A fiber detector concept is suggested allowing to registrate particles within less than 100 nsec with a space point precision of about 100 {mu}m at low occupancy. The fibers should be radiation hard ...for 1 Mrad/year. Corresponding prototypes have been build and tested at a 3 GeV electron beam at DESY. Preliminary results of these tests indicate that the design goal for the detector is reached.
The energy and line shape of the 3P-1S transition in pionic hydrogen have been measured with a reflecting crystal spectrometer combined with a cyclotron trap and Charge Coulped Devices (CCDs). The ...instrumental resolution was 0.7 eV (FWHM) at 2.9 keV. Results for the strong interaction energy shift and broadening of the ground state and the corresponding πN s-wave scattering lengths will be presented soon.
The previously unmeasured neutron time-of-flight distributions for the reaction pisup minusital pr arrowpisup 0ital n in gaseous targets at pressures of 17 and 40 bar have been measured. The kinetic ...energy of the pisup minusital p atoms at the instant of the nuclear reaction has been evaluated from the Doppler broadening of the neutron time-of-flight spectra. Evidence was found for pisup minusital p atoms with kinetic energies of 75 eV. The present experimental data were interpreted within a cascade model that takes the evolution of the kinetic-energy distribution during the cascade into account. The parameters of the model were determined from experiments measuring neutron time of flight in liquid hydrogen and x-ray yields in gas. Coulomb deexcitation is responsible for the significant fraction of the high-energy component, whose intensities are compatible with the calculations of Bracci and Fiorentini Nuovo Cimento 43A, 9 (1978). Stark mixing is found to be significantly stronger than in the commonly used straight-line approximation; the initial mean kinetic energy of 1--2 eV is consistent with the results of muonic hydrogen. The model therefore describes the cascade of pionic hydrogen over a range of pressures of three orders of magnitude. The implications for high-resolution x-ray measurements of the 1ital S-level nuclear width are discussed.
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