Construction status and prospects of the Hyper-Kamiokande project

The Hyper-Kamiokande project is a 258-kton Water Cherenkov together with a 1.3-MW high-intensity neutrino beam from the Japan Proton Accelerator Research Complex (J-PARC). The inner detector with 186-kton fiducial volume is viewed by 20-inch photomultiplier tubes (PMTs) and multi-PMT modules, and thereby provides state-of-the-art of Cherenkov ring reconstruction with thresholds in the range of few MeVs. The project is expected to lead to precision neutrino oscillation studies, especially neutrino CP violation, nucleon decay searches, and low energy neutrino astronomy. In 2020, the project was officially approved and construction of the far detector was started at Kamioka. In 2021, the excavation of the access tunnel and initial mass production of the newly developed 20-inch PMTs was also started. In this paper, we present a basic overview of the project and the latest updates on the construction status of the project, which is expected to commence operation in 2027

Prospects for neutrino astrophysics with Hyper-Kamiokande

Hyper-Kamiokande is a multi-purpose next generation neutrino experiment. The detector is a two-layered cylindrical shape ultra-pure water tank, with its height of 64 m and diameter of 71 m. The inner detector will be surrounded by tens of thousands of twenty-inch photosensors and multi-PMT modules to detect water Cherenkov radiation due to the charged particles and provide our fiducial volume of 188 kt. This detection technique is established by Kamiokande and Super-Kamiokande. As the successor of these experiments, Hyper-K will be located deep underground, 600 m below Mt. Tochibora at Kamioka in Japan to reduce cosmic-ray backgrounds. Besides our physics program with accelerator neutrino, atmospheric neutrino and proton decay, neutrino astrophysics is an important research topic for Hyper-K. With its fruitful physics research programs, Hyper-K will play a critical role in the next neutrino physics frontier. It will also provide important information via astrophysical neutrino measurements, i.e., solar neutrino, supernova burst neutrinos and supernova relic neutrino. Here, we will discuss the physics potential of Hyper-K neutrino astrophysics

Theory of (e,2e) spectroscopy in the case of copper oxide materials

The qualitative theory of (e, 2e) spectroscopy for the valence states of copper oxide materials is developed. It is shown, that cuprate oxides' intrinsic properties such as Cu-O hybridization, strong coulombic and antiferromagnetic correlations, and effects of doping can be studied within the EMS. This is very encouraging, because these properties are believed to be a key point in the understanding of high-Tc superconductivity of the cuprate oxides

Multiple ionization of C+, N+ and O+ ions by fast electron impact

Absolute cross sections for electron impact single and multiple ionization of C+, N+ and O+ ions leading to the formation of Cq + (q = 2-4), Nq + (q = 2-5) and Oq + (q = 2-5) are reported. The animated crossed beam method is applied in the energy range extending from the respective thresholds up to 2.5 keV. The concerned target ions belong to the second row of the periodic table, with configurations 2s22px (x = 1-3). The maximum cross sections for the multiply charged products Cq + are found to be in the range from 2.3× 10-20 cm2 (for C4 +) up to 6.3× 10-17 cm2 (for C2 +); for N q + they range from 3.0× 10-22 cm2 (for N5 +) up to 5.1× 10-17 cm2 (for N 2 +) and, lastly, for Oq + they range from 5.5× 10-22 cm2 (for O5 +) up to 5.2× 10 -17 cm2 (for O2 +). The corresponding threshold energies are found to be in satisfactory agreement with spectroscopic values. The general feature of the measured cross sections is investigated. Their values for single ionization are reasonably explained by the calculations using the Coulomb-Born approximation with exchange, while those for multiple ionization are found to agree well with the semiempirical model for q = 3, but they appear to be notably overestimated by a semiempirical Bethe-Born-type formula when q > 3. © 2013 IOP Publishing Ltd