Frederick A. Kirsten

The TOPAZ Time Projection Chamber

Abstract A Time Projection Chamber (TPC) is under construction for the TOPAZ e + e − experiment at TRISTAN. The dimension of the TPC is 260 cm in diameter and 300 cm in axial length. Fin-type fine field cages are set inside GFRP insulator cylinders which also serve as the pressure container. The sector is made of multilayer G10 boards for better electric and thermal isolation. The cathode pads are substantially larger in area than those of the PEP4-TPC and having zigzag-shaped boundary. These serve to maintain high spatial resolution with fewer number of pad channels. Signals are amplified by low noise preamplifiers and shaping amplifiers, and, stored and digitized by FASTBUS based CCD-digitizers. Digitized information is preprocessed and sent to VAX 11/780 at a rate 2 MHz per 32 bit word. Nitrogen LASER beam will be used extensively with the LASER beacon system for calibration. Test results on production prototypes are also reported.

GENERATOR OF NANOSECOND LIGHT PULSES FOR PHOTOTUBE TESTING

This mercury‐capsule light‐pulse generator was developed to test and evaluate the high‐speed features of multiplier phototubes and low‐level image tubes. Light pulses and electrical trigger pulses are generated simultaneously in an arc discharge at a usual repetition rate of 60 per second. The electrical pulse is used as a time reference for the light pulse. The time required for both the light and the electrical pulse to rise from 10 to 90% of peak amplitude is less than 5×10−10 sec. The light pulse rises to a maximum and falls to 50% peak amplitude in less than 1.5×10−9 sec. The electrical pulse power available is large. Time resolution of 10−10 sec is typical of measurements made with conventional fast oscilloscopes, while elaboration of technique permits relative time measurements that are better in some cases by at least three orders of magnitude. The light is emitted from a region a few mils in diameter, and thus may often be considered to come from a point source. An S4 photosurface subtending 0.1 ...

Acoustic spark chamber

Abstract Positions of the tracks produced by cosmic rays in a 15-kV four gap spark chamber were determined by measuring the time of flight T of the shock waves produced by sparks in argon. A pair of acoustic probes, using barium-titanate piezoelectric transducers is placed in each gap of the spark chamber. Times, T 1 i, in >sec for each probe i , are measured by a time-sorter and printed 2 sec after the passage of the particle through the chamber; from these, the position and the angle of the track was reconstructed by a program. With the spark energy of 2 joules, signals of the order of 1 V are obtained from the transducer. These signals are of N-wave form, with the rise-time of 1 >sec or less. The full width one-dimensional resolution in the spark position is 0.33 mm up to a distance of 52 cm; and 0.41 mm at 1 meter (giving an accuracy to 1:2500). The full-width spatial resolution, measured with three probes per gap is 0.8 ± 0.4 mm. The time-of-flight vs distance dependence is linear up to 2 meters. The recovery time of the probes is 10 >sec, suggesting the possibility of handling up to ten tracks during a long-spill accelerator pulse, with two probes per gap; and up to 20 with six probes per gap.

Test routines and monitoring for a large counter experiment

Abstract Some recent multichannel scintillation-counter experiments are so complex that the use of test routines and fault monitoring becomes essential. In a recent experiment, it was desired to initially align the system, provide continuous calibration during the experiment, and rapidly locate the cause of threshold drift or catastrophic failure. A test and monitoring system was devised in which synthesized pulses are injected into several points of the system, and the operation is automatically compared with the desired response. If the system performance does not agree within prescribed limits, an alarm sounds. Through a program that varies the amplitude of the test signal, one can check coincidence-circuit threshold and feed-through characteristics. By programming delay between input pulses, the resolving time can be measured. Several novel monitoring devices have been developed which allow one to assess the display of a large volume of information at a glance. One unit for reading time delays involves the use of a cathode-ray-tube raster display, another unit for reading binary information employs a transistor-driven incandescent lamp panel.

An electronic data-acquisition system for use with a complex nuclear physics experiment

Abstract An electronic data-acquisition system is used with a nuclear physics experiment of such complexity that data processing required a high-speed computer. The system acquires data from 168 signal channels of scintillation counters and four channels of chronotron circuits. It has the capacity to store 10 events during the 0.1-sec-long Bevatron beam pulse. The storage time for the information from each event, consisting of 168 bits from the counters plus 12 bits from the chronotrons, is 40μsec. In the interval between beam pulses, the stored information is punched onto paper tape in a form suitable for computer input. This report describes the over-all characteristics and operation of the system. The specific parts of the system and techniques for semi-automatic testing are given in the companion reports.

A FASTBUS digitizer system for TOPAZ TPC

Abstract A large scale digitzer system for 11000 channels of the TOPAZ TPC was constructed based on FASTBUS and installed for TRISTAN at KEK. Each digitizer card is equipped with 16 channels of CCD with a moderate speed of A/D converter. Output data are arithmetically corrected for pedestals, zero-suppressed and applied with a PRE/POST mechanism by an on-board sequencer; they are followed by a sparse data scan with an intelligent data scanner.

Digitizing Electronics for the EMI Multi-Wire Proportional Chambers

A complete system of electronics for digitizing pulses from a large array of multi-wire proportional counters is described. The system is based on the method of coupling the chamber pulses onto delay lines developed by Perez-Mendez. All three wire planes of each chamber are digitized, giving positional information for each avalanche in the chamber on three coordinates, x, y and a redundant coordinate. The system will be used with an array of 30 ch-iambers each one meter square, which will serve as an External Muon Identifier (EMI) for the 15-foot diameter bubble chamber in the neutrino beam line at NAL. Up to 16 events can be digitized in a 60 us beam spill.

A Short Description of the CAMAC Branch Highway

This paper presents a short summary and description of the CAMAC Branch Highway. The purpose of the branch and some of its characteristics are explained. Certain operational sequences are described in detail. The paper is intended to serve as an introduction to the CAMAC Branch Highway Specification, and is one of a series of papers on CAMAC topics. It is a revised version of a paper previously published. Since the first version was published, a revision of the branch highway specification has been issued. The present paper is based only on the revised specification. Information on the differences between the original and revised specifications is available.

Some Characteristics of Interfaces between CAMAC and Small Computers

The typical CAMAC system is operated in conjunction with a small computer. In the usual case, the computer acts as a repository for data generated by CAMAC, and also controls and directs the CAMAC operations. This paper discusses some of the aspects of the hardware interface, and also some of the interaction between the computer and the CAMAC system.

A MWPC Instrumentation System with Small Dead-Time and with Provision for Automatic Testing and Calibration

This paper describes some of the system features of a large array of instrumentation to be used for data collection in an experiment utilizing multi-wire proportional chambers (MWPC) of both the amplifierper-wire and the delay-line types. The system is designed to uniquely meet special functional requirements for background reduction and dead-time reduction in high counting-rate experiments at FERMILAB.