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The X-ray cascade from antiprotonic atoms was studied for 208Pb and 209Bi. Widths and shifts of the levels due to the strong interaction were determined. Using modern antiproton-nucleus optical potentials the neutron densities in the nuclear periphery were deduced. Assuming two parameter Fermi distributions (2pF) describing the proton and neutron densities the neutron rms radii were deduced for both nuclei. The difference of neutron and proton rms radii /\r_np equal to 0.16 +-(0.02)_{stat} +- (0.04)_{syst} fm for 208Pb and 0.14 +- (0.04)_{stat} +- (0.04)_{syst} fm for 209Bi were determined and the assigned systematic errors are discussed. The /\r_np values and the deduced shapes of the neutron distributions are compared with mean field model calculations., 22 pages, 8 tables, 15 figures

2 pages, 1 table, 1 figure.-- PACS nrs.: 21.10.Tg, 23.20.Lv, 27.90.+b., The low-energy structure of Ac-231 has been investigated by means of γ, conversion electrons, γ-γ and γ-e- spectroscopy following the β(-)-decay of Ra-231. Here, we report on the precise determination of the Ra-231 β-decay half-life.

15 pages, 6 tables, 10 figures.--PACS nrs.: 23.20.Lv; 23.20.Nx; 21.10.Tg; 27.50.+e, The properties of the excited states of Kr-76, populated in the decay of Rb-76 produced at ISOLDE isotopic separator, have been investigated by using K-conversion electron, gamma-ray, and gamma-gamma coincidence measurements. The lifetimes of several levels have been measured by means of the advanced time-delayed beta gamma gamma(t) method. The identification of 19 new levels and 55 transitions and the information deduced on spin and/or parity of the observed states from K-conversion coefficients, log ft values and decay properties have led to an improved knowledge of the level scheme. In particular, six 1(-) states have been definitely identified and J(pi)=2(-) has been assigned to the 2227 keV level, on which a band proposed to have negative-parity and even-spin had been previously observed. The strengths of the E0 and E2 transitions deexciting the 0(2)(+) and 0(3)(+) states (the latter is here identified with the state at 1598 keV) have been measured. The experimental data concerning the 0(2)(+) state have been analyzed in a simple two states mixing model and in the framework of the proton-neutron interacting boson model., This work was supported in part by the Swedish Research Council, the Spanish C.I.C.Y.T. under Contract No.AEN94-0833-C02-02, the Norwegian Research Council and the Polish Scientific Research Committee.

25 pages, 5 tables, 9 figures.-- PACS nrs.: 21.10.-k; 23.20.-g; 23.20.Lv; 23.20.Nx.-- Available online Dec 5, 2001., The γ-rays following the β- decay of Ac-229 have been investigated by means of γ-ray singles and γγ-coincidence measurements using Ge detectors. Multipolarities of 40 transitions in Th-229 have been established by measuring conversion electrons with a mini-orange electron spectrometer. The half-lives of the 146.35, 164.53 and 261.96 keV levels have been measured using the advanced time delayed betagammagamma(t) method. The low-lying states in Th-229 and observed transition rates have been interpreted within the quasiparticle-phonon model with inclusion of Coriolis coupling. Two octupole correlated parity partner bands, with K-π = 5/2(±) and K-π = 3/2(±), were identified in Th-229., This work was supported in part by the Polish Scientific Research Committee, the Swedish Natural Science Research Council, the Norwegian Research Council, the Spanish CICYT under contracts AEN94–0833-C02–02 and AEN96–1662, the Canadian Natural Sciences and Engineering Research Council, the Grant Agency of Czech Republic under the contract 202/99/1718, and UK Engineering and Physical Science Research Council.

38 pages, 8 tables, 9 figures.-- PACS nrs.: 23.20.-g; 21.10.Tg; 21.10.Re; 27.90.+b.-- Printed version published Apr 9, 2001., The structure of Ra-231, the heaviest odd Ra nucleus currently accessible for detailed spectroscopic investigation, has been studied in the beta (-) decay of Fr-231. The main purpose has been to verify whether fast B(E1) rates and significant octupole correlations recently established in Ra-229 persist in Ra-231. The excited stares in Ra-231 have been determined for the first time. Spins and parities have been deduced from conversion electron measurements, while level half-lives in the ps and ns ranges have been measured with the Advanced Time Delayed beta gamma gamma (t) method. The moderately fast B(E1) rates found For transitions connecting the lowest-lying K-pi = 5/2(+/-) and K-pi = 1/2(+/-) hands, reveal the persistence of octupole collective effects in Ra-231, although the B(E1) rates are lower than in Ra-229. These findings reinforce the differences in the B(E1) systematics between isotonic Ra and Th nuclei., This work was partially supported by the Spanish CICYT “Plan Nacional de Altas Energías” (under contracts AEN96-1662 and AEN96-1679), the Swedish Natural Science Research Council, the Czech Republic Grant Agency (under grant 202/99/1718) and the Polish Scientific Research Committee. L.M. Fraile would like to thank the OSIRIS group at Studsvik in Sweden for their generous hospitality and the Margit & Folke Pehrzon Foundation for the financial support for his stay at Studsvik.

36 pages, 5 tables, 9 figures.-- PACS nrs.: 23.20.−g; 21.10.Tg; 21.10.Re; 27.90.+b., The structure of Ra-229 has been studied in the β- decay of Fr-229. Spins and parities have been determined from the conversion electron measurements, while half-lives for the 137.5, 142.7, 168.8, 213.0 and 479.0 keV levels have been measured in the ps and ns ranges via the fast timing βγγ(t) method. Our data confirm the previous results and enrich the knowledge of the structure of this nucleus by 25 new states and several strong transitions. Structural similarities are established between Ra-229 and its N = 141 isotone Th-231. The experimental results are compared with the theoretical predictions of the quasiparticle-phonon model with inclusion of Coriolis coupling. The reduced transition probabilities, and especially the moderately fast B(E1) rate for the 137.5 keV transition connecting the band-heads of the K-π = 5/2(±) parity doublet bands, reveal the presence of significant octupole correlations in Ra-229., This work was partially supported by the Spanish CICYT "Plan National de Altas Energias" (under contracts AEN96-1662 and AEN96-1679), the Margit & Folke Pehrzon Foundation, the Swedish Natural Science Research Council, Czech Republic Grant Agency (under contract 202/96/ 1744) and the Polish Scientific Research Committee (under grant KBN-2-P03B-OOl-11).

19 pages, 4 tables, 4 figures.-- PACS nrs.: 21.10.-k; 23.20.-g; 23.20.Lv; 23.20.Nx., Spins and parities for collective states in Ra-228 have been determined from conversion electron measurements with a mini-orange β spectrometer. The fast-timing βγγ(t) method has been used to measure lifetimes of T(1/2) = 550(20) ps and 181(3) ps for the 2(1)(+) and 4(1)(+) members of the K = 0(+) band, and T(1/2) ≤ 7 ps and ≤ 6 ps for the 1(1)(-) and 3(1)(-) members of the K = 0(-) band, respectively. The quadrupole moments, Q(0), deduced from the B(E2;2(1)(+) --> 0(1)(+)) and B(E2;4(1)(+) -->2(1)(+)) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(EI) rates of ≥ 4 x 10(-4) e(2)fm(2), which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for Ra-228. The new results are consistent with the B(E1) rates recently measured for the neighbouring Ra-227 and reveal octupole correlations in Ra-228., This work was supported in part by the Polish Scientific Research Committee under grant KBN-2-P03B-001-11, the Swedish Natural Science Research Council, the Norwegian Research Council, the Spanish C.I.C.Y.T. under contracts AEN94-0833-C02-02 and AEN96-1662, the Canadian Natural Sciences and Engineering Research Council, and UK Engineering and Physical Science Research Council. One of us (K.G.) would also like to thank the OSIRIS group for their generous hospitality and financial support during the stay at Studsvik.

26 pages, 4 tables, 10 figures.-- PACS nrs.: 21.10.−k; 23.20.−g; 23.20.Lv; 23.20.Nx., The γ-rays following the β- decay of Rn-227 have been investigated by means of γ-ray singles and γγ-coincidence measurements using an array of 12 Compton-suppressed Ge detectors. The fast-timing βγγ(t) method has been used to measure six level lifetimes. Multipolarities of 32 transitions in Fr-227 have been established by measuring conversion electrons with a mini-orange electron spectrometer. Most of the observed transitions have been placed in a level scheme comprising 38 excited states of Fr-227, The low-lying levels are interpreted in terms of seven rotational bands. The observed E1 strengths for two transitions connecting the K-π = 3/2(±) bands are consistent with the transitional character of Fr-227, and confirm the presence of octupole correlations in this nucleus., This work was supported in part by the Natural Sciences and Engineering Research Council of Canada, the Norwegian Research Council, the Polish Scientific Research Committee under grant KBN-2-P03B-001-11, the Spanish CICYT under contracts AEN94-0833-C02-01 and AEN94-0833-C02-02, the Swedish Natural Science Research Council, and the UK Engineering and Physical Sciences Research Council. J.F.C.C. and J.F.S. acknowledge receipt of EPSRC studentships.