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14 pages, 496 KiB

Open AccessArticle

Origin of Plutonium-244 in the Early Solar System

by Maria Lugaro, Andrés Yagüe López, Benjámin Soós, Benoit Côté, Mária Pető, Nicole Vassh, Benjamin Wehmeyer and Marco Pignatari

Universe 2022, 8(7), 343; https://0-doi-org.brum.beds.ac.uk/10.3390/universe8070343 - 22 Jun 2022

Cited by 1 | Viewed by 1440

Abstract

We investigate the origin in the early Solar System of the short-lived radionuclide

^{244}

Pu (with a half life of 80 Myr) produced by the

r a p i d

(r) neutron-capture process. We consider two large sets of r-process [...] Read more.

We investigate the origin in the early Solar System of the short-lived radionuclide

^{244}

Pu (with a half life of 80 Myr) produced by the

r a p i d

(r) neutron-capture process. We consider two large sets of r-process nucleosynthesis models and analyse if the origin of

^{244}

Pu in the ESS is consistent with that of the other r and

s l o w

(s) neutron-capture process radioactive nuclei. Uncertainties on the r-process models come from both the nuclear physics input and the astrophysical site. The former strongly affects the ratios of isotopes of close mass (

^{129}

I/

^{127}

I,

^{244}

Pu/

^{238}

U, and

^{247}

Pu/

^{235}

U). The

^{129}

I/

^{247}

Cm ratio, instead, which involves isotopes of a very different mass, is much more variable than those listed above and is more affected by the physics of the astrophysical site. We consider possible scenarios for the evolution of the abundances of these radioactive nuclei in the galactic interstellar medium and verify under which scenarios and conditions solutions can be found for the origin of

^{244}

Pu that are consistent with the origin of the other isotopes. Solutions are generally found for all the possible different regimes controlled by the interval (

δ

) between additions from the source to the parcel of interstellar medium gas that ended up in the Solar System, relative to decay timescales. If r-process ejecta in interstellar medium are mixed within a relatively small area (leading to a long

δ

), we derive that the last event that explains the

^{129}

I and

^{247}

Cm abundances in the early Solar System can also account for the abundance of

^{244}

Pu. Due to its longer half life, however,

^{244}

Pu may have originated from a few events instead of one only. If r-process ejecta in interstellar medium are mixed within a relatively large area (leading to a short

δ

), we derive that the time elapsed from the formation of the molecular cloud to the formation of the Sun was 9-16 Myr. Full article

(This article belongs to the Special Issue Nuclear Astrophysics in the Era of High Precision Astronomy)

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15 pages, 3659 KiB

Open AccessArticle

NEAR: A New Station to Study Neutron-Induced Reactions of Astrophysical Interest at CERN-n_TOF

by Gianpiero Gervino, Oliver Aberle, Ana-Paula Bernardes, Nicola Colonna, Sergio Cristallo, Maria Diakaki, Salvatore Fiore, Alice Manna, Cristian Massimi, Pierfrancesco Mastinu, Alberto Mengoni, Riccardo Mucciola, Elizabeth Musacchio González, Nikolas Patronis, Elisso Stamati, Pedro Vaz and Rosa Vlastou

Universe 2022, 8(5), 255; https://0-doi-org.brum.beds.ac.uk/10.3390/universe8050255 - 20 Apr 2022

Cited by 8 | Viewed by 2252

Abstract

We present NEAR, a new experimental area at the CERN-n_TOF facility and a possible setup for cross section measurements of interest to nuclear astrophysics. This was recently realized with the aim of performing spectral-averaged neutron-capture cross section measurements by means of the activation [...] Read more.

We present NEAR, a new experimental area at the CERN-n_TOF facility and a possible setup for cross section measurements of interest to nuclear astrophysics. This was recently realized with the aim of performing spectral-averaged neutron-capture cross section measurements by means of the activation technique. The recently commissioned NEAR station at n_TOF is now ready for the physics program, which includes a preliminary benchmark of the proposed idea. Based on the results obtained by dedicated Monte Carlo simulations and calculation, a suitable filtering of the neutron beam is expected to enable measurements of Maxwellian Averaged Cross Section (MACS) at different temperatures. To validate the feasibility of these studies we plan to start the measurement campaign by irradiating several isotopes whose MACS at different temperatures have recently been or are planned to be determined with high accuracy at n_TOF, as a function of energy in the two time-of-flight measurement stations. For instance, the physical cases of ⁸⁸Sr(n,

γ

), ⁸⁹Y(n,

γ

), ⁹⁴Zr(n,

γ

) and ⁶⁴Ni(n,

γ

) are discussed. As the neutron capture on ⁸⁹Y produces a pure

β

-decay emitter, we plan to test the possibility to perform activation measurements on such class of isotopes as well. The expected results of these measurements would open the way to challenging measurements of MACS by the activation technique at n_TOF, for rare and/or exotic isotopes of interest for nuclear astrophysics. Full article

(This article belongs to the Special Issue Nuclear Astrophysics in the Era of High Precision Astronomy)

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Review

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10 pages, 445 KiB

Open AccessReview

Challenges and Requirements in High-Precision Nuclear Astrophysics Experiments

by György Gyürky

Universe 2022, 8(4), 216; https://0-doi-org.brum.beds.ac.uk/10.3390/universe8040216 - 28 Mar 2022

Viewed by 1484

Abstract

In the 21th century astronomical observations, as well as astrophysical models, have become impressively precise. For a better understanding of the processes in stellar interiors, the nuclear physics of astrophysical relevance—known as nuclear astrophysics—must aim for similar precision, as such precision is not [...] Read more.

In the 21th century astronomical observations, as well as astrophysical models, have become impressively precise. For a better understanding of the processes in stellar interiors, the nuclear physics of astrophysical relevance—known as nuclear astrophysics—must aim for similar precision, as such precision is not reached yet in many cases. This concerns both nuclear theory and experiment. In this paper, nuclear astrophysics experiments are put in focus. Through the example of various parameters playing a role in nuclear reaction studies, the difficulties of reaching high precision and the possible solutions are discussed. Full article

(This article belongs to the Special Issue Nuclear Astrophysics in the Era of High Precision Astronomy)

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