Fading of thermoluminescence induced in lunar fines

Journal Article · Mon Sep 17 04:00:00 EDT 1973 · Nature (London) Phys. Sci., v. 245, no. 142, pp. 41-43

DOI:https://doi.org/10.1038/physci245041a0· OSTI ID:4359402

Hwang, F S.W.

It is stated that rapid fading of thermoluminescence induced in Apollo rock samples has been observed. A significant decay was observed in the third peak of the glow curve when a sample was kept at --l96 deg C after irradiation with l60 MeV protons to 400 kR at this temperature. This fading occurred in only about 2 hr. and was attributed to nonthermal leakage, possibly by tunnelling'' of trapped carriers. The present author has analyzed the trapping parameters of some glow peaks in lunar fines, using both isothermal annealing and initial rise'' techniques, with a view to obtaining a better understanding of their TL propenties. The samples were irradiated with either /sup 90/Sr BETA rays or / sup 90/Co gamma rays at room temperature, and showed the same response to both types of irradiation. The prominent glow peak at ~ 155 deg C consisted of one very unstable and some relatively stable components at room temperature; its isothermal decay was investgated by irradiating the samples with BETA rays to a standard dose of 1 MR and then keeping it at constant temperature for various times. The curves obtained showed that the decay mode was not a simple exponential decay, as expcted for first order kinetics models, and implied that the prominent peak consisted of multiple trapping levels. The isothermal decay curve for a given temperature could be resolved into three components, as in the case of multiple nuclear decay modes. Each component represented the isothermal decay of an individual peak of the corresponding trapping levels, and the halflives at various temperatures were obtained for each individual peak. Mechanisms are discussed, and it is concluded that the fading at low temperature is temperature dependent, but not by nonthermal tunnelling'' means. This is perhaps due to carriers hopping out'' from shallow surface traps by vibration. (UK)

• Research Organization: Univ. of Birmingham, Eng.
• NSA Number: NSA-29-013680
• OSTI ID: 4359402
• Journal Information: Nature (London) Phys. Sci., v. 245, no. 142, pp. 41-43, Journal Name: Nature (London) Phys. Sci., v. 245, no. 142, pp. 41-43; ISSN NPSCA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

*LUNAR MATERIALS-- THERMOLUMINESCENCE
BETA PARTICLES
GAMMA RADIATION
GLOW CURVE
HIGH TEMPERATURE
MOON
N56700* --Physics (Astrophysics & Cosmology)--Planetary Phenomena
PEAKS
PROTONS
TRAPPING