Mainz 2012 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 30: Hadronenstruktur und -spektroskopie
HK 30.2: Talk
Wednesday, March 21, 2012, 17:00–17:15, RW 1
Precise spectroscopy of pionic atoms at RIKEN — •H. Weick1, G.P.A. Berg2, H. Fujioka3, H. Geissel1, R.S. Hayano4, S. Hirenzaki5, N. Ikeno5, N. Inabe6, K. Itahashi6, S. Itoh4, D. Kameda6, T. Kubo6, H. Matsubara4, S. Michimasa4, K. Miki7, H. Miya4, M. Nakamura6, T. Nishi4, S. Noji4, S. Ota4, K. Suzuki8, H. Takeda6, K. Todoroki4, K. Tsukada9, T. Uesaka6, and K. Yoshida6 — 1GSI, Darmstadt — 2Notre Dame University, USA — 3Kyoto University, Japan — 4University of Tokyo, Japan — 5Nara Women’s University, Japan — 6RIKEN, Japan — 7Osaka University, Japan — 8SMI Vienna, Austria — 9Tohoku University, Japan
Precision spectroscopy of pionic atoms provides unique information on the isovector πN interaction connected to the reduction of the chiral symmetry breaking at normal nuclear density. Experiments at GSI on Sn isotopes yielded the first quantitative estimation of its reduction to be about 33% compared to that in the vacuum [PRL92(2004)072302].
The pionic atoms are formed on the target nucleus in a Sn(d,3He) reaction. The new BigRIPS separator can accept much more 3He and the RIKEN SRC cyclotron can deliver much higher deuteron beam intensity than in the former experiments, but require a careful dispersion matching in the spectrometer to achieve the resolution despite a much worse momentum spread and position detectors for MHz count rate.
The results of bound states in 122Sn from the 2010 experiment at RIKEN will be discussed with respect to the achievable resolution as well as the necessary calibration steps be explained.