Seminars
Neutron Cross Sections: Linking the Lab to the Cosmos
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Europe/Vienna
Besprechungsraum (PSK 3.OG)
Besprechungsraum
PSK 3.OG
Description
"In the early days of the Manhattan Project when an unknown cross section was required, the procedure for obtaining a value was straightforward. One would approach Fermi and request a guess. Invariably he would decline to hazard a guess. The next step, as the story goes, was to recite a lengthy sequence of numbers and if one produced a gleam in Fermi’s eye that was the value to use."
H. Goldstein (talk at Atomenergie, Sweden, September 1953)
In a post-Fermi era, we prefer and endeavour to measure neutron-induced cross-section data. Neutron cross-sections are directly requested in many subfields of physics and applications ranging from nuclear astrophysics to nuclear technology and medicine.
CERN’s neutron time-of-flight (n_TOF) facility is dedicated to high-precision measurements of neutron reaction cross-sections across a neutron spectrum from meV to GeV. Since 25 years the facility has produced unique high-quality neutron data-sets for nuclear astrophysics, nuclear technologies and medicine as well as fundamental research. Two particular physics cases were studied directly related to cosmology: the Re-Os nuclear clock and the lithium problem. Two other examples related to galactic nucleosynthesis, galactic evolution and our understanding of star formation are the direct and for the first time 26Al and 41Ca (n,a) reaction cross-section measurements.
Beyond that, when designing experiments and analysing their data, neutrons can be a major background component in rare event searches detector activation and radiation damage. Two ongoing projects aim to improve neutron data on Argon for the DUNE collaboration or on Oxygen for Hyper-Kamiokande which will enhance the accuracy of their Monte-Carlo simulations.
Despite almost 100 years since the discovery of the neutron 1932, improvements in technologies and modelling tools, drive the request for new and more precise measurements of neutron cross-sections, ultimately assisting the improvement of our understanding of physics in different ways.