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Register a new userDipole strength in 144Sm studied via (gamma,n), (gamma,p) and (gamma,alpha) reactions
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Photoactivation measurements on 144Sm have been performed with bremsstrahlung endpoint energies from 10.0 to 15.5 MeV at the bremsstrahlung facility of the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf. The measured activation yield for the 144Sm(gamma,n) reaction is compared with the calculated yield using cross sections from previous photoneutron experiments. The activation yields measured for all disintegration channels 144Sm(gamma,n), (gamma,p) and (gamma,alpha) are compared to the yield calculated by using Hauser-Feshbach statistical models. A new parametrization of the photon strength function is presented and the yield simulated by using the modified photon strength parameters are compared to the experimental data.
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In a recent work, the cross section measurement of the 64Zn(p,alpha)61Cu reaction was used to prove that the standard alpha-nucleus optical potentials used in astrophysical network calculation fail to reproduce the experimental data at energies relevant for heavy element nucleosynthesis. In the present paper the analysis of the obtained experimental data is continued by comparing the results with the predictions using different parameters. It is shown that the recently suggested modification of the standard optical potential leads to a better description of the data.
High-statistics differential cross sections for the reactions gamma p -> p eta and gamma p -> p eta-prime have been measured using the CLAS at Jefferson Lab for center-of-mass energies from near threshold up to 2.84 GeV. The eta-prime results are the most precise to date and provide the largest energy and angular coverage. The eta measurements extend the energy range of the worlds large-angle results by approximately 300 MeV. These new data, in particular the eta-prime measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.
Due to the high sensitivity of the N N --> N N gamma reaction to the nucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to investigate details of the nucleon-nucleon interaction. Such investigations can be performed at the cooler synchrotron COSY in the Research Centre Juelich, by dint of the COSY-11 detection system. The results of the identification of Bremsstrahlung radiation emitted via the d p --> d p gamma reaction in data taken with a proton target and a deuteron beam are presented and discussed.
The COMPTEL instrument performed the first mapping of the 1.809 MeV photons in the Galaxy, triggering considerable interest in determing the sources of interstellar 26Al. The predicted 26Al is too low compared to the observation, for a better understanding more accurate rates for the 25Mg(p; gamma)26Al reaction are required. The 25Mg(p;gamma)26Al reaction has been investigated at the resonances at Er= 745; 418; 374; 304 keV at Ruhr-Universitat-Bochum using a Tandem accelerator and a 4piNaI detector. In addition the resonance at Er = 189 keV has been measured deep underground laboratory at Laboratori Nazionali del Gran Sasso, exploiting the strong suppression of cosmic background. This low resonance has been studied with the 400 kV LUNA accelerator and a HPGe detector. The preliminary results of the resonance strengths will be reported.
This paper presents results from partial-wave analyses of the photoproduction reactions $gamma p rightarrow eta p$ and $gamma n rightarrow eta n$. World data for the observables DSG, $Sigma$, $T$, $P$, $F$, and $E$ were analyzed as part of this work. The dominant amplitude in the fitting range from threshold to a c.m. energy of 1900 MeV was found to be $S_{11}$ in both reactions, consistent with results of other groups. At c.m. energies above 1600 MeV, our solution deviates from published results, with this work finding higher-order partial waves becoming significant. Data off the proton suggest that the higher-order terms contributing to the reaction include $P_{11}$, $P_{13}$, and $F_{15}$. The final results also hint that $F_{17}$ is needed to fit double-polarization observables above 1900 MeV. Data off the neutron show a contribution from $P_{13}$, as well as strong contributions from $D_{13}$ and $D_{15}$.
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