R. Fox

A Logarithmic Detection System Suitable for a 4π Array

A low pressure multiwire proportional counter, a Bragg curve counter, and an array of CaF2/plastic scintillator telescopes have been developed in a geometry suitable for close packing into a 4π detector designed to study nucleus-nucleus reactions at 100-200 MeV/nucleon. The multiwire counter is hexagonal in shape and gives X-Y position information using resistive charge division from nichrome-coated stretched polypropylene foils. The Bragg curve counter is a hexagonal pyramid with the charge taken from a Frisch gridded anode. A field shaping grid gives the Bragg curve counter a radial field. The scintillator telescopes are shaped as truncated triangular pyramids such that when stacked together they form a truncated hexagonal pyramid. The light signal of the CaF2-plastic combination is read with one phototube using a phoswich technique to separate the ΔE signal from the E signal. The entire system has been tested so far for particles with 1 ≤ Z ≤ 18 and gives good position, charge, and time resolution.

A new four channel pulse shape discriminator

A renewed interest in neutron - gamma discrimination and the need to process rates up to several MHz per channel led to the development of a new, four channel pulse shape discriminator (PSD) in 1/12 NIM format. By revisiting old techniques and running simulations of new ideas, it was determined that the best PSD performance is obtained by measuring the time between the rising edge of the pulse and the intersection point of the curves of the integrated short component with the trailing edge of the pulse. Pulse shape discrimination can be performed at up to 4 MHz detector rate. The module was tested with different neutron and gamma sources as well as at high neutron flux and was found to provide good energy independent neutron / gamma discrimination in a wide energy range with low dead time. A 96-channel system using 24 of these modules is now being operated.

Performance of the high-energy single-event effects test Facility (SEETF) at Michigan State university's national Superconducting Cyclotron laboratory (NSCL)

The performance of Michigan State Universitys Single-Event Effects Test Facility (SEETF) during its inaugural runs is evaluated. Beam profiles and other diagnostics are presented, and prospects for future development and testing are discussed.

Reaction filters. Charged-particle multiplicity and linear momentum transfer

Abstract The relation between charged-particle multiplicity and linear momentum transfer to heavy reaction residues has been investigated with a 4π charged-particle detector for the reactions 36Ar+238U at E A =35 MeV and 14N+238U at E A =50 MeV . The multiplicity of charged particles at backward angles (θ > 35°) incrreases linear momentum transfer while the multiplicity of charged particles in the forward direction is almost independent of the linear momentum transfer.

Real-time results without real-time systems

The data acquisition system at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, East Lansing, is based on commodity PC components running an unmodified Linux kernel. A commercial PCI-VME bus bridge connects the readout processors of this system to digitization hardware. While Linux is not a real-time system, this paper shows how we have structured the readout software to meet the requirements of the NSCL without the use of real-time or embedded components.

A multitasking, multisinked, multiprocessor data acquisition front end

A description is given of a generalized data-acquisition front-end system that is based on MC68020 processors running a commercial real-time kernel (pSOS) and is implemented primarily in a high-level language (C). This system has been attached to the back-end online computing system at NSCL by means of a high-performance Ethernet protocol. Data may be simultaneously sent to any number of back-end systems. Fixed fraction sampling along links to back-end computing is also supported. A nonprocedural program generator simplifies the development of experiment-specific code. >

Status of the NSCL 4 pi data acquisition system

A status report on the VME-Ethernet-VAX-based data acquisition system used with the 200-plus-element NSCL 4 pi detector is given. Included are the design of the system and a report on the level of implementation and current performance. Two hardware modules unique to the system are discussed. One is the fast decision module, a CAMAC module used as a programmable trigger, and the other is a VME module used to interface the VME to the LeCroy ECLine. >

Overview of the Data Acquisition System at NSCL

The integrated data acquisition/analysis system for nuclear experiments is described. The selection criteria for the multi-processor system is discussed and the current configuration and planned expansion is shown. Operational rates and limitations of this system are given for some typical experiments. An overview of the multi-tasking software and user interfaces is given.

Portable data flow in UNIX

We describe the dataflow of a nuclear physics data acquisition system. The system features a high speed active routing subsystem which allows an arbitrary number of data producers to contribute data to the system. Data are then routed to an arbitrary number of data consumers. Low overhead route-by-reference mechanisms are used to allow high rate operations. The system has been ported to a variety of UNIX systems. Timings are given for the routing component of the system on several systems. Finally, we give an example of a set of programs which can be added to the system to produce a complete data acquisition system. >

Progress on the Data Acquisition System at NSCL

We report on the progress made in data acquisition software development. Specifically, a unique generalized data routing scheme has been developed which allows user online analysis programs to be safely integrated into the acquisition system without endangering data sent to event recording devices. We describe the structure of the system. Performance is discussed and throughput calculated from it. User experience with the system is also discussed. We show how this routing system may easily be adapted to loosely coupled multiprocessor systems.