International Initiative on Fundamental Parameters

To continue the long-lasting International Initiative on Fundamental Parameters (https://www.exsa.hu/fpi.php), LNHB and PTB are happy to arrange for another online workshop with the following agenda topics in late spring:

  • Presentations of recent FP determinations,
  • Proposal of potential joint activities (e.g. update of databases, organisation of joint experiments, etc.),
  • Discussion and prioritisation of such activities and follow-up events.

An international initiative on establishing accurate critical data for interactions of X-rays with matter

Accurate critical data related to the interactions of X-rays with matter, called atomic Fundamental Parameters (FP), are of paramount importance in many branches of physics and technology, such as fundamental and plasma physics, characterization of nano- and energy materials, microelectronics, astrophysics, biological studies, biomedical, environmental sciences, cultural heritage, and law enforcement.

In order to meet current and upcoming demands, the International Initiative on X-ray Fundamental Parameters (IIFP) was created in 2008 as an expression of common interest in the improvement of X-ray fundamental parameters in a joint effort of several national metrology and designated institutes (LNE/Laboratoire National Henri Becquerel, France; National Institute of Standards and Technology, USA; National Institute for Materials Science, Japan and Physikalisch-Technische Bundesanstalt, Germany), academic laboratories (University of Fribourg, Switzerland; NOVA University Lisbon, Portugal; Technical University of Vienna, Austria and University of Surrey, UK), and industrial companies.

Under the auspices of the European X-ray Spectrometry Association (EXSA), the IIFP holds annual or bi-annual workshops, where expert groups meet to present recent results and identify new needs (see https://www.exsa.hu/fpi.php for its chronology). The last meeting, hosted by the Laboratoire National Henri Becquerel, was held on Friday 27 October 2023 during the QUANT2023 school.

The IIFP works follow the guidelines described in the roadmap document available at IIFP_Roadmap_V2.pdf that was established during specific workshops and is regularly updated.

The main motivation of the IIFP is to overcome the uneven quality and incompleteness of current X-ray fundamental parameters, which constitute a serious limitation for further progress of X-ray technologies. This stimulates discussions between the expert groups and initiates new experimental measurements and new calculations of FPs with reduced relative uncertainties, taking advantage of modern technologies. In a joint effort between metrology, academic and industry partners, the IIFP is more specifically working on:

  1. Experimental measurements based on new facilities such as synchrotron radiation and high-resolution detectors with reduced and traceable uncertainties; comparison between different experimental approaches for validating the derived FPs;
  2. Theoretical calculations using the most recent theoretical approaches; the Multi-Configuration Dirac-Fock (MCDF) enables the determination of many of the significant atomic parameters due to the possibility of including a large amount of electronic correlation and radiative corrections. The comparison of experimental and theoretical results on selected elements assesses the validity of calculation that should be used when experimental approaches are difficult or impossible;
  3. Preparation of a standardized FP database established through a co-work of national metrology and designated institutes providing user access to reliable data.

Through the IIFP, a number of collaborative experiments and calculations have been performed and recent traceable FPs have been determined and published. It is expected that these results of the initiative will benefit a large community of users.

More information: https://www.exsa.hu/fpi.php