Experimental investigations of the hypernucleus _Λ⁴H

¹ Institut für Kernphysik, Johannes Gutenberg-Universität, D-55099 Mainz, Germany
² Department of Physics, University of Ljubljana, and Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
³ Helmholtz Institute Mainz, D-55099, Mainz, Germany
⁴ Department of Physics, University of Zagreb, HR-10002 Zagreb, Croatia
⁵ LPC-Clermont, Université Blaise Pascal, CNRS/IN2P3, F-63177 Aubière Cedex, France
⁶ Department of Physics, Tohoku University, Sendai, 980-8571, Japan
⁷ Yerevan Physics Institute, 375036 Yerevan, Armenia
⁸ Department of Physics, Hampton University, Hampton, Virginia 23668, USA

^a e-mail: patrick@kph.uni-mainz.de
^b Part of doctoral thesis.
^c Present address: Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
^d Present address: Research Center for Electron Photon Science, Tohoku University, Sendai 982-0826, Japan.

Published online: 25 March 2016

Abstract

Negatively charged pions from two-body decays of stopped _Λ⁴H hypernuclei were studied in 2012 at the Mainz Microtron MAMI, Germany. The momenta of the decay-pions were measured with unprecedented precision by using high-resolution magnetic spectrometers. A challenge of the experiment was the tagging of kaons from associated K⁺∧ production off a Be target at very forward angles. In the year 2014, this experiment was continued with a better control of the systematic uncertainties, with better suppression of coincident and random background, improved particle identification, and with higher luminosities. Another key point of the progress was the improvement in the absolute momentum calibration of the magnetic spectrometers.