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We propose a novel method for producing very-neutron-rich hypernuclei and corresponding resonance states by employing charge-exchange reactions via pp( 12 C, 12 N K + )n Λ with single-charge-exchange and ppp( 9 Be, 9 C K + )nn Λ with double-charge-exchange, both of which produce Λ K + in a target nucleus. The feasibility of producing very-neutron-rich hypernuclei using the proposed method was analysed by applying an ultra-relativistic quantum molecular dynamics model to a 6 Li + 12 C reaction at 2 A GeV. The yields of very-neutron-rich hypernuclei, signal-to-background ratios, and background contributions were investigated. The proposed method is a powerful tool for studying very-neutron-rich hypernuclei and resonance states with a hyperon for experiments employing the Super-FRS facility at FAIR and HFRS facility at HIAF.

Neutron imaging is a nondestructive and noninvasive inspection technique with a wide range of potential applications. However, the fundamentals of this technique still need to be improved, one of which involves achieving micrometer scale or even better resolution, which is a challenging task. Recently, a high-resolution neutron imaging device based on fine-grained nuclear emulsions was developed. Although these detectors demonstrate exceptionally high resolutions, they have several limitations. Furthermore, these detectors require an additional chemical development process and are thus not reusable. To overcome these limitations, we investigated whether neutron imaging devices based on fluorescent nuclear track detectors were suitable for high-resolution neutron imaging. Fluorescent nuclear track detectors are reusable solid-state detectors that do not require additional chemical processing. A novel technique combining neutron imaging based on fluorescent nuclear track detectors with a neutron converter layer formed using B C was developed with unprecedented resolution. The neutron imaging of a gadolinium-based grating with a periodic structure of 9 m was performed using the proposed fluorescent nuclear track detector-based neutron imaging device, and the grating structure was successfully resolved. The measured resolution was 0.887 ± 0.009 m, which is the 1 10–90% edge response obtained using optical images of the fluorescent nuclear track detectors.

A hypernucleus, a subatomic bound system with at least one hyperon, is a great test ground to investigate nuclear forces and general baryonic interactions with up, down and strange quarks. Hypernuclei have been extensively studied for almost seven decades in reactions involving cosmic rays and with accelerator beams. In recent years, experimental studies of hypernuclei have entered a new stage using energetic collisions of heavy-ion beams. However, these investigations have revealed two puzzling results related to the lightest three-body hypernuclear system, the so-called hypertriton, and the unexpected existence of a bound state of two neutrons with a Λ hyperon. Solving these puzzles will not only impact our understanding of the fundamental baryonic interactions with strange quarks but also of the nature of the deep interior of neutron stars. In this Perspective, we discuss approaches to solving these puzzles, including experiments with heavy-ion beams and the analysis of nuclear emulsions using state-of-the-art technologies. We summarize ongoing projects and experiments at various facilities worldwide and outline future perspectives.The study of hypernuclei contributes to the understanding of the fundamental baryonic interactions and the physics of neutron stars. This Perspective discusses different experimental approaches to answer open questions regarding hypernuclei.

In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of Δ p / p = 6 × 10 −4 in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of Ξ 12 Be) and E94 (missing-mass spectroscopy of Λ 7 Li, Λ 10 B, and Λ 12 C) experiments.

Hypertriton is the lightest hypernucleus and a benchmark in hypernuclear physics. However, it has recently been suggested that its lifetime and binding energy values may differ from the established values. To solve this puzzle, it is necessary to measure both values with a higher precision. For the precise measurement of the binding energy, we are aiming at developing a novel technique to measure the hypertriton binding energy with unprecedented accuracy by combining nuclear emulsion data and machine learning techniques. The analysis will be based on the J-PARC E07 nuclear emulsion data. Furthermore, a machine-learning model is being developed to identify other single and double-strangeness hypernuclei.

We performed a measurement of the inclusive missing-mass spectrum of the $^{12}$C$(K^-, K^+)$ reaction at an incident beam momentum of 1.8 GeV/c. This measurement was carried out by using the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Facility in J-PARC. From the missing-mass of the $^{12}$C$(K^-, K^+)$ reaction, the binding energy of a $\\Xi ^-$ hyperon in a core $^{11}$B nucleus, $B_{\\Xi ^-}$, can be calculated. Our experimental setup yielded a good energy resolution of 8.2 MeV (full width at half maximum), which allowed us to observe significant enhancements in the proximity of the $^{12}_{\\Xi }$Be production threshold region. In order to extract information from the missing-mass spectrum, we employed several fitting parameters assumptions. A good agreement with the spectrum shape was obtained by adding two Gaussian functions, with the constant experimental resolution for the $\\Xi$-hypernuclear states, to the background distribution. The peak positions were obtained to be $B_{\\Xi ^-} = 8.9 \\pm 1.4$ (stat.) $^{+3.8}_{-3.1}$ (syst.) MeV and $B_{\\Xi ^-} = -2.4 \\pm 1.3$ (stat.) $^{+2.8}_{-1.2}$ (syst.) MeV. Another model assumption, one Breit–Wigner function with $B_{\\Xi ^-} = -2.7 \\pm 2.2$ (stat.) $^{+0.5}_{-0.7}$ (syst.) MeV and $\\Gamma = 4.1 \\pm 2.1$ (stat.) $^{+1.2}_{-0.7}$ (syst.) MeV, also yielded a similar $\\chi ^2$ value.

Abstract We have measured, for the first time, the inclusive missing-mass spectrum of the $^{12}$C$(K^-, p)$ reaction at an incident kaon momentum of 1.8 GeV/$c$ at the J-PARC K1.8 beamline. We observed a prominent quasi-elastic peak ($K^-p \\rightarrow K^-p$) in this spectrum. In the quasi-elastic peak region, the effect of secondary interaction is apparently observed as a peak shift, and the peak exhibits a tail in the bound region. We compared the spectrum with a theoretical calculation based on the Green’s function method by assuming different values of the parameters for the $\\bar{K}$–nucleus optical potential. We found that the spectrum shape in the binding-energy region $-300 \\, \\text{MeV} < B_{K} < 40$ MeV is best reproduced with the potential depths $V_0 = -80$ MeV (real part) and $W_0 = -40$ MeV (imaginary part). On the other hand, we observed a significant event excess in the deeply bound region around $B_{K} \\sim 100$ MeV, where the major decay channel of $K^- NN \\to \\pi\\Sigma N$ is energetically closed, and the non-mesonic decay modes ($K^- NN \\to \\Lambda N$ and $\\Sigma N$) should mainly contribute. The enhancement is fitted well by a Breit–Wigner function with a kaon-binding energy of 90 MeV and width 100 MeV. A possible interpretation is a deeply bound state of a $Y^{*}$-nucleus system.

We propose a novel method for producing very-neutron-rich hypernuclei and corresponding resonance states by employing charge-exchange reactions via pp(\\(^12\\)C, \\(^12\\)N \\(K^+\\))n\\(\\) with single-charge-exchange and ppp(\\(^9\\)Be, \\(^9\\)C \\(K^+\\))nn\\(\\) with double-charge-exchange, both of which produce \\( K^+\\) in a target nucleus. The feasibility of producing very-neutron-rich hypernuclei using the proposed method was analysed by applying an ultra-relativistic quantum molecular dynamics model to a \\(^6\\)Li+\\(^12\\)C reaction at 2 \\(A\\) GeV. The yields of very-neutron-rich hypernuclei, signal-to-background ratios, and background contributions were investigated. The proposed method is a powerful tool for studying very-neutron-rich hypernuclei and resonance states with a hyperon for experiments employing the Super-FRS facility at FAIR and HFRS facility at HIAF.