Proton-proton bremsstrahlung towards the elastic limit at 190 MeV incident beam energy

AbstractA series of nucleon–nucleon bremsstrahlung (NNγ) experiments at 190 MeV incident beam energy have been performed at KVI in order to gain more insight into the dynamics governing the bremsstrahlung reaction. After initial measurements wherein the bremsstrahlung process was studied far away from the elastic limit, a new study was used to probe the process nearer to the elastic limit by measuring at lower photon energies. Measured cross sections and analyzing powers are compared with the predictions of a microscopic model and those of two soft-photon models. The theoretical calculations overestimate the data by up to ≈30%, for some kinematics

GDR γ-ray decay in 156Dy∗ from regions selected on temperature and angular momentum

The strength distribution of the GDR built on highly excited states in a restricted temperature domain in Dy-156 and Dy-155 nuclei has been deduced by subtraction of gamma-ray spectra obtained for the decay of Dy-154* and Dy-156* from regions selected on angular momentum. The resulting difference spectra have been analyzed within the statistical model. The results show a large deformation (\beta\ similar to 0.51 +/- 0.29 and 0.35 +/- 0.14) for the angular-momentum regions with [J] similar to 32 ($) over bar h at T approximate to 1.8 +/- 0.2 MeV and [J] similar to 46 ($) over bar h at T approximate to 1.7 +/- 0.2 MeV respectively, in satisfactory agreement with calculations performed in the framework of Landau theory of shape transitions and statistical fluctuations. The deduced centroid energies are in agreement with the systematics of the GDR built on the ground state. The width of the GDR shows a systematic increase with increasing temperature

Experimental studies of the dilepton emission from Nucleon-Nucleon interactions below pion production threshold

The real- and virtual-photon emission during interactions between few-nucleon systems have been investigated at KVI with a 190 MeV proton beam. Here I will concentrate on the discussion of the results of the virtual-photon emission for the proton-proton system and proton-deuteron capture. Predictions of a fully-relativistic microscopic-model of the proton-proton interaction are discussed. For the proton-deuteron capture process the data is compared with predictions of a relativistic gauge-invariant impulse approximation and a Faddeev calculation. For the virtual photon processes, the nucleonic electromagnetic response functions were obtained for the first time and are compared to model predictions