Measurement of balmer and lyman X-rays in antiprotonic hydrogen isotopes at pressures below 300 hPa

Abstract

X-Rays of Balmer and Lyman transitions in antiprotonic hydrogen and of Balmer transitions in antiprotonic deuterium were observed at pressures below 300 hPa using Si(Li) semiconductor detectors. The measurement was performed at the LEAR-facility at a beam momentum of 202 MeV/c. In order to stop antiprotons in a low pressure gaseous target with high efficiency, a novel technique, the cyclotron trap has been used. Absolute yields were determined and compared with cascade calculations. A distinct difference in the cascade of antiprotonic hydrogen and deuterium is found. The parameters of strong interaction in antiprotonic hydrogen are determined to beɛ 1s=−(620±100) eV,Γ 1s=(1130±170) eV andΓ 2p=(32±10) meV.