[en] The BaBar experiment at the SLAC B-Factory is designed mainly for the study of CP violation in the B-meson system. Its silicon vertex tracker (SVT), now under construction, has an original design, sensibly different from the usual silicon strips vertex detectors, and developed to satisfy the requirements of the asymmetric collider events topologies, the background rejection and the physics measurements. The SVT characteristics and the role that its measurements play in the physics analysis are presented here. (orig.)

[en] Some selection criteria to identify the production of t-anti t pairs in the e⁺e^- interaction in the case that the production threshold for this process is below that of W⁺W^- pairs are discussed. Since the mass of the top quark is expected to be in the range 44 GeVt<200 GeV there is chance that it is lighter than the W. In this case it can be produced with the LEP machine when its centre of mass energy will be increased up to the W⁺W^- threshold. The identification of heavy quark production in e⁺e^- interaction has already been studied. A new criterion based on the identification of the semileptonic decay of the top quark is presented. These events, that have a very peculiar topology, can be also used to measured the mass of the quark

[en] A large acceptance gas RICH detector is presently under construction for the spectrometer of the COMPASS Experiment. Its design parameters are presented and the main characteristics of the vessel, the mirrors system, the photon detectors and the front-end electronics are discussed together with some results from prototyping activities

[en] A dedicated Monte Carlo has been built to study the optical properties of the RICH 1 detector presently under construction for the COMPASS experiment at CERN. In this paper we focus on the optimization of the position of the photon detector with respect to the RICH mirror and on the alignment of the mirror elements forming the mirror surface

[en] RICH-1 is a Cherenkov Imaging detector in operation at the COMPASS experiment at CERN SPS since 2001. MWPCs equipped with CsI photocathodes have been used as photon detectors, for the full detection area in the first years of operation, and for 75% of the area after a detector upgrade in 2006. The mean number of detected photons per particle has been extracted from the data collected during six years of COMPASS data taking. An indirect measurement of possible variations of the CsI quantum efficiency versus time is obtained from this analysis

[en] In this paper we describe the design of the re-configurable front-end boards (BORA boards) for the 82944 channel RICH-1 (Ring Imaging CHerenkov) of the Compass Collaboration (NA58). The front-end electronics controls the sample-and-hold operation after the arrival of an event trigger, acquires the analog voltages from the pre-amp VLSI and converts them into 10 bits at a rate of 20 Ms/s per analog channel. The digitized analogue values are then written into FIFOs. A subsequent operation compares the readings of each and every channel with corresponding programmable thresholds, and transmits those values larger than the threshold, together with the channel number, through an optical fiber to subsequent processing stages of the acquisition system. The overall operation of the board is controlled and supervised by a fast DSP. The availability of local intelligence allows the board to present innovative features such as: to be part of a computer network that connects several similar boards of the detector with a PC. The presence of the DSP allows testing the operability and linearity of the analog channels; and creating engineering frames containing local temperatures and voltages and transmitting the results through the network. The operator can reconfigure the hardware and software of the board by downloading programs from the PC

[en] The set-up of the COMPASS experiment (NA58 at CERN SPS) consists of two spectrometers (a large-angle one followed by a small-angle spectrometer) both equipped with a gas RICH (RICH 1 and RICH 2) for hadron identification. RICH 1 is currently under construction, while RICH 2 will be added at a second stage. RICH 1 design parameters and technological choices are discussed

[en] RICHONE is the pattern recognition and PID code for COMPASS RICH-1. RICHONE is part of CORAL, the COMPASS software system, a C++ framework developed within the collaborations using up-to-date techniques and tools

[en] This paper describes the reconfigurable read-out system for the 82944 RICH-1 channels of the COMPASS experiment (NA58) at CERN. The system is based on 192 identical large front-end boards (BORA board). BORA was designed for acquiring, digitizing, threshold subtracting and transmitting event data. The overall operation of the board is controlled and supervised by a DSP tightly interacting with an FPGA that acts as a parallel co-processor. The DSP allows characterizing each analog channel by locally calculating noise and pedestal. Each BORA communicates with the outside world through two optical fibers and through a dedicated DSP network. One optical fiber is used to receive event triggers, and the other one is used to transmit event data to subsequent processing stages of the acquisition system. The DSP network allows reconfiguring and reprogramming the DSPs and FPGAs as well as acquiring sample events to visualize the overall operation of the system. The whole RICH has eight DSP networks working in parallel. These networks are handled by DOLINA, a PC resident multiprocessor board containing eight DSPs. Each network is formed by 24 BORA DSPs and 1 DOLINA DSP. The read-out system can steadily work up to a trigger rate of 75 kHz with maximum pixel occupancy of 20%, reaching a transmission data rate of 5.13 Gbytes/s

[en] The design of the COMPASS RICH-1 gas system, its operational modes, the cleaning setups for the preparation of the radiator gas and transmission measurement installations are described. The gas system in presently fully operational and satisfactory transmission of VUV light through the radiator gas has been reached