AGATA Collaboration(Avigo, R. et al), Domingo-Pardo, C., Gadea, A., & Gonzalez, V. (2020). Low-lying electric dipole gamma-continuum for the unstable Fe-62(,)64 nuclei: Strength evolution with neutron number. Phys. Lett. B, 811, 135951–6pp.
Abstract: The gamma-ray emission from the nuclei Fe-62,Fe-64 following Coulomb excitation at bombarding energy of 400-440 AMeV was measured with special focus on E1 transitions in the energy region 4-8 MeV. The unstable neutron-rich nuclei Fe-62,Fe-64 were produced at the FAIR-GSI laboratories and selected with the FRS spectrometer. The gamma decay was detected with AGATA. From the measured gamma-ray spectra the summed E1 strength is extracted and compared to microscopic quasi-particle phonon model calculations. The trend of the E1 strength with increasing neutron number is found to be fairly well reproduced with calculations that assume a rather complex structure of the 1(-) states (three-phonon states) inducing a strong fragmentation of the E1 nuclear response below the neutron binding energy.
|
Lauritsen, T. et al, & Perez-Vidal, R. M. (2016). Characterization of a gamma-ray tracking array: A comparison of GRETINA and Gammasphere using a Co-60 source. Nucl. Instrum. Methods Phys. Res. A, 836, 46–56.
Abstract: In this paper; we provide a formalism for the characterization of tracking arrays with emphasis on the proper corrections required to extract their photopeak efficiencies and peak-to-total ratios. The methods are first applied to Gammasphere, a well characterized 4 pi array based on the principle of Compton suppression, and subsequently to GRETINA. The tracking efficiencies are then discussed and some guidelines as to what clustering angle to use in the tracking algorithm are presented. It was possible, using GEANT4 simulations, to scale the measured efficiencies up to the expected values for the full 4 pi implementation of GRETA.
|
Pasqualato, G. et al, Gadea, A., & Jurado, M. (2023). An alternative viewpoint on the nuclear structure towards 100Sn: Lifetime measurements in 105Sn. Phys. Lett. B, 845, 138148–7pp.
Abstract: This work aims at presenting an alternative approach to the long standing problem of the B(E2) values in Sn isotopes in the vicinity of the N=Z double-magic nucleus Sn-100, until now predominantly measured with relativistic and intermediate-energy Coulomb excitation reactions. The direct measurement of the lifetime of low-lying excited states in odd-even Sn isotopes provides a new and precise guidance for the theoretical description of the nuclear structure in this region. Lifetime measurements have been performed in Sn-105 for the first time with the coincidence Recoil Distance Doppler Shift technique. The lifetime results for the 7/2(1)(+) first excited state and the 11/2(1)(+) state, 2(+)(Sn-104) circle times nu 1g(7/2) multiplet member, are discussed in comparison with state-of-the-art shell model and mean field calculations, highlighting the crucial contribution of proton excitation across the core of Sn-100. The reduced transition probability B(E2) of the 11/2(1)(+) core-coupled state points out an enhanced staggering with respect to the B(E2; 2(1)(+) -> 0(1)(+)) in the even-mass Sn-104 and Sn-106 isotopes.
|
Sajjad Athar, M., Ruiz Simo, I., & Vicente Vacas, M. J. (2011). Nuclear medium modification of the F2(x, Q^2) structure function. Nucl. Phys. A, 857(1), 29–41.
Abstract: We study the nuclear effects in the electromagnetic structure function F-2(x, Q(2)) in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. The ratios R-F2(A) (x, Q(2)) = 2F(2)(A)(x, Q(2))/AF(2)(D)(x, Q(2)) are obtained and compared with recent JLab results for light nuclei with special attention to the slope of the x distributions. This magnitude shows a non-trivial A dependence and it is insensitive to possible normalization uncertainties. The results have also been compared with some of the older experiments using intermediate mass nuclei.
|
Korichi, A., Lauritsen, T., Wilson, A. N., Dudouet, J., Clement, E., Lalovic, N., et al. (2017). Performance of a gamma-ray tracking array: Characterizing the AGATA array using a Co-60 source. Nucl. Instrum. Methods Phys. Res. A, 872, 80–86.
Abstract: The AGATA (Advanced GAmma Tracking Array) tracking detector is being designed to far surpass the performance of the previous generation, Compton-suppressed arrays. In this paper, a characterization of AGATA is provided based on data from the second GSI campaign. Emphasis is placed on the proper corrections required to extract the absolute photopeak efficiency and peak-to-total ratio. The performance after tracking is extracted and GEANT4 simulations are used both to understand the results and to scale the measurements up to predicted values for the full 4 pi implementation of the device.
|
