Simulation of hybrid trickle bed reactor-reverse osmosis process for the removal of phenol from wastewater

YesPhenol and phenolic derivatives found in different industrial effluents are highly toxic and extremely harmful to human and the aquatic ecosystem. In the past, trickle bed reactor (TBR), reverse osmosis (RO) and other processes have been used to remove phenol from wastewater. However, each of these technologies has limitations in terms of the phenol concentration in the feed water and the efficiency of phenol rejection rate. In this work, an integrated hybrid TBR-RO process for removing high concentration phenol from wastewater is suggested and model-based simulation of the process is presented to evaluate the performance of the process. The models for both TBR and RO processes were independently validated against experimental data from the literature before coupling together to make the hybrid process. The results clearly show that the combined process significantly improves the rejection rate of phenol compared to that obtained via the individual processes

Search for astrophysical electron antineutrinos in Super-Kamiokande with 0.01wt% gadolinium-loaded water

We report the first search result for the flux of astrophysical electron antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection and higher signal efficiency thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd with a $22.5\times552$ $\rm kton\cdot day$ exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure-water ($22.5 \times 2970 \rm kton\cdot day$) owing to the enhanced neutron tagging

Spectroscopy of 16B from quasi-free (p,pn) reaction with 17B

Spectroscopy of 16B plays an essential role in understanding the halo structure in 17B, but very limited knowledge has so far been obtained. We have carried out a kinematically complete measurement on the spectroscopy of 16B by using quasi-free (p,pn) reaction on 17B. The level scheme of 16B up to 5 MeV was made clear for the first time

Mass, Spectroscopy, and Two-Neutron Decay of Be 16

The structure and decay of the most neutron-rich beryllium isotope, Be16, has been investigated following proton knockout from a high-energy B17 beam. Two relatively narrow resonances were observed for the first time, with energies of 0.84(3) and 2.15(5) MeV above the two-neutron decay threshold and widths of 0.32(8) and 0.95(15) MeV, respectively. These were assigned to be the ground (Jπ=0+) and first excited (2+) state, with Ex=1.31(6) MeV. The mass excess of Be16 was thus deduced to be 56.93(13) MeV, some 0.5 MeV more bound than the only previous measurement. Both states were observed to decay by direct two-neutron emission. Calculations incorporating the evolution of the wave function during the decay as a genuine three-body process reproduced the principal characteristics of the neutron-neutron energy spectra for both levels, indicating that the ground state exhibits a strong spatially compact dineutron component, while the 2+ level presents a far more diffuse neutron-neutron distribution

Quasifree Neutron Knockout Reaction Reveals a Small s-Orbital Component in the Borromean Nucleus 17B

International audienceA kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus B17, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s1/2 and 0d5/2 orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s1/2. Our finding of such a small 1s1/2 component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B17. The present work gives the smallest s- or p-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo

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

Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

We present the results of the charge ratio (R) and polarization (Pμ0) measurements using the decay electron events collected from 2008 September to 2022 June by the Super-Kamiokande detector. Because of its underground location and long operation, we performed high precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be R=1.32±0.02 (stat.+syst.) at EμcosθZenith=0.7+0.3−0.2 TeV, where Eμ is the muon energy and θZenith is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while this suggests a tension with the πK model of 1.9σ. We also measured the muon polarization at the production location to be Pμ0=0.52±0.02 (stat.+syst.) at the muon momentum of 0.9+0.6−0.1 TeV/c at the surface of the mountain; this also suggests a tension with the Honda flux model of 1.5σ. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near 1 TeV/c. These measurement results are useful to improve the atmospheric neutrino simulations