Projektbeschreibung
Hochpräzise Messungen der Protonen- und Neutronenenergie bei der stellaren Nukleosynthese
Das EU-finanzierte Projekt SHADES möchte neue Messdaten zu einer Reaktion bereitstellen, die von entscheidender Bedeutung für die Synthese schwerer Elemente im Universum ist: Ne-22(alpha,n)Mg-25. Hochpräzise Messungen dieser Reaktion sind seit Jahren Ziel der in der nuklearen Astrophysik tätigen Wissenschaftlerinnen und Wissenschaftler. Sehr geringe Reaktionsgeschwindigkeiten bei niedriger Energie haben in den letzten 20 Jahren jedoch jeglichen Fortschritt bei direkten Messungen verhindert. Durch die Entwicklung eines spezialisierten Neutronendetektors möchte das Projektteam diese wichtige stellare Reaktion direkt im Energiebereich des glühenden Sterns, dem sogenannten Gamow-Fenster, messen. Der SHADES-Datensatz wird ein besseres und solideres Bild von der Menge der produzierten schweren Elemente in der stellaren Nukleosynthese vermitteln.
Ziel
A crucial source of neutrons in stars is the nuclear reaction Ne-22(alpha,n)Mg-25, of major importance for the synthesis of heavy elements. Currently there is an established picture of the astrophysical scenario but only limited availability of reliable experimental data, with several key ingredients under dispute. SHADES will perform a direct measurement of the reaction to resolve the main open questions. The goal is to decrease the uncertainty in the astrophysical reaction rate in the relevant temperature range by at least one order of magnitude, providing a significant leap ahead from the state of the art. SHADES will deliver an increase in sensitivity of more than two orders of magnitude over the state of the art. We will gather direct experimental data over the entire astrophysically relevant energy range. We will construct a neutron detector specifically designed for this measurement. Beam-induced background, a severe problem in the past, will be discriminated by measuring the neutron energy while still maintaining a very detection high efficiency. In recent years research on capture-gated techniques and combinations of different detector types to measure neutron energies has increased greatly. The novel detector array will perfectly fit this profile and find a large field of applications also outside of nuclear astrophysics. The main measurements will be done with the new accelerator LUNA MV, allowing long-term high-intensity, high-energy resolution alpha bombardments. An extended, recirculating gas target will guarantee target stability under intense ion beams. The location of the experiment deep underground will drastically reduce the external background, the main limiting factor so far for low-energy measurements. In my team there will be also leading experts in the field to update the current stellar models using the new dataset to provide a greatly improved and much more robust picture of this important branch of stellar nucleosynthesis.
Wissenschaftliches Gebiet
Schlüsselbegriffe
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Finanzierungsplan
ERC-STG - Starting GrantGastgebende Einrichtung
80138 Napoli
Italien