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Kaskulov, M., Hernandez, E., & Oset, E. (2010). On the background in the gamma p -> omega(pi(0)gamma)p reaction and mixed event simulation. Eur. Phys. J. A, 46(2), 223–230.
Abstract: In this paper we evaluate sources of background of the gamma p -> omega p reaction, with the omega detected through its pi(0)gamma decay channel, to compare with the experiment carried out at ELSA. We find background from gamma p -> pi(0)pi(0)p followed by decay of a pi(0) into two gamma, recombining one pi(0) and one gamma, and from the gamma p -> pi(0)eta p reaction with subsequent decay of the eta into two photons. This background accounts for the data at pi(0)gamma invariant masses beyond 700 MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once this is done, we perform an event mixing simulation to reproduce the calculated background and we find that the method provides a good description of the background. A closer look reveals this is accidental. We show that the mixed event generated background in the region of the omega mass and beyond is completely tied to the events at low pi(0)gamma invariant masses where the d sigma/dM(pi 0 gamma) distribution is much larger. This has as a consequence that the mixed event method produces the same background at high invariant masses independently of the actual background in that region, as a consequence of which, the method is unsuited to give the background at energies around the peak of the omega and beyond.
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Kim, Y. H. et al, & Perez-Vidal, R. M. (2017). Prompt-delayed gamma-ray spectroscopy with AGATA, EXOGAM and VAMOS plus. Eur. Phys. J. A, 53(8), 162–8pp.
Abstract: A new experimental setup to measure prompt-delayed gamma-ray coincidences from isotopically identified fission fragments, over a wide time range of 100 ns-200 μs, is presented. The fission fragments were isotopically identified, on an event-by-event basis, using the VAMOS++ large acceptance spectrometer. The prompt gamma rays emitted at the target position and corresponding delayed gamma rays emitted at the focal plane of the spectrometer were detected using, respectively, thirty two crystals of the AGATA gamma-ray tracking array and seven EXOGAM HPGe Clover detectors. Fission fragments produced in fusion and transfer-induced fission reactions, using a U-238 beam at an energy of 6.2MeV/u impinging on a Be-9 target, were used to characterize and qualify the performance of the detection system.
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Kucuk, L. et al, Orrigo, S. E. A., Montaner-Piza, A., Rubio, B., Gelletly, W., Algora, A., et al. (2017). Half-life determination of T-z =-1 and T-z =-1/2 proton-rich nuclei and the beta decay of Zn-58. Eur. Phys. J. A, 53(6), 134–10pp.
Abstract: We have measured the beta-decay half-lives of 16 neutron-deficient nuclei with T-z = -1/2 and -1, ranging from chromium to germanium. They were produced in an experiment carried out at GANIL and optimized for the production of Zn-58, for which in addition we present the decay scheme and absolute Fermi and Gamow-Teller transition strengths. Since all of these nuclei lie on the rp-process pathway, the T-1/2 values are important ingredients for the rp-process reaction flow calculations and for models of X-ray bursters.
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Labiche, M., Ljungvall, J., Crespi, F. C. L., Chen, S., Bordes, J., Goasduff, A., et al. (2023). Simulation of the AGATA spectrometer and coupling with ancillary detectors. Eur. Phys. J. A, 59(7), 158–12pp.
Abstract: The design study of the AGATA array began with the development of the AGATA simulation code using GEANT4. The latter played a key part in the final design of the array and provided a cost effective solution for the early development of the tracking algorithm. The code has since been maintained and developed by the collaboration to provide more realistic simulations, with reaction chambers, ancillary detectors and surrounding mechanical structures completing the entire setup.
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Lewandowski, L., Reiter, P., Birkenbach, B., Bruyneel, B., Clemente, E., Eberth, J., et al. (2019). Pulse-Shape Analysis and position resolution in highly segmented HPGe AGATA detectors. Eur. Phys. J. A, 55(5), 81–13pp.
Abstract: The performance of the Pulse-Shape Analysis (PSA) in AGATA HPGe detectors was investigated and improved employing a -ray source measurement based on e+e- annihilation radiation after decays of Na-22 by + decay. The first interaction positions of the two 511keV rays were determined and the connecting line of these two positions was compared to the known source position as a measure for the PSA performance. The position resolution and its dependence on the PSA parameters were investigated by varying most relevant input quantities: the charge carrier mobility of the holes, the response of the employed measuring electronics especially the preamplifier rise time. The relative statistical weight of charge signals and transient signals was scrutinized. The optimal distance metric of the grid-search algorithm and its impact on the position resolution were determined.
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Liang, W. H., Molina, R., & Oset, E. (2010). Radiative open charm decay of the Y(3940), Z(3930), X(4160) resonances. Eur. Phys. J. A, 44(3), 479–486.
Abstract: We determine the radiative decay amplitudes for the decay into D* and (D) over bar gamma, or (D) over bar gamma(s)* and s. of some of the charmonium- like states classified as X, Y, Z resonances, plus some other hidden charm states which are dynamically generated from the interaction of vector mesons with charm. The mass distributions as a function of the (D) over bar gamma or (D) over bar (s)gamma. invariant mass show a peculiar behavior as a consequence of the D* (D) over bar gamma* nature of these states. The experimental search of these magnitudes can shed light on the nature of these states.
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Liang, W. H., Molina, R., Xie, J. J., Doring, M., & Oset, E. (2015). Predictions for the X(YZ) and X(YZ) with X(4160), Y(3940), Z(3930). Eur. Phys. J. A, 51(5), 58–7pp.
Abstract: We investigate the decay of and with R being the , , resonances. Under the assumption that these states are dynamically generated from the vector-vector interaction, as has been concluded from several theoretical studies, we use a reaction mechanism of quark production at the elementary level, followed by hadronization of one final pair into two vectors and posterior final state interaction of this pair of vector mesons to produce the resonances. With this procedure we are able to predict five ratios for these decays, which are closely linked to the dynamical nature of these states, and also predict the order of magnitude of the branching ratios which we find of the order of , well within the present measurable range. In order to further test the dynamical nature of these resonances we study the and decays close to the and thresholds and make predictions for the ratio of the mass distributions in these decays and the decay widths. The measurement of these decays rates can help unravel the nature of these resonances.
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Liang, W. H., Uchino, T., Xiao, C. W., & Oset, E. (2015). Baryon states with open charm in the extended local hidden gauge approach. Eur. Phys. J. A, 51(2), 16–14pp.
Abstract: In this paper we examine the interaction of DN and D* N states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the Weinberg-Tomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalar-baryon and vector-baryon states. We find two states with nearly zero width, which are associated to the I > (c) (2595) and I > (c) (2625). The lower state, with J (P) = 1/2(-), couples to DN and D* N, and the second one, with J (P) = 3/2(-), to D* N. In addition to these two I > (c) states, we find four more states with I = 0, one of them nearly degenerate in two states of J (P) = 1/2, 3/2. Furthermore we find three states in I = 1, two of them degenerate in J = 1/2, 3/2.
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Mach, H., Lindroth, A., Ruchowska, E., Kvasil, J., Fogelberg, B., Gulda, K., et al. (2016). On the enhanced E1 transitions in the K=3/2 parity doublet band in Ra-223. Eur. Phys. J. A, 52(6), 172–10pp.
Abstract: We have applied the fast timing beta gamma gamma(t) technique to remeasure lifetimes of selected states in Ra-223 populated in the beta(-) decay of Fr-223. T-1/2 = 587(12) ps and 210(13) ps have been obtained for the 3/2(-) and 5/2(-) states at 50.1 and 79.7 keV, that are more accurate than the previous values of 630(70) ps and 166(55) ps, respectively. Our vertical bar D0 vertical bar value of 0.155(10) e.fm obtained for the K = 3/2 configuration together with the available values of vertical bar D0 vertical bar for the K = 1/2 and K = 5/2 parity doublet bands establish the configuration dependence of vertical bar D0 vertical bar at low spins in this nucleus. Results of theoretical calculations performed for Ra-223, using the quasiparticle-phonon model (QPM) with inclusion of the Coriolis coupling, reasonably well reproduce octupole correlations in this nucleus.
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Mijatovia, T., Szilner, S., Corradi, L., Montanari, D., Pollarolo, G., Fioretto, E., et al. (2016). Study of the cross section determination with the PRISMA spectrometer: The Ar-40+Pb-208 case. Eur. Phys. J. A, 52(4), 113–6pp.
Abstract: The PRISMA spectrometer's response function was successfully applied to match three angular and magnetic settings over a wide angular range for measurements of quasi-elastic reactions in Ar-40 + Pb-208 . The absolute scale of cross sections has been obtained by using the Rutherford cross section at the forward angles and the information from the energy distributions measured with the spectrometer without and with coincidences with the CLARA -array. The semi-classical model GRAZING has been used to test the unfolding procedure and for comparison with the corrected cross sections.
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