Kurzfassung: The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive background U and Th in the liquid scintillator can be controlled to 10 g/g. With ten years of data acquisition, approximately 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If eV , JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3 (2 ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure using B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of reported by solar neutrino experiments and the KamLAND experiment.

Kurzfassung: We present the detection potential for the diffuse supernova neutrino background (DSNB) at the Jiangmen Underground Neutrino Observatory (JUNO), using the inverse-beta-decay (IBD) detection channel on free protons. We employ the latest information on the DSNB flux predictions, and investigate in detail the background and its reduction for the DSNB search at JUNO. The atmospheric neutrino induced neutral current (NC) background turns out to be the most critical background, whose uncertainty is carefully evaluated from both the spread of model predictions and an envisaged in situ measurement. We also make a careful study on the background suppression with the pulse shape discrimination (PSD) and triple coincidence (TC) cuts. With latest DSNB signal predictions, more realistic background evaluation and PSD efficiency optimization, and additional TC cut, JUNO can reach the significance of 3σ for 3 years of data taking, and achieve better than 5σ after 10 years for a reference DSNB model. In the pessimistic scenario of non-observation, JUNO would strongly improve the limits and exclude a significant region of the model parameter space.

Kurzfassung: JUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the , , , and oscillation parameters using reactor antineutrinos, which is one of the primary physics goals of the experiment. The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site, the nuclear reactors in the surrounding area and beyond, the detector response uncertainties, and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector. It is found that the and oscillation parameters will be determined to 0.5% precision or better in six years of data collection. In the same period, the parameter will be determined to about % precision for each mass ordering hypothesis. The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.

Kurzfassung: We discuss JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo via detecting inverse beta decay reactions of electron anti-neutrinos resulting from the annihilation. We study possible backgrounds to the signature, including the reactor neutrinos, diffuse supernova neutrino background, charged- and neutral-current interactions of atmospheric neutrinos, backgrounds from muon-induced fast neutrons and cosmogenic isotopes. A fiducial volume cut, as well as the pulse shape discrimination and the muon veto are applied to suppress the above backgrounds. It is shown that JUNO sensitivity to the thermally averaged dark matter annihilation rate in 10 years of exposure would be significantly better than the present-day best limit set by Super-Kamiokande and would be comparable to that expected by Hyper-Kamiokande.

Kurzfassung: The Jiangmen Underground Neutrino Observatory (JUNO), the first multi-kton liquid scintillator detector, which is under construction in China, will have a unique potential to perform a real-time measurement of solar neutrinos well below the few MeV threshold typical of Water Cherenkov detectors. JUNO's large target mass and excellent energy resolution are prerequisites for reaching unprecedented levels of precision. In this paper, we provide estimation of the JUNO sensitivity to 7 Be, pep , and CNO solar neutrinos that can be obtained via a spectral analysis above the 0.45 MeV threshold. This study is performed assuming different scenarios of the liquid scintillator radiopurity, ranging from the most optimistic one corresponding to the radiopurity levels obtained by the Borexino experiment, up to the minimum requirements needed to perform the neutrino mass ordering determination with reactor antineutrinos — the main goal of JUNO. Our study shows that in most scenarios, JUNO will be able to improve the current best measurements on 7 Be, pep , and CNO solar neutrino fluxes. We also perform a study on the JUNO capability to detect periodical time variations in the solar neutrino flux, such as the day-night modulation induced by neutrino flavor regeneration in Earth, and the modulations induced by temperature changes driven by helioseismic waves.

Kurzfassung: 〈sec〉The interaction of highly charged ions with solid surfaces is a very complex multi-body process. When the ions are close to the solid surfaces, the potential energy of the ions will be deposited in a tiny area of the target surfaces in a short time and then emitting X rays, which has important scientific significance and application in Astrophysics and plasma diagnosis. For experiments on the interaction of highly charged ions with surfaces, not only the X-ray energy spectrum but also the X-ray yield should be measured accurately. The precise measurement of the X-ray yield depends on the ability to accurately measure the beam-current intensity. In the past, the beam-current intensity was acquired by measuring the target current. Since the interaction between highly charged ions and solids involves the emission of secondary electrons, the actual measured target current is the sum of the initial beam-current intensity and the intensity caused by the secondary electrons, resulting in inaccurate X-ray yield calculations. In this experiment, a new analytical device, beam-current density meter, has been designed, which can measure the beam-current intensity with an accuracy of 0.1 nA. By measuring the current on the density meter instead of the target current, the influence of secondary electrons is almost avoided, and a more accurate X-ray yield is obtained.〈/sec〉〈sec〉This paper reports the characteristic X-ray spectra of oxygen atoms emitted from the interaction of 1.5–20 keV/〈i〉q〈/i〉 highly charged 〈inline-formula〉〈tex-math id="M13"〉\begin{document}${\rm{O}} ^{q+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M13.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M13.png"/〉〈/alternatives〉〈/inline-formula〉 ions with aluminum surfaces. For the X rays emitted by 〈inline-formula〉〈tex-math id="M14"〉\begin{document}$ {\rm{O}}^{q+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M14.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M14.png"/〉〈/alternatives〉〈/inline-formula〉(〈i〉q〈/i〉 = 3, 5, 6) ions, the experimental results show that it is due to the close collisions with aluminum atoms after entering the surfaces, while the X rays emitted by 〈inline-formula〉〈tex-math id="M15"〉\begin{document}${\rm{O}} ^{7+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M15.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M15.png"/〉〈/alternatives〉〈/inline-formula〉 ions mainly come from the decay of hollow atoms. Under the condition of equal kinetic energy, the X-ray yield of 〈inline-formula〉〈tex-math id="M16"〉\begin{document}${\rm{O}} ^{7+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M16.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M16.png"/〉〈/alternatives〉〈/inline-formula〉 ions with K-shell vacancy is about one order of magnitude higher than that of 〈inline-formula〉〈tex-math id="M17"〉\begin{document}$ {\rm{O}}^{q+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M17.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M17.png"/〉〈/alternatives〉〈/inline-formula〉(〈i〉q〈/i〉 = 3, 5, 6) ions, and X-ray yield of 〈inline-formula〉〈tex-math id="M18"〉\begin{document}$ {\rm{O}}^{6+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M18.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M18.png"/〉〈/alternatives〉〈/inline-formula〉 ions without〈i〉 〈/i〉K-shell vacancy is also significantly higher than that of 〈inline-formula〉〈tex-math id="M19"〉\begin{document}${\rm{O}} ^{3+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M19.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M19.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M20"〉\begin{document}$ {\rm{O}}^{5+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M20.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M20.png"/〉〈/alternatives〉〈/inline-formula〉 ions. Generally, the X-ray yield and ionization cross-section is associated with the initial electron configuration of incident ions, and increases with the growth of ions kinetic energy. Based on the semi-classical approximation theory of binary collision, we have estimated the kinetic energy threshold for the emission of the K〈sub〉α〈/sub〉-X rays of 〈inline-formula〉〈tex-math id="M22"〉\begin{document}$ {\rm{O}}^{q+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M22.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M22.png"/〉〈/alternatives〉〈/inline-formula〉(〈i〉q〈/i〉 = 3, 5, 6) ions as interacting with the aluminum target. As the incident kinetic energy is lower than the kinetic energy threshold, for 〈inline-formula〉〈tex-math id="M23"〉\begin{document}${\rm{O}} ^{6+} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M23.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20210757_M23.png"/〉〈/alternatives〉〈/inline-formula〉 ions interacting with the sample, there may have a multi-electron excitation process that induces this K-electron ionization of the incident ions.〈/sec〉

Kurzfassung: The study of the interaction between highly charged ions and solid surfaces not only has great significance for basic scientific research such as atomic physics, astrophysics, and high energy density physics but also has promising application prospects in biomedicine, nanotechnology, surface analysis, and microelectronics. In this paper, the intermediate Rydberg states formed during highly charged 〈inline-formula〉〈tex-math id="M10"〉\begin{document}${\rm{O}}^{7+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M10.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M10.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M11"〉\begin{document}${\rm{N}}^{6+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M11.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M11.png"/〉〈/alternatives〉〈/inline-formula〉 ions incident on Al surface are studied theoretically by using the two-state vector model. Both the probability of electron capture into different Rydberg states 〈inline-formula〉〈tex-math id="M12"〉\begin{document}$\left(n_{A}=2-7\right)$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M12.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M12.png"/〉〈/alternatives〉〈/inline-formula〉 and the most probable neutralization distances are given. The calculation shows that the larger principal quantum number 〈inline-formula〉〈tex-math id="M13"〉\begin{document}$n_{A}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M13.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M13.png"/〉〈/alternatives〉〈/inline-formula〉 is relevant to smaller probability. Therefore, the X-rays emitted by 〈inline-formula〉〈tex-math id="M14"〉\begin{document}${\rm{O}}^{7+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M14.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M14.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M15"〉\begin{document}${\rm{N}}^{6+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M15.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M15.png"/〉〈/alternatives〉〈/inline-formula〉 ions incident on the Al surface come mainly from the de-excitation of the smaller 〈inline-formula〉〈tex-math id="M16"〉\begin{document}$n_{A}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M16.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M16.png"/〉〈/alternatives〉〈/inline-formula〉 to the ground state. In order to confirm the calculations, we measured the X-ray emission spectra of 〈inline-formula〉〈tex-math id="M17"〉\begin{document}${\rm{O}}^{7+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M17.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M17.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M18"〉\begin{document}${\rm{N}}^{6+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M18.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M18.png"/〉〈/alternatives〉〈/inline-formula〉 ions in collisions with the Al surface in the energy range of 3–20 keV/q. The experiments were performed at an ECR ion source located in Institute of modern physics. We also calculated the transition energies (n〈i〉p〈/i〉–1〈i〉s〈/i〉) from different high Rydberg states to the ground state by using the FAC code. The center of the measured 〈i〉K〈/i〉 X-ray peak is close to the calculated transition energy from the principal quantum number n = 2 to n = 1, it is consistent with our results obtained by the two-state vector model as well. In addition, we found the experimental 〈i〉K〈/i〉 X-ray yield for 〈inline-formula〉〈tex-math id="M19"〉\begin{document}${\rm{O}}^{7+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M19.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M19.png"/〉〈/alternatives〉〈/inline-formula〉 ions incidence at lower energy collisions is almost the same with 〈inline-formula〉〈tex-math id="M20"〉\begin{document}${\rm{N}}^{6+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M20.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M20.png"/〉〈/alternatives〉〈/inline-formula〉 ions, but larger at higher energy collisions. When the ion incident kinetic energy is low, the X-ray emission is mainly owing to the decay of “above the surface” hollow atoms. Because of the small difference in the critical distances for the capture of electrons by 〈inline-formula〉〈tex-math id="M21"〉\begin{document}${\rm{O}}^{7+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M21.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M21.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M22"〉\begin{document}${\rm{N}}^{6+}$\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M22.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20212434_M22.png"/〉〈/alternatives〉〈/inline-formula〉 to form hollow atoms, the X-ray yields produced in both cases are almost the same at low energy collisions. In contrast, as increasing the incident energy, the ions have a long-range in the target, so the contribution from the decay of “above the surface” and “below the surface” hollow atoms need to be considered at the same time.