The DISTO Data Acquisition System at SATURNE

TL;DR

The paper describes the design and implementation of the DISTO data acquisition system at SATURNE, enabling high-rate data collection for a large-acceptance magnetic spectrometer used in proton scattering experiments.

Contribution

It introduces a comprehensive data acquisition system integrating VME CPUs, front-end electronics, and UNIX workstations for efficient high-rate data collection and online monitoring in particle physics experiments.

Findings

Able to record 3500 events per burst with 15% dead time.

Integrated multiple hardware components for real-time data processing.

Supports online event analysis and monitoring.

Abstract

The DISTO collaboration has built a large-acceptance magnetic spectrometer designed to provide broad kinematic coverage of multi-particle final states produced in $pp$ scattering. The spectrometer has been installed in the polarized proton beam of the Saturne accelerator in Saclay to study polarization observables in the $\vec{p} p \to p K^{+} \vec{Y}$ ($Y = \Lambda, \Sigma^{0}$ or $Y^{*}$) reaction and vector meson production ($\phi, \omega$ and $\rho$) in $pp$ collisions. The data acquisition system is based on a VME 68030 CPU running the OS/9 operating system, housed in a single VME crate together with the CAMAC interface, the triple port ECL memories, and four RISC R3000 CPU. The digitization of signals from the detectors is made by PCOS III and FERA front-end electronics. Data of several events belonging to a single Saturne extraction are stored in VME triple-port ECL memories using a hardwired fast sequencer. The buffer, optionally filtered by the RISC R3000 CPU, is recorded on a DLT cassette by DAQ CPU using the on-board SCSI interface during the acceleration cycle. Two UNIX workstations are connected to the VME CPUs through a fast parallel bus and the Local Area Network. They analyze a subset of events for on-line monitoring. The data acquisition system is able to read and record 3500 ev/burst in the present configuration with a dead time of 15%.