Study of pollution in the El Jadida-Safi Atlantic coastal zone (Morocco) by using PIXE and SSNTD methods

In this work PIXE experiments were performed for measuring heavy and light elements (ranging from aluminium to lead) concentrations inside various polluted and unpolluted soils as well as liquid samples collected from different phosphate factory sewers in the El Jadida-Safi Atlantic coastal region (Morocco). In addition, uranium (238U) and thorium (232Th) contents were evaluated in the same samples studied by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The influence of the phosphate industry wastes on the concentrations of both radioactive and non-radioactive elements of the samples studied was investigated

Calculated Electronic Energy Loss of Heavy Ions at Low Energies in LR-115, Kapton, SiO2, and Al2O3 Amorphous Materials

The electronic stopping powers of LR-115 and Kapton polymeric foilshave been estimated, using Monte Carlo simulations, for 9Be, 11B, 12C, 14N, 16O, and 35Cl ions covering the energy range ~0.1-1.0 MeV/n. Comparison of stopping power based on Lindhard, Scharff, and Schiott (LSS) theory with the corresponding values obtained by SRIM and MSTAR codes in LR-115 and Kapton polymeric foils illustrate a significantly large deviations. However, a semiempirical equation has been proposed here and tested for better stopping power calculations at low-energy regime in the domain of LSS theory for Z = 4-8 ions across materials. Furthermore, the electronic energy losses for 9Be and 16O ions in SiO2 and Al2O3, respectively, have been calculated in the energy range of ~0.1-1.0 MeV/n. The calculated stopping powers exhibit up to 10 % deviation from the experimental values and MSTAR data

Dating of a quaternary limestone cave by combining the SSNTD technique with paleodose measurements: application to the stalagmite and stalactite growth

Abstract Uranium ( 238 U) and thorium ( 232 Th) contents were evaluated in di erent stalagmite and stalactite samples belonging to a quaternary limestone cave by using a method based on determining mean critical angles of etching of the CR-39 and LR-115 II solid-state nuclear track detectors (SSNTDs). Annual absorbed -, ÿ-and -dose rates were determined in the stalagmite and stalactite materials. The stalagmite and stalactite samples were dated by exploiting data obtained for the total annual absorbed dose rates and measuring the corresponding paleodoses. Results obtained were compared with those obtained by classic thermoluminescence and U=Th disequilibrium methods. The studied speleothem began from about 121 kyr and continued to about 69 kyr, coinciding almost with the last interglaciation corresponding to the fourth and ÿfth isotope stages. The formation rates of the stalagmite and stalactite samples were found equal to 0.88 and 0:94 cm kyr −1 , respectively

Developpement des techniques de dosimetrie appliquees a la datation par thermoluminescence

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

U and

Uranium (238U) and thorium (232Th) concentrations were measured in different foods widely consumed in Morocco by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). Data obtained were compared to those obtained by using isotope dilution mass spectrometry (IDMS). Total daily intakes of 238U and 232Th for a typical food basket were estimated to be 1.3 ± 0.1 mBq d-1 and 0.98 ± 0.08 mBq d-1, 1.4 ± 0.1 mBq d-1 and 1.06 ± 0.08 mBq d–1, 1.7 ± 0.1 mBq d–1 and 1.26 ± 0.08 mBq d–1 and 2.0 ± 0.1 mBq d–1 and 1.5 ± 0.1 Bq d–1 for the 2–7 years, 7–12 years, 12–17 years and adult’s age groups, respectively. Alpha-activities due to annual 238U and 232Th intakes from the ingestion of the studied foodstuffs were determined in different organs and tissues of the human body of members of the public by using the ICRP gastrointestinal tract and systemic part models for these radionuclides. Committed equivalent doses due to annual intakes of 238U and 232Th were evaluated in the human body organs and tissues for different age groups of the Moroccan population by exploiting data obtained for alpha-doses deposited by 1 Bq of 238U and 1 Bq of 232Th in the considered human organs and tissues. The influence of the mass of the target tissue and activities due to 238U and 232Th on the committed equivalent doses due to annual intakes of these radionuclides in the organs and tissues of the human body was studied

Experimental location of helium atoms in 6H-SiC crystal lattice after implantation and after annealing at 400 degrees C

International audienceThe question of the helium behavior in silicon carbide has been studied at the atomic scale by numerical simulations, but no experiment has been carried out to assess the results hitherto. This paper describes the first experiments allowing this comparison. 6H-SiC single crystals were implanted with 50-keV He ions at a fluence of 10(15) He/cm(2) at room temperature. The as-received and as-implanted samples were analyzed by RBS and NRA in channeling mode along the main crystallographic planes and across three main axes. The measurements have shown that a portion of the He is located in the interstitial tetrahedral sites as predicted by the numerical simulations. The same measurements were performed on an implanted sample subsequently annealed at 400 degrees C under Ar atmosphere. They have shown that the quantity of He detected in interstitial tetrahedral sites T-Si and T-C has not significantly changed whereas that of He detected in the main crystallographic plane and in the main axis has increased. This increase is likely caused by He atoms migration at 400 degrees C toward interstitial positions located inside vacancies such as V-Si and VSiVC. In parallel a partial recovery of the Si and C sublattices has been observed. (C) 2015 Elsevier B.V. All rights reserved

Microstructure effects on He diffusion in sintered UO2_2 by μ\muNRA

A two-dimensional analysis of helium in UO2 sintered disks has been achieved on a micrometric scale by using the NRA technique and upgrading the detection arrangement. The transmission mode detection procedures, localization of the region scanned and normalization of the helium lateral distributions are now well established. For sintered UO2 pellets implanted at a dose of 2 × 1016 3He/cm2, the results show that the lateral helium distribution is correlated to the sample microstructure after annealing for 1 h at 1300 °C. The enhanced desorption of helium in the vicinity of grain boundaries points to them playing an essential part in helium diffusion in UO2