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Title: Direct measurements of the lifetime of medium-heavy hypernuclei

Abstract

The lifetime of a Λ particle embedded in a nucleus (hypernucleus) decreases from that of free Λ decay mainly due to the opening of the Λ NNN weak decay channel. Furthermore, 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. This paper presents a direct measurement of the lifetime of medium-heavy hypernuclei that were hyper-fragments produced by fission or break-up from heavy hypernuclei initially produced with a 2.34 GeV photon-beam incident on thin Fe, Cu, Ag, and Bi target foils. For each event, fragments were detected in coincident pairs by a low-pressure multi-wire proportional chamber system. The lifetime was extracted from decay time spectrum formed by the difference of the time zeros between the pairs. The measured lifetime from each target is actually a statistical average over a range of mass with mean about 1/2 of the target mass and appears to be a constant of about 200 ps. Although this result cannot exclude unexpected shorter or longer lifetimes for some specific hypernuclei or hypernuclear states, it shows that a systematic decrease in lifetime as hypernuclear mass increasesmore » is not a general feature for hypernuclei with mean mass up to A ≈ 130. On the other hand, the success of this experiment and its technique shows that the time delayed fissions observed and used by all the lifetime measurements done so far on heavy hypernuclei could likely have originated from hyper-fragments lighter than the assumed masses.« less

Authors:
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Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Org.:
(HKS (JLab E02-017) Collaboration)
OSTI Identifier:
1462230
Report Number(s):
JLAB-PHY-12-1674; DOE/OR/23177-2397; arXiv:1212.1133
Journal ID: ISSN 0375-9474; PII: S0375947418300538
Grant/Contract Number:  
AC05-06OR23177; FG02-97ER41047; 11175075; 11135002; 11075068; 11505087; lzujbky-2015-71
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Physics. A
Additional Journal Information:
Journal Volume: 973; Journal Issue: C; Journal ID: ISSN 0375-9474
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Hypernuclei; Lifetime; Fragment; Hyper-fragment; Weak decay

Citation Formats

Qiu, X., Tang, L., Chen, C., Margaryan, A., Wood, S. A., Achenbach, P., Ahmidouch, A., Albayrak, I., Androic, D., Asaturyan, A., Asaturyan, R., Ates, O., Badui, R., Baturin, P., Boeglin, W., Bono, J., Brash, E., Carter, P., Chen, X., Chiba, A., Christy, M. E., Dalton, M. M., Danagoulian, S., De Leo, R., Doi, D., Elaasar, M., Ent, R., Fenker, H., Fujii, Y., Furic, M., Gabrielyan, M., Gan, L., Garibaldi, F., Gaskell, D., Gasparian, A., Gogami, T., Hashimoto, O., Horn, T., Hu, B., Hungerford, Ed V., Jones, M., Kanda, H., Kaneta, M., Kawama, D., Khanal, H., Kohl, M., Liyanage, A., Luo, W., Maeda, K., Markowitz, P., Marikyan, G., Maruta, T., Matsumura, A., Maxwell, V., Mkrtchyan, A., Mkrtchyan, H., Nagao, S., Nakamura, S. N., Narayan, A., Neville, C., Niculescu, G., Niculescu, M. I., Nunez, A., Nuruzzaman, ., Okayasu, Y., Petkovic, T., Pochodzalla, J., Reinhold, J., Rodriguez, V. M., Samanta, C., Sawatzky, B., Seva, T., Shichijo, A., Tadevosyan, V., Taniya, N., Tsukada, K., Veilleux, M., Vulcan, W., Wesselmann, F. R., Yamamoto, T., Ye, Z., Yokota, K., Yuan, L., Zhamkochyan, S., and Zhu, L. Direct measurements of the lifetime of medium-heavy hypernuclei. United States: N. p., 2018. Web. doi:10.1016/j.nuclphysa.2018.03.001.
Qiu, X., Tang, L., Chen, C., Margaryan, A., Wood, S. A., Achenbach, P., Ahmidouch, A., Albayrak, I., Androic, D., Asaturyan, A., Asaturyan, R., Ates, O., Badui, R., Baturin, P., Boeglin, W., Bono, J., Brash, E., Carter, P., Chen, X., Chiba, A., Christy, M. E., Dalton, M. M., Danagoulian, S., De Leo, R., Doi, D., Elaasar, M., Ent, R., Fenker, H., Fujii, Y., Furic, M., Gabrielyan, M., Gan, L., Garibaldi, F., Gaskell, D., Gasparian, A., Gogami, T., Hashimoto, O., Horn, T., Hu, B., Hungerford, Ed V., Jones, M., Kanda, H., Kaneta, M., Kawama, D., Khanal, H., Kohl, M., Liyanage, A., Luo, W., Maeda, K., Markowitz, P., Marikyan, G., Maruta, T., Matsumura, A., Maxwell, V., Mkrtchyan, A., Mkrtchyan, H., Nagao, S., Nakamura, S. N., Narayan, A., Neville, C., Niculescu, G., Niculescu, M. I., Nunez, A., Nuruzzaman, ., Okayasu, Y., Petkovic, T., Pochodzalla, J., Reinhold, J., Rodriguez, V. M., Samanta, C., Sawatzky, B., Seva, T., Shichijo, A., Tadevosyan, V., Taniya, N., Tsukada, K., Veilleux, M., Vulcan, W., Wesselmann, F. R., Yamamoto, T., Ye, Z., Yokota, K., Yuan, L., Zhamkochyan, S., & Zhu, L. Direct measurements of the lifetime of medium-heavy hypernuclei. United States. doi:10.1016/j.nuclphysa.2018.03.001.
Qiu, X., Tang, L., Chen, C., Margaryan, A., Wood, S. A., Achenbach, P., Ahmidouch, A., Albayrak, I., Androic, D., Asaturyan, A., Asaturyan, R., Ates, O., Badui, R., Baturin, P., Boeglin, W., Bono, J., Brash, E., Carter, P., Chen, X., Chiba, A., Christy, M. E., Dalton, M. M., Danagoulian, S., De Leo, R., Doi, D., Elaasar, M., Ent, R., Fenker, H., Fujii, Y., Furic, M., Gabrielyan, M., Gan, L., Garibaldi, F., Gaskell, D., Gasparian, A., Gogami, T., Hashimoto, O., Horn, T., Hu, B., Hungerford, Ed V., Jones, M., Kanda, H., Kaneta, M., Kawama, D., Khanal, H., Kohl, M., Liyanage, A., Luo, W., Maeda, K., Markowitz, P., Marikyan, G., Maruta, T., Matsumura, A., Maxwell, V., Mkrtchyan, A., Mkrtchyan, H., Nagao, S., Nakamura, S. N., Narayan, A., Neville, C., Niculescu, G., Niculescu, M. I., Nunez, A., Nuruzzaman, ., Okayasu, Y., Petkovic, T., Pochodzalla, J., Reinhold, J., Rodriguez, V. M., Samanta, C., Sawatzky, B., Seva, T., Shichijo, A., Tadevosyan, V., Taniya, N., Tsukada, K., Veilleux, M., Vulcan, W., Wesselmann, F. R., Yamamoto, T., Ye, Z., Yokota, K., Yuan, L., Zhamkochyan, S., and Zhu, L. Thu . "Direct measurements of the lifetime of medium-heavy hypernuclei". United States. doi:10.1016/j.nuclphysa.2018.03.001.
@article{osti_1462230,
title = {Direct measurements of the lifetime of medium-heavy hypernuclei},
author = {Qiu, X. and Tang, L. and Chen, C. and Margaryan, A. and Wood, S. A. and Achenbach, P. and Ahmidouch, A. and Albayrak, I. and Androic, D. and Asaturyan, A. and Asaturyan, R. and Ates, O. and Badui, R. and Baturin, P. and Boeglin, W. and Bono, J. and Brash, E. and Carter, P. and Chen, X. and Chiba, A. and Christy, M. E. and Dalton, M. M. and Danagoulian, S. and De Leo, R. and Doi, D. and Elaasar, M. and Ent, R. and Fenker, H. and Fujii, Y. and Furic, M. and Gabrielyan, M. and Gan, L. and Garibaldi, F. and Gaskell, D. and Gasparian, A. and Gogami, T. and Hashimoto, O. and Horn, T. and Hu, B. and Hungerford, Ed V. and Jones, M. and Kanda, H. and Kaneta, M. and Kawama, D. and Khanal, H. and Kohl, M. and Liyanage, A. and Luo, W. and Maeda, K. and Markowitz, P. and Marikyan, G. and Maruta, T. and Matsumura, A. and Maxwell, V. and Mkrtchyan, A. and Mkrtchyan, H. and Nagao, S. and Nakamura, S. N. and Narayan, A. and Neville, C. and Niculescu, G. and Niculescu, M. I. and Nunez, A. and Nuruzzaman, . and Okayasu, Y. and Petkovic, T. and Pochodzalla, J. and Reinhold, J. and Rodriguez, V. M. and Samanta, C. and Sawatzky, B. and Seva, T. and Shichijo, A. and Tadevosyan, V. and Taniya, N. and Tsukada, K. and Veilleux, M. and Vulcan, W. and Wesselmann, F. R. and Yamamoto, T. and Ye, Z. and Yokota, K. and Yuan, L. and Zhamkochyan, S. and Zhu, L.},
abstractNote = {The lifetime of a Λ particle embedded in a nucleus (hypernucleus) decreases from that of free Λ decay mainly due to the opening of the ΛN → NN weak decay channel. Furthermore, 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. This paper presents a direct measurement of the lifetime of medium-heavy hypernuclei that were hyper-fragments produced by fission or break-up from heavy hypernuclei initially produced with a 2.34 GeV photon-beam incident on thin Fe, Cu, Ag, and Bi target foils. For each event, fragments were detected in coincident pairs by a low-pressure multi-wire proportional chamber system. The lifetime was extracted from decay time spectrum formed by the difference of the time zeros between the pairs. The measured lifetime from each target is actually a statistical average over a range of mass with mean about 1/2 of the target mass and appears to be a constant of about 200 ps. Although this result cannot exclude unexpected shorter or longer lifetimes for some specific hypernuclei or hypernuclear states, it shows that a systematic decrease in lifetime as hypernuclear mass increases is not a general feature for hypernuclei with mean mass up to A ≈ 130. On the other hand, the success of this experiment and its technique shows that the time delayed fissions observed and used by all the lifetime measurements done so far on heavy hypernuclei could likely have originated from hyper-fragments lighter than the assumed masses.},
doi = {10.1016/j.nuclphysa.2018.03.001},
journal = {Nuclear Physics. A},
number = C,
volume = 973,
place = {United States},
year = {Thu Mar 08 00:00:00 EST 2018},
month = {Thu Mar 08 00:00:00 EST 2018}
}

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