Single-arm Spectrometer Research Articles

Heavy ion results from LHCb

The LHCb detector is a single-arm spectrometer fully instrumented in the forward rapidity at the LHC. In this contribution we introduce some of the most recent results in heavy ion collisions, the upgrades for LHC Run3 and the future perspectives of the heavy ion program from the LHCb experiment.

The LHCb Silicon Tracker

The LHCb experiment is designed to perform high-precision measurements of CP violation and search for new physics using the enormous flux of beauty and charm hadrons produced at the LHC. The LHCb detector is a single-arm spectrometer with excellent tracking and particle identification capabilities. The Silicon Tracker is part of the tracking system and measures very precisely the particle trajectories coming from the interaction point in the region of high occupancies around the beam axis. The LHCb Silicon Tracker covers a total sensitive area of about 12m2 using silicon micro-strip detectors with long readout strips. It consists of one four-layer tracking station before the LHCb dipole magnet and three stations after. The detector has performed extremely well since the start of the LHC operation despite the fact that the experiment is collecting data at instantaneous luminosities well above the design value. This paper reports on the operation and performance of the Silicon Tracker during the Physics data taking at the LHC during the last two years.

LHCb detector status and upgrade

The LHCb experiment is a specialized experiment for B and D physics at the CERN LHC. The layout of the experiment and the various components are described, with an overview of their performance. Global running conditions and performance are also shown. The motivation for the foreseen detector upgrade is presented, together with the proposed new detectors, to be installed during Long Shutdown 2, in 2018. 1 General overview The LHCb detector is intended to study beauty and charm physics. At LHC, the production is mainly in the forward and backward directions. Both b particles are going in the same direction, thus a single arm spectrometer allows measuring the interesting b decay together with tracks from the other b decay, for flavour tagging. The overall detector layout is shown in figure 1. The vertex locator measures all tracks near the interaction point, a dipole magnet and tracking stations after are providing accurate momentum measurement, two RICH detectors, calorimeters and a muon system provide full particle identification.

Performance of LHCb Silicon Tracker Detector in the LHC

The LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux of beauty and charmed hadrons produced at the LHC. The LHCb detector is a single-arm spectrometer with excellent tracking and particle identification capabilities. The Silicon Tracker is part of the tracking system and measures very precisely the particle trajectories coming from the interaction point in the region of high occupancies around the beam axis. The LHCb Silicon Tracker covers a total sensitive area of about 12 m(2) using silicon micro-strip technology. This paper reports on the operation and performance of the Silicon Tracker during the Physics data taking at the LHC. (C) 2012 Published by Elsevier B.V. Selection and/or peer review under responsibility of the organizing committee for TIPP 11.

The LHCb Upgrade

Abstract The LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux of beauty and charmed hadrons produced at the LHC. The LHCb detector is a single-arm spectrometer with excellent tracking and particle identification capabilities. The operation and the results obtained from the data collected in 2010 and 2011 demonstrate that the detector is robust and functioning very well. In the next years, LHCb will measure a large number of interesting channels in heavy flavor decays. However, the limit of 1 fb−1 of data per year cannot be overcome without improving the detector. An upgraded spectrometer with a 40MHz readout and a much more flexible software-based triggering system will increase the data rate as well as the efficiency specially in the hadronic channels, widening our physics scope beyond that of heavy flavor. Here, the different possibilities under study for the different detectors are reviewed as well as the ongoing R&D activities.

The LHCb Trigger: Present and Future

Abstract LHCb is a single arm spectrometer covering the pseudo-rapidity range between 1.9 and 4.9, and has been optimised to perform flavour physics measurements at the LHC. The present two stage trigger system is able to select charm and beauty decay products with high efficiency due the highly inclusive approach of triggering on partially reconstructed decays and the use of a novel multivariate classifier at the second stage. The trigger can select both leptonic and purely hadronic decays. The performance of the trigger is determined from the data itself without having to rely on Monte-Carlo simulation and is presented. LHCb has recently submitted their upgrade LOI, which mainly aims at profiting from much larger luminosities by moving towards a single fully software based trigger. The upgrade strategy and expected performance are presented.

Commissioning and performance of the LHCb outer tracker

The LHCb experiment is a single arm spectrometer, designed to study CP violation in B-decays at the Large Hadron Collider (LHC). It is crucial to accurately and efficiently detect the charged decay particles, in the high-density particle environment of the LHC. For this, the Outer Tracker was constructed, consisting of ∼ 55 , 000 straw tubes, covering in total an area of 360 m 2 of double layers. The detector is foreseen to operate under large particle rates, up to 100 kHz/cm in the region closest to the beam. The front-end electronics is expected to provide the precise (0.5 ns) drift-time measurement, at an average occupancy of 5% and at 1 MHz trigger rate. At the time of the conference, the detector has been commissioned with cosmic-ray events and with the first LHC beam collision data. After dedicated studies to establish timing and spatial alignment, the first results on the detector performance (efficiency, resolutions, etc.) have been obtained.

Alignment of the LHCb detector with Kalman filter fitted tracks

The LHCb detector, operating at the Large Hadron Collider at CERN, is a single arm spectrometer optimised for the detection of forward b and anti-b production for b physics studies. The reconstruction of vertices and tracks is done by silicon micro-strip and gaseous straw-tube based detectors. To obtain excellent momentum, mass and vertex resolutions, the detectors need to be aligned well within the hit resolution for a given detector. We present a general and easy to configure alignment framework which uses the closed from method of alignment with Kalman filter fitted tracks to determine the alignment parameters. This allows us to use the standard LHCb track model and fit, and correctly take complexities such as multiple scattering and energy loss corrections into account. With this framework it is possible to align any detector for any degree of freedom.

The Front-End Electronics of the straw tube tracker for the LHCb experiment

The LHCb experiment is a single-arm spectrometer, designed to study CP violation in B-decays at the Large Hadron Collider (LHC). It is crucial to accurately and efficiently track the charged decay products, in the high-density particle environment of the LHC. For this, the Outer Tracker has been constructed, consisting of ∼55,000 straw tubes, distributed over a sensitive area of 12 double layers of 6×5m2 each. The detector is foreseen to operate up to 100kHz/cm per straw in the region closest to the beam. The task of the Front-End Electronics is to provide the precise (0.5ns) drift-time measurement, at an average occupancy of 5% and at a 1MHz trigger rate. The tracking procedure requires high-efficiency (low thresholds), while at the same time putting stringent limits on the noise level. The modular detector structure reflects on the FE electronics: 128 channels are read out by one FE “Box”. The mass production and installation of 450 FE-Boxes is completed. Quality checks have been performed in several stages, at the level of individual boards and at the global level with dedicated test systems mimicking the real detector and capable of simulating all the readout functionalities. At the time of the conference, all FE electronics has been commissioned in situ with test-pulses, cosmic rays and the with first beam events from LHC. No dead channels and very few noisy channels have been found. An upgrade is currently under study, aiming at digitizing and reading out events at each beam-crossing.

Installation and commissioning of a high-efficiency and high-resolution straw tube tracker for the LHCb experiment

The LHCb experiment is a single arm spectrometer, designed to study CP violation in B-decays at the Large Hadron Collider (LHC). It is crucial to accurately and efficiently detect the charged decay particles, in the high-density particle environment of the LHC. For this, the Outer Tracker (OT) was constructed, consisting of ∼55,000 straw tubes, covering in total an area of 360m2 of double layers. The detector is foreseen to operate under large particle rates, up to 100kHz/cm per straw in the region closest to the beam. The front-end electronics is expected to provide the precise (0.5ns) drift-time measurement, at an average occupancy of 5% and at 1MHz trigger rate. The tracking procedure requires high-efficiency (low thresholds), while at the same time putting stringent limits on the noise level. The modular detector structure reflects on the FE electronics: 128 channels are read out by one FE Box. During installation, the dark current, the response to radioactive sources, and the gas-tightness of all detector units was checked and only a handful of bad channels were found. Special hardware and dedicated procedures, integrated within the experimental control system, have been designed for the detector calibration during data taking. At the time of the conference, the detector has been installed and commissioned with the help of cosmic rays events producing tracks through OT. During the first days of the LHC commissioning, the detector was operated on nominal voltage and large-multiplicity events originating at the circulating beam were recorded and studied.

The front end electronics of the LHCb straw tube tracker

The LHCb experiment is a single-arm spectrometer, designed to study B-hadron decays at the Large Hadron Collider (LHC). It is crucial to accurately and efficiently track the charged decay products with the Outer Tracker straw tube detector, in the high-density particle environment of the LHC. The Outer Tracker Front End electronics provide the precise (0.5 ns) drift-time measurement, at an average occupancy of 5% and at a 1 MHz trigger rate. The tracking procedure requires high-efficiency, while at the same time putting stringent limits on the noise level. The mass production and installation of 450 fully operational Front End boxes is completed. Quality checks have been performed at several stages, at the level of individual boards and at the global level with dedicated test systems mimicking the real detector and capable of simulating all the readout functionalities. An excellent overall threshold uniformity is achieved with low noise levels.

Construction, installation and commissioning of a high-efficiency and high-resolution straw tube tracker for the LHCb experiment

The LHCb experiment is a single arm spectrometer, designed to study CP violation in B-decays and search for new physics in rare B-decays at the large hadron collider (LHC). In such studies it is crucial to accurately and efficiently track the charged decay products in the high-density environment of the LHC. For this, the outer tracker (OT) was constructed, consisting of 55,000 straw tubes and covering an area of 360 m 2 of module layers. The detector is foreseen to operate under large particle rates, up to 100 kHz/cm per straw in the region closest to the beam. Before and during installation the detector modules and front end (FE) electronics have been extensively tested. The detector has been installed and commissioned with the help of cosmic ray events.

The RICH system of the LHCb experiment: Status and performance

The LHCb experiment is a single forward arm spectrometer at the LHC at CERN. Particle identification (pion, kaon and proton discrimination) is a crucial requirement to meet the physics goals of the experiment. This is provided by two Ring Imaging Cherenkov (RICH) detectors providing particle identification coverage between 1 and 100 GeV/ c. After a brief description of the LHCb experiment and RICH detectors, the results from the latest beam test using the final detector components and readout system will be given and the anticipated particle identification performance of the RICH detectors from Monte Carlo simulations will be presented. Finally, a technique to calibrate the particle identification performance of the RICH system with data using D * decays will be described.

Performance of the outer tracker detector of LHCb

The LHCb experiment is a single arm spectrometer, designed to study CP violation in B-decays at the Large Hadron Collider. The Outer Tracker is part of its tracking system and consists of ∽ 55000 straw tubes. It is now fully installed and partially equipped with readout electronics. After a short description of the detector, the read-out electronic performances are discussed. Some results about the detector ageing are also presented. Finally the performance of the final detector has been checked with a beam test at DESY and some results are shown.

Status of the LHCb Dipole Magnet

The LHCb experiment focuses on the precision measurement of CP violation and rare decays in the B-meson system. It plans to operate with an average luminosity of 2 /spl times/ 10/sup 32/ cm/sup -2/s/sup -1/ that should be obtained from the beginning of the LHC operation. The LHCb detector exploits the forward region of the pp collisions at the LHC collider. It requires a single arm spectrometer with a large dipole magnet of 4 Tm of total integrated field, having the capability to stand frequent polarity changes and providing good lateral field homogeneity. For reasons of cost, simplicity and robustness, a magnet with resistive coils has been chosen. The magnet has a free aperture of /spl plusmn/300 mrad horizontally and /spl plusmn/250 mrad vertically demanding a sloping gap of 2.2 to 3.5 m vertically (the direction of the field) and 2.6 to 4.2 m horizontally. The total weight of the magnet is about 1600 t. The power dissipation in the aluminum coils will be 4.2 MW. Low carbon steel plates of 100 mm thickness are used to assemble the yoke. The coils are wound from hollow aluminum conductor of 50 mm /spl times/ 50 mm cross-section with a central cooling channel of 25 mm diameter. To reach good field quality the coils are bent by 45/spl deg/ toward the gap along the horizontal aperture and the pole pieces have large shims. The magnet design will be reviewed; the magnet assembly in the underground area of the experiment and test results will be reported.

Status of the LHCb VErtex LOcator

LHCb is a single-arm spectrometer at the LHC. It is dedicated to the study of CP violation in the B-hadron system. The VErtex LOcator (VELO) is a silicon microstrip detector providing accurate measurements of event primary and secondary vertices, impact parameters, and tracks. The second-level trigger decision of LHCb is mainly based on information from a full readout of the VELO. This document gives a general introduction to LHCb as a context for a more extensive description of the VELO. The VELO design emphasises the need for precise reconstruction of tracks down to momenta of a few GeV. The VELO operates inside the LHC beam-pipe, and the sensors, the hybrids, and the foil separating the primary and secondary vacuua must be built with the minimum possible material. The R– φ strip layout is optimised for efficient trigger operation and precise measurements at the smallest radii. The performance must be maintained in the harsh radiation environment close to the LHC beams. These issues have led to a choice of n-on-n, double metal technology for the VELO. This document describes the current status of the VELO design, incorporating changes which have been made in the context of the recent overall optimisation of the LHCb detector (“LHCb light”) (Status of the LHCb Detector Reoptimisation, 2003, CERN/LHCC/2003-003), and summarises the underlying R&D for the technology choice. Issues concerning the electronics, the mechanical integration into LHCb and the LHC machine are discussed in detail elsewhere (LHCb Vertex Locator Technical Design Report, 2001, CERN/LHCC/2001-011).

Photomultiplier pulse Read Out system for the preshower detector of the lhcb experiment

The second generation experiment for CP violation studies in B decays, LHCb, is a 20-m-long single-arm spectrometer to be installed on the future Large Hadron Collider at CERN. For its precision measurement purpose, it combines precise vertex location and particle identification, in addition to a performance trigger system able to cope with high flux. The first level of trigger is mainly based on the fast response of the calorimetric subsystem. Of major importance is the 6000 channels preshower detector that aims to validate the electromagnetic nature of calorimetric showers. It consists of two-radiation-length lead sheet in front of a scintillator plane. Scintillator signals are extracted from plastic cells using wavelength-shifting fibres coupled to multi-anode photomultiplier tubes. The preshower Read Out system has to cope with fluctuating photomultiplier pulses caused by small amounts of photoelectrons, in addition to strong constraints imposed by the 40MHz LHC bunch-crossing frequency.A special Read Out electronics including perfect 40MHz integrators able to shape fluctuating photomultiplier pulses has been designed, and successfully realized. The temporal shape of photomultiplier pulse and the upstream Read Out system for preshower are described in this document.

George Briggs Collins

George Briggs Collins

Status of the LHCb magnet system

The LHCb experiment focuses on the precision measurement of CP violation and rare decays in the B-meson system. It plans to operate with an average luminosity of 2 /spl times/ 10/sup 32/ cm/sup -2/ s/sup -1/, which should be obtained from the beginning of the LHC operation. The LHCb detector exploits the forward region of the pp collisions at the LHC collider. It requires a single-arm spectrometer for the separation and momentum measurement of the charged particles with a large dipole magnet of a free aperture of /spl plusmn/300 mrad horizontally and /spl plusmn/250 mrad vertically. The magnet is designed for a total integrated field of 4 Tm. The pole gap is 2.2 to 3.5 m vertically (the direction of the field) and 2.6 to 4.2 m horizontally. The overall length of the magnet (in beam direction) is 5 m and its total weight about 1500 t. The power dissipation in the aluminum coils will be 4.2 MW. The magnet yoke is constructed from low carbon steel plates of 100 mm thickness. The maximum weight of one plate does not exceed 25 t. The coils are wound from large hollow aluminum conductor of 50 mm /spl times/ 50 mm cross-section with a central cooling channel of 25 mm diameter for the pressurized demineralized water. Each of the two coils is composed of 15 monolayer pancakes of 15 turns per pancake. To reach good field quality the coils are bent by 45/spl deg/ toward the gap along the horizontal aperture of /spl plusmn/300 mrad and the pole pieces have large shims. The underlying magnet design, its present status and milestones will be reviewed.

Sea level muon spectra at large zenith angles derived from the latest JACEE primary nucleon spectrum

Sea level muon energy spectra at large zenith angles have been derived from the latest JACEE primary spectrum using the Fermilab Single-Arm Spectrometer data on charged-meson production. The role of increasing total cross-section on the final result for the energy spectra has been investigated here with special emphasis. The inclusion of the rising total cross-section at cosmic range of energies, it is seen, has come into much use in explaining the observed data at very high energies.