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On 18 July 2009, the Asian Nuclear Physics Association (ANPhA) [1] was officially launched in Beijing by representatives from China, Korea, Japan, and Vietnam.The main objectives of ANPhA are clear...

Here, we consider the future of accelerators in nuclear physics. First, we look at the future of unstable beams toward a broader region of nuclei. Second, we review the possibilities in generating new forms of nuclear matter with heavy-ion beams. Third, we discuss the efforts to produce stronger powered proton beams for generating secondary particles, including neutrinos, kaons, muons, and anti-protons. Fourth, we discuss the possible electron–ion scatterings including their colliders. Other subjects such as hadron spectroscopy are not covered.

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.

The baryon structure may be modified in nuclear medium. The quark meson coupling model predicts that the beta decay rate of a Λ hyperon in Λ hypernuclei decreases by 20% at maximum. We propose an experiment to precisely measure the beta-decay rate of 5ΛHe at J-PARC via the (π+, K+) reaction. A feasibility study via GEANT4 simulation has been done, showing that the background can be suppressed down to ~ 3.9% of the betadecay electron yield, using a calorimeter covering the whole solid angle around the target. The measurement of the beta-decay of a Λ in a nucleus is found to be feasible.

The J-PARC Hadron Experimental Facility was constructed with an aim to explore the origin and evolution of matter in the universe through experiments with intense particle beams. In the past decade, many results from particle and nuclear physics experiments have been obtained at the present facility. To expand the physics programs to as yet unexplored regions, the extension project of the Hadron Experimental Facility has been extensively discussed. This contribution presents the physics of the extension of the Hadron Experimental Facility to resolve issues related to strangeness nuclear physics, hadron physics, and flavor physics.

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 Δp/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 Ξ12Be) and E94 (missing-mass spectroscopy of Λ7Li, Λ10B, and Λ12C) experiments.

Recent results and future prospects in strangeness nuclear and hadron physics are summarized from an experimental point of view based on plenary presentations in the HYP2022 conference.

As an introduction to the “topical session on ΛNN three-body force” in HYP2022, a scenario to solve the hyperon puzzle and to elucidate high density matter in neutron stars is proposed. It is related to the J-PARC Hadron Facility extension project, in which experimental studies of ΛNN three-body force (3BF) via high precision spectroscopy of Λ hypernuclei and high quality ΛN scattering are one of the flagship subjects in the project. Development of theoretical methods to extract 3BF effects from experimental data and to reliably extrapolate them to higher density is challenging but extremely important.

We present a new proposal, J-PARC E90, to measure a missing-mass spectrum near the ΣN threshold for the d(K−, π−) reactions at 1.4 GeV/c. While many previous experiments support apparent enhancement near the ΣN thresh-old, the dynamical origin of this so-called “ΣN cusp” remains yet unsolved. The enhancement suggests either a cusp structure or a weakly bound state. One of the keys to making it clear is improving the missing-mass resolution and statistics. Our new experiment can achieve the missing-mass resolution of 0.4 MeV in σ using the K1.8 beam line and S-2S spectrometers at J-PARC. Further-more, we can suppress quasi-free background processes with the time projection chamber (HypTPC), which operated nicely for the H-dibaryon search experi-ment (J-PARC E42). The J-PARC E90 aims to extract the scattering length of the ΣN system with isospin T = 1/2 and spin-triplet channels.

We measured the (K^−, π^+) reaction spectra at 1.8 GeV/c for the graphite and the polyethylene targets in the J-PARC E05 pilot experiment. By comparing the spectra for these two targets, it was found that Σ^*−(1385) in the ^11B nucleus is quite broadened. Furthermore, we also compared broadness of Σ^*−(1385) with K^*(892) obtained in the (K^−, p) spectrum. Σ^*−(1385) seems to be much more broadened in nuclei than K^*(892). We gave a possible interpretation, which is related to compositeness of decuplet baryons, for this situation.

Recent progress in strangeness nuclear physics is reported. The high-resolution ( e , e ′ K + ) reaction spectroscopy has been established at JLab as a new means to study Λ hypernuclear structure. Precision γ -ray spectroscopy of hypernuclei has revealed fine structure of various light Λ hypernuclei and clarified Λ N spin-dependent interactions. Production of neutron-rich Λ hypernuclei has become successful by using the ( π − , K + ) reaction at KEK. Several experimental data have implied existence of deeply-bound K ¯ -nuclear systems, and their theoretical research is also activated. Kaonic X ray measurements in light nuclei are also being carried out. The J-PARC and other facilities will allow us to accelerate these experimental studies of Λ hypernuclei and K − nuclear systems and to extend hypernuclear physics to double strangeness systems.

In J-PARC heavy-ion project, we aim at studies of QCD phase structures and hadron properties in high baryon density close to the neutron star core. We have developed a heavy-ion acceleration scheme with a new linac and a new booster with existing two synchrotrons with the goal beam rate of about 10 11 Hz. We have also designed a large acceptance spectrometer based on a toroidal magnet. We have evaluated the spectrometer performance, and demonstrated reconstructing dielectron and dimuon spectra with full detector simulations. Finally, we designed a hypernuclear spectrometer which can utilize the full intensity ion beams.

We have measured an inclusive missing-mass spectrum of the 12 C(K−, p) reaction over wide energy region at the kaon incident momentum of 1.8 GeV/c at J-PARC K1.8 beam line. This measurement was carried out as a by-product of a pilot run of J-PARC E05 experiment, which searched for the Ξ-hypernuclei via 12C(K−, K+) reaction. We have compared the observed missing-mass spectrum with a DWIA calculation to study the K-nucleus interaction. In this comparison, we have changed the depth of both real and imaginary parts of the optical potential between the K and nucleus. It is found that the observed spectrum is best reproduced by the calculation of the potential depth of V0 ∼ −80 MeV (real part) and W0 ∼ −40 MeV (imaginary part). On the other hand, we have observed a definitive excess around the deeply bound region BK ≳ 100 MeV. The excess cannot be explained by the any optical potential and quasi-free background reaction. It is well fitted with a Breit-Wigner function with a binding energy of 90 MeV and a width of 100 MeV, which can be interpreted as a deeply bound Λ(1405) nucleus.

The 13th International Conference on Hypernuclear and Strange Particle Physics (HYP2018) is summarized based on plenary talks given in the conference. It covers recent results and future prospects of theoretical and experimental studies on baryon-baryon interactions, hypernuclei, strangeness production, hadrons and nuclei with heavy flavors, and related subjects.

For the full understanding of baryon-baryon interactions in flavor SU(3), the ΞN interaction is the last missing piece of information. So far, we have revealed the ΛN interaction to be attractive (UΛ ≈ 30 MeV), and ΣN interaction to be repulsive in the medium to heavy mass-number region. The ΛΛ bonding energy is weakly attractive. While we have a few experimental observations suggesting the ΞN interaction would be attractive, there still exist large theoretical ambiguities weather it is attractive or not. Experimental determinations on the existence of bound states of Ξ hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a 12C(K−, K+) reaction, which strongly suggests the existence of Ξ-hypernuclear bound states, is presented.For the full understanding of baryon-baryon interactions in flavor SU(3), the ΞN interaction is the last missing piece of information. So far, we have revealed the ΛN interaction to be attractive (UΛ ≈ 30 MeV), and ΣN interaction to be repulsive in the medium to heavy mass-number region. The ΛΛ bonding energy is weakly attractive. While we have a few experimental observations suggesting the ΞN interaction would be attractive, there still exist large theoretical ambiguities weather it is attractive or not. Experimental determinations on the existence of bound states of Ξ hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a 12C(K−, K+) reaction, which strongly suggests the existence of Ξ-hypernuclear bound states, is presented.

Experimental results from the J-PARC E13 experiments are summarized. A new experimental set up of E13 has established a platform for the future γ-ray hypernuclear spectroscopy at J-PARC using kaon beams. New γ rays are identified in HeΛ4 and FΛ19. The energy of 1.406 MeV for the HeΛ4(1+→0+) transition confirmed a sizable effect of Charge Symmetry Breaking (CSB) in ΛN interaction in the A=4 hypernuclear system. The identification of four γ rays in FΛ19 is made for the first time in sd shell hypernuclei. Especially, energy spacing of the ground state doublet is found to be 315.5 keV. A good agreement with two theoretical calculations suggests that the theoretical formalism used in p shell hypernuclei is also applicable to heavier hypernuclei. Lastly, an overview of the future J-PARC E63 experiment is given.

J-PARC E07 is the most complex emulsion experiment to date investigating double hypernuclei with a hybrid emulsion method. This experiment aims to detect 104 Ξ− stop events, ten times more events than the past experiments. Thus, an unequivocal identification of several new double hypernuclei is expected. The beam exposure has been completed at the K1.8 beam line of the J-PARC hadron facility in June 2017. The photographic development of all emulsion sheets has also been completed in February 2018. The emulsion sheets are presently being analyzed with dedicated optical microscopes. Current statistics is comparable to that of E373 and so far 10 events of 3-vertices topology have been detected. A typical event of double Λ hypernucleus and a twin Λ hypernucleus are introduced. We plan to complete the main part of the emulsion scanning within a year.

International audience; Although more detailed analysis for deriving the cross section of \(\Sigma p\) scattering is necessary to derive the cross section of \(\Sigma p\) scattering, we have confirmed that CFT has enough angular resolution of tracking and energy resolution in order for the identification of the scattering events and particles.

International audience; J-PARC E40 aims to measure the differential cross sections of the Σ^±p elastic scatterings and the Σ^−p → Λn conversion. A clear peak of Σ^− was observed in a missing mass spectrum of the π^−p → K^+X reaction and recoil protons from the πp elastic scattering were successfully observed in the data taken in the summer 2018. The rest of data taking is coming in the spring 2019.

A double-$\Lambda$ hypernucleus, ${}_{\Lambda\Lambda}\mathrm{Be}$, was observed by the J-PARC E07 collaboration in nuclear emulsions tagged by the $(K^{-},K^{+})$ reaction. This event was interpreted as a production and decay of $ {}_{\Lambda\Lambda}^{\;10}\mathrm{Be}$, ${}_{\Lambda\Lambda}^{\;11}\mathrm{Be}$, or ${}_{\Lambda\Lambda}^{\;12}\mathrm{Be}^{*}$ via $\Xi^{-}$ capture in ${}^{16}\mathrm{O}$. By assuming the capture in the atomic 3D state, the binding energy of two $\Lambda$ hyperons$\,$($B_{\Lambda\Lambda}$) of these double-$\Lambda$ hypernuclei are obtained to be $15.05 \pm 0.11\,\mathrm{MeV}$, $19.07 \pm 0.11\,\mathrm{MeV}$, and $13.68 \pm 0.11\,\mathrm{MeV}$, respectively. Based on the kinematic fitting, ${}_{\Lambda\Lambda}^{\;11}\mathrm{Be}$ is the most likely explanation for the observed event., Comment: 11 pages, 3 figures

We have developed a new germanium (Ge) detector unit for hypernuclear γ-ray spectroscopy at J-PARC, which comprises a new Ge detector array Hyperball-J. A compact pulse-tube refrigerator is coupled to a coaxial Ge detector in order to achieve lower crystal temperatures as a means to increase radiation hardness. The obtained crystal temperature is 72 K, while an energy resolution is maintained at (FWHM) 3.1(1) keV for 1.33 MeV γ rays using a gate-integrated shaping amplifier (ORTEC 973U). Gain shifts with changing crystal temperature are also confirmed for the Ge detector.

We have carried out a pilot data taking of the J-PARC E05 experiment to search for the bound state peaks of $^{12}_\Xi$Be in the $^{12}$C$(K^-, K^+)X$ reaction at 1.8 GeV/$c$. The measurement was performed at the K1.8 beam line of the J-PARC hadron experimental hall with a typical $K^-$ beam intensity of $6\times 10^{5}$ every six seconds. So far the best energy resolution of about 6 MeV$_{FWHM}$ was achieved with the existing SKS spectrometer. With a reasonable statistics, we have succeeded to observe peak structures in the bound region, which seems to suggest that the potential depth of $\Xi$ would be deeper than 14 MeV estimated in the previous measurements.

A low-cost multi-channel analyzer (MCA) system was developed using a custom-build interface circuit and a PC sound card. The performance of the system was studied using γ-ray spectroscopy measurements with a NaI(Tl) scintillation detector. Our system successfully measured the energy of γ-rays at a rate of 1000 counts per second (cps).

The strangeness photoproduction processes near the threshold have been intensively studied by measuring K + in reactions such as γ + p → K + + Λ ( Σ 0 ) . There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have an effort to measure the γ + d → K 0 ( Λ ) + X reaction in the π + π − ( p π − ) decay channel of K S 0 (Λ) using a liquid D2 target and internally-tagged photon beams ( E γ = 0.80 – 1.08 GeV ) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005–2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.

A γ-ray spectroscopy experiment via the C 12 ( π + , K + ) reaction was carried out at KEK-PS in 2005. The K6 beam line and Superconducting Kaon Spectrometer (SKS) were employed to obtain a missing mass spectrum for 12ΛC. An upgraded germanium detector array, Hyperball2, was introduced to detect γ rays emitted from hypernuclei in coincidence with the ( π + , K + ) reaction. As a result of further analysis, a γ-ray peak at 6048 keV (preliminary) was newly observed and assigned as the M1 transition from the 6-MeV excited state to the ground state.

Recent results and future directions of the γ-ray spectroscopy of Λ hypernuclei are discussed. A further analysis of the last KEK experiment (E566) has revealed a new γ transition in 12ΛC at 6048 keV (preliminary), which is ascribed to the M 1 ( 1 3 − → 1 1 − ) transition. At J-PARC, studies will be extended from p-shell to s-shell and sd-shell hypernuclei. In the first part of the J-PARC E13 experiment, we will measure the 4ΛHe( 1 + → 0 + ) transition to study charge-symmetry breaking in the ΛN interaction and investigate the 19ΛF hypernucleus to study ΛN spin–spin interaction further using one of the sd-shell hypernuclei. In the second part of E13, we will precisely measure the spin-flip B ( M 1 ) value for the 7ΛLi( 3 / 2 + → 1 / 2 + ) transition. Beyond E13, we plan to study impurity effects by observing possible changes in nuclear deformation caused by the presence of a Λ in sd-shell hypernuclei, as well as to investigate various heavier Λ hypernuclei in order to precisely determine the energies of Λ single-particle orbits.

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K 0 with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K 0 + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K 1, as ~ −1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K + Λ.

In the J-PARC E27 experiment, we search for a K − pp bound state via the d(π +, K +) reaction at 1.7 GeV/c at the K1.8 beam line. The binding energy and decay width of the K − pp bound state can be obtained in the missing mass measurement with a good energy resolution of 2 MeV/c 2. A range counter array (RCA) was constructed to detect the two high-momentum protons from the K − pp decay and to reduce the background such as quasi-free hyperon production. Recently, we have carried out a pilot run in June, 2012. The d(π +, K +) missing-mass spectrum has been obtained for the first time. In this report, an overview of the E27 experiment and a preliminary result on this pilot run are presented.

The fundamental motivation to study the non-mesonic weak decay (NMWD) of hypernuclei is that it provides the unique means for study of baryon–baryon weak interaction in SU3f symmetry group. The new channel of NMWD, namely the recently confirmed three-body channel, seems to have a surprisingly big branching ratio so that it makes its accurate measurement prerequisite of the baryon–baryon weak interaction study. We report a new result of \({\Gamma_{2N}(^{11}_{\Lambda} {\rm B})}\) from E508 experiment of KEK-PS, though preliminary yet, which agrees with the previous result of \({^{12}_{\Lambda}}\) C from the same experiment, those from FINUDA experiment and those of the recent theoretical predictions.

The first experiment at the J-PARC hadron facility, the J-PARC E19 experiment, aims at searching for the Θ + pentaquark in the hadronic reaction π − p → K − X using the missing-mass technique. Based on a superconducting magnet excited at 2.5 T, the spectrometer achieved the high mass resolution of 1.4 MeV/c2 for the Θ + production process. The first data taking was performed in the autumn of 2010. No significant structure was observed in the missing-mass spectrum. The upper limit obtained for the differential cross section is 0.26 μb/sr in the laboratory frame at a 90 % CL.

Calcification of the internal carotid artery (ICA) hinders accurate evaluation of the stenosis by conventional ultrasonography due to acoustic shadow. We examined the relationship between acceleration time (AcT) and ICA origin stenosis. One hundred thrity seven samples (266 vessels) that enforced duplex ultrasonography in our hospital were targeted. The results have shown that there is a significant relationship between AcT and stenosis. AcT of more than 110 msec suggests that the stenosis is more than 60% by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method. AcT is thought to be useful for the diagnosis of ICA stenosis with calcification. (*English Translation of J Jpn Coll Angiol 2011; 51: 365-371)

A combination of the production of Λ hypernuclei via hadron beams and their precision γ -ray spectroscopy using a Ge detector array, Hyperball/Hyperball2, has played essential roles in studies of hypernuclear structure. After a brief summary of our previous studies for p -shell hypernuclei at KEK-PS and BNL-AGS, we describe our plans of hypernuclear γ -ray spectroscopy experiments at J-PARC, in particular, the first experiment E13 starting in 2012, in which we further study ΛN interaction and measure Λ -spin-flip B ( M 1 ) values using light hypernuclei such as He Λ 4 , Li Λ 7 , B Λ 10 , B Λ 11 and F Λ 19 .

The fundamental motivation to study the non-mesonic weak decay (NMWD) of Λ hypernuclei is that it provides the unique channel for the information of the baryon–baryon weak interaction in SU3f group. The relative strength of the two main channels of NMWD whose decay processes are the Λp → np and Λn → nn has been the long standing puzzle during last several decades. The puzzling status has been settled down recently with the Γn / Γp value converging to \({\sim 0.5}\) . The large experimental values of Γn / Γp of the previous measurements turned out to be due to the surprisingly large contribution of the competing three-body NMWD, ΛNN → nNN process. This paper discusses about the first measurement of the branching ratio of the three-body NMWD process and the renormalized intra-nuclear cascade method adopted to disentangle the contribution of the three-body process out of those due to final state interaction. And the prospects of the more accurate measurement of the three-body process also are presented.

Fundamental interest on Non Mesonic Weak Decay (NMWD) is that it provides practically the only means to study the elementary ΔS = 1 baryon-baryon weak interaction process, Λ N → NN (Λ p → np and Λ n → nn ), since it is difficult to be realized in the free space. Thanks to the recent developments in experimental and theoretical studies, the relative strength of two channels, the Γn/Γp ratios whose experimental and theoretical values have showed a long standing discrepancy have been converged to ~ 0.5 and the discrepancy problem finally has been solved.1–3 However, despite the progresses, the decay interaction of NMWD is not yet well established and there remain the important issues such as the discrepancy of asymmetry parameter between experimental and theoretical values, confirmation of 3-body NMWD process, and whether the I = 1/2 rule for ΔS = 1 decay would hold or not in NMWD. Especially the recent experimental indication of the 3-body decay process Λ NN → NNN whose contribution was predicted to be significant in the theoretical calculations seems to be strong and showed a surprisingly large contribution in the quenching of singles and coincidence nucleon yields in NMWD. Recent results of the asymmetry parameter αnm of NMWD showed small values for both s -shell [Formula: see text] and p -shell [Formula: see text] and consistent with each other. However, the discrepancy of the theoretical values from those of experimental ones remains to be understood. It now becomes one of the urgent issues in NMWD study to determine the contribution of the 3-body NMWD channel experimentally, in order to understand the discrepancy of the asymmetry papameter, and to test the ΔI = 1/2 rule for NMWD which are the main purposes of J-PARC 50 GeV PS experiment, E18 and E22.

Since the 1st generation experiment, E89-009, which was successfully carried out as a pilot experiment of (e,e'K+) hypernuclear spectroscopy at JLab Hall C in 2000, precision hypernuclear spectroscopy by the (e,e'K+) reactions made considerable progress. It has evolved to the 2nd generation experiment, E01-011, in which a newly constructed high resolution kaon spectrometer (HKS) was installed and the “Tilt method” was adopted in order to suppress large electromagnetic background and to run with high luminosity. Preliminary high-resolution spectra of 7 Λ He and 28 Λ Al together with that of 12 Λ B that achieved resolution better than 500 keV(FWHM) were obtained. The third generation experiment, E05-115, has completed data taking with an experimental setup combining a new splitter magnet, high resolution electron spectrometer (HES) and the HKS used in the 2nd generation experiment. The data were accumulated with targets of 7 Li, 9 Be, 10 B, 12 C and 52 Cr as well as with those of CH 2 and H 2 O for calibration. The analysis is under way with particular emphasis of determining precision absolute hypernuclear masses. In this article, hypernuclear spectroscopy program in the wide mass range at JLab Hall C that has undergone three generation is described.

Photoproduction of the K 0 from the deuteron and the carbon nucleus has been investigated at the Laboratory of Nuclear Science, Tohoku University in Sendai. The Neutral Kaon Spectrometer and the Neutral Kaon Spectrometer 2 were developed to detect π + π − pairs coming from the decay of the K S 0 . The resulting K 0 momentum spectra for inclusive K 0 photoproduction were compared with theoretical calculations based on isobar models for γ + n → K 0 + Λ , utilizing the spectator hypothesis. An upgrade of the inner detectors to enhance the acceptance for the coincidence measurement of the K S 0 and Λ is underway. We expect that the exclusive and kinematically complete measurement of the reaction will provide us with direct access to the center-of-mass observables that are important for further understanding the mechanism for strangeness photoproduction.