Search

Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new QEC=5437±67 keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+⟶1+) as B(GT)=2.94−0.28+0.32. Investigation of this result in state-of-the-art shell model approaches accounting for the first time experimentally observed spectrum of GT transitions points to a perfect agreement for N=50 isotones. The excitation energy of the long-lived isomeric state in $^{94}$Rh was determined for the first time to be 293±21 keV. This, together with the shell model calculations, allows the level ordering in $^{94}$Rh to be understood.

The main motivation for the European Commission (EC) to fund Integrating Activities (IAs) is to offer transnational access to Europe’s leading research infrastructures, including those of Nuclear P...

Rolf H. SiemssenOn 29 January 2021, Professor Rolf H. Siemssen passed away. He meant a lot to many of us and for the nuclear physics community nationally and internationally. We have lost a very co...

It has been discussed that lightning flashes emit high-energy electrons, positrons, photons, and neutrons with single energies of several tens of MeV. In the first part of this paper we study the absorption of neutron beams in the atmosphere. We initiate neutron beams of initial energies of 350 keV, 10 MeV, and 20 MeV at source altitudes of 4 km and 16 km upward and downward and see that in all these cases neutrons reach ground altitudes and that the cross-section areas extend to several km2. We estimate that for terrestrial gamma-ray flashes approximately between 10 and 2000 neutrons per ms and m2 are possibly detectable at ground, at 6 km, or at 500 km altitude. In the second part of the paper we discuss a feedback model involving the generation and motion of electrons, positrons, neutrons, protons, and photons close to the vicinity of lightning leaders. In contrast to other feedback models, we do not consider large-scale thundercloud fields but enhanced fields of lightning leaders. We launch different photon and electron beams upward at 4 km altitude. We present the spatial and energy distribution of leptons, hadrons, and photons after different times and see that leptons, hadrons, and photons with energies of at least 40 MeV are produced. Because of their high rest mass hadrons are measurable on a longer time scale than leptons and photons. The feedback mechanism together with the field enhancement by lightning leaders yields particle energies even above 40 MeV measurable at satellite altitudes.

It has been discussed that lightning flashes emit high‐energy electrons, positrons, photons, and neutrons with single energies of several tens of MeV. In the first part of this paper we study the absorption of neutron beams in the atmosphere. We initiate neutron beams of initial energies of 350 keV, 10 MeV, and 20 MeV at source altitudes of 4 km and 16 km upward and downward and see that in all these cases neutrons reach ground altitudes and that the cross‐section areas extend to several km2. We estimate that for terrestrial gamma‐ray flashes approximately between 10 and 2000 neutrons per ms and m2 are possibly detectable at ground, at 6 km, or at 500 km altitude. In the second part of the paper we discuss a feedback model involving the generation and motion of electrons, positrons, neutrons, protons, and photons close to the vicinity of lightning leaders. In contrast to other feedback models, we do not consider large‐scale thundercloud fields but enhanced fields of lightning leaders. We launch different photon and electron beams upward at 4 km altitude. We present the spatial and energy distribution of leptons, hadrons, and photons after different times and see that leptons, hadrons, and photons with energies of at least 40 MeV are produced. Because of their high rest mass hadrons are measurable on a longer time scale than leptons and photons. The feedback mechanism together with the field enhancement by lightning leaders yields particle energies even above 40 MeV measurable at satellite altitudes., Key Points A terrestrial gamma‐ray flash between 10 and 2000 neutrons per ms and m2 is possibly detectable at 0 km, 6 km, or 500 km altitudeCombining the feedback mechanism with the electric fields of lightning leaders can explain beams of leptons and photons above 40 MeVThe cross‐section area of neutron beams between 350 keV and 20 MeV initiated at 4 km and 16 km altitude extends to several km2

14th International Workshop on Meson Production, Properties and Interaction, Cracow, Poland, 2 Jun 2016 - 7 Jun 2016; The European physical journal / Web of Conferences Web of Conferences : proceedings proceedings 130, 02010 (2016). doi:10.1051/epjconf/201613002010, We performed a missing-mass spectroscopy experiment of the ^12C(p, d) reaction at 2.5 GeV proton energy in order to search for eta' mesic nuclei. An excitation-energy spectrum of ^11C was obtained around the eta' production threshold. As no significant peak structure was observed in the spectrum, upper limits of the formation cross section of eta' mesic nuclei have been determined. Preliminary results of the experiment as well as future prospects are given., Published by EDP Sciences, Les Ulis

Editorial; International audience; During the period from September 2010 to December 2014, the European project European Nuclear Science and Applications Research (ENSAR) coordinated research activities of the Nuclear Physics community performing research in three major subfields: Nuclear Structure, Nuclear Astrophysics, and Nuclear Applications.

The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a $^{9}$Be target with a $^3$He beam at an incident energy of 30 MeV. Angular distributions for $^9$Be($^3$He,$^3$He)$^{9}$Be, $^9$Be($^3$He,$^4$He)$^{8}$Be, $^9$Be($^3$He,$^5$He)$^{7}$Be, $^9$Be($^3$He,$^6$Li)$^6$Li and $^9$Be($^3$He,$^5$Li)$^7$Li reaction channels were measured. Experimental angular distributions for the corresponding ground states (g.s.) were analysed within the framework of the optical model, the coupled-channel approach and the distorted-wave Born approximation. Cross sections for channels leading to unbound $^5$He$_{g.s.}$, $^5$Li$_{g.s.}$ and $^8$Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of $^{9}$Be was obtained from the transfer channels. It was concluded that cluster transfer is an important mechanism in the investigated nuclear reactions. In the present work an attempt was made to estimate the relative strengths of the interesting $^8$Be+$n$ and $^5$He+$\alpha$ cluster configurations in $^9$Be. The branching ratios have been determined confirming that the $^5$He+$\alpha$ configuration plays an important role. The configuration of $^9$Be consisting of two bound helium clusters $^3$He+$^6$He is significantly suppressed, whereas the two-body configurations ${}^{8}$Be+$n$ and ${}^{5}$He+$\alpha$ including unbound $^8$Be and $^5$He are found more probable.

In 2013 NuPECC celebrated its 25th birthday. A quarter of a century of continuous and successful work of this expert board clearly deserves special attention and a moment of reflection. On this occasion, a ceremony was organiszd in Krakow on 11 October 2013 in the presence of a number of NuPECC chairs—Juha Aysto, Angela Bracco, Brian Fulton, Sydney Gales, Muhsin Harakeh, Gunther Rosner—the present NuPECC members (see http://www.nupecc.org/index.php?display=staff/list), and our permanent scientific secretary Gabriele-Elisabeth (Sissy) Korner (Figure 1). Sissy Korner, who has been connected with NuPECC from the very beginning, deserves special thanks for her dedication and efforts over the years that have been essential to carry out the mission and activities of NuPECC with success.

In the fusion-fission reaction {sup 40}Ar+{sup 116}Cd{r_arrow}{sup 156}Dy{r_arrow}fission, performed at beam energies {ital E}{sub {ital b}}=216 MeV and 238 MeV, {gamma} rays were measured in coincidence with fission fragments. The {gamma}-ray spectra are interpreted using a modified version of the statistical-model code CASCADE. From a comparison of the experimental and calculated spectra it is deduced that the nuclear viscosity is in the range 0.01{lt}{gamma}{lt}4. The extracted fission time scale is of the order of 10{sup {minus}19} s. {copyright} {ital 1996 The American Physical Society.}

The strength distribution of high-energy γ-rays emitted in the statistical decay of the 156 Dy ∗ compound nucleus, with E ∗ = 92.5 MeV , has been measured inclusively and for selected decay pathways in which isomers in 149 Dy, 151 Dy and 152 Dy were populated. For both spectra a deformation | β | = 0.3 is deduced and the centroid energies agree with those found from ground-state systematics. The high-energy γ-ray spectrum triggered on isomeric decay shows an increase of the width of the GDR in comparison with the inclusive spectrum.

Equilibrium charge-state distributions for singly and doubly ionized [sup 3]He ions of energy [ital E]([sup 3]He)=200 MeV ([beta]=0.36) have been measured for atomic targets ranging from carbon to bismuth ([ital Z]=6,14,28,40,50,67,73,83). A magnetic spectrometer was used to simultaneously measure the rate of [sup 3]He[sup +] ions and the current of the incident beam of [sup 3]He[sup 2+] ions. The ratio of the fraction of ions [ital Y]([sup 3]He)[sup +]/[ital Y]([sup 3]He[sup 2+]) was found to increase from 3[times]10[sup [minus]9] for [ital Z]=6 to 2[times]10[sup [minus]7] for [ital Z]=83. Very good agreement with the experimental ratios was obtained for calculated ratios based on theoretical stripping (ionization) and capture cross sections. The cross sections are dominated by capture from [ital K] orbits only for atoms up to about [ital Z]=25. For target atoms with high [ital Z], contributions up to principal quantum numbers [ital n]=4 ([ital N] orbits) must be included.

The (e, e'd) reaction has been measured on 4 He, 6 Li, and 12 C. The theoretical description of this reaction is discussed both in a quasielastic cluster-knockout approach and in a microscopic approach. Results of these descriptions are compared with the measured (e, e'd) cross sections as a test of the deuteron-knockout mechanism and of the possibility of extracting nuclear-structure information. It is shown that a quasielastic approach is valid only in limiting cases like the 6 Li(e, e'd) reaction. The excitation of a T = 1 state in the 12 C(e, e'd) 10 B reaction can be described in the microscopic approach as a transition from a 1 S 0 pn cluster to a 3 S 1 deuteron. The form of the momentum distributions extracted from the data within a semi-microscopic approach, representing the motion of the pn cluster in the nucleus, is in global agreement with model calculations. However, the dependence of the measured cross sections as a function of momentum transfer is not well described, which results in a sizable uncertainty in the absolute normalization of the extracted momentum distributions.

The isospin-forbidden neutron decay of the isobaric analog state in Bi-208 has been measured, following its excitation via the Pb-208(He-3, t)Bi-208 reaction at 61.2 MeV. In contrast to the proton decay, which is direct, the neutron decay spectrum has a statistical shape. Its branching ratio is determined to be (37 +/- 3)%. The results suggest that the damping of the isospin impurity is fast. Therefore, neutron decay results mostly from the final stage of the damping process and does not contribute to the width of the IAS.

Electron scattering on the fp-shell nuclei 65 Cu and 71 Ga has been investigated. Measurements have been performed up to a momentum transfer of 2.7 fm −1 at forward and at backward scattering angles in order to separate the transverse and longitudinal form factors of the low-lying excited states. This allowed the extraction of the transition densities and probabilities, which are compared to particle-core coupling calculations: particle-vibration coupling model (PVCM) and quasiparticle-cluster vibration model (QCVM). These models appear to be more applicable to 65 Cu than to 71 Ga. Reasons for this are discussed. In general the transition charge densities confirm the distinction between quasiparticle states and collective excitations, that one expects already on the basis of spectroscopic factors. The relative importance of quasiparticle and phonon contributions to the transitions is reflected in the specific shapes of the transition densities for each level. Transition current densities are often less well predicted than charge densities and are quite sensitive to the model used.

The isoscalar giant dipole resonance (ISGDR) in 208Pb has been investigated using inelastic scattering of 200 MeV α particles at and near 0° where the angular distribution of the ISGDR can be clearly differentiated from other modes. The “difference of spectra” technique was employed to separate the contribution from the high-energy octupole resonance (HEOR). Results from a preliminary analysis of the data are consistent with the expected positions of the ISGOR and HEOR, as well as their expected angular distributions near 0°.

The cross section of the isovector giant dipole resonance (GDR) has been measured in the Sn-116, Sn-124(alpha, alpha'gamma0), 150Nd(alpha, alpha'gamma0) and Pb-208(alpha, alpha'gamma0) reactions at E(alpha) = 120 MeV and 0-degrees less-than-or-equal-to THETA(alpha') less-than-or-equal-to 3-degrees. The results are compared with DWBA calculations performed with nuclear GDR form factors that depend on the relative difference between the radii of proton and neutron distributions (DELTAR(PN)/R0). Taking a linear combination of form factors provided by the Gold-haber-Teller and Steinwedel-Jensen models in a ratio that fits the GDR systematics, the DELTAR(PN) Values for Sn-116, 124Sn and Pb-208 were deduced by comparing measured and calculated cross sections to be 0.02 +/- 0.12 fm, 0.21 +/- 0. 11 fm, and 0. 19 +/- 0.09 fm, respectively. For the deformed 150Nd, the neutron-skin thickness along and perpendicular to the symmetry axis was found to be 0.22 +/- 0.16 and 0.50 +/- 0.15 fm, respectively, yielding beta2n/beta2p = 0.92 +/- 0.08.

Expérience GANIL/LISE/EXOGAM; International audience; We have performed the first direct lifetime measurement of the state in 74Zn. The neutron-rich 74Zn beam was produced by in-flight fragmentation of 76Ge at the Grand Accélérateur National d'Ions Lourds and separated with the LISE spectrometer. The lifetime of the state was measured by the recoil-distance Doppler-shift method with the Cologne plunger device combined with the EXOGAM detectors.

Two positive-parity and two negative-parity groups of states of non-collective character with excitation energies ranging from 3 to 7 MeV and spins as high as 21 ħ have been established in 192 Pb. The main features of each group are described phenomenologically as four-quasiparticle configurations, arising from coupling of the 2 + 1 , 4 + 1 and 6 + 1 states to a specific aligned neutron two-quasiparticle configuration. Supporting evidence for this interpretation and the importance of proton excitations in this singly closed-shell nucleus is obtained from the predictions of the quasiparticle multi-step shell model (QMSM). In addition, a four-quasiparticle structure of predominant neutron character is proposed on the basis of comparisons with the experimental data on 194 Pb and with the results of the QMSM calculations.

The structure of 192Pb has been investigated using the 173Yb(24Mg, 5n) reaction at Eb = 132 MeV. The level scheme has been extended up to an excitation energy of 7 MeV and a spin of 23 ħ. Two collective bands of levels linked by M1 transitions and four groups of states of non-collective character have been observed. Based on comparison with experimental data on odd-A Tl isotopes and with cranked shell-model calculations assuming an oblate shape, the collective Ml bands are interpreted as having an underlying proton 2-quasiparticle configuration coupled to a pair of rotation-aligned i 13 2 neutrons. The four groups of non-collective level-sequences are understood as 4-quasiparticle excitations associated with aligned neutron 2-quasiparticle states that involve a mixture of neutron and proton degrees of freedom.

The low-lying states of 144Nd have been investigated up to an excitation energy of 3.1 MeV by means of high-resolution inelastic electron scattering. Transition charge densities have been extracted for natural-parity states. The experimental data have been compared with the predictions of the quasiparticle-phonon model. The calculations show that both collective and single-particle degrees of freedom are important for describing the low-lying states of 144Nd. A comparison of the present data with data for 142Nd and 142Ce emphasizes the role played by the two valence neutrons outside the N = 82 closed shell.

In a search for nuclear deformation effects in the (e, e'p) reaction, proton knockout from the spherical nucleus 142Nd and the transitional isotope 146Nd has been investigated. Momentum distributions for the transitions to the discrete states below 1.3 MeV excitation energy in 141Pr and below 0.6 MeV in 145Pr have been measured and compared to results of calculations with the Nilsson + BCS model, assuming 146Nd to be deformed and including Coriolis coupling. For the transitions to the 72+ states (1g72 knockout) the spectroscopic strength changes in going from 142Nd to 146Nd but the shape of the momentum distribution remains fairly unchanged. The same is true for the 52+ states. For the transition to the 32+ state at 0.348 MeV in 145Pr, the measured momentum distribution is influenced by a mixture of ∼ 25% s-wave in agreement with the prediction of a close-lying 12+ state in the deformed shell model. The theory is well able to account for the increased level density in 145Pr and for the other experimental features observed, but the calculated spectroscopic factors are systematically larger than the experimental ones.

An experiment was performed to measure the lifetimes of the states in the superdeformed band reported in $^{192}\mathrm{Pb}$. No evidence for such a band was found, despite the fact that the experimental conditions were nearly identical to those of an earlier measurement where this band was proposed. The problems and questions encountered in the analysis are described. The arguments presented here indicate that further measurements are needed to establish the existence of a superdeformed band in this nucleus unambiguously.

The excited states in 150 Nd up to an excitation energy of 2.0 MeV were investigated by inelastic electron scattering. The momentum-transfer range covered was 0.5–2.8 fm −1 . The extracted transition charge densities of the positive-parity states were compared to microscopic Hartree-Fock-Bogoliubov calculations. The overall agreement between the data and the calculations is good, indicating that the dynamic properties of the rotational collective degrees of freedom in statically deformed nuclei can be well described in this microscopic model. The transition charge densities of the positive- and negative-parity states were compared to a macroscopic rotation-vibration model. The agreement between this model and the data is good to excellent, confirming the predominantly collective nature of the excited states of this nucleus. It is shown that by assuming a vibration of a certain multipolarity, it is possible to determine the K -value of the band, of which the state is a member, from the position of the maximum of the transition charge density.

Excited states in 146 Nd up to an excitation energy of 3.0 MeV were investigated by inelastic electron scattering in a momentum-transfer range of 0.5–2.8 fm −1 . Transition charge densities were extracted for natural-parity states with spins ranging from 0 + up to 5 − . The experimental transition charge densities have been compared to microscopic calculations performed in the framework of the quasiparticle-phonon model (QPM) and the density-dependent Hartree-Fock-Bogoliubov model (DDHFB). The QPM assumes a spherical nucleus, whereas the DDHFB model is most suitable for strongly deformed nuclei. Both models are thus complementary in describing this transitional nucleus. On the basis of the DDHFB calculations it is shown that 146 Nd is softly deformed in its ground state; the agreement with the experimental data for the first excited 2 + and 4 + states indicates that at low excitation energies 146 Nd can be considered to be a deformed nucleus. This feature is also analysed and confirmed for the first excited 3 − and 5 − states by means of the macroscopic rotation-vibration model. At higher excitation energies the level structure is well predicted by the QPM. Moreover, all higher states observed in the experiment have transition charge densities peaking at the same radius. This is typical for spherical nuclei. Therefore, it is concluded that 146 Nd is slightly deformed at low excitation energies, but undergoes a shape transition at higher energies, turning spherical.

Electron-induced proton knock-out from the isotones 30Si, 31P and 32S is studied. The extracted r.m.s. radii of the bound-state wave functions, momentum distributions and spectral functions are presented and the systematics are discussed. The momentum distributions and r.m.s. radii for knock-out from the 2s12 and 1d52 orbitals are found to be similar for all three isotones. The 2s12 orbit is filled smoothly in going from 30Si to 32S, but it is neither completely empty nor completely filled in 30Si and 32S, respectively. The experimental results are compared to shell-model calculations and to the results of a quasi-particle phonon model calculation. Although the distribution of spectroscopic strength as a function of energy can be reproduced reasonably well by the latter model, its value, integrated up to 24 MeV excitation energy, is not compatible with the model value.

The 1 hBAR-omega low-energy isoscalar dipole strength has been studied in Pb-208, Zr-90, Ni-58 and Ca-40, using the (alpha, alpha'gamma(0)) reaction at 0-degrees. The fraction of the isoscalar dipole EWSR exhausted by the observed 1- states in the four nuclei is at maximum 14.7%, 8.0%, 5.0% and 4.3%, respectively.

The low-lying excited states in 142 Nd were investigated by inelastic electron scattering. The momentum transfer range covered was 0.5–2.8 fm −1 . Transition charge densities were extracted for natural-parity states from 0 + up to 9 − and up to an excitation energy of 3.5 MeV. For several new excited states spin and parity assignments have been suggested. The experimental transition charge densities have been interpreted with the aid of the quasiparticle-phonon model (QPM). The QPM is well-suited to investigate the contribution of collective and single-particle degrees of freedom to excited states in spherical nuclei. On the basis of the QPM calculations it is shown that in 142 Nd both degrees of freedom play an important role, as well as the interplay between them. Both the strength distribution and the structure of the transition charge densities of the low-lying excited states are well described by the calculations. The origin of the structure in the nuclear interior usually predicted by microscopic calculations but not observed experimentally is explained. An argument for the proton number dependence of the excitation energy of the 3 1 − state in the N = 82 isotones is given.

Inelastic electron scattering off 110Cd and 104,106,108,110Pd was studied in an effective momentum transfer range 0.3–2.55 fm−1. The form-factor data were analyzed in a model-independent Fourier-Bessel expansion. Excitation energy spectra and transition strengths have been calculated in the framework of the interacting boson approximation, in a model space extended with one g-boson. The behaviour of the experimental transition charge densities extracted for hexadecapole excitations was used to study in detail effects of the addition of one hexadecapole g-boson on the dynamic properties of low-lying collective excitations in this mass region.

Expressions are derived for the use of an explicit folding model in the analysis of inelastic proton scattering. It is shown that the use of phenomenological (transition) potentials can be considered to be a form of implicit folding. Differential cross sections from the 28Si(p,p′)28Si reaction at Ep = 26.3 and 65 MeV have been analyzed with a folding model based on the effective nucleon-nucleon interaction of Jeukenne, Lejeune and Mahaux. Coupled-channels calculations with a rotation-vibration model have been performed for the 0+, 2+, 4+ and 6+ members of the (rotational) ground-state band, the 3−, 4− and 5− members of a Kπ = 3− octupole band and the 1− and 3− members of a Kπ = 0− or 1− octupole band. For most states a satisfactory description could be obtained. However, the situation with respect to the 1− state is quite unsatisfactory. Two excited 0+ states can also be described reasonably with a macroscopic nuclear model. The members of the ground-state band, the two excited 0+ states and several other positive-parity states were also analyzed in coupled-channels calculations using transition densities obtained with a microscopic model. The ground-state band is described reasonably, for the other states the description is less satisfactory.

The (He-3, t) charge-exchange reaction has been studied at theta = 0-degree-C and bombarding energies of E(He-3) = 76.5 MeV and 200 MeV. Spectra were measured using magnetic analysis for target nuclei of C-12, C-13, O-16, F-19, Si-28, Si-29, Si-30, Zr-90, Sn-117, Sn-120, (nat)Ta, (nat)W, Au-197, Pb-208, Th-230, Th-232, U-234, U-236, U-238 and Pu-244. The measurements at 76.5 MeV concentrated on the isobaric analog states of several actinide nuclei, particularly on their widths and the branching ratios for proton decay. Cross sections, Q-values and total widths were determined for the transitions to the isobaric analog states. Coulomb displacement energies derived from the measured Q-values display the influence of deformed nuclear shapes. Escape widths GAMMA-up and spreding widths GAMMA-down of the isobaric analog states in five actinide nuclei were deduced from the measured proton-decay branching ratios. They were found to be in agreement with predictions which postulate isospin mixing via the Coulomb force with the (T0-1)-component of the isovector giant monopole resonance. The measurements at 200 MeV were concerned with transitions to isobaric analog states in both light and heavy nuclei, including several actinide nuclei, but Gamow-Teller resonances and transitions to numerous other states were also observed. The measured cross sections for several transitions to isobaric analog states from Si-30 to Pb-208 were used to extract the effective interaction V(tau) for non-spin-flip (He-3, t) charge exchange at E(He-3) almost-equal-to 200 MeV. The interaction strength V(tau) decreases by a factor 0.6 when compared to previously measured values for the energy range E(He-3) = 65 to 90 MeV. An angular distribution from theta(t) = 0-degree to 16-degrees for the transition to the isobaric analog state in Sb-120 measured at E(He-3) = 200 MeV was found to be in very good agreement with microscopic calculations.

Angular distributions from the 28 Si(p, p') 28 Si reaction at E p = 26.3 MeV have been measured. The resolution obtained was 11–15 keV. Coupled-channels calculations have been performed for the 0 + , 2 + , 4 + and 6 + states of the ground-state band, for the 3 − , 4 − and 5 − memers of a K π = 3 − octupole band and the 1 − and 3 − members of a K π = 0 − octupole band. In most cases, the calculations, which are based on a rotation-vibration model, give satisfactory results. The same analysis for an experiment with 65 MeV polarised protons leads to a consistent description. The analysis of several members of an excited K π = 0 + band (band head at 6.69 MeV) and the 2 + states at 7.38 and 7.42 MeV, which were considered to be of mixed character, did not yield a good description.

Results are presented of a high-resolution inelastic proton scattering experiment on the even Hg isotopes 198Hg, 200Hg, 202Hg and 204Hg performed at Ep=28MeV. Highly enriched targets were used. A special target preparation technique has been developed in order to prepare thin (≈160 μg/cm2) homogeneous targets, which resulted in a high (≈17 keV) energy resolution. Several previously unknown levels were observed. Angular distributions for levels up to between 2.6 and 4.4 MeV (depending on the isotope) have been obtained. The study of these four isotopes made it possible to compare analogous levels in these isotopes. A macroscopic CC analysis, using a symmetric rotational model, was performed for the ground, 2+1 and 4+1 states, which were assumed to be members of a ground-state band. For the 2+2 states a phenomenological CC analysis was performed, yielding Bp(E2)-values that are about a factor of two larger than the electromagnetic B(E2)-values. This is assumed to be due to a large neutron contribution to the excitation of these states. For the analysis of the remaining levels a quasi-DWBA scheme was used, in which the coupling of the 2+1 state with the ground state was included, but no further couplings were taken into account. This allowed making Jπ assignments for some levels. In 200Hg a low-lying 4+ state is observed, which was previously incorrectly given a 3+ assignment, while also in 198Hg and 202Hg low-lying 4+2 states are observed. The summed excitation strength of the 4+1 and 4+2 states appears to be approximately constant in the studied isotopes. From our analysis of the 4+ states there is, in agreement with results from other experiments, evidence that a shape transition may occur between 200Hg and 202Hg. It is not clear, however, within which nuclear model this shape transition should be described.

Differential cross sections from the Mg-24(He-3,t)Al-24 reaction have been measured from 0 to 32-degrees in the laboratory system. DWBA calculations using an effective projectile-nucleon interaction are compared with the data to verify the applicability of such an approach as well as to deduce spectroscopic information. By employing DWBA in conjunction with transition amplitudes obtained from realistic microscopic wave functions, J-pi assignments could be made. Strength normalizations for all observed transitions to positive-parity T = 1 final states of Al-24 are given. Localized DELTA-L = 1 strength around 10 MeV in excitation energy contains most of the expected isovector giant dipole resonance (GDR) and the magnetic quadrupole resonance (MQR) strengths with systematics that are consistent with those for most light, self-conjugate nuclei. A comparison with Coulomb-energy shifted (gamma, n) data assists in locating the GDR analog. The isovector 0- strength is not directly observed, but the total expected DELTA-L = 1, DELTA-S = 1 cross section is found in the broad collective "bump" at about 10 MeV and in a number of lower-lying states of negative parity.

Inelastic electron scattering off the nucleus 110 Cd has been studied. The experimental transition charge densities of the first three 2 + states have been extracted in a model-independent way. The transition charge density of the 2 + 3 state exhibits an unusual shape. Measured transition strengths and excitation energies are compared to calculations made in the framework of the neutron-proton IBA (IBA-2) and that of configuration mixing IBA (cm-IBA2). This has allowed to trace the origin of the character of the 2 + 3 state.

The decay of the isoscalar giant monopole and quadrupole resonances and of the underlying continuum in 124Sn has been studied with the 124Sn(α, α'n)123Sn reaction. The data are compared with calculations based on the statistical model to extract the non-statistical decay component. The giant monopole resonance (GMR) decay mode is predominantly statistical; non-statistical processes account for 15% of the decay. Possible evidence for a pre-equilibrium decay branch of the GMR between 5% and 10% was found. The non-statistical fraction of the decay of the GMR decreases with increasing excitation energy. The contribution of neutron knock-out was found to be in qualitative agreement with PWIA calculations.