Quantifyng Rare Earth Element Content in High Concentrated Samples by ko-NAA
Bibliographic record
Abstract
Les terres rares (REEs) sont representes par les elements de la serie des lanthanides incluant le scandium et yttrium. Actuellement, une grande attention est donnee aux REEs a cause de leur application dans plusieurs domaines de pointe. Dans ce contexte il y a un besoin accru pour des techniques analytiques capables de caracteriser une gamme large de concentrations, en commencant avec les mineraux de faible concentration, jusqu’a leur raffinage; donc ayant des hautes concentrations en REEs. Cet etude se propose d’evaluer la performance de la methode d’analyse par activation neutronique k0 (k0-NAA) appliquee dans le Laboratoire d’analyse par activation neutronique de Polytechnique Montreal pour la determination avec precision des REE dans des matrices minerales de haute concentration. Les principaux facteurs qui influencent la methode ont ete investigues, en incluant les donnees nucleaires, la temperature dans les sites d’irradiation, les interferences nucleaires et spectrales, l’attenuation mutuelle des rayons gamma ainsi que l’autoprotection contre les neutrons. Afin de realiser cet objectif, des echantillons mono-element prepare avec des solutions standard certifiees et des oxydes standard certifies ont ete irradies, comptes et analyses. Finalement, les protocoles d’analyse ont ete optimises en termes d’irradiation, decroissance et comptage afin de reduire le temps total d’analyse. Les incertitudes introduites par les facteurs mentionnes plus haut ont ete evaluees. La capacite globale de la methode amelioree k0-NAA pour les REEs a ete mise en œuvre avec un materiel standard certifie du Projet canadien pour la certification des materiaux de reference (REE-2) avec des concentrations de 7.2 mg kg-1 pour Yb jusqu’a 9610 mg kg-1 pour Ce. Les concentrations des REEs ont ete mesurees avec des incertitudes plus faibles que 7% (a 95% intervalle de confiance) et ont ete consistantes avec les concentrations specifiees dans la certification du REE-2. ---------- The rare earth elements (REE) are comprised of lanthanide series, from lanthanum to lutetium plus scandium and yttrium. Due to the rising applications of REEs in different fields of technology a lot of attention has been drawn to the extraction of these elements. Therefore, a reliable and accurate characterization technique is required to determine variable levels of REEs starting from mineral matrices all the way to processed samples. The aim of this work is to evaluate the capability of k0-neutron activation analysis (k0-NAA) implemented at Polytechnique Montreal for accurate determination of rare earth elements in high concentrated mineral matrices. Individual factors affecting the measurements including nuclear data used for the calculations, neutron temperature effects, nuclear interferences, spectral interferences, gamma-ray self-attenuation and neutron self-shielding were investigated. Mono rare earth element standard solutions and rare earth oxides were used to investigate these phenomena separately. Several improvements were applied to the current method. Analysis protocols were optimized in terms of irradiation, decay and counting times to obtain accurate results in shorter turnaround times, and uncertainty contributions from aforementioned factors were evaluated. To validate the overall capability of the improved k0-NAA method for REE, a certified reference material (CRM) from Canadian Certified Reference Materials Project (REE-2) with REE content ranging from 7.2 mg kg-1 for Yb to 9610 mg kg-1 for Ce was used. The REE concentration was determined with uncertainty below 7% (at 95% confidence level) and proved to be consistent with the CRM certified concentrations.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".