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25 pages, 1962 KiB

Open AccessArticle

Searching for Dark Matter Axions via Atomic Excitations

by J. D. Vergados, S. Cohen, F. T. Avignone and R. Creswick

Particles 2024, 7(1), 96-120; https://doi.org/10.3390/particles7010006 - 27 Jan 2024

Cited by 1 | Viewed by 1969

Axions can be considered as good dark matter candidates. The detection of such light particles can be achieved by observing axion-induced atomic excitations. The target is in a magnetic field so that the m-degeneracy is removed, and the energy levels can be suitably adjusted. Using an axion-electron coupling indicated by the limit obtained by the Borexino experiment, which is quite stringent, reasonable axion absorption rates have been obtained for various atomic targets The obtained results depend, of course, on the atom considered through the parameters

ϵ

(the spin−orbit splitting) as well as

δ

( the energy splitting due to the magnetic moment interaction). This assumption allows axion masses in the tens of

μ

eV if the transition occurs between members of the same multiplet, i.e.,

| J_{1}, M_{1} = - J_{1} ⟩ \to | J_{1}, M_{1} = - J + 1 ⟩, J_{1} \neq 0

, and axion masses in the range 1 meV–1 eV for transitions of the spin−orbit splitting type

| J_{1}, M = - J_{1} ⟩ \to | J_{2}, M_{2} = - J_{1} + q ⟩, q = - 1, 0, 1

, i.e., three types of transition. The axion mass that can be detected is very close to the excitation energy involved, which can vary by adjusting the magnetic field. Furthermore, since the axion is absorbed by the atom, the calculated cross-section exhibits the behavior of a resonance, which can be exploited by experiments to minimize any background events. Full article

(This article belongs to the Special Issue Feature Papers for Particles 2023)

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10 pages, 453 KiB

Open AccessArticle

How Long Does the Hydrogen Atom Live?

by David McKeen and Maxim Pospelov

Universe 2023, 9(11), 473; https://doi.org/10.3390/universe9110473 - 4 Nov 2023

Cited by 4 | Viewed by 2207

Abstract

It is possible that the proton is stable while atomic hydrogen is not. This is the case in models with new particles carrying baryon number which are light enough to be stable themselves, but heavy enough so that proton decay is kinematically blocked. Models of new physics that explain the neutron lifetime anomaly generically have this feature, allowing for atomic hydrogen to decay through electron capture on a proton. We calculate the radiative hydrogen decay rate involving the emission of a few hundred keV photon, which makes this process experimentally detectable. In particular, we show that the low energy part of the Borexino spectrum is sensitive to radiative hydrogen decay, and turn this into a limit on the hydrogen lifetime of order

10^{30} s

or stronger. For models where the neutron mixes with a dark baryon,

χ

, this limits the mixing angle to roughly

10^{- 11}

, restricting the

n \to χ γ

branching to

10^{- 4}

, over a wide range of parameter space. Full article

(This article belongs to the Special Issue Neutron Lifetime)

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58 pages, 10202 KiB

Open AccessReview

Borexino Results on Neutrinos from the Sun and Earth

by Sindhujha Kumaran, Livia Ludhova, Ömer Penek and Giulio Settanta

Universe 2021, 7(7), 231; https://doi.org/10.3390/universe7070231 - 6 Jul 2021

Cited by 17 | Viewed by 4863

Abstract

Borexino is a 280-ton liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso in Italy. Since the start of its data-taking in May 2007, it has provided several measurements of low-energy neutrinos from various sources. At the base of its success lie unprecedented levels of radio-purity and extensive thermal stabilization, both resulting from a years-long effort of the collaboration. Solar neutrinos, emitted in the Hydrogen-to-Helium fusion in the solar core, are important for the understanding of our star, as well as neutrino properties. Borexino is the only experiment that has performed a complete spectroscopy of the pp chain solar neutrinos (with the exception of the hep neutrinos contributing to the total flux at

10^{- 5}

level), through the detection of pp,

^{7}

Be, pep, and

^{8}

B solar neutrinos and has experimentally confirmed the existence of the CNO fusion cycle in the Sun. Borexino has also detected geoneutrinos, antineutrinos from the decays of long-lived radioactive elements inside the Earth, that can be exploited as a new and unique tool to study our planet. This paper reviews the most recent Borexino results on solar and geoneutrinos, from highlighting the key elements of the analyses up to the discussion and interpretation of the results for neutrino, solar, and geophysics. Full article

(This article belongs to the Special Issue Italian Research Facilities for Fundamental Physics)

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12 pages, 877 KiB

Open AccessArticle

Sensitivity of a Liquid Xenon Detector to Neutrino–Nucleus Coherent Scattering and Neutrino Magnetic Moment from Reactor Neutrinos

by Kaixuan Ni, Jianyang Qi, Evan Shockley and Yuehuan Wei

Universe 2021, 7(3), 54; https://doi.org/10.3390/universe7030054 - 3 Mar 2021

Cited by 11 | Viewed by 3132

Abstract

Liquid xenon is one of the leading targets to search for dark matter via its elastic scattering on nuclei or electrons. Due to their low-threshold and low-background capabilities, liquid xenon detectors can also detect coherent elastic neutrino–nucleus scattering (CE

ν

NS) or neutrino–electron [...] Read more.

ν

NS) or neutrino–electron scattering. In this paper, we investigate the feasibility of a compact and movable liquid xenon detector with an active target mass of O(10∼100) kg and single-electron sensitivity to detect CE

ν

NS from anti-neutrinos from a nuclear reactor. Assuming a single- and few-electron background rate at the level achieved by the XENON10/100 experiments, we expect a 5-

σ

detection of CE

ν

NS with less than 400 kg-days of exposure. We further investigate the sensitivity of such a detector to neutrino magnetic moment with neutrino electron scattering. If an electronic recoil background rate of 0.01∼0.1 events/keV/kg/day above 1 keV can be achieved with adequate shielding, a liquid xenon detector can reach a neutrino magnetic moment sensitivity of

10^{- 11} μ_{B}

, which would improve upon the current most-constraining laboratory limits from the GEMMA and Borexino experiments. Additionally, such a detector would be able to probe the region compatible with a magnetic moment interpretation of the low-energy excess electronic recoil events recently reported by XENON1T. Full article

(This article belongs to the Special Issue Nuclear Issues for Neutrino Physics)

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14 pages, 1045 KiB

Open AccessArticle

Solar Neutrinos Spectroscopy with Borexino Phase-II

by Lino Miramonti, Matteo Agostini, Konrad Altenmueller, Simon Appel, Victor Atroshchenko, Zara Bagdasarian, Davide Basilico, Gianpaolo Bellini, Jay Benziger, Daniel Bick, Irene Bolognino, Giuseppe Bonfini, David Bravo, Barbara Caccianiga, Frank Calaprice, Alessio Caminata, Silvia Caprioli, Marco Carlini, Paolo Cavalcante, Francesca Cavanna, Alexander Chepurnov, Koun Choi, Laura Collica, Stefano Davini, Alexander Derbin, XueFeng Ding, Antonio Di Ludovico, Lea Di Noto, Ilia Drachnev, Kirill Fomenko, Andrey Formozov, Davide Franco, Federico Gabriele, Cristiano Galbiati, Michael Gschwender, Chiara Ghiano, Marco Giammarchi, Augusto Goretti, Maxim Gromov, Daniele Guffanti, Caren Hagner, Thibaut Houdy, Ed Hungerford, Aldo Ianni, Andrea Ianni, Anna Jany, Dominik Jeschke, Vladislav Kobychev, Denis Korablev, Gyorgy Korga, Tobias Lachenmaier, Matthias Laubenstein, Evgeny Litvinovich, Francesco Lombardi, Paolo Lombardi, Livia Ludhova, Georgy Lukyanchenko, Liudmila Lukyanchenko, Igor Machulin, Giulio Manuzio, Simone Marcocci, Jelena Maricic, Johann Martyn, Emanuela Meroni, Mikko Meyer, Marcin Misiaszek, Valentina Muratova, Birgit Neumair, Lothar Oberauer, Bjoern Opitz, Vsevolod Orekhov, Fausto Ortica, Marco Pallavicini, Laszlo Papp, Omer Penek, Lidio Pietrofaccia, Nelly Pilipenko, Andrea Pocar, Alessio Porcelli, Georgy Raikov, Gioacchino Ranucci, Alessandro Razeto, Alessandra Re, Mariia Redchuk, Aldo Romani, Nicola Rossi, Sebastian Rottenanger, Stefan Schöenert, Dmitrii Semenov, Mikhail Skorokhvatov, Oleg Smirnov, Albert Sotnikov, Lee F. F. Stokes, Yura Suvorov, Roberto Tartaglia, Gemma Testera, Jan Thurn, Maria Toropova, Evgenii Unzhakov, Alina Vishneva, Bruce Vogelaar, Franz Von Feilitzsch, Stefan Weinz, Marcin Wojcik, Michael Wurm, Zachary Yokley, Oleg Zaimidoroga, Sandra Zavatarelli, Kai Zuber and Grzegorz Zuzel Show full author list Hide full author list

Universe 2018, 4(11), 118; https://doi.org/10.3390/universe4110118 - 7 Nov 2018

Cited by 2 | Viewed by 4983

Abstract

Solar neutrinos have played a central role in the discovery of the neutrino oscillation mechanism. They still are proving to be a unique tool to help investigate the fusion reactions that power stars and further probe basic neutrino properties. The Borexino neutrino observatory has been operationally acquiring data at Laboratori Nazionali del Gran Sasso in Italy since 2007. Its main goal is the real-time study of low energy neutrinos (solar or originated elsewhere, such as geo-neutrinos). The latest analysis of experimental data, taken during the so-called Borexino Phase-II (2011-present), will be showcased in this talk—yielding new high-precision, simultaneous wide band flux measurements of the four main solar neutrino components belonging to the “pp” fusion chain (pp, pep,

^{7}

Be,

^{8}

B), as well as upper limits on the remaining two solar neutrino fluxes (CNO and hep). Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference on New Frontiers in Physics (ICNFP 2018))

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