Khan, Arani Ali

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.

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.

In this paper, a dual band bandpass filter with improved rejection between the two passbands and selectivity, is presented. The two passbands are centered at 2.4 GHz and 3.5 GHz with Fractional Bandwidths (FBW) of 4% and 5.5% respectively. Trisection topology is used to create both the passbands using rectangular SIW resonators resonating at its fundamental TE110 and next higher order TE210 modes. To reduce the circuit foot print, two layer structure is adopted. This design offers two transmission zeroes (TZs) in between the passbands resulting at least 48 dB rejection over 2.75 GHz-3.25 GHz. The measured reflection and transmission losses are better than 11.2 dB and 3.21 dB for first whereas they are better than 15.5 dB and 3.01 dB for the second passband respectively.

A low-profile single-layered filtenna scheme for single/dual-frequency channels are demonstrated. The designs utilize a half-mode substrate integrated waveguide (HMSIW) resonator. The HMSIW technology was employed to realize the filtenna compactness, and a via-slot combination was organized to increase the functioning bandwidth, exhibiting two resonances in the respective passband. Besides, the design has been scaled for dual-frequency channel applications. The dual-channel for transceiver application was apprehended by arranging the scaled version of single-channel filtenna. Finally, dual-channel filtenna was fabricated and its performance was validated experimentally. The measured results are in good agreement with the simulated counterpart. The results show that the design exhibits impedance bandwidths of around 3.0 % i.e., 8.63-8.88 GHz and 4.2% i.e. 9.26-9.66 GHz for lower and upper-frequency pass channels, respectively. The proposed design has a consistent broadside radiation pattern and polarization in the operating bands, manifesting the proposed filtenna can be a promising candidate for multi-service wireless communication systems. The proposed design also exhibits good performance in terms of port isolation, flat in-band gain response, and out-of-band frequency selectivity.

In this paper, substrate integrated waveguide (SIW) filters with multilayer configuration are presented. Such configurations reduce circuit footprint area without compromising the passband loss. Here it is shown that a metallic post can provide magnetic as well as electric coupling. Further, it is shown that proper placement of the slots, used here to obtain coupling between two adjacent layers, can provide next harmonic suppression. Finally, a four-pole prototype is designed which provides symmetrically placed transmission zeros. The filter offers a measured insertion loss of 1.55 dB at f0=2.20 GHz. The stopband rejections are at least 40 dB at (f0 ± 0.2) GHz and the next harmonic is suppressed at least by 28 dB.

In this paper, a novel mode decoupling technique of a SIW dual mode square resonator is presented. It is then utilized to design a self diplexing radiator. A single corner cut square cavity with a triangular ring slot on top is used for dual mode excitation and mode decoupling. Both the electric and magnetic mode couplings are used simultaneously to improve the port isolation. Once the single square cavity is optimized for good port isolation, two extra TE110 mode cavities are further added to improve the isolation. Finally, 37 dB port isolation is achieved. The measured gains are 4.45 dBi and 4.20 dBi at 10.5 GHz and 11.7 GHz respectively. The proposed design can be used in a transceiver system without any circulator, switch or additional bandpass filter.

In this article, a new design of a microstrip to empty substrate integrated waveguide with reduced fabrication complexity is presented. A tapered microstrip section is used for mode and impedance matching. The guiding medium below the transition area is air. The proposed design is validated both in X and K-band. Finally, a prototype of such back-to-back transition is fabricated for X-band operation. The measured results show that the insertion loss of the back-to-back transition is less than 1 dB with return loss better than 15 dB over 7.2–11.2 GHz, whereas the return loss is better than 10 dB over the entire X-band. The leakage from the transitions is also studied.