ELFT HÍRADÓ

[László Bottyán <bottyan.laszlo AT wigner.hu>]

Tisztelt Kollégák,

Emlékeztetőül újraküldöm a meghívót a

Budapesti Neutronközpont on-line, magyar nyelvű

     "Karenténbeszámoló"  előadássorozatának következő eseményére:

Szentmiklósi László:
    "Kiterjedt és strukturált minták prompt-gamma aktivációs analízise"

 Időpont: 2021. január 13. 14:00
 Kapcsolódási link (ami 13:30-tól él):

https://us02web.zoom.us/j/89357230887?pwd=a1dkSnNVVEhtTzJlSWdkRy96OGhNQT09

vagy

Zoom meeting ID: 893 5723 0887              Password: 565497

A kivonat és az előadás diái angol nyelven készültek.

Bottyán László
szemináriumfelelős


Kivonat:

L. Szentmiklósi, B. Maróti, Z. Kis, J. Janik, L. Z. Horváth

Prompt-gamma activation analysis of bulky and structured samples

Prompt-gamma activation analysis (PGAA) is originally intended to measure
the elemental composition of small, homogeneous, and regular-shaped
samples. In the analytical practice, however, these criteria would often
limit the applicability of the technique.

Representative bulk composition measurement of valuable, homogeneous, but
bulky objects with irregular geometrical shapes (whole-rock geological
samples, meteorites, ancient stone tools, cast bronze artifacts,
industrial items) is a typical task at the Budapest PGAA facility. Here,
any sampling, powdering is in obvious conflict with the requirement of
non-destructivity. So far, approximations had to be made when correcting
the negative matrix effect, i.e. the neutron self-shielding and gamma
self-absorption.

To make the PGAA technique more competitive and fully utilize its most
attractive feature, the non-destructivity, even for objects with arbitrary
shapes, sizes, and matrices, accurate corrections shall be determined for
each studied object. The case-by-case geometry has to be defined based on
data from 3D structured-light optical scanning or segmentation of
neutron/X-ray tomography data. The latter is still applicable when
non-homogeneous or heterogeneous samples are to be investigated. These
detailed object geometries are, on the one hand, useful in creating
plastic replicas of the object for measurement setup, and to produce
gentle custom sample holders. On the other hand, they can be loaded into
Monte Carlo simulation frameworks, such as MCNP 6.2, where the instrument
components (detector, shielding, sample chamber) and the properties of the
neutron beam are already carefully implemented. With these sophisticated
simulations, we attempt to reproduce the complex interactions of neutrons
and gamma-rays with the sample matter.

Another relevant class of samples is non-homogeneous. For local
composition analysis of structured samples, this calculation is also
applicable. A set of benchmark objects were created from two or three
layers of metals, as well as 3×3×3 unit cubes of typical materials, such
as Cu, Fe, PTFE, graphite, Pb, Sn, limestone. They were measured in
various geometrical arrangements to generate position-sensitive PGAA and
imaging data for validating the calculations. As many of these materials
emit gamma-rays at several energies, the effect of gamma-ray
self-absorption can also be observed on the identical unit cubes.

Acknowledgments
This work was part of Project no. 124068 and received support from the
National Research, Development and Innovation Fund of Hungary, financed
under the K_17 funding scheme. L.Sz. thanks for the János Bolyai Research
Fellowship of the Hungarian Academy of Sciences

E-mail: szentmiklosi.laszlo AT ek-cer.hu, szentm AT bnc.hu