J.R. Waters

SPARK CHAMBERS WITH FERRITE CORE MEMORIES

Abstract It is demonstrated that small, conventional ferrite memory cores can be used with a wire spark chamber for recording spark locations. This removes the necessity for photographing the spark tracks and enables the information to be fed directly into a computer for analysis.

Precautions in the measurement of tritium concentrations in air when using flow-through ion chambers

Abstract Instruments with flow-through ion chambers are frequently used to measure the concentration of tritium gas in air. However, these simple instruments can give erroneous results because of: cigarette smoke, aerosols, ions, ambient gamma-ray field changes, moisture and condensation, absorption and memory effects, clogged filters, fission product gases, radon, and incorrect instrument calibration. The causes of these errors are explained and chart recordings are presented showing some of them in action. Most problems can be avoided using the proper instrument design and safeguards described and by adequate calibration techniques. A tritium monitor should be checked and calibrated with tritium gas, not gamma-rays or ions. The most accurate calibration is obtained when the instrument operates in a closed loop so that the tritium concentration is constant, a steady meter reading being obtained independent of air flow rate and instrumental time constants.

Some Measurements of the Efficiency for Observing Photoelectrons in Image Intensifiers

A method is described for measuring the efficiency with which photoelectrons can be detected in an image intensifier system. A weak light is shone onto the first cathode and the photoelectron current measured. The light is then attenuated by a large known factor and compared with the number of spots observed in a given time. A simple system was used to demonstrate this method; a maximum efficiency of 85% was achieved. The results of experiments with a filament scintillation chamber and a Cerenkov detector using image intensifiers are discussed and yield some information about the electron detection efficiency. A simple method of finding the detection threshold is also mentioned with two typical examples of its results.

A scintillation chamber—image intensifier beam profile detector

Abstract An instrument for use in surveying beams of charged particles is described. It consists of a scintillation chamber mounted on an RCA single stage image intensifier (C74035) lens-coupled to an intensifier orthicon (C74036) in a television camera. Charged particles enter the ends and travel down the length of the c filaments causing flashes of light which are amplified and displayed on the monitor kinescope. This system has been used as a detector of weak secondary beams from an accelerator with considerable success. It facilitates the setting up, alignment, and focusing of such beams and is quicker and more efficient than other methods.

Filament Scintillation Chamber Experiments at Princeton University

Publisher Summary This chapter provides an overview of the filament scintillation chamber experiments at Princeton University. Initial work on filament scintillation chambers by the Princeton University group was directed toward assembling intensifier systems capable of viewing minimum ionizing tracks. This work focused on cathode efficiencies, overall system gains, background noise, angular distribution of light from phosphors, resolution and methods of recording. As a result of this work, it was concluded that a system adequate for reliable recording of minimum tracks had been assembled, and many examples of cosmic ray mesons were recorded. These were obtained using a system consisting of a two-stage RCA 70050 intensifier, lens-coupled to an RCA two-stage intensifier orthicon. In the later stages of the work, systems of image tubes and lenses were assembled and used without precise measurements of overall gains. However, it generally turns out that an overall gain of about 106 is used, assuming that the video stage accounts for a factor of l02.