학술논문
Missing-mass spectroscopy with the ${}^{6}$Li($\pi^{-}, K^{+}$)X reaction to search for ${}^{6}_{\Lambda}$H
Document Type
Working Paper
Author
Honda, R.; Agnello, M.; Ahn, J. K.; Ajimura, S.; Akazawa, Y.; Amano, N.; Aoki, K.; Bhang, H. C.; Chiga, N.; Endo, M.; Evtoukhovitch, P.; Feliciello, A.; Fujioka, H.; Fukuda, T.; Hasegawa, S.; Hayakawa, S. H.; Hosomi, K.; Hwang, S. H.; Ichikawa, Y.; Igarashi, Y.; Imai, K.; Ishibashi, N.; Iwasaki, R.; Joo, C. W.; Kiuchi, R.; Lee, J. K.; Lee, J. Y.; Matsuda, K.; Matsumoto, Y.; Matsuoka, K.; Miwa, K.; Mizoi, Y.; Moritsu, M.; Nagae, T.; Nagamiya, S.; Nakagawa, M.; Naruki, M.; Noumi, H.; Ota, R.; Roy, B. J.; Saha, P. K.; Sakaguchi, A.; Sako, H.; Samanta, C.; Samoilov, V.; Sasaki, Y.; Sato, S.; Sekimoto, M.; Shimizu, Y.; Shiozaki, T.; Shirotori, K.; Soyama, T.; Sugimura, H.; Takahashi, T.; Takahashi, T. N.; Tamura, H.; Tanabe, K.; Tanaka, T.; Tanida, K.; Tokiyasu, A. O.; Tsamalaidze, Z.; Ukai, M.; Yamamoto, T. O.; Yamamoto, Y.; Yang, S. B.; Yoshida, K.
Source
Phys. Rev. C 96, 014005 (2017)
Subject
Language
Abstract
We searched for the bound state of the neutron-rich $\Lambda$-hypernucleus ${}^{6}_{\Lambda}$H, using the ${}^{6}$Li($\pi^{-}, K^{+}$)X double charge-exchange reaction at a $\pi^{-}$ beam momentum of 1.2 GeV/c at J-PARC. A total of $1.4 \times 10^{12}$ $\pi^{-}$ was driven onto a ${}^{6}$Li target of 3.5-g/$\rm cm^2$ thickness. No event was observed below the bound threshold, i.e., the mass of ${}^{4}_{\Lambda}$H + 2n, in the missing-mass spectrum of the ${}^{6}$Li($\pi^{-}, K^{+}$)X reaction in the $2^{\circ}$ < $\theta_{\pi K}$ < $20^{\circ}$ angular range. Furthermore, no event was found up to 2.8 MeV/$c^2$ above the bound threshold. We obtained the the double-differential cross section spectra of the ${}^{6}$Li($\pi^{-}, K^{+}$)X reaction in the angular range of $2^{\circ}$ < $\theta_{\pi K}$ < $14^{\circ}$. An upper limit of 0.56 nb/sr (90% C.L.) was obtained for the production cross section of the ${}^{6}_{\Lambda}$H hypernucleus bound state. In addition, not only the bound state region, but also the $\Lambda$ continuum region and part of the $\Sigma^{-}$ quasi-free production region of the ${}^{6}$Li($\pi^{-}, K^{+}$)X reaction, were obtained with high statistics. The present missing-mass spectrum will facilitate the investigation of the $\Sigma^{-}$-nucleus optical potential for $\Sigma^{-}$-${}^{5}$He through spectrum shape analysis.
Comment: 24 pages, 17 figures
Comment: 24 pages, 17 figures