摘要:

The slow-neutron flux as a junction of distance from a 90μg252Cf neutron source buried several feet below the surface of the ground was measured with BF3detectors in damp sand and clay strata. From 1 to 7ft from the source, the expected decrease in flux was observed, However, when similar measurements were made in shallow holes near the air-soil interface, the decrease with distance was less than exponential and a peak was noted at a distance of 8ft from the source. A qualitative explanation of the peak is given indicating that the density of thermal neutrons in the high-density thermal strata located several inches below the surface is a junction of the incident neutron energy and that the optimum incident energy is ~2 MeV. For this reason252Cf is a good neutron source for the purpose of in situ capture gamma analysis of soil constituents when used for mineral exploration purposes.

ISSN:0550-3043    

DOI:10.13182/NT69-A28377

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

A vacuum-type thermionic diode, designed for student laboratory use, is described which features variable electrode spacing, interchangeable electrodes, and a guard-ring structure. Experiments discussed include a measurement of emitter and collector work junctions, a study of the dependence of space-charge effects on electrode spacing, and field emission studies. Results are generally reproducible and in reasonable agreement with other published data. A space-charge correlation originally developed by Houston and Webster is tested against experimental data for the first time, and a unique measurement of the Schottky parameter at elevated temperature is reported.

ISSN:0550-3043    

DOI:10.13182/NT69-A28378

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

ISSN:0550-3043    

DOI:10.13182/NT69-A28379

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor