David O. Williams

The importance of being networked

Several branches of the physical sciences, and high-energy particle physics in particular, have used computer networks routinely for many years. In some countries, such as the United Kingdom and Italy, the physics community has been a major force behind the development of computer networking for the whole national scientific and academic community. On an international basis, the last decade has seen the birth and growth of HEPnet – the high-energy physics network – on a European and even intercontinental basis (see Fluckiger in Further reading). Indeed, the current generation of major particle physics experiments, run as international collaborations, could not have come to fruition without computer networking.

PLLS, a Portable Interactive Language System

PILS (a Portable Interactive Language System) has been designed and implemented at CERN to improve the portability of interactive programs used in the electronics test environment. The syntax of PILS is discussed, with emphasis on the features which distinguish PILS from some other interactive languages, such as data types, modules, control structures, full subroutines and functions with parameters, access to external (normally FORTRAN) libraries. The fact that PILS is written in PASCAL and has been designed for easy transportability is emphasised. PILS is a language SYSTEM which means that the command and editing interfaces are identical on all implementations. The status of PILS on various computer systems is discussed, and remarks are made on the status of the first PILS compiler (for VAX/VMS and VAX/UNIX) and on plans for future PILS versions. A particular implementation of PILS on a small CERN test system is briefly described.

Development of Large-Area Fast-Rich Prototypes with Pad Readout and Solid Photocathodes

In the frame of the RD26 collaboration at CERN we have built and tested several prototypes of fast-RICH detectors suitable for the construction of large systems. The detectors used a solid photocathode consisting of a 500 nm CsI layer evaporated on a conventional pad readout board of a MWPC operated with a methane/isobutane mixture at atmospheric pressure. The results indicate that such a detector may be used for long periods of time in stable operating conditions provided the gas mixture is continuously flushed through the detector. Evidence is presented for a significant loss of transmission of Cherenkov photons in the NaF radiator due to internal anisotropy of the crystal. We present the results of the performance of the photocathodes, the quantum efficiency of the CsI we have extracted from the measured Cherenkov photons and the identification achievable in a high density environment such as the detector ALICE planned for the heavy ion LHC. The results of a study of primary and secondary electron photoemission of CsI layers indicate that the surface structure and electron yield depend on the source material and on the heat treatment of the layer.

A review of wide-area aspects of high performance networking☆

Abstract This paper provides a broad overview of many aspects of wide-area networking, with an emphasis on the evolution of the Internet in Europe. The reality of todays Internet is contrasted with the vision of a future Global Information Infrastructure. The pivotal integrating role played by the World Wide Web in the explosive growth of the internet is highlighted. Potential GII infrastructures are analysed; various factors influencing Internet evolution are discussed; the likely economic and social impact of the Internet is briefly reviewed. The present status and planned evolution of high-performance academic and research networking in both Europe and the USA is presented, and brief comments are made on the situation elsewhere. A report is made on the present status of the liberalisation of the regulatory regimes of European telecoms, and the overall political background in which European networking finds itself is discussed. Suggestions for further reading are provided.

Particle identification by Cherenkov ring imaging using a neural network approach

The performance of a back-propagation neural network for particle identification using a RICH detector has been studied. When trained on 8000 simulated events in 14 iterations using a general back-propagation algorithm it correctly identifies 86% of the events out of a sample of 1000 experimentally measured pion and proton events at 3.5 GeV/c beam momentum. The identification efficiency is 70%. This is compatible with what is obtained by conventional, but mathematically much more complicated, identification algorithms.

Language requirements for embedded systems

Abstract This paper deals with the programming language requirements of embedded computer systems. Some of those requirements do not match well with the approach of conventional programming language design, which has aimed to hide details of the underlying computer hardware from the programmer. Furthermore, in embedded systems it is often necessary for the language to be able to deal with multiple tasks, multiple processors, and all of the related communications issues. Finally the language(s) used must not be treated in isolation, but as one (very important) component of the software engineering process.

Software and languages for microprocessors

Abstract This paper forms the basis for lectures given at the 6th Summer School on Computing Techniques in Physics, organised by the Computational Physics group of the European Physics Society, and held at the Hotel Ski, Nove Město na Moravě, Czechoslovakia, on 17–26 September 1985. Various types of microprocessor applications are discussed and the main emphasis of the paper is devoted to ‘embedded’ systems, where the software development is not carried out on the target microprocessor. Some information is provided on the general characteristics of microprocessor hardware. Various types of microprocessor operating system are compared and contrasted. The selection of appropriate languages and software environments for use with microprocessors is discussed. Mechanisms for interworking between different languages, including reasonable error handling, are treated. The CERN developed cross-software suite for the Motorola 68000 family is described. Some remarks are made concerning program tools applicable to microprocessors. PILS, a Portable Interactive Language System, which can be interpreted or compiled for a range of microprocessors, is described in some detail, and the implementation techniques are discussed.

A Charged-Particle Detector Based on Proportional Tubes with a Segmented Cathode and Cathode Readout

A charged-particle detector based on proportional tubes with cathode readout is described. The cathode is sectionalized into 2.2 × 2.2-cm pads. The detector was tested on high-energy particle beams. At an anode-to-cathode distance of 1.1 cm, the spatial resolution was 1.25 mm along the anode wire. A simulation model of the detector on the basis of the measured pad-response function was proposed, compared to the experimental data, and used to calculate the two-track resolution. The detector can be used in various experiments as a large-area multiparticle two-coordinate detector.

Alternate returns

It is suggested that facilities for the direct transfer of control upon return from a called subprogram/procedure, similar to (but preferably improving upon) the Alternate RETURN in FORTRAN-77, provide an important tool for the software designer.

Trends in mass storage technology and possible impacts on high energy physics experiments

Abstract The reasons for the wide-spread use of magnetic tapes to record data from high energy physics experiments are analysed. Problems due to the sequential nature of the medium and to the large amount of human intervention required are discussed. It is suggested that a high capacity removable disk might resolve these problems. An analysis of track-to-track spacing in magnetic recording shows that multi-track tape is unlikely to be of major interest. A discussion of helical recording shows that the proposed Ampex Super High Bit Rate Recorder might allow for extremely high data rates at future general-purpose facilities. A review of optical disk recording shows that it has great potential for physics data recording. Several areas needing careful attention to product design are indicated. Holographic tape storage is briefly reviewed.