Status and future plan of the spectroscopy of pionic atoms

Y Watanabe ,Hiroshi Suzuki ,Yo Murakami ,N Fukuda ,N Inabe ,K Todoroki ,K Itahashi ,M Dozono ,K Tsukada ,Kota Okochi ,Hiroyuki Miya ,K Suzuki ,Hiroyuki Takeda ,M Takaki ,N Nakatsuka ,H Geißel ,K Miki ,S Ota ,H Yamakami ,H Weick ,Masaki Nakamura ,R Hayano ,D Kameda ,Hiroaki Matsubara ,T Uesaka ,G.p.a Berg ,Hiroyuki Fujioka ,T Kubo ,Y K Tanaka ,S Michimasa ,Takahiro Nishi ,S Noji ,Satoshi Itoh ,Hiroyuki Yamada ,T Furuno ,Kôichi Yoshida

doi:10.1088/1742-6596/503/1/012037

Abstract

The spectroscopy of deeply bound pionic atoms provides a way to understand the restoration of chiral symmetry breaking at finite density. We have been performing a series of experiments of missing-mass spectroscopy of the (d,3He) reaction at RIBF to investigate pionic atoms of several Sn isotopes. As a first step, we conducted a pilot experiment to measure deeply bound pionic states of 121Sn and successfully observed the deeply bound pionic states. In addition to the experiment at RIBF, we are planning the spectroscopy of deeply bound pionic atoms in inverse kinematics and conducted a feasible study by simulations. We showed that by using a deuterium gaseous active target TPC and silicon detectors, the Q-value resolution is about 500 keV (FWHM) and the yield of the pionic 1s state is 20 counts/day, indicating the experiment is feasible.

Highlights

Chiral symmetry and its spontaneous breakdown plays an important role in the low energy quantum chromodynamics
Feasibility study of the spectroscopy using inverse kinematics We are planning to conduct the spectroscopy of pionic atoms with unstable nuclei
In order to use unstable nuclei, the inverse kinematics method is adopted where heavy ions are used as a beam and deuterons are used as a target

Summary

Introduction

Chiral symmetry and its spontaneous breakdown plays an important role in the low energy quantum chromodynamics. The chiral symmetry is known to be restored in hot or dense medium and the order parameter of the chiral symmetry breaking | qq | is reduced[1, 2]. The spectroscopy of deeply-bound pionic atoms is one of the methods that enables us to investigate experimentally the chiral symmetry restoration in the nuclear medium. The order parameter | qq | is related. Published under licence by IOP Publishing Ltd to the isovector parameter b1 of the s-wave part of the pion-nucleus optical potential[3, 4, 5, 6]

Methods

Results

Conclusion