Accession Number : ADA319178

Title :   Solid Counters: Scintillation Counters,

Descriptive Note : Quarterly rept. 1 Feb-1 May 48,

Corporate Author : TECHNICAL INFORMATION SERVICE (AEC) OAK RIDGE TN

Personal Author(s) : Wouters, Louis

PDF Url : ADA319178

Report Date : JUN 1948

Pagination or Media Count : 11

Abstract : In the early phases of nuclear research, scintillation counters proved valuable for detection of alpha particles. In this technique, as perfected by Rutherford and his co-workers, scintillations produced by the excitation of fluorescent and phosphorescent screens were observed visually. The method has been revived in modern form, principally by Kallman, with the use of photomultiplier tubes for the observation of light pulses, and large, transparent crystals for the conversion of as much of the energy of a penetrating particle into light as possible. A wide range of fluorescent materials has been tested by various workers. On the basis of reported efficiency and response time, the work at this laboratory was initiated using naphthalene. The first experimental arrangement consisted of a 1P21 P.M. tube mounted in a glass container stuffed with moth flakes and immersed in liquid air as shown in. With radium gamma ray source, a ratio of about 20 was observed between the counting rate of this set-up as compared with that of the photomultiplier surface alone exposed to the gamma radiation under otherwise identical conditions. As a consequence of the sensitivity (about 10 per cent gamma counting efficiency) of even this crude and inelegant device, as well as of its very simplicity, a program was undertaken with the aim of devising a rugged and adaptable basic counter unit. This program received added impetus when it was discovered that the much greater usable light output of anthracene made possible the elimination of the refrigerant. With respect to pulse width, it will be seen that the fortuitous condition exists whereby the minimum, independently observed pulse width coincides with the maximum resolution of simple, fairly conventional electronic recording equipment.

Descriptors :   *SCINTILLATION COUNTERS, FLUORESCENCE, EXCITATION, REACTION TIME, RESOLUTION, COUNTING METHODS, CRYSTALS, LIGHT PULSES, RECORDING SYSTEMS, PHOTOMULTIPLIER TUBES, ANTHRACENES, NAPHTHALENES.

Subject Categories : Nuclear Instrumentation

Distribution Statement : APPROVED FOR PUBLIC RELEASE