1212.1133 (X. Qiu et al.)

Direct Measurements of the Lifetime of Heavy Hypernuclei    [PDF]

X. Qiu, L. Tang, A. Margaryan, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan, O. Ates, R. Badui, P. Baturin, W. Boeglin, J. Bono, E. Brash, P. Carter, C. Chen, X. Chen, A. Chiba, E. Christy, M. M. Dalton, S. Danagoulian, R. De Leo, D. Doi, M. Elaasar, R. Ent, H. Fenker, Y. Fujii, M. Furic, M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, T. Gogami, O. Hashimoto, T. Horn, B. Hu, E. V. Hungerford, M. Jones, H. Kanda, M. Kaneta, M. Kawai, D. Kawama, H. Khanal, M. Kohl, A. Liyanage, W. Luo, K. Maeda, P. Markowitz, T. Maruta, A. Matsumura, V. Maxwell, A. Mkrtchyan, H. Mkrtchyan, S. Nagao, S. N. Nakamura, A. Narayan, C. Neville, G. Niculescu, M. I. Niculescu, A. Nunez, Nuruzzaman, Y. Okayasu, T. Petkovic, J. Pochodzalla, J. Reinhold, V. M. Rodriguez, C. Samanta, B. Sawatzky, T. Seva, A. Shichijo, V. Tadevosyan, N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan, F. R. Wesselmann, S. A. Wood, L. Ya, T. Yamamoto, Z. Ye, K. Yokota, L. Yuan, S. Zhamkochyan, L. Zhu

The lifetime of a Lambda particle embedded in a nucleus (hypernucleus) decreases from that of free Lambda decay due to the opening of the Lambda N to NN weak decay channel. However, it is generally believed that the lifetime of a hypernucleus attains a constant value (saturation) for medium to heavy hypernuclear masses, yet this hypothesis has been difficult to verify. The present paper reports a direct measurement of the lifetime of medium-heavy hypernuclei produced with a photon-beam from Fe, Cu, Ag, and Bi targets. The recoiling hypernuclei were detected by a fission fragment detector using low-pressure multi-wire proportional chambers. The experiment agrees remarkably well with the only previously-measured single-species heavy-hypernucleus lifetime, that of Fe56_Lambda at KEK, and has significantly higher precision. The experiment disagrees with the measured lifetime of an unknown combination of heavy hypernuclei with 180View original: http://arxiv.org/abs/1212.1133