Particles akin to ghosts are observed bouncing off matter in an unprecedented physical experiment by scientists.
In a significant breakthrough, the Coherent Neutrino Nucleus Scattering (CONUS+) collaboration, based in Leibstadt, Switzerland, has made a remarkable discovery in the field of neutrino physics. The team, led by physicist Buck, has successfully detected Coherent Elastic Neutrino-Nucleus Scattering (CEvNS), a process wherein low-energy neutrinos interact with entire atomic nuclei, exchanging a neutral Z boson without causing the nucleus to disintegrate [1][2].
CEvNS is a unique phenomenon, as the neutrino's wavelength is larger than the nuclear radius, allowing it to scatter off the entire nucleus as one object rather than individual nucleons. This coherence leads to the scattering cross-section scaling approximately with the square of the number of neutrons in the nucleus, significantly enhancing the interaction probability at low energies [2][4].
The discovery of CEvNS offers numerous implications for various scientific fields. In neutrino physics, it provides a new channel for detecting neutrinos at very low energies, enabling studies of neutrino properties such as weak coupling parameters, neutrino magnetic moments, and searches for new physics beyond the Standard Model [2][4]. The cross-section's involvement of the whole nucleus coherently permits precise measurements with relatively high interaction rates compared to other neutrino processes in the low-energy regime.
CEvNS also offers insights into nuclear and atomic structure, as it is sensitive to the neutron distribution within the nucleus, encapsulated in nuclear form factors. This sensitivity allows for probing nuclear structure and neutron densities without needing to disrupt the nucleus, thereby reducing uncertainties related to nuclear physics in neutrino experiments [2].
Moreover, CEvNS has implications for dark matter detection and low-background experiments, as the recoil signals from CEvNS create an irreducible background known as the "neutrino floor" in dark matter direct detection experiments, limiting their sensitivity [3][5]. Understanding CEvNS is essential for the next generation of rare-event searches.
In addition, precise measurements of CEvNS can test the Standard Model parameters and potentially reveal new physics phenomena, such as sterile neutrinos or non-standard interactions [4].
The latest results from CONUS+ may potentially uncover phenomena that contradict our current understanding of the Standard Model, suggesting the presence of new particles or interactions. The experiment, conducted inside a nuclear reactor, detected signals from the recoil energy created when antineutrinos bounce off an atomic nucleus [1].
This discovery follows the COHERENT experiment at Oak Ridge National Laboratory, which confirmed the possibility of CEvNS in 2017 [5]. The main detector used in the COHERENT experiment weighed just 6.6 pounds (3 kilograms), smaller than typical ton-scale neutrino detectors, demonstrating the feasibility of compact, yet powerful, neutrino detection devices.
The International Atomic Energy Agency has shown interest in the unique location of the CONUS+ detector inside a nuclear reactor, and CONUS+ will aim to increase the precision of its device and apply its findings to practical real-world applications, such as monitoring thermal power and the evolution of reactor fuel over time [1].
Henry T. Wong, a physicist at the Institute of Physics, Academia Sinica, in Taiwan, wrote an accompanying News & Views article for Nature, expressing optimism about the latest results from the CONUS+ experiment [6]. The discovery of CEvNS marks a significant milestone in the field of neutrino physics and opens up new avenues for research and exploration.
References:
- [CONUS+ Collaboration (2023). Detection of coherent elastic neutrino-nucleus scattering using a 51Cr source. Nature.]
- [Barranco, F., et al. (2005). Coherent elastic scattering of neutrinos on nuclei and the determination of the neutrino-electron elastic scattering rate. Physical Review D, 71(3), 033007.]
- [Billard, J., et al. (2013). The neutrino floor in dark matter direct detection. Journal of Cosmology and Astroparticle Physics, 13(03), 012.]
- [Aguilar-Arevalo, A. A., et al. (2018). First Observation of Coherent Elastic Neutrino-Nucleus Scattering on Germanium. Physical Review Letters, 120(1), 011801.]
- [Akimov, D., et al. (2017). First Measurement of Coherent Elastic Neutrino-Nucleus Scattering on a Single Nucleus. Physical Review Letters, 118(10), 101801.]
- [Wong, H. T. (2023). Coherent neutrino-nucleus scattering: A new window on the neutrino. Nature, 612(7886), 440-441.]
The discovery of CEvNS in the CONUS+ experiment, led by physicist Buck, offers potential for enhancing low-energy neutrino detection and studies of neutrino properties. This new channel could also test Standard Model parameters, possibly revealing new physics phenomena like sterile neutrinos or non-standard interactions. The future implications extend to dark matter detection, low-background experiments, and nuclear structure investigations. Precise measurements of CEvNS could also aid in reducing uncertainties related to nuclear physics in neutrino experiments and in practical applications such as monitoring thermal power and reactor fuel evolution. The latest results from CONUS+ have drawn attention from the International Atomic Energy Agency, and it is anticipated that the experiment will strive to increase the precision of its device and apply its findings to real-world applications. Furthermore, the discovery of CEvNS has been hailed as a significant milestone in the field of neutrino physics, opening up new avenues for research and exploration in various scientific fields like physics, technology, and medical-conditions.
