G. Poelz

Nuclear γ-rays following muon capture

Abstract The identification of the nuclear γ-rays that occur when muon capture leads to excited nuclei made it possible to evaluate the distribution of excited nuclei formed after the capture process. Mono-isotopic elements were used as targets, and γ-ray spectra were recorded using Ge(Li) detectors. In most cases the observed γ-rays accounted for a high fraction of the capture process. It could be concluded that the probability of zero neutron emission after muon capture was less than 5 % contrary to the findings of Kaplan and the predictions of Singer. The chance of single neutron emission was highest, about 50 %, and it dropped with increasing neutron multiplicity. The probability of forming a particular excited state in an isotope was in general about proportional to the spin, and about inversely proportional to the energy of the state.

Nuclear radii of light nuclei from muonic X-ray measurements

Abstract Measurements of the muonic 2p-1s transition energies in nuclei with Z ⩽ 17 are reported. Nuclear charge radii are deduced and compared with data from electron scattering.

Pionic 2p level widths in light nuclei

Abstract The yields of muonic and pionic 2p-1s X-ray transitions are given for Be, 10 B. nat B and C. Pionic 2p populations are calculated, and the natural widths of the pionic 2p levels from Be to Na are deduced by comparison with X-ray transition rates calculated with realistic pion wave functions.

Intensities of mesonic 2p - 1s X-rays in N, 16O, 18O, F, and Na

Abstract The yields of pionic and muonic 2p-1s X-rays are given for N, 16 O, 18 O, F, and Na. The populations of the pionic 2p levels are determined and the natural widths are deduced.

Measurement of the vacuum polarization in muonic atoms

The energy levels in atoms are shifted by radiative correc-tions. While in electron atoms the self-energy is dominating com-pared with the vacuum polarization, the opposite holds for muonic atoms. Muonic transitions, where other corrections caused by the finite size and nuclear polarization are small compared to the vacuum polarization, provide an excellent tool for the measurement of the vacuum polarization.

π-mesic 4f-3d and 5g-4f X-ray

Abstract Pionic 4f-3d X-rays from In, I, Cs, La and Pr, and 5g-4f X-rays from Ta, Pt, Au, Hg, Tl 206 Pb, Pb, and Bi have been measured with Ge detectors. Energies and widths were determined, taking quadrupole splitting into account whenever necessary.

Condensed-state effects in muonic X-ray spectra

Abstract Intensity measurements of muonic X-rays in targets of different physical or chemical composition are reported.

New determination of the π− and νμ masses

Abstract The rest mass of the π− meson has been determined by measurements of the energies of π-mesonic X-rays with Ge(Li) detectors to be (139.549 ± 0.008) MeV (standard deviation). An upper limit of 0.6 MeV was deduced for the rest mass of the μ-neutrino (90% confidence).

CONDENSED-STATE EFFECTS IN PIONIC AND MUONIC X-RAY SPECTRA.

Abstract Intensity measurements of pionic and muonic X-rays in targets of different physical or chemical composition are reported.

PIONIC 3d--2p TRANSITIONS.

Abstract Pionic 3d-2p transitions from Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn have been measured with Ge counters. Data for 2p-level shifts and widths are given.