Neutron-rich hypernuclei: evidence for 6ΛH and search for 9ΛHe
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چکیده
The FINUDA experiment at DAΦNE, Frascati, has found evidence for the neutron-rich hypernucleus ΛH studying (π , π−) pairs in coincidence from the K− stop+ 6Li→ 6 ΛH+π + production reaction followed by ΛH→ 6He+π− weak decay. The production rate of ΛH undergoing this two-body π − decay has been found to be (2.9 ± 2.0) · 10−6/K− stop. Its binding energy has been evaluated to be BΛ(ΛH) = (4.0 ± 1.1) MeV with respect to 5H + Λ, jointly from production and decay. A systematic difference of (0.98 ± 0.74) MeV between BΛ values derived separately from decay and from production has been tentatively assigned to the ΛH 0 + g.s. → 1 excitation. A similar investigation has been carried out for the neutron-rich hypernucleus ΛHe studying the K− stop + 9Be → ΛHe + π reaction in coincidence with the ΛHe → 9Li + π− weak decay; an upper limit for the production rate of ΛHe undergoing the two-body π − decay has been found to be 4.2 ·10/Kstop (90% C.L.). a e-mail: [email protected] b deceased EPJ Web of Conferences DOI: 10.1051/ C © Owned by the authors, published by EDP Sciences, 2012 , epjconf 20123 / 01023 (2012) 37 701023 This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Article available at http://www.epj-conferences.org or http://dx.doi.org/10.1051/epjconf/20123701023 EPJ Web of Conferences
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تاریخ انتشار 2012