scholarly journals Using X-Ray As An Irradiation Source For Direct ESR Dating of Fossil Teeth

2021 ◽  
Author(s):  
Wenjing Yu ◽  
A.I.R. Herries ◽  
R. Joannes-Boyau
Keyword(s):  
Electron Spin Resonance ◽  
Gamma Rays ◽  
Tooth Enamel ◽  
X Rays ◽  
Internal Dose ◽  
Esr Dating ◽  
X Ray ◽  
Spin Resonance ◽  
The Difference ◽  
Powder Enamel

Abstract In this paper we have tested the potential application of X-rays as an irradiation source in Electron Spin Resonance dating of tooth enamel. Both modern and fossil samples were used to assess the feasibility of dose estimations using this alternative irradiator. Equivalent doses obtained with gamma-rays on fossil powder enamel was frequently less than the doses obtained on fragments using only X-rays. It is believed that a combination of NOCORs (non-orientated CO2- radicals) and local internal dose discrepancy may be the origin of the difference. Here, we show that testing penetration attenuation for each individual irradiation source is required to accurately estimate the maximum enamel thickness and produce reliable protocols. The use of a known laboratory additive dose allows the calculation of an absorption equivalent coefficient between gamma-rays and X-rays. We conclude that X-rays are an alternative irradiation source for ESR dating protocols, however, limitations remain in particular with alpha efficiency.

Electron spin resonance (ESR) dating of the origin of modern man

1992 ◽  
Vol 337 (1280) ◽  
pp. 145-148 ◽  
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Cultural Evolution ◽  
Tooth Enamel ◽  
Archaeological Sites ◽  
Esr Dating ◽  
Spin Resonance ◽  
Anatomically Modern Humans ◽  
Radioactive Radiation ◽  
Accumulated Dose

Many materials found in archaeological sites are able to trap electronic charges as a result of bombardment by radioactive radiation from the surrounding sediment. The presence of these trapped charges can be detected by electron spin resonance (ESR) spectroscopy: the intensity of the ESR signal is a measure of the accumulated dose and thus of the age. Tooth enamel is ubiquitous at archaeological sites and is well suited for ESR dating, with a precision of about 10-20%. This method has now been used to date many sites critical to the biological and cultural evolution of modern man. Dates for sites in Israel and Africa have demonstrated the existence of anatomically modern humans more than 100 ka ago.

ChemInform Abstract: X-RAY PHOTOELECTRON AND ELECTRON SPIN RESONANCE SPECTRA OF IRON(III) PARABACTIN

1984 ◽  
Vol 15 (35) ◽  
Author(s):  
J. P. ROBINSON ◽  
E. F. WAWROUSEK ◽  
J. V. MCARDLE ◽  
G. COYLE ◽  
I. ADLER
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
X Ray ◽  
Spin Resonance

X-ray photoelectron spectroscopy and electron spin resonance studies on O2 and N2O plasma oxidation of silicon

1996 ◽  
Vol 39 (3) ◽  
pp. 173-178 ◽  
Author(s):  
Atsushi Masuda ◽  
Yasuto Yonezawa ◽  
Akiharu Morimoto ◽  
Minoru Kumeda ◽  
Tatsuo Shimizu
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Photoelectron Spectroscopy ◽  
Plasma Oxidation ◽  
X Ray ◽  
Spin Resonance

A Study of the Effect of Extended Hounsfield Unit Range and Voxel Size on Defect Detection in Friction Stir Welds

2020 ◽  
Author(s):  
Ahmad M. R. Baydoun ◽  
Ramsey F. Hamade
Keyword(s):  
Gamma Rays ◽  
Dissimilar Materials ◽  
Hounsfield Unit ◽  
Ct Scanning ◽  
Ultrasonic Waves ◽  
X Rays ◽  
Internal Defects ◽  
Voxel Size ◽  
X Ray ◽  
Friction Stir

Abstract Friction stir welding (FSW) is a novel welding method that is garnering attention, in part, due to its ability to join dissimilar materials. One of the challenges in producing dissimilar friction welded joints is ensuring the welds are defect-free. Nondestructive testing (NDT) methods such as ultrasonic waves, gamma rays, X-rays, and X-ray CT, are gaining popularity as a method to detect internal defects in FSW joints. In this study, dissimilar AA1050-AA6061-T6 FSW lap welds are Manufactured and then examined using an NDT X-ray CT technique. The effects of two critical X-ray CT scanning parameters (voxel size and Hounsfield unit (HU)) on the detection of internal defects are investigated. The samples are scanned via X-ray CT at two different voxel sizes (2.457 E−02 and 1.420 E−03 mm3) and two HU ranges (12-bit and 16-bit depth). The generated Digital Imaging and Communications in Medicine (DICOM) images are segmented based on a proper HU threshold found via the Otsu thresholding method. The findings show that Small voxel size (higher resolution) improves the ability of detecting internal defects and improves the effectiveness of the thresholding process. Higher HU range results in a wider separation between detected material peaks, thus enhancing the effectiveness of the thresholding process as well.

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