Giant-resonance data were taken with the spectrometer central angle ( θ$_{spec}$ ) set at 0 $^{◦}$, 2.5 $^{◦}$, 3.5$^{◦}$, 5.0$^{◦}$, 6.5$^{◦}$, and 8.0$^{◦}$, covering the angular range from 0◦ to 9.0 ◦ in the laboratory system. The actual angular resolution of the MWDCs, including the nominal broadening of scattering angle due to the emittance of the $^{4}$He++ beam and the multiple Coulomb- scattering effects, was about 0.15 ◦ [42]. The vertical acceptance was limited to ± 20 mr by a 2-mm-thick tantalum collimator. The energy bite of the Grand Raiden spectrometer and the special MWDC arrangements for the 0 ◦ measurements limited the excitation energy range observed to E$_{x}$ =8.5–31.5 MeV. The incident $^{4}$He ++ beam was stopped at three independent Faraday Cups (FC) according to the different settings of Grand Raiden [29]. In the measurements at large angles ( θ ≥ 6 . 5 $^{◦}$), the beam was stopped on the FC mounted inside the scattering chamber (SC-FC). For measurements at 0 $^{◦}$, the FC was located downstream of the MWDCs [29]; the incident $^{4}$He++ particles were guided to a vacuum pipe situated at the high-momentum side of the MWDCs and finally stopped at the 0 $^{◦}$-FC. A third FC was used for measurements in the scattering- angle region 2 ◦ ≤ θ ≤ 5 $^{◦}$. This FC was installed behind the Q1-magnet of the Grand Raiden (Q1-FC) [43]. The use of these three Faraday-cups allowed us to obtain reliable values of accumulated charges for the incident $^{4}$He ++ beam at different scattering angles. Normalization of the FCs was obtained with a beamline polarimeter located upstream from the target. The polarimeter target was inserted in the beam, and the scattered $^{4}$He++ particles counted, before and after each change of the FC. The overall accuracy of this normalization is estimated to be ∼ 2%, including systematic errors from slight changes in the direction of the beam during the measurement [42]. The ion-optics of the Grand Raiden spectrometer is such that the particles scattered from the target position are focused vertically and horizontally at the focal plane. Using this property, the instrumental background was completely eliminated. While inelastically scattered α particles are focused at the focal plane, background events due to the rescattering of α particles from the wall and pole surfaces of the spectrometer show a flat distribution in the vertical-position spectra at the focal plane, as shown in Fig. 1. The peak region in the vertical position spectrum was treated as true+background events. The off-center regions were treated as background only. Figure 2(a) shows the horizontal position spectrum for the $^{112}$Sn( α, α $^{′}$) reaction at 0$^{◦}$. The background spectrum has no distinct structure in the giant resonance region. Finally, we have obtained clean spectra by subtracting the background 5