[en] A method has been developed where primary γ-rays after nuclear reactions with one ejectile only, can be projected out from the total γ-ray spectrum. These primary γ-ray spectra are shown to be, under certain conditions, a new source for determination of nuclear level densities and γ-ray strength functions. Results for ¹⁶²Dy, ¹⁶⁶Er and ¹⁷²Yb are presented. The level density is used for determination of nuclear temperature and heat capacity. Fine structures in the level density and the temperature suggest changes in the pair correlation

[en] The energy dependent nuclear level densities of 205-208Pb nuclei below the nuclear binding energies were determined by using the Oslo method. The experimental primary γ-ray per excitation energy bin have been extracted for scattering and transfer reactions. The Axel-Brink hypothesis was then used to separate out level density and γ-strength function from the primary γ spectra. The influence of closed shells is quite obvious in the measured level densities

[en] Two experiments to identify hyperdeformation in Xe-nuclei have been made using the reaction 82Se(48Ca,xn)130-xXe, the first one with the EUROBALL-IV array equipped with a BGO calorimeter and the second one with the Gammasphere array. A bombarding energy of 195 MeV was used with the VIVITRON and 206 MeV with the ATLAS accelerator. No discrete hyperdeformed bands have been identified, but a ridge structure with 4 (ℎ/2π)²/J ∼ 0.048 MeV corresponding to a very large deformation was observed. A fluctuation analysis revealed that these ridges are composed of more than 10 rotational bands with ≥ 5 transitions each. Seven and four discrete bands extending from I ∼ 20 to I ∼ 60 have been identified in 125Xe and in 126Xe respectively, with a ΔEγ of 100 - 120 keV. These bands are most probably related to a potential energy minimum at ε ∼ 0.35 and a small γ-deformation predicted by Ultimate Crancker calculations. The transition quadrupole moments, crossing frequencies and alignments observed in the bands compare very well with those expected for this minimum

[en] The nuclear level densities of 44,45Sc and 50,51V have been measured using the Oslo method. From the level density thermal properties such as entropy and temperature are deduced. Also the radiative strength functions (RSF) of 50,51V have been extracted. The gross properties of the RSF are generally described by the low-energetic tail of the giant electric dipole resonance (GEDR). At γ energies below ∼ 3 MeV, the RSFs show an unexpected enhancement

[en] High-spin states in ^163,164Lu have been populated in the ¹³⁹La(²⁹Si,xn) reaction and their decay has been studied using the EUROBALL γ-ray spectrometer array. In ¹⁶⁴Lu eight new superdeformed (SD) bands have been found. In ¹⁶³Lu the previously known SD band is extended to lower and higher spins and its decay to the normal-deformed states has been established. In addition, a new SD band is identified. Calculations with the Ultimate Cranker code predict large triaxiality (γ≅±20 deg.) for all these bands

[en] The level density and the γ-strength function have been extracted experimentally. From the level densities thermodynamical quantities such as temperature and heat capacity can be found. Structures in the micro-canonical temperature are interpreted as the onset of new degrees of freedom by the breaking of Cooper pairs. The S-shape in the heat capacity curves, found within the canonical ensemble, indicates the pairing-phase transition, and a critical temperature for the quenching of pair correlations is found. The pygmy resonance at 3.3(1) MeV in 172Yb has now been established with a strength of B(M1)=6.5(15)μ_N² and M1 multipolarity, the so-called scissors mode. In addition, a strong unexpected enhancement of the radiative strength function (RSF) has been found at low γ-ray energy in medium light Fe nuclei and also in the heavier Mo nuclei

[en] Radiative strength functions (RSFs) in ^93-98Mo have been extracted using the (³He,αγ) and (³He,³He^'γ) reactions. The RSFs are U shaped as function of γ energy with a minimum at around E_γ=3 MeV. The minimum values increase with neutron number because of the increase in the low-energy tail of the giant electric dipole resonance with nuclear deformation. The unexpected strong increase in strength below E_γ=3 MeV, here called soft pole, is established for all ^93-98Mo isotopes. The soft pole is present at all initial excitation energies in the 5-8-MeV region

[en] Level densities for ^93-98Mo have been extracted using the (³He,αγ) and (³He,³He^'γ) reactions. From the level densities thermodynamical quantities such as temperature and heat capacity can be deduced. Data have been analyzed by utilizing both the microcanonical and the canonical ensemble. Structures in the microcanonical temperature are consistent with the breaking of nucleon Cooper pairs. The S shape of the heat capacity curves found within the canonical ensemble is interpreted as consistent with a pairing phase transition with a critical temperature for the quenching of pairing correlations at T_c∼0.7-1.0MeV