Observation of ^4_ΛH Hyperhydrogen by Decay-Pion Spectroscopy in Electron Scattering

Esser, A. and Nagao, S. and Schulz, F. and Achenbach, P. and Ayerbe Gayoso, C. and Bohm, R. and Borodina, O. and Bosnar, Damir and Bozkurt, V. and Debenjak, L. and Distler, M. O. and Friščić, Ivica and Fujii, Y. and Gogami, T. and Hashimoto, O. and Hirose, S. and Kanda, H. and Kaneta, M. and Kim, E. and Kohl, Y. and Kusaka, J. and Margaryan, A. and Merkel, H. and Mihovilovć, M. and Muller, U. and Nakamura, S. N. and Pochodzalla, J. and Rappold, C. and Reinhold, J. and Saito, T. R. and Sanchez Lorente, A. and Sánchez Majos, S. and Schlimme, B. S. and Schoth, M. and Sfienti, C. and Širca, S. and Tang, L. and Thiel, M. and Tsukada, K. and Weber, A. and Yoshida, K. (A1 Collaboration) (2015) Observation of ^4_ΛH Hyperhydrogen by Decay-Pion Spectroscopy in Electron Scattering. Physical Review Letters, 114 (23). pp. 232501-5. ISSN 0031-9007

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At the Mainz Microtron MAMI, the first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a ^9Be target in order to study the Λ binding energy of light hypernuclei. Positively charged kaons were detected by a short-orbit spectrometer with a broad momentum acceptance at 0° forward angles with respect to the beam, efficiently tagging the production of strangeness in the target nucleus. Coincidentally, negatively charged decay pions were detected by two independent high-resolution spectrometers. About 10^3 pionic weak decays of hyperfragments and hyperons were observed. The pion momentum distribution shows a monochromatic peak at p_π ≈ 133 MeV=c, corresponding to the unique signature for the two-body decay of hyperhydrogen ^4_ΛH → ^4He + π^−, stopped inside the target. Its Λ binding energy was determined to be B_Λ = 2.12 ± 0.01 (stat) ± 0.09 ðsystÞMeV with respect to the ^3H + Λ mass.

Item Type: Article
Date: 12 June 2015
Subjects: NATURAL SCIENCES > Physics > Nuclear Physics
Additional Information: Copyright (2015) by the American Physical Society.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 11 Jun 2015 10:41
Last Modified: 11 Jun 2015 10:41
URI: http://digre.pmf.unizg.hr/id/eprint/4043

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