated production of hA, may lead to four beauty jets well recognizable using the precise microvertex detector measurements. No evidence for a signal was found, leading to limits on BR(Z→hA→4b) from 3.5 to 5.5×10−4 at 95% contidence level, depending on the mass of the ligthest Higgs. When combined with the results of the recent DELPHI standard Higgs search, this result allows the kinematical limit to be reached for the masses of h and A in the minimal supersymmetric extension of the Standard Model (MSSM) scheme. It also allows the tanβ≤1 domain to be explored, and a region above the kinematic limit for direct hA production is constrained by considering virtual hA production. Results are also given in the general two-doublet scheme.

An analysis of inclusive production of K0 and the meson resonances K*±(892), ρ0(770),f0(975) andf2(1270) in hadronic decays of the Z0 is presented, based on about 973,000 multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. Overall multiplicities have been determined as 1.962±0.060 K0 mesons, 0.712±0.067 K*±(892) and 1.21±0.15ρ0(770) per hadronic Z0 decay. The average multiplicities off0(975) for scaled momentum,x p , in the range 0.05≤x p ≤0.6 and off2(1270) for 0.05≤x p ≤1.0 are 0.098±0.016 and 0.170±0.043 respectively. Thef0(975) and ρ0(770)x p -spectra have similar shapes. Thef2(1270)/ρ0(770) ratio increases withx p . The average multiplicities and the differential cross sections are compared with the JETSET Parton Shower model. The model with default parameters fails to reproduce the experimental K0 momentum spectrum at low momentum, describes the K*±(892) and ρ0(770)x p -spectrum shapes, but significantly overestimates their production rates.

Two measurements of <img src="/fulltext-image.asp?format=htmlnonpaginated&src=V030943W4762642V_html\10052_2005_Article_BF01578666_TeX2GIFIE2.gif" border="0" alt=" $$\Gamma _{b\bar b} /\Gamma _{had} $$ " /> are presented. Both measurements use 250000Z decays taken with the DELPHI detector in 1991 and rely mainly on the precision of the microvertex detector. One tagging method is as simple as possible so that background rates can be reliably predicted by simulation. The other one uses a more involved tagging technique and reduces the dependence on simulation as much as possible. Combining both results, <img src="/fulltext-image.asp?format=htmlnonpaginated&src=V030943W4762642V_html\10052_2005_Article_BF01578666_TeX2GIFIE3.gif" border="0" alt=" $$\Gamma _{b\bar b} /\Gamma _{had} $$ " /> is found to be 0.2209±0.0041(stat.)±0.0042(syst.)±0.0018 <img src="/fulltext-image.asp?format=htmlnonpaginated&src=V030943W4762642V_html\10052_2005_Article_BF01578666_TeX2GIFIE4.gif" border="0" alt=" $$\Gamma _{c\bar c} $$ " />.