We calculate the energy levels of the metastable states of an antiprotonic helium atom. The coupled rearrangement channel method is employed to describe a dual character of the atom effectively. Calculated transition frequencies between the metastable states are in good agreement with the observed values. The uncertainty of an antiproton mass is estimated by the calculated transition frequencies with the slightly shifted antiproton mass from the proton mass. When a more accurate value of the charge-to-mass ratio of antiproton is considered, the uncertainty of antiproton mass and charge is estimated at 54 ppb which improves the value recommended by the particle data by a factor of ten.
Authors:Y. Saiki, M. Fukuzaki, T. Sekine, Y. Kino, and H. Kudo
Particle growing processes were investigated for technetium(VII) sulfide (Tc2S7) colloids produced in a mixture of Na2S and TcO4- solutions by laser-induced photoacoustic spectroscopy (LPAS). Analysis of the LPAS signal intensities indicated that the particle size increased in the solution with an increase of standing time, while the number of particles remained constant. It was revealed that the size of colloid particles increased by deposition of Tc2S7 on the particle surfaces, not by coagulation of colloid particles. The formation mechanism and growing process of the colloids are discussed based on the LaMer model, which deals with nucleation processes.