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: Physics Motivation and Experimental

Version 4.02

Spectroscopic study of $\Lambda$ hypernuclei
up to medium-heavy mass region
through the (e,e'K$^+$) reaction
( Update to the conditionally approved E97-008 )

O. Hashimoto (Spokesperson)$^*$, S.N. Nakamura (Spokesperson), Y. Fujii,
H. Tamura, T. Takahashi, K. Maeda, H. Kanda,
T. Miyoshi, H. Yamaguti, Y. Okayasu, K. Tsukada

Department of Physics, Tohoku University, Sendai, 980-8578, Japan

S. Kato

Department of Physics, Yamagata University, Yamagata, 990-8560, Japan

H. Noumi

Institute for Particle and Nuclear Physics, KEK, Tsukuba, 305-0801, Japan

T. Motoba

Laboratory of Physics, Osaka Electro-Communication University, Neyagawa, 572-8530, Japan

L. Tang (Spokesperson), O.K. Baker, L. Cole, M. Christy, L. Gan, A. Gasparian, P. Gueye, B. Hu, C. Jackson, C. Keppel, Y. Sato, A. Uzzle, L. Yuan, X.F. Zhu

Department of Physics, Hampton University, Hampton, VA 23668, USA

J. Reinhold (Spokesperson), P. Markowiz

Department of Physics, Florida International University, Miami, FL 27411 USA

Ed. V. Hungerford, K. Lan, G.H. Xu

Department of Physics, University of Houston, Houston, TX 77204 USA

R. Carlini, R. Ent, H. Fenker, K. Garrow, D. Mack, G. Smith, W. Vulcan, S. Wood, C. Yan

Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 USA

A. Ahmidouch, S. Danagoulian

Department of Physics, North Carolina A& T State University, Greensboro, NC 27411 USA

D. Dehnhard, H. Jungust, J. Liu

Department of Physics, University of Minnesota, Minnesota, USA

N. Simicevic, S. Wells

Department of Physics, Louisiana Tech University, Ruston, LA USA

M. Elaasar

Department of Physics, Southern University at New Orleans, New Orleans, Louisiana, USA

R. Asaturyan, H. Mkrtchyan, A. Margaryan, S. Stepanyan, V. Tadevosyan

Yerevan Physics Institute, Armenia

D. Androic, M. Planinic, M. Furic

Department of Physics, University of Zagreb, Croatia

T. Angelescu

Department of Physics, University of Bucharest, Bucharest, Romania

V. P. Likhachev

Department of Physics, University of Sao Paulo, Sao Paulo, Brasil

December 14, 2000

* Contact person

Osamu Hashimoto

Department of Physics, Tohoku University, Sendai, 980-8578, Japan
Telephone 81-22-217-6452
Fax 81-22-217-6455

Proposal to JLAB PAC-19


We propose to perform a spectroscopic study of $\Lambda$ hypernuclei for wide mass region using the (e,e'K$^+$) reaction. The expected results will provide $\Lambda$ hypernuclear spectra with the best energy resolution ($\sim$ 300 keV) ever achieved. An energy resolution of a few hundred keV and high statistical accuracy of the level structure will yield knowledge on the single-particle behavior of a $\Lambda$ hyperon in a medium mass nuclear system, and allow precise studies of the effective $\Lambda$-N interaction. The experiment will take full advantage of high quality electron beam at Jlab by introducing a new experimental geometry and a high resolution kaon spectrometer system now under construction.

The (e,e'K$^{+}$) reaction has unique characteristics as outlined below.

The proposed experiment has two goals,

  1. Excitation spectra of medium-heavy $\Lambda$ hypernuclei will be studied using the $^{28}$Si(e,e'K$^+$) $^{28}_{\Lambda }$Al and $^{51}$V(e,e'K$^+$) $^{51}_{\Lambda }$Ti reactions. This will provide precision binding energies and widths for the $\Lambda$ hyperon in its various states in nuclear mass up to A=50. The new structures and/or spin-orbit splittings suggested by the recent $( \pi ^ + ,{\rm K}^ +)$ reaction spectrum in the medium-heavy hypernuclei can be fully investigated with unprecedented energy resolution.

  2. Precision measurement of $^{12}$C(e,e'K$^+$) $^{12}_{\Lambda }$B will be used in order to study the detailed structure of a typical $p$-shell $\Lambda$ hypernucleus in a qualitative way. In particular, the precision spectrum of $^{12}_{\Lambda }$B can be compared to its the mirror symmetric hypernuclei, $^{12}_{\Lambda }$C, which was studied with high statistics but limited resolution by the $( \pi ^ + ,{\rm K}^ +)$ reaction.

This experiment can now be undertaken with some confidence due to the pioneering and successful E89-009 experiment, completed in the spring of 2000. We have made a through examination of this experiment, and propose a new experimental geometry for the (e,e'K$^{+}$) reaction. This geometry will reduce the bremsstrahlung count-rate in the electron spectrometer, which limited the production rate in the experiment, while preserving the resolution and increasing the signal rate. To increase the coincidence rate and improve the resolution a new high-resolution, large-acceptance kaon spectrometer (HKS) is under construction to replace the SOS spectrometer which was used in E89-009.

This proposed experiment will be the first of the series of studies we would intend to undertake using the new kaon spectrometer.

next up previous
: Physics Motivation and Experimental
Satoshi N. Nakamura 平成16年12月2日