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Energies and intensities of 53 nuclear γ-lines in muonic atoms of Sm, Gd, Eu, Tm, Yb, Ta, W, Re, Os, Ir, Pt, Hg, Tl, and Bi have been measured with Ge(Li) detectors. By comparison with γ-lines from radioactive sources the isomer shifts for transitions from nuclear rotational levels, quadrupole and octupole vibrational levels, and single-particle levels have been deduced. The effect limiting the accuracy of the extracted isomer shifts is the correction for the magnetic hyperfine splitting of the nuclear levels.

Muonic X-ray energies of the K-series of the light natural elements Be, B, C and N have been determined with a precision of 5 to 10 eV. Equivalent nuclear charge radii have been deduced. The results, expressed in terms of rms radii, are of similar or better accuracy than recent electron scattering data. Of particular interest is the rms radius of carbon as a reference value for elastic electron scattering cross sections. A model-independent evaluation yields 〈r 2 〉 1 2 = 2.467 (17) fm .

We have determined the magnetic hyperfine structure (HFS) in four nuclear transitions of muonic 209Bi. The results yielded an improved value of the magnetic HFS constant of the ground state. A 1 ( 9 2 − ) = 2.00 (7) keV . New experimental values were established for three excited states, namely A 1 ( 13 2 + ) = 2.9 (2) keV , A 1 ( 9 2 + ) = 2.1 (2) keV and A 1 ( 15 2 + ) = 2.4 (2) keV . In addition, the isomer shifts (IS) of the above-mentioned transitions were determined making use of the HFS constants. We find the following IS's of excited states: 13 2 + , 3.77 (28) keV ; 9 2 + , 6.56 (32) keV ; 15 2 + , 6.29 (18) keV .

In order to test the QED corrections, and in particular the vacuum polarization, muonic 4f-3d transitions in Ba and Ce and 5g-4f transitions in Tl and Pb have been measured using Ge(Li) detectors. An absolute energy accuracy of ± 8 eV corresponding to a relative error of 17–19 ppm has been obtained. The experimental energies agree with theory within the total uncertainty of ± 10 eV. This corresponds to a test of the QED vacuum polarization calculations of between 0.35 % and 0.50 %.

Energies of muonic X-rays of the Lyman series of seven light natural elements (F, Na, Al, Si, P, S and K) have been determined with an accuracy of between 15 and 30 eV. Equivalent charge radii have been deduced. For μ−-K, transitions to the 2s state allowed an additional constraint on the Fermi c-t diagram. The results are in good agreement with, and generally of an order of magnitude higher precision than, comparable electron scattering data.

The results of precise measurements of the energies of the 2p32−1s12and 2p12−1s12 muonic X-ray transitions of 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo and 100Mo are reported. The data were analyzed in terms of the Barrett moments 〈rke−αr〉 of the nuclear charge distributions from which the equivalent nuclear radii Rk and the differences ΔRk between neighboring isotopes were computed. Systematic shell effects have been observed at the neutron numbers N = 50 and N = 56.

Energies and intensities of muonic X-rays, nuclear γ-rays and μ-capture γ-rays were measured in natural muonic thallium with Ge(Li) detectors. The absolute intensities of higher μ X-rays were reproduced by a cascade calculation starting with a statistical population at n = 20 including K-, L- and M- conversion. The electron screening effect was deduced from energies of higher μ X-rays. Eight prompt nuclear μ-rays were found, due to an excitation of (4.1 ±1.0) % and (14.6 ± 3.0) % of the first 3 2 + level in μ 203 T1 and μ, 205 T1, respectively, and of (8.8 ± 0.9) % of the 5 2 − level at 2.63 MeV in 205 T1. This excitation explains the anomalous intensity ratios of the 2p-ls and 3d-2p fine structure components. From the nuclear y-rays of the first excited states were deduced: the magnetic h.f. splittings e 203 ( 1 2 ) = 2.57 ± 0.15 keV , e 205 ( 1 2 ) = 2.30 ± 0.02 keV, muonic isomer shifts ΔE is (203) = 0.26 ± 0.15 keV, ΔE is (205) = −(0.31 ± 0.11) keV; E2/M1 mixing ratios δ μ 2 (203) = 0.89 ± 0.27, δ μ 2 (205) = 1.00 ± 0.05, and the half-life in the presence of the muon T μ ( 3 2 ) = 1.4 ± 0.1 nsec in 205 T1. The values of e( 1 2 ) and ΔE ls were compared with shell-model calculations. From δ μ 2 and T gm ( 3 2 ) evidence for a magnetic nuclear polarization was found. From the 2p-ls, 3d-2p, 3p-2s and 2s-2p transitions the size and shape of the nuclear charge distribution and a nuclear polarization due to the 1s 1 2 muon of ΔE np = 8.3 ± 1.2 keV and 9.5 ± 1.2 keV for 203 Tl and 205 T1 respectively were determined in agreement with theoretical estimates. An isotope shift of ΔE = 10.35 ± 0.25 keV was measured for the 1s 1 2 state which is compared with data from optical spectroscopy. From an analysis of the time distribution of delayed γ-rays from μ-capture, an isotopic effect of (5.4 ± 2.5) % was found for the capture rates, in fair agreement with predictions from Primakoff's μ-capture formula.

NaI(T1) and Ge(L1) detectors have been used singly and in coincidence to study the gamma rays associated with the decay of 67 h 99 Mo Twenty-four of the twenty-eight observed transitions have been located by energy fit and by coincidence data, the remainder by energy fit alone The resulting decay scheme consists of levels at 140 5 ( 7 2 + ) , 142 6 ( 1 2 − ) , 181 1 ( 5 2 + ) 509 1 ( 3 2 − ) , 534 3, 671 5 ( 5 2 − ) , 761 6 ( 5 2 + ) , 920 5 ( 3 2 + , 1 2 + ) , 1004 0 ( 3 2 − ) , 1072 9 ( 5 2 − ) , 1129 3 ( 1 2 − , 3 2 − ) , 1142 0 3 2 − ) , 1199 ( 1 2 − , 3 2 − )

Electric quadrupole X-ray transitions (5g → 3d, 4f → 2p, and 3d → 1s) have been observed in muonic Tl, Pb and Bi. From the 3 → 1 transitions, energy splittings of the n = 3 levels were deduced. From a comparison of the relative intensities of E1 and E2 transitions, the population ratios 5g 5f , 4f 4d , and 3d 3p were deduced. These ratios are well reproduced by a cascade calculation assuming a statistical initial population at n = 20, including K, L and M shell conversion. In the case of 205 T1 discrepancies between the experimental and the calculated 3d-1s/3p-1s intensity ratio can be explained by nuclear excitation. From the 3 p 3 2 → 1 s 1 2 intensity in 209 Bi we can deduce the ratio of the radiationless to the X-ray transition width and give limits for prompt neutron emission from the 3d level.