S. Femino

Light response and particle identification with large CsI(TI) crystals coupled to photodiodes

The light response of large CsI(TI) crystals supplied by various companies and coupled to photodiodes has been investigated. Energy resolution measurements and Z = 1 isotopic identification using the two gates method have been performed with in-beam experiments.

Timing performances and edge effects of detectors worked from 6-in. silicon slices

Abstract Prototypes of new passivated implanted planar silicon detectors, obtained for the first time from 6 in. silicon slices, have been tested. The time and energy resolutions have been studied as a function of the type and energy of the detected particles, in order to test the performances of these detectors for time of flight measurements in the Chimera project. Some problems arising from edge effects observed in double-pad detectors have been solved by using a guard ring.

The enhanced data acquisition system for the 4/spl pi/ detector CHIMERA

CHIMERA is a second generation 4/spl pi/ detector for high resolution light particles and fragments measurements in the field of intermediate energy nuclear physics. An enhanced data acquisition, control and trigger system has been developed to manage the almost 5000 electronic channels of the detector. Data acquisition is based on fast data link (FDL) connection between 9U VME crates. FDL is a highly programmable VME device. It performs data readout and transfer to a destination board VME CPU, FIC8243, running the real time OS9 operating system. Data read and transfer is performed by a fast protocol (sparse data scan) whose performances have been improved introducing the chained block transfer mode (CELT) technique. Data collected by the CPU are broadcasted to the analysis stations for on-line data analysis and storage. All commands from and to VME CPU are sent by socket based network protocols. Complete remote control of the electronic front-end is obtained by a system of client-server applications. A first level event selection and control during readout is assured by a trigger system based on a new VME 9U board (MUSE), fully integrated with the FDL readout system.

The data acquisition and control system for the 4/spl pi/ detector CHIMERA

CHIMERA (Charged Heavy Ions Mass and Energy Resolving Array), a new 4/spl pi/ detector for charged particles is under development at various sites of the Istituto Nazionale di Fisica Nucleare. This paper describes the new data acquisition system built to handle the signals coming out from the detector with a rate up to 1 kHz on almost 5000 electronic channels. The required average throughput for the system is in the order of the 1 MB/s. The used converters allow double-range conversion on 15 bits, in less than 50 /spl mu/s for all the 64 channels. The FDL link connects the different VME 9U crates performing a programmable hardware readout with a rate up to 100 MB/s. It uses a fast hardware protocol (Sparse Data Scan) to read the data buffers and send them to a FIC 8243 CPU board. A FIC 8243 dual-processor board forwards data (through Ethernet) to the analysis station (266 MHz Digital AlphaStation or Sun Sparcstation). A DLT (Digital Linear Tape) unit connected to analysis station is used to store data. The new data acquisition system has been tested under beam conditions at the Laboratorio Nazionale del Sud (Catania, Italy) and at GANIL (Caen, France).

Detector array control and triggering

A commercial DSP-based board installed in a host-PC was employed for the fast, on-line and real-time computation of special algorithms, in order to perform event selection and operate as a 2nd level trigger. Moreover an ad hoc built interface, realized using PLDs with a view to connecting the DSP-board to the ADCs and to the data acquisition system, has been tested in order to evaluate the performances of these programmable devices used as a look-up-table and as a decisional part of a 1st level trigger.

The on-line computational and control system for the 4/spl pi/-detector CHIMERA

A commercial two-DSP-based board is the basic unit of the on-line computational and control system under development for the multidetector CHIMERA. The system design includes a small scale parallel and distributed architecture of PCs, used as both host and user and network interface, and of DSP boards, up to three for each host. The system is able to accomplish the on-beam control of CHIMERA, by means of the on-line computation of special algorithms, instead of using the usual techniques of special pulses to be sent off-beam. The physical data, collected and organized in UDP-packets by the data acquisition system, are read through a 10 Mbit/s Ethernet network. The PC-software, running under Windows NT 4.0, is based on threads and assures the communication and program managing and the result presentation. The DSP-software written in C++ takes care of the communication with the PC and of the computation. The preliminary on beam results for the first three wheels (about 100 telescopes), obtained employing two bi-processor boards located in the PCI-bus of a Pentium MMX PC are also presented.

Real-time computing of special algorithms with a DSP-based board

The on-line computation of special algorithms, as power-law for particle identification in nuclear physics, is a basic problem requiring real-time computational resources that have to fit time constraints, due to the randomness of nuclear events, and assure correctness. Present work concentrates on the possibility to use a low cost commercially available DSP boards for this purpose. The used DSP board computes in real-time transcendental functions expanded in Chebychev polynomial series with assembler routines ad hoc written, in order to perform the identification of the charged particles emitted in nuclear reactions. In particular a presentation of an emulation framework is described where Assembler DSP algorithms are tested at full speed, while input and output are tested at low velocity, by using two host PC, simulating peripherals for the I/O data.

DATA ACQUISITION AND REAL-TIME COMPUTING BY A DSP-BASED SYSTEM

Abstract A digital signal processor (DSP) based two-parameter data acquisition system, connected to two analog-to-digital converters (ADCs) by means of an ad hoc built interface, was developed in order to perform real-time, on-line data processing. The interface, realized with programmable logic devices (PLD); may also work as a table of pre-computed values through which it is possible to carry out a simple analysis on the incoming or outcoming data.

Extending a monoprocessor real-time system in a DSP-based multiprocessing environment

The paper deals with the evaluation of the real-time behavior of a proposed kind of computing system for monitoring and controlling multidetector arrays used in nuclear physics experiments. The system was implemented by extending a previous monoprocessor system in a multiprocessing environment, based on ADSP-21060-SHARC digital signal processors. The proposed system is being developed within the CHIMERA multidetector project.

CHIMERA multidetector at Laboratori Nazionali del Sud

The installation of CHIMERA multidetector, designed in order to study central collisions in heavy ion reactions at intermediate energy, is going on at LNS and the first experiment with the forward part (688 telescopes) is running since May 1999. The aim of this contribution is to present the status of the project.