C. Willmott

The DIRAC experiment at CERN has achieved a sizeable production of π+π− atoms and has significantly improved the precision on its lifetime determination. From a sample of 21 227 atomic pairs, a 4% measurement of the S-wave ππ scattering length difference |a0−a2|=(0.2533−0.0078+0.0080|stat|syst−0.0073+0.0078)Mπ+−1 has been attained, providing an important test of Chiral Perturbation Theory.

The European Hybrid Spectrometer is described in its preliminary version for the NA16 charm experiment. The performance of the small hydrogen bubble chamber LEBC and the detectors of the spectrometer is discussed. In particular the combination of the bubble chamber information with the spectrometer data is described in detail. The track reconstruction efficiency is 90%. The precision with which vertices seen in the bubble chamber are reconstructed is around 10 μm and the two track resolution is 40 μm. Therefore very complex event configurations, in particular charm particle decays, can be reconstructed correctly.

The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δpp = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

An initial measurement of the lifetime of the positive muon to a precision of 16 parts per million (ppm) has been performed with the FAST detector at the Paul Scherrer Institute. The result is tau_mu = 2.197083 (32) (15) microsec, where the first error is statistical and the second is systematic. The muon lifetime determines the Fermi constant, G_F = 1.166353 (9) x 10^-5 GeV^-2 (8 ppm).

Abstract The operation of the ISIS2 pictorial drift chamber in the European Hybrid Spectrometer at the CERN SPS is described. The data analysis and calibration procedure are outlined. After a brief presentation of the quality of the spatial data form the chamber, the dE/dx data are treated in some detail. It is shown that an ionisation resolution of 3.5% rms (or 8.3%fwhm) is routinely obtained on a large majority of tracks entering the 8 m2 acceptance of the device; this is within 20% of the theoretical limit of the performance. Samples of tracks identified as electrons, pions or protons by kinematic fitting to conversions or strange particle decays are used to check the quality of the mass identification. Misidentification rates and confidence levels for mass separation as a function of momentum for each mass pair are given. Some data are given on the effects of space charge and a measurement of the relativistic rise is reported.

Using data obtained with EHS equipped with the Rapid Cycling Bubble Chamber (RCBC) exposed to a proton beam of 360 GeV/c, we calculate topological cross sections. We present in great detail the procedure and the techniques used to correct raw data. Finally, we give multiplicity moments and multiplicity correlations and we compare the values obtained in our experiment, together with data at other energies, with different models.

Results on cross sections, longitudinal and transverse momentum distributions forK /0 , Λ and $$\bar \Lambda $$ production in 360GeV/cpp interactions are presented as obtained from EHS equipped with the Rapid Cycling Bubble Chamber (RCBC). The Λ and $$\bar \Lambda $$ polarizations are measured. The cross section for the diffractive components is given using the recoil spectrum. The data are discussed with respect to charm production.

The 40 MHz bunched muon beam set up at CERN was used in May 2003 to make a full test of the drift tubes local muon trigger. The main goal of the test was to prove that the integration of the various devices located on a muon chamber was adequately done both on the hardware and software side of the system. Furthermore the test provided complete information about the general performance of the trigger algorithms in terms of efficiency and noise. Data were collected with the default configuration of the trigger devices and with several alternative configurations at various angles of incidence of the beam. Tests on noise suppression and di-muon trigger capability were performed.

The intermediate and forward gamma detectors of EHS are used to reconstructπ°'s produced by 360 GeV/cpp interactions in the Rapid Cycling Bubble Chamber (RCBC). Using thepp forwardbackward symmetry, the inclusiveπ° production cross section is obtainedσ π°=(132±11) mb. The averageπ° multiplicity is determined as a function of the charged particle multiplicity. The (1−x) dependence is given for differentp T regions.

We have implemented and evaluated a positron emission tomography (PET) demonstrator using two monolithic detector blocks operating in coincidence with dedicated application-specific integrated circuit (ASIC) readout. Each detector is composed of a monolithic lutetium yttrium orthosilicate (LYSO) scintillator coupled to a pair of Hamamatsu S8550-02 APD arrays. The front-end electronics of this demonstrator is based on the VATA240 ASIC readout, which sums the charge provided by each row and column of the APD array. The ASIC has been characterized obtaining a noise per row or column less than 2000 electrons rms with the APD at its inputs and a good linear response in the range from 5 fC to 30 fC. We have acquired energy spectra of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs radioactive sources, achieving energy resolutions between 13.2% and 14.1% full width at half maximum (FWHM) at 511 keV. We have estimated the interaction position over the surface of the monolithic blocks using Neural Networks (NN) position determining algorithms, obtaining spatial resolutions at the detector level down to 2.1 mm FWHM. By using this detector technology and electronics we have achieved images of point sources with spatial resolutions as good as 2.1 mm FWHM for filtered back projection (FBP) reconstructions methods with single slice rebinning (SSRB). Based on the results obtained with this demonstrator, we are developing a PET insert for existing magnetic resonance imaging (MRI) equipment, to be installed in a collaborating hospital and used for clinical PET-MRI of the human brain.

We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. The proposed scanner is based on annihilation gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) coupled to magnetically-compatible avalanche photodiodes (APD) matrices. The light distribution generated on the LYSO:Ce block provides the impinging position of the 511 keV photons by means of a positioning algorithm. Several positioning methods, from the simplest Anger Logic to more sophisticate supervised-learning Neural Networks (NN), can be implemented to extract the incidence position of gammas directly from the APD signals. Finally, an optimal method based on a two-step Feed-Forward Neural Network has been selected. It allows us to reach a resolution at detector level of 2 mm, and acquire images of point sources using a first BrainPET prototype consisting of two monolithic blocks working in coincidence. Neural networks provide a straightforward positioning of the acquired data once they have been trained, however the training process is usually time-consuming. In order to obtain an efficient positioning method for the complete scanner it was necessary to find a training procedure that reduces the data acquisition and processing time without introducing a noticeable degradation of the spatial resolution. A grouping process and posterior selection of the training data have been done regarding the similitude of the light distribution of events which have one common incident coordinate (transversal or longitudinal). By doing this, the amount of training data can be reduced to about 5% of the initial number with a degradation of spatial resolution lower than 10%.

A prototype of the CMS Barrel Muon Detector incorporating all the features of the final chambers was built using the mass production assembly procedures and tools. The performance of this prototype was studied in a muon test beam at CERN and the results obtained are presented in this paper.

On the Compact Muon Solenoid (CMS) experiment for Large Hadron Collider (LHC) at CERN laboratory, the drift tube chambers are responsible for muon detection and precise momentum measurement. In this paper the first level of the read out electronics for these drift tube chambers is described. These drift tube chambers will be located inside the muon barrel detector in the so-called minicrates (MCs), attached to the chambers. The read out boards (ROBs) are the main component of this first level data acquisition system, and they are responsible for the time digitalization related to Level 1 Accept (L1A) trigger of the incoming signals from the front-end electronics, followed by a consequent data merging to the next stages of the data acquisition system. ROBs' architecture and functionality have been exhaustively tested, as well as their capability of operation beyond the expected environmental conditions inside the CMS detector. Due to the satisfactory results obtained, final production of ROBs and their assembly in the MCs has already started. A total amount of 250 MCs and approximately 1500 ROBs are being produced and tested thoroughly at CIEMAT (Spain). One set of tests, the burn-in tests, will guarantee ten years of limited maintenance operation. An overview of the system and a summary of the different results of the tests performed on ROBs and MCs will be presented. They include acceptance tests for the production chain as well as several validation tests that insure proper operation of the ROBs beyond the CMS detector conditions.

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory.

We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. Previous results have demonstrated that our detector concept, based on monolithic scintillator crystals coupled to magnetically-compatible APD matrices with a dedicated ASIC front-end, is suitable for this application. In this work we present the final design of our PET scanner and report on the characterization of a prototype demonstrator used to validate the coincidence processing and data readout architecture.

We are developing a human brain PET scanner prototype compatible with MRI based on monolithic scintillator crystals, APD matrices and a dedicated ASIC front-end readout. In this work we report on the performance of individual detector modules and on the operation of such modules in PET coincidence. Results will be presented on the individual characterization of detector blocks and its ASIC front-end readout, with measured energy resolutions of 13% full-width half-maximum (FWHM) at 511 keV and spatial resolutions of the order of 2 mm FWHM. First results on PET coincidence performance indicate spatial resolutions as good as 2.1 mm FWHM for SSRB/FBP reconstruction of tomographic data obtained using a simple PET demonstrator based on a pair of monolithic detector blocks with ASIC readout.

Two drift tubes (DTs) chambers of the CMS muon barrel system were exposed to a 40 MHz bunched muon beam at the CERN SPS, and for the first time the whole CMS Level-1 DTs-based trigger system chain was tested. Data at different energies and inclination angles of the incident muon beam were collected, as well as data with and without an iron absorber placed between the two chambers, to simulate the electromagnetic shower development in CMS. Special data-taking runs were dedicated to test for the first time the Track Finder system, which reconstructs track trigger candidates by performing a proper matching of the muon segments delivered by the two chambers. The present paper describes the results of these measurements.

In this work we present experimental results obtained with a PET prototype module based on monolithic block detectors of LYSO:Ce coupled to 2 Hamamatsu S8550-02 APD arrays and a dedicated ASIC front end readout. This module has been designed to be compatible with strong magnnetic fields and will be used on a research prototype for PET/MRI human brain imaging. The front-end electronics presented is based on a new ASIC: the VATA240. This ASIC implements the sum of the signals provided by the 8 pixels of each column and row of the detector array, composed of two APD modules. Using these 16 summed channels instead of the output of the 64 single pixels. the signal to noise ratio of the overall detector response is enhanced. To estimate the impinging photon direction we use Neural Networks (NN). The use of the summed channels also reduces the complexity of the NN algorithms implemented. The characterization of the VATA240 ASIC and the adjustment of key parameters have been carried out, and both the spatial and energy resolution with an electronically-collimated <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na radioactive source have been experimentally evaluated.

Gamma detectors based on monolithic scintillator blocks coupled to APDs matrices have proved to be a good alternative to pixelated ones for PET scanners. They provide comparable spatial resolution, improve the sensitivity and make easier the mechanical design of the system. In this study we evaluate by means of Geant4-based simulations the possibility of replacing the APDs by SiPMs. Several commercial matrices of light sensors coupled to LYSO:Ce monolithic blocks have been simulated and compared. Regarding the spatial resolution and linearity of the detector, SiPMs with high photo detection efficiency could become an advantageous replacement for the APDs.

Three multiple sampling drift chambers were set up exactly as in a big collider detector. Studies with cosmic rays, 55Fe sources, and a laser beam led to the choice of the operating point in argon-ethane. Using a long-focused UV laser beam and displacing the middle chamber by S = 3.8 mm, which corresponds to the sagitta of a 45 GeV track in a 5 kG field, we obtain a resolution of Δ S/S ⩽1.5%.

We are developing a positron emission tomography (PET) insert based on avalanche photodiode (APD) arrays and monolithic LYSO:Ce scintillators for human brain functional studies to be used inside a clinical magnetic resonance imaging (MRI) equipment. In a previous work [1], we demonstrated the performance of our detectors by implementing an experimental setup consisting of two monolithic blocks working in coincidence, which were read out by the first version of an application-specific integrated circuit (ASIC), VATA240, followed by external coincidence and digitalization modules. This preliminary demonstrator showed good spatial resolution at detector level on the order of 2.2 mm full-width at half-maximum (FWHM) and good imaging qualities, which achieved reconstructed images of 22Na point sources with spatial resolutions of 2.1 mm FWHM. Nevertheless, we detected image distortions and compressions due to the non-linearities close to the edge of the crystals and the simplicity of that demonstrator with the absence of neighbor blocks [1]. In this work we have implemented a larger scale PET demonstrator, which is based on the new updated ASIC (VATA241) [2] and is formed by two sectors of four monolithic detector blocks placed face-to-face. This new prototype demonstrator has been built for validating the data readout architecture, the coincidence processing implemented in a Xilinx Virtex 5 field programmable gate array (FPGA), as well as the continuous neural networks (NN) training method required to determine the points of entrance over the surface of our monolithic detector blocks.

We are developing a positron emission tomography (PET) insert for existing magnetic resonance (MR) equipment, aiming at hybrid MR–PET imaging. Our detector block design is based on trapezoid-shaped LYSO:Ce monolithic scintillators coupled to magnetically compatible Hamamatsu S8550-02 silicon avalanche photodiode (APD) matrices with a dedicated ASIC front-end readout from GammaMedica-Ideas (Fornebu, Norway). The detectors are position sensitive, capable of determining the incidence point of 511 keV gammas with an intrinsic spatial resolution on the order of 2 mm by means of supervised learning neural-network (NN) algorithms. These algorithms, apart from providing continuous coordinates, are also intrinsically corrected for depth of interaction effects and thus parallax-free. Recently we have implemented an advanced prototype featuring two heads with four detector blocks each and final front-end and readout electronics, improving the spatial resolution of reconstructed point source images down to 1.7 mm full width at half maximum (FWHM). Presently we are carrying out operational tests of components and systems under magnetic fields using a 3 T MR scanner. In this paper we present a description of our project, a summary of the results obtained with laboratory prototypes, and the strategy to build and install the complete system at the nuclear medicine department of a collaborating hospital.

The drift tubes based CMS barrel muon trigger, which uses self-triggering arrays of drift tubes, is able to perform the identification of the muon parent bunch crossing using a rather sophisticated algorithm. The identification is unique only if the trigger chain is correctly synchronized. Some beam test time was devoted to take data useful to investigate the synchronization of the trigger electronics with the machine clock. Possible alternatives were verified and the dependence on muon track properties was studied.

The Fibre Active Scintillator Target (FAST) experiment at the Paul Scherrer Institute (PSI) is designed for a high-precision measurement of the μ+ lifetime, in the order of a few parts per million. This paper describes the design, construction and performance of the FAST detector and its readout electronics, trigger and data acquisition system.

A prototype of the L3 muon chamber module, designed for measuring muon track positions, was built and tested. Measured simulated tracks made by an UV laser beam used for the internal alignment of the chambers in the module appeared to display a systematic positional error. The module measures the slope of laser tracks with high precision. The induced charge mechanism of proportional chambers creates an error in the slope of the same track if measured using a single wire plane. A simulation of the wire signals resulted in a good description of the error; also the calculated decrease in the signal size for tracks parallel to the wire plane tallied with the measurements.

The drift chambers in the barrel region of the CMS detector are exposed to magnetic stray fields. To study the performance of the muon reconstruction and the drift time-based muon trigger, prototypes were tested under the expected magnetic field conditions at the H2 test facility at CERN. The results indicate that the overall chamber performance will not be affected. Only the bunch crossing identification capability in the small region near η=1.1, corresponding to the border of the solid angle region covered by the barrel, will be weakened.

The L3 detector is designed to measure the muon momentum with a 2% resolution at p = 45 GeV/c. We discuss here the systems we developed to reach the required accuracy and control the mechanical alignment at running time. We also report on the test done on the muon spectrometer with UV lasers and cosmic rays.

The L3 muon spectrometer is presented. Characteristics, useful for experiments at future accelerators, are highlighted. Particular emphasis is given to the systems envisaged to keep the error on the relative alignment of detectors below 30 μm and so reach a momentum resolution Δpp = 2% at p = 45 GeV/c.

Being close to the completion of CMS installation, the three levels of the final read-out system of the Drift Tube (DT) chambers are presented. Firstly, the Read Out Boards (ROB), responsible for time digitalization of the signals generated by a charged particle track. Secondly, the Read Out Server (ROS) boards receive data from 25 ROB channels through a 240 Mbps copper link and perform data merging for further transmission through a 800 Mbps optical link. Finally, the Detector Dependent Unit (DDU) boards merge data from 12 ROS to build an event fragment and send it to the global CMS DAQ through an SLINK64 output at 320 MBps. These boards also receive synchronization commands from the TTC system (Timing, Trigger and Control), perform errors detection on data and send a fast feedback to the TTS (Trigger Throttling System). The functionality of these electronics has been validated in laboratory and in several test-beams, including an exercise integrated with a fraction of the whole CMS detector and electronics that demonstrated proper operation and integration within the final CMS framework.

The BrainPET scanner is a magnetically-compatible human PET insert based on APDs and LYSO:Ce monolithic scintillators, which is currently under development at CIEMAT, intended for the operation inside magnetic resonance imaging (MRI) equipment. An ASIC called VATA241 was specifically designed for the BrainPET project. This ASIC includes a constant fraction discriminator (CFD) in its architecture and presents a better robustness and reliability with respect to the first leading-edge-based ASIC [1], which was successfully utilized in our first BrainPET demonstrator for validating the principle of operation of our detector blocks [2]. In this work we have characterized the VATA241 in terms of noise, time walk, jitter, linearity and operation with detector blocks. Moreover, we have carried out its optimization performance by adjusting the corresponding different bias currents. Based on the characterization carried out by CIEMAT, manufacturer Gamma Medica-Ideas (GM-I) has performed the tuning of the simulation model of this ASIC as well as the optimization of the timing performance for the fabrication of the final VATA241.2 ASIC, which will be used in our full-ring PET scanner.

We have analyzed the performance of a PET demonstrator formed by two sectors of four monolithic detector blocks placed face-to-face. Both front-end and read-out electronics have been evaluated by means of coincidence measurements using a rotating <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na source placed at the center of the sectors in order to emulate the behavior of a complete full ring. A continuous training method based on neural network (NN) algorithms has been carried out to determine the entrance points over the surface of the detectors. Reconstructed images from 1 MBq <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na point source and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na Derenzo phantom have been obtained using both filtered back projection (FBP) analytic methods and the OSEM 3D iterative algorithm available in the STIR software package [1]. Preliminary data on image reconstruction from a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na point source with ∅ = 0.25 mm show spatial resolutions from 1.7 to 2.1 mm FWHM in the transverse plane. The results confirm the viability of this design for the development of a full-ring brain PET scanner compatible with magnetic resonance imaging for human studies.

Abstract Methods allowing the precise determination of momenta in the TeV region are demonstrated. Their application in future collider detectors will enable, by magnetic analysis, 1–2% mass resolution for 1 TeV dimuons.

Abstract Prototypes of large drift chambers, designed to measure the coordinate of the muons along the electron positron beam direction in the L3-LEP muon spectrometer, have been built in the CIEMAT-JEN. We report measurements of the drift velocity and space resolution obtained with these modules.

Read-out boards (ROB) are one of the key elements of readout system for CMS barrel muon drift chambers. To insure proper and reliable operation under all detector environmental conditions an exhaustive set of tests have been developed and performed on the 30 pre-series ROB s before production starts. These tests include operation under CMS radiation conditions to detect and estimate SEU rates, validation with real chamber signals and trigger rates, studies of time resolution and linearity, crosstalk analysis, track pattern generation for calibration and on-line tests, and temperature cycling to uncover marginal conditions. We present the status of the readout boards (ROB) and tests results.

Abstract The Cortex control information system framework is being developed at CERN. It offers basic functions to allow the sharing of information, control and analysis functions; it presents a uniform human interface for such information and functions; it permits upgrades and additions without code modification and it is sufficiently generic to allow its use by most of the existing or future control systems at CERN. Services will include standard interfaces to user-supplied functions, analysis, archive and event management. Cortex does not attempt to carry out the direct data acquisition or control of the devices; these are activities which are highly specific to the application and are best done by commercial systems or user-written programs. Instead, Cortex integrates these application-specific pieces and supports them by supplying other commonly needed facilities such as collaboration, analysis, diagnosis and user assistance.

The Fibre Active Scintillator Target (FAST) experiment is a novel imaging particle detector currently operating in a high-intensity π+ beam at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The detector is designed to perform a high precision measurement of the μ+ lifetime, in order to determine the Fermi constant, Gf, to 1 ppm precision. A dedicated second level (LV2) hardware trigger system has been developed for the experiment. It performs an online analysis of the π/μ decay chain by identifying the stopping position of each beam particle and detecting the subsequent appearance of the muon. The LV2 trigger then records the muon stop pixel and selectively triggers the Time-to-Digital Converters (TDCs) in the vicinity. A detailed description of the trigger system is presented in this paper.

Measurements of cosmic rays in the L3 multisampling chambers are presented. The study of tracks with polar angles from 30° < θ < 130° w.r.t. the wires show increasing pulse height like 1/sin θ. Using inclined tracks, we find a ±1.5 cm region of reduced accuracy near the glass supports of the 5.4 m long wires.

The design and construction of simple and stable drift chambers, suited for production in large quantities and sizes, is presented. These chambers are under construction for the muon detector of the L3 experiment at LEP.

Several irradiation tests of the electronics of the CMS barrel muon detector were performed using neutrons, protons and heavy ions. The Single Event Upset rate on some tested devices was measured, while upper limits were obtained for devices having experienced no failure. Single Event Transients on front-end electronics and destructive effects on the High-voltage distribution electronics were observed. Overcurrent protection and error correction circuits were included in the irradiated boards and were tested.

The Fiber Active Scintillator Target (FAST) is an imaging particle detector intended for high precision muon lifetime measurement. This measurement will lead to a determination of the Fermi coupling constant (C,) with an uncertainty of Ippm, one order of magnitude better than the current world average. This contribution presents a description of the detector instrumentation and the first results, which have validated the design of the system.

We present here the development, main features and calibration procedures for a new type of gas Cherenkov detector, based upon the ability to control its threshold by regulating the temperature of the gas used as radiator. We also include the performance of this detector in particle identification.

An FPGA based trigger system for an imaging particle detector has been designed and produced. The main capabilities of the system are the recognition of the track pattern of the incoming particles, the calculation of its stopping pixel and the time discrimination of events. The description of the implemented algorithms, the FPGA architecture, the developed hardware and the main operation results are included in this paper. The trigger system has already been installed in the FAST detector and operated during the 2005 data taking period with very satisfactory performance. Therefore, this trigger system will be used in the detector for further operation in the incoming years

On the CMS experiment for LHC collider at CERN, the drift tube chambers (DT's) are responsible of muon detection and precise momentum measurement. Described in this paper is the first level of the read out electronics for these DT chambers that will be located inside the muon barrel detector in the so-called minicrates (MC), attached to the chambers. The read out boards (ROB) are the main component of this first level data acquisition system, and they are in charge of the time digitalization related to level 1 accept trigger of the incoming signals from the front-end electronics, following a consequent data merging to next stages of the data acquisition chain. Its architecture and functionality has been exhaustively tested, as well as its capability of operation beyond the expected environmental and radiation conditions inside the CMS detector. The satisfactory results obtained have allowed to proceed with ROB final production and its assembly in the MCs. A total amount of 250 MCs and around 1500 ROBs are being produced and tested thoroughly at CIEMAT (Spain), including burn-in tests for guaranteeing ten years of limited maintenance operation. An overview of the system and a summary of the different results of the tests performed on ROB's and MC will be presented. They include acceptance tests for the production chain as well as some validation tests that insured proper operation of the ROB's beyond the CMS detector conditions.

The second level trigger (LV2) system of the FAST detector is described in this paper. The fiber active scintillator target (FAST) is an imaging particle detector intended for muon lifetime measurement with a precision of 1 ppm. The aim of the trigger system is to reduce the data throughput that the data acquisition (DAQ) chain must handle to make the experiment able to run with a first level trigger rate of 1 MHz. The electronic system is being designed at CIEMAT (Madrid, Spain). A first prototype was developed and satisfactory results have been obtained under beam operation conditions.

The final architecture of the read-out system for the CMS drift tube chambers is presented. It is staged in two levels: firstly, the Read Out Boards (ROB), responsible for the time digitalization of the incoming signals from the front-end electronics related to Level 1 Accept trigger; and a second level, the Read Out Server boards (ROS), for merging data from ROB s and transmitting the information out of the cavern to the DAQ system interface (DDU/FED). The chosen architecture, as well as the link bandwidths, failure detection and power supply protection circuitry, etc, fulfil the experiment requirements of trigger and hit rate, radiation tolerance, limited supervision and power consumption, among others.