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Masashi Kaneta

Publications and source records attributed to Masashi Kaneta.

6 recordsLinked to original sources
arXiv2026

Precise measurement of the $Λ$-binding energy difference between $^3_Λ$H and $^4_Λ$H via decay-pion spectroscopy at MAMI

We performed high-precision decay-pion spectroscopy of light $Λ$ hypernuclei at the Mainz Microtron (MAMI) using the A1 spectrometer facility. By measuring the monochromatic $π^-$ momentum from the two-body weak decay $^3_Λ\mathrm{H} \to {}^3\mathrm{He} + π^-$ and referencing it to the $^4_Λ\mathrm{H} \to {}^4\mathrm{He} + π^-$ decay, we determined the $Λ$ binding energy of $^3_Λ\mathrm{H}$ with unprecedented accuracy. The obtained value, $B_Λ(^3_Λ\mathrm{H}) = 0.523 \pm 0.013~(\mathrm{stat.}) \pm 0.075~(\mathrm{syst.})$~MeV, is consistent with the STAR result, but indicates a significantly deeper binding than inferred from earlier measurements. This result implies a stronger $Λ$-deuteron interaction and provides stringent constraints on hyperon-nucleon interactions.

nucl-ex↗
arXiv2024

Development of a real-time beam profile monitor for GeV photons and its application in accelerator facilities

A real-time beam profile monitoring system is proposed for GeV photon beams at the BM4 beamline of the Mikamine site, Research Center for Accelerator and Radioisotope Science (RARiS; previously known as ELPH) at Tohoku University. This monitoring system enhances the capability to monitor the entire beamline by incorporating newly developed beam profile monitors (BPMs) for upstream and midstream sections, in addition to the existing high-speed BPM used for downstream monitoring. This paper reports on the detection mechanisms of the newly developed BPMs and the actual measurement results obtained using the integrated beam monitoring system. The new BPMs are composed of plastic scintillation fibers and silicon photomultipliers, enabling high-precision, real-time measurements. Data acquisition utilizes streaming TDC, a firmware commonly employed in the J-PARC Hadron-hall, allowing real-time detection of high-intensity photon beams with count rates reaching several tens of MHz. With sufficient statistical data, the BPM achieved a 1-s beam-profiling accuracy of 10 μm. The proposed BPM system serves as a valuable resource for future physics experiments at the BM4 photon beamline and will significantly contribute to ongoing accelerator research endeavors.

physics.ins-det↗
arXiv2004

Centrality Dependence of Chemical Freeze-out in Au+Au Collisions at RHIC

We will report centrality dependence of chemical freeze-out temperature ($T_{ch}$), light quark chemical potential ($μ_{q}$), strange quark chemical potential ($μ_{s}$), and strangeness saturation factor ($γ_{s}$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 130 and 200 GeV. A systematic study for combination of ratios for chemical freeze-out fit is studied and we have found small ombination dependences. The results show $γ_{s}$ increasing with centrality but the other parameters have less sensitivity to the centralities.

nucl-th↗
arXiv2001

Hadron freeze-out conditions in high energy nuclear collisions

Systematic trend of the hadron freeze-out conditions from AGS/SPS to RHIC is discussed. The most interesting results from collisions at RHIC are that the system is indeed approaching net-baryon free and the transverse expansion is much stronger than that from collisions at AGS/SPS energies. In order to understand the trend of the collective velocity, an energy scan between $\sqrt{s_{NN}} = 20 - 200 GeV, is important. In addition, systematic studies on the anisotropy parameter $v_2$ and the transverse momentum distributions of $ϕ, Ω,$ and $J / ψ$ are necessary as they will help in determining whether the collectivity is developed at the partonic stage.

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