Luna

Sito Luna 1

 

Abstract

The LUNA experiment (Laboratory for Underground Nuclear Astrophysics) at the Gran Sasso National Laboratories (LNGS) recreates the nuclear processes that occurred during primordial nucleosynthesis and continue today within stars throughout their evolution.
The direct measurements of these extremely rare processes are highly challenging in surface-level laboratories due to cosmic rays constantly bombarding the Earth, which can completely obscure the weak signal expected. Thanks to the 1400 meters of rock from Mount Aquila, which shields the experimental halls from the cosmic rays, the LNGS provides an ideal environment for studying these processes.
In the "cosmic silence" of the LNGS, the LUNA collaboration has explored many key reactions for the hydrogen and helium burning, as well as primordial nucleosynthesis, by using stable particle beams onto solid and gaseous targets.

 luna1 2024

Experimental setup used with the LUNA 50 kV accelerator (left). Radio frequency ion source of the LUNA 400 kV accelerator (right). The pink light emitted by the hydrogen plasma is visible.


Description

The LUNA experiment began its research activities in the early 1990s with the installation of a 50 kV accelerator at the LNGS laboratories. The LUNA 50 kV, used until 2003, was the first underground accelerator specifically designed for nuclear astrophysics measurements. In 2000, a new 400 kV accelerator, LUNA 400 kV, of the Cockcroft-Walton type and single-stage design, was installed. The LUNA 400 kV accelerator provides intense hydrogen and helium beams with excellent temporal stability and high energy resolution. The LUNA 400 kV accelerator is still in operation, and the produced beam can be delivered in two different beamlines, each equipped with a solid or gas target station.
The use of passive shielding (e.g., lead, copper, and polyethylene) around the detectors, combined with a significant reduction in cosmic ray background radiation, by about six orders of magnitude compared to surface laboratories, has made LUNA the leading experiment in the world for the direct measurement of cross sections of astrophysical interest.
The first reaction, measured directly at energies relevant to the Sun was the 3He(3He,2p)4He. This measurement excluded the presence of resonances at solar energies, resolving the solar neutrino "puzzle" observed in the Homestake experiment by Nobel laureate R. Davis.
The direct cross section measurement of the reaction 14N(p,γ)15O, which still plays a crucial role in the solar model, reduced the expected neutrino flux produced during the CNO cycle in the Sun by a factor of 2 and provided an updated estimation of the age of the Milky Way.
A long experimental campaign has been dedicated to the study of the 3He(4He,γ)7Be reaction. This reaction plays a decisive role in the Sun by controlling the flux of the 7Be and 8Be neutrinos, as well as in Big Bang Nucleosynthesis through the production of 7Li. Thanks to the results obtained from the LUNA experiment, combined with other measurements at higher energies, the uncertainty in the standard solar model predictions for neutrino fluxes has been reduced by a factor of 2.
Recently, the high-precision measurement of the D(p,γ)3He cross-section, published in Nature (2020), provided an independent estimation of baryonic density during Big Bang nucleosynthesis, which is in excellent agreement with recent analyses of cosmic microwave background (CMB) radiation.
The LUNA collaboration remains highly ambitious in addressing the open questions within the nuclear astrophysics community. The scientific program of the LUNA experiment continues with measurements at the LUNA 400 kV accelerator and is currently expanding including astrophysically relevant processes at high energies, thanks to the new 3.5 MV accelerator at the Bellotti Ion Beam Facility (IBF), which was inaugurated in October 2023.
The complete list of reactions studied and currently under investigation by the LUNA collaboration is available on the official LUNA website. 

Sito Luna 2

Overview of the IBF facility and the solid-target experimental setup developed by the LUNA collaboration for ongoing measurements.


Spokesperson
This email address is being protected from spambots. You need JavaScript enabled to view it. (INFN Roma)

 

Collaboration

INFN LNGS /*GSSI, Italy
T. Chillery, A. Compagnucci*, F. Ferraro, R. M. Gesuè*, M. Junker
HZDR Dresden, Germany
D. Bemmerer, A. Boeltzig, E. Masha
INAF Teramo, Italy
O. Straniero
INFN Laboratori Nazionali di Legnaro, Italy
M. Campostrini, V. Rigato
INFN Lecce, Italy

R. Perrino
INFN Roma 1, Italy
A. Formicola, C. Gustavino, M. Vagnoni
Konkoly Observatory, Hungarian Academy of Sciences, Hungary
M. Lugaro
MTA-ATOMKI Debrecen, Hungary
L. Csedreki, Z. Elekes, Z. Fülöp, G. Gyürky, T. Szücs
University of Bari and INFN Bari, Italy

G.F. Ciani, V. Paticchio, L. Schiavulli
University of Genova and INFN Genova, Italy
P. Corvisiero, P. Prati, M. Rossi, S. Zavatarelli
University of Milano and INFN Milano, Italy
R. Depalo, G. Gosta, A. Guglielmetti
University of Napoli and INFN Napoli, Italy
A. Best, D. Dell’Aquila, A. Di Leva, G. Imbriani, D. Mercogliano, D. Rapagnani
University of Padova and INFN Padova, Italy
R. Biasissi, C. Broggini, A. Caciolli, P. Marigo, R. Menegazzo, D. Piatti, J. Skowronski, S. Turkat
University of Torino and INFN Torino, Italy
F. Cavanna, P. Colombetti, G. Gervino, S. Sariyal
University of Edinburgh, United Kingdom
M. Aliotta, L. Barbieri, C.G. Bruno, T. Davinson, J. Jones, J. Marsh, D. Robb, R. Sidhu

 

Official website