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Gottardo, A. et al, Gadea, A., & Algora, A. (2019). New spectroscopic information on Tl-211,Tl-213: A changing structure beyond the N=126 shell closure. Phys. Rev. C, 99(5), 054326–7pp.
Abstract: The neutron-rich isotopes Tl-211,Tl-213, beyond the N = 126 shell closure, have been studied for the first time in isomer gamma-ray decay, exploiting the fragmentation of a primary uranium beam at the Fragment Separator-Rare Isotopes Investigation at GSI setup. The observed isomeric states in Tl-211,Tl-213 show a deviation from the seniority-like scheme of Tl-209. The possible interpretation of the data is discussed on the basis of energy-level systematics and shell-model calculations.
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Bizzeti, P. G., Sona, P., Michelagnoli, C., Melon, B., Bazzacco, D., Farnea, E., et al. (2015). Analyzing power of AGATA triple clusters for gamma-ray linear polarization. Eur. Phys. J. A, 51(4), 49–11pp.
Abstract: We have investigated the ability of AGATA triple clusters to measure the linear polarization of gamma rays, exploiting the azimuthal-angle dependence of the Compton scattering differential cross section. To this aim, partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of Pd-104 and Pd-108, which decay to the ground state by emission of gamma rays of 555.8 keV and 433.9 keV, respectively. Pulse-shape analysis and gamma-ray tracking techniques have been used to determine the position and time sequence of the interaction points inside the germanium crystals. Anisotropies in the detection efficiency have been taken into account using 661.6 keV gammas from a Cs-137 radioactive source. We obtain an average analyzing power of 0.451(34) at 433.9 keV and 0.484(24) at 555.8 keV.
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Gottardo, A. et al, Gadea, A., & Algora, A. (2014). Isomeric decay spectroscopy of the Bi-217 isotope. Phys. Rev. C, 90(3), 034317–6pp.
Abstract: The structure of the neutron-rich bismuth isotope Bi-217 has been studied for the first time. The fragmentation of a primary U-238 beam at the FRS-RISING setup at GSI was exploited to perform gamma-decay spectroscopy, since μs isomeric states were expected in this nucleus. Gamma rays following the decay of a t(1/2) = 3 μs isomer were observed, allowing one to establish the low-lying structure of Bi-217. The level energies and the reduced electric quadrupole transition probability B(E2) from the isomeric state are compared to large-scale shell-model calculations.
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Gottardo, A. et al, Gadea, A., & Algora, A. (2013). New μs isomers in the neutron-rich Hg-210 nucleus. Phys. Lett. B, 725(4-5), 292–296.
Abstract: Neutron-rich nuclei in the lead region, beyond N = 126, have been studied at the FRS-RISING setup at GSI, exploiting the fragmentation of a primary uranium beam. Two isomeric states have been identified in Hg-210: the 8(+) isomer expected from the seniority scheme in the vg(9/2) shell and a second one at low spin and low excitation energy. The decay strength of the 8(+) isomer confirms the need of effective three-body forces in the case of neutron-rich lead isotopes. The other unexpected low-lying isomer has been tentatively assigned as a 3(-) state, although this is in contrast with theoretical expectations.
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Jaworski, G., Palacz, M., Nyberg, J., de Angelis, G., de France, G., Di Nitto, A., et al. (2012). Monte Carlo simulation of a single detector unit for the neutron detector array NEDA. Nucl. Instrum. Methods Phys. Res. A, 673, 64–72.
Abstract: A study of the dimensions and performance of a single detector of the future neutron detector array NEDA was performed by means of Monte Carlo simulations, using GEANT4. Two different liquid scintillators were evaluated: the hydrogen based BC501A and the deuterated BC537. The efficiency and the probability that one neutron will trigger a signal in more than one detector were investigated as a function of the detector size. The simulations were validated comparing the results to experimental measurements performed with two existing neutron detectors, with different geometries, based on the liquid scintillator BC501.
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