Alexander Booth

The CDF Event-Builder

The Collider Detector at Fermilab (CDF) uses a FASTBUS network for real-time data acquisition (DAQ) with the current system comprising more than 500 FASTBUS modules. A central element in the DAQ pipeline is a hardware event builder whose role is to read out the front end scanners, reformat the data into YBOS bank structure, and transmit the data to a Level 3 trigger system which is composed of multiple processors from the Advanced Computer Project (ACP) at Fermilab. This paper describes the development of the hardware event-builder and includes some results from testing the prototype in reading out the detector, reformatting the data and writing it to the Level 3 ACP farm.

Effects of various event building techniques on data acquisition system architectures

The preliminary specifications for various new detectors throughout the world including those at the Superconducting Super Collider (SSC) already make it clear that existing event building techniques will be inadequate for the high trigger and data rates anticipated for these detectors. In the world of high‐energy physics many approaches have been taken to solving the problem of reading out data from a whole detector and presenting a complete event to the physicist, while simultaneously keeping deadtime to a minimum. This paper includes a review of multiprocessor and telecommunications interconnection networks and how these networks relate to event building in general, illustrating advantages and disadvantages of the various approaches. It presents a more detailed study of recent research into new event building techniques which incorporate much greater parallelism to better accommodate high data rates. The paper lists trends in data acquisition system needs giving specific requirements and a proposed arc...

A proposed scalable parallel open architecture data acquisition system for low to high rate experiments, test beams and all SSC detectors

A data acquisition system architecture which draws heavily from the communications industry is proposed. The architecture is totally parallel (i.e. without any bottlenecks), capable of data rates of hundreds of gigabytes per second from the detector and into an array of online processors (i.e. processor farm), and uses an open systems architecture to guarantee compatibility with future commercially available online processor farms. The main features of the system are standard interface ICs to detector subsystems wherever possible, fiber-optic digital data transmission from the near-detector electronics, a self-routing parallel event builder, and the use of industry-supported, high-level language programmable processors in the proposed Bottom Collider Detector (BCD) system for both triggers and online filters. A brief status report of an ongoing project to build a prototype of the proposed data acquisition system architecture is given. The major component of the system, a self-routing parallel event builder, is described in detail. >

Architecture and development of the CDF hardware event builder

A hardware event builder (EVB) has been developed for use at the collider detector experiment at Fermi National Accelerator (CDF). The event builder presently consists of five FASTBUS modules and has the task of reading out the front-end scanners, reformatting the data into YBOS band structure, and transmitting the data to a level-3 (L3) trigger system which is composed of multiple VME processing nodes. The event builder receives its instructions from a VAX-based buffer manager program via a Unibus processor interface. The buffer manager instructs the event builder to read out one of the four CDF front end buffers. The event builder informs the buffer manager when the event has been formatted and is then instructed to push it up to the L3 trigger system. Once the event is in the L3 system, a decision is made as to whether to write the event to tape. The authors describe the EVB modules and discuss the flexibility of the EVB architecture, the measured system throughput, and the prototyping of the EVB. >

Fast data acquisition with the CDF event builder

The CDF (Collider Detector at Fermilab) event builder is an intelligent FASTBUS device that performs parallel readout of a set of FASTBUS slaves on multiple-cable segments, formats the data, and writes the reformatted data to a FASTBUS slave module. The authors review the properties of this device and summarize its performance in the CDF data acquisition system. Preliminary performance of the prototype is being evaluated, and an event rate of approximately 30 Hz appears possible in the near future. >

SIDES-Segment Interconnect Diagnostic Expert System

The authors describe SIDES, an intelligent program designed to diagnose SIs (segment interconnects) both in situ as they operate in a data acquisition network, and in the laboratory in an acceptance/repair environment. They discuss issues such as knowledge acquisition and the extraction of knowledge from human experts and other knowledge sources. It is noted that SIDES can benefit high-energy-physics experiments, where SI problems can be diagnosed and solved more quickly. Equipment pool technicians can also benefit from SIDES, which decreases the number of SIs erroneously turned in for repair and acts as an intelligent assistant to the technician in the diagnosis and repair process. >

A graphical environment for DAQ simulations

At the Superconducting Super Collider Laboratory (SSCL) a tool called DAQSIM has been developed to study the behavior of data acquisition (DAQ) systems. This paper reports and discusses the graphics used in DAQSIM. DAQSIM graphics includes a graphical user interface, animation, debugging, and control facilities. DAQSIM graphics not only provides a convenient DAQ simulation environment, it also serves as an efficient manager in simulation development and verification. >

Simulation and modeling of data acquisition systems for future high energy physics experiments

The authors describe work undertaken at Fermilab in which several sophisticated tools have been brought together to provide an integrated systems engineering environment specifically aimed at designing data acquisition systems. Results of simulation experiments in which the effects of varying trigger rates, event sizes, and event distributions, over processors are clearly seen in terms of throughput and buffer usage in an event-building switch are also presented. In the context of the switch-based data acquisition system, it was possible to identify potential bottlenecks, determine buffer depths, aid system diagnosis, and better understand the interaction between different subunits as well as the system as a whole. >

A knowledge-based approach to network and module diagnosis

Abstract With the ever increasing complexity of high energy physics experiments and the increasing number of component parameters in detectors and their associated data-acquisition systems, it is important to transfer human expertise into computer programs such that they exhibit human reasoning, but react more quickly and more consistently to rapidly changing stimuli. This paper describes how knowledge-based systems are being used at Fermilab to diagnose networks and modules.