[en] This thesis describes the theory concerning DWBA and CCBA calculations and shows how the obtained deformation parameters can be converted into isoscalar transition rates and energy weighted sum rule strength. It describes the experimental method used for measuring inelastically scattered alpha particles. In addition the way the spectra have been analysed is described. It describes the experimental results and DWBA analysis of the angular distributions. In addition a coupled channel analysis is given for some strongly coupled states. (Auth.)

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[en] The ¹⁶O(α,p)¹⁹F and ¹²C(α,p)¹⁵N reactions at E/sub α/ = 40 MeV are studied with the analyzed beam of the K.V.I. cyclotron. Representative spectra at THETA/sub L/ = 15⁰ are shown in Fig. 1. The selectivity of the reaction is clearly demonstrated: In both reactions only a few levels at high excitation energies are strongly excited

[en] The cross sections of the members of the ground state band O⁺, 2⁺ (1.37 MeV) and 4⁺ (4.12 MeV) and the γ-band 2⁺ (4.24 MeV), 3⁺ (5.24 MeV) and 4⁺ (6.01 MeV) in ²⁴Mg have been measured in inelastic α-scattering at Esub(α) = 120 MeV. The data can be well described by a coupled channels calculation performed in the framework of the asymmetric rotational model. (C.F.)

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[en] The inelastic α-scattering reaction at Esub(α) = 120 MeV with an energy resolution of 90-150 keV has been used to investigate isoscalar strength distributions in ²⁴,²⁶Mg, ²⁸Si and ⁴⁰Ca. For ²⁴,²⁶Mg and ²⁸Si the E2 strength between Esub(x) = 14 and 27 MeV is strongly fragmented. In ⁴⁰Ca the E2 strength is mainly concentrated near Esub(x) approx. equal to 65 Asup(1/3) MeV, although here the onset of fragmentation can be observed. The sum rule strength for the different multipolarities was obtained by applying for each nucleus an L-dependent normalization procedure. In this way we observed in total in ²⁴,²⁶Mg, ²⁸Si and ⁴⁰Ca for excitation energies up to 27 MeV an amount of (61⁺⁸sub(-)₆), (50⁺⁹sub(-)₈) , (38⁺⁸sub(-)₆) and (94 +- 14)%, respectively, of the isoscalar E2 energy weighted sum rule (EWSR) of which (36⁺⁷sub(-)₇), (24^+7-₅) and (74 +- 12)% was found between Esub(x) = 14 and 27 MeV. In addition isoscalar E0, E3 and E4 strength was observed in this excitation energy region. A detailed comparison has been made between the isoscalar quadrupole strength distribution observed in the ²⁴,²⁶Mg(α,α') reaction and the E2 strength excitation function obtained from radiative α-capture measurements. In the low excitation energy region coupled channel effects have been observed, especially for the excitation of the 3⁺ states. Moreover, a considerable percentage of the lh/2πω isoscalar dipole and octupole strength has been observed for excitations below 14 MeV. (orig.)

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[en] The ¹⁶O(α,p)¹⁹F reaction has been studied at Esub(α)=40 MeV. In this reaction high-spin states at high excitation energy are selectively excited. A study of positive parity states ranging from Jsup(π)=1/2⁺ to 13/2⁺ shows that the reaction can be described in terms of a direct transfer of a three-nucleon cluster with internal quantum numbers l=0 and s=1/2. An analysis in terms of a zero-range DWBA calculation accounts rather well for the shape of the angular distributions. The relative spectroscopic factors S for the transitions to the Jsup(π) states have been compared with the intensity of the (lambda,μ)=(6,0) component in the SU(3) wave functions and are found to be in excellent agreement with calculated values. The analysis of the transitions to the negative parity states indicates that the shape of their angular distributions is sensitive to whether the transferred three-nucleon cluster originates from a p(sd)² or a (sd)²(fp) coupling. (Auth.)

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