First experimental determination of the radiative-decay probability of the 31− state in ¹²C for estimating the triple alpha reaction rate in high temperature environments

The triple alpha reaction is one of the most important reactions in the nuclear astrophysics. However, its reaction rate in high temperature environments at T₉>2 was still uncertain. One of the major origins of the uncertainty was that the radiative-decay probability of the 3⁻₁ state in ¹²C was unknown. In the present work, we have determined the radiative-decay probability of the 3⁻₁ state to be 1.3[+1.2][-1.1] × 10⁻⁶ by measuring the ¹H(¹²C, ¹²Cp) reaction for the first time, and derived the triple alpha reaction rate in high temperature environments from the measured radiative-decay probability. The present result suggests that the 3⁻₁ state noticeably enhances the triple alpha reaction rate although the contribution from the 3⁻₁ state had been assumed to be small

Search For A Ξ Bound State In The 12C(K-,K+)X Reaction At 1.8 Gev/c

The 26th International Nuclear Physics Conference, 11-16 September, 2016, Adelaide, Australia

Measurement of differential cross sections for Σ⁺p elastic scattering in the momentum range 0.44–0.80 GeV/c

クォーク間の「芯」をとらえた --物質が安定して存在できる理由の理解に貢献--. 京都大学プレスリリース. 2022-09-05.We performed a novel Σ⁺+p scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400 Σ⁺+p elastic scattering events were identified from 4.9 × 10⁷ tagged Σ⁺+ particles in the Σ⁺+ momentum range 0.44-0.80 GeV/c. The differential cross sections of the Σ⁺+p elastic scattering were derived with much better precision than in previous experiments. The obtained differential cross sections were approximately 2 mb/sr or less, which were not as large as those predicted by the fss2 and FSS models based on the quark cluster model in the short-range region. By performing phase-shift analyses for the obtained differential cross sections, we experimentally derived the phase shifts of the ³S₁ and ¹P₁ channels for the first time. The phase shift of the ³S₁ channel, where a large repulsive core was predicted owing to the Pauli effect between quarks, was evaluated as 20° < |δ₃S₁| < 35°. If the sign of δ₃S₁ is assumed to be negative, the interaction in this channel is moderately repulsive, as the Nijmegen extended-sort-core models predicted

Active target MAIKo to investigate cluster structures in unstable nuclei

Study on clustering of nucleons in nuclei is recently focusing on unstable nuclei where new kinds of structures, namely molecular structures with excess nucleons, are predicted. The Coulomb shift of energy in the mirror system is suggested to reflect the size of these structures. Although the missing mass spectroscopy is expected to give access to these structures even beyond particle decay thresholds without any biases in excitation energy spectra but the detection of very low energy particles is challenging. To satisfy the requirement, a new active target system MAIKo has been developed at RCNP. The detector was commissioned using a 13C beam under the same kinematical condition as that of RI beam experiments

High resolution spectroscopy of hypernuclei with active fiber target

We are planning to carry out a high-resolution spectroscopy of Ξ hypernucleus at the J-PARC K1.8 beamline, which provides a highintensity K− beam (J-PARC E70 experiment). The high-resolution spectroscopy aims to be realized by introducing a new magnetic spectrometer S-2S and an active fiber target AFT. In this article, the role of the AFT in this experiment and its development status are described

Preparation status of missing-mass spectroscopy for hypernuclei with S-2S magnetic spectrometer

J-PARC E70 experiment measures the missing-mass of Ξ hypernuclei (12ΞBe) in Hadron Experimental Facility at J-PARC. We aim to reach the best missing-mass resolution of 2 MeV/c2 in FWHM with a new magnetic spectrometer S-2S. The high-resolution spectroscopy of Ξ hypernuclei will play an important role to understand the unknown ΞN interaction. The experiment will start at the beginning of 2023. This article presents the preparation status

Time-Reversal Measurement of the p-Wave Cross Sections of the [7]Be(n,α)[4]He Reaction for the Cosmological Li Problem

ビッグバン元素合成研究に残る最後の重要核反応確率を初測定 --ビッグバン元素合成の謎がさらに深まる--. 京都大学プレスリリース. 2017-02-06

First observation of a nuclear s-state of a Ξ hypernucleus, \u3csup\u3e15\u3c/sup\u3eΞC

Bound systems of Ξ- -14N are studied via Ξ- capture at rest followed by emission of a twin single-Λ hypernucleus in the emulsion detectors. Two events forming extremely deep Ξ- bound states were obtained by analysis of a hybrid method in the E07 experiment at J-PARC and reanalysis of the E373 experiment at KEK-PS. The decay mode of one event was assigned as Ξ- +14N → 5λHe +5λHe +4He + n. Since there are no excited states for daughter particles, the binding energy of the Ξ- hyperon, BΞ-, in the 14N nucleus was uniquely determined to be 6.27 ± 0.27MeV. Another Ξ- -14N system via the decay 9 λBe +5λHe + n brings a BΞ- value, 8.00 ± 0.77MeV or 4.96 ± 0.77MeV, where the two possible values of BΞ- correspond to the ground and the excited states of the daughter 9λ Be nucleus, respectively. Because the BΞ- values are larger than those of the previously reported events (KISO and IBUKI), which are both interpreted as the nuclear 1p state of the Ξ-14Nsystem, these newevents give the first indication of the nuclear 1s state of the Ξ hypernucleus, 15ΞC

Revised triple alpha reaction rate in high temperature environments

info:eu-repo/semantics/publishe