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PANDA Collaboration(Singh, B. et al), & Diaz, J. (2016). Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR. Eur. Phys. J. A, 52(10), 325–23pp.
Abstract: Simulation results for future measurements of electromagnetic proton form factors at PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel (p) over barp -> e(+)e(-) is studied on the basis of two different but consistent procedures. The suppression of the main background channel, i.e. (p) over barp -> pi(+)pi(-), is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance.
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Guerrero, C., Domingo-Pardo, C., Kappeler, F., Lerendegui-Marco, J., Palomo, F. R., Quesada, J. M., et al. (2017). Prospects for direct neutron capture measurements on s-process branching point isotopes. Eur. Phys. J. A, 53(5), 87–5pp.
Abstract: The neutron capture cross sections of several unstable key isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure directly due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n, gamma) measurement, where high neutron fluxes and effective background rejection capabilities are required. At present there are about 21 relevant s-process branching point isotopes whose cross section could not be measured yet over the neutron energy range of interest for astrophysics. However, the situation is changing with some very recent developments and upcoming technologies. This work introduces three techniques that will change the current paradigm in the field: the use of gamma-ray imaging techniques in (n,gamma) experiments, the production of moderated neutron beams using high-power lasers, and double capture experiments in Maxwellian neutron beams.
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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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Colovic, P. et al, & Gadea, A. (2017). Stretched configuration of states as inferred from gamma-ray angular distributions in Ar-40+Pb-208 neutron transfer reactions. Eur. Phys. J. A, 53(8), 166–6pp.
Abstract: Angular distributions of.-rays for selected transitions in Ar-40,Ar-41,Ar-42 isotopes have been studied with the PRISMA magnetic spectrometer coupled to the CLARA gamma array. These transitions were populated in Ar isotopes reached via neutron transfer in the Ar-40 + Pb-208 reaction. By comparison with the shape of the experimental angular distribution of the known E2 transitions we established more firmly the spin and parity of excited states. In particular, in Ar-41 for the (11/2(-)) state through the (11/2(-)) -> 7/2(-) transition whose structure was discussed in terms of a phonon-fermion coupled state. The comparison with the expected fully aligned spin indicated that a high level of spin alignment has been reached.
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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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Vento, V. (2017). AdS gravity and the scalar glueball spectrum. Eur. Phys. J. A, 53(9), 185–4pp.
Abstract: The scalar glueball spectrum has attracted much attention since the formulation of Quantum Chromodynamics. Different approaches give very different results for the glueball masses. We revisit the problem from the perspective of the AdS/CFT correspondence.
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Doncel, M., Gadea, A., Valiente-Dobon, J. J., Quintana, B., Modamio, V., Mengoni, D., et al. (2017). Determination of lifetimes of nuclear excited states using the Recoil Distance Doppler Shift Method in combination with magnetic spectrometers. Eur. Phys. J. A, 53(10), 211–5pp.
Abstract: The current work presents the determination of lifetimes of nuclear excited states using the Recoil Distance Doppler Shift Method, in combination with spectrometers for ion identification, normalizing the intensity of the peaks by the ions detected in the spectrometer as a valid technique that produces results comparable to the ones obtained by the conventional shifted-to-unsifted peak ratio method. The technique has been validated using data measured with the gamma-ray array AGATA, the PRISMA spectrometer and the Cologne plunger setup. In this paper a test performed with the AGATA-PRISMA setup at LNL and the advantages of this new approach with respect to the conventional Recoil Distance Doppler Shift Method are discussed.
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n_TOF Collaboration(Sabate-Gilarte et al.), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2017). High-accuracy determination of the neutron flux in the new experimental area n_TOF-EAR2 at CERNx. Eur. Phys. J. A, 53(10), 210–13pp.
Abstract: A new high flux experimental area has recently become operational at the nTOF facility at CERN. This new measuring station, nTOF-EAR2, is placed at the end of a vertical beam line at a distance of approximately 20m from the spallation target. The characterization of the neutron beam, in terms of flux, spatial profile and resolution function, is of crucial importance for the feasibility study and data analysis of all measurements to be performed in the new area. In this paper, the measurement of the neutron flux, performed with different solid-state and gaseous detection systems, and using three neutronconverting reactions considered standard in different energy regions is reported. The results of the various measurements have been combined, yielding an evaluated neutron energy distribution in a wide energy range, from 2meV to 100MeV, with an accuracy ranging from 2%, at low energy, to 6% in the high-energy region. In addition, an absolute normalization of the n_TOF-EAR2 neutron flux has been obtained by means of an activation measurement performed with 197 Au foils in the beam.
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Garcia Canal, C. A., Tarutina, T., & Vento, V. (2017). Deuteron structure in the deep inelastic regime. Eur. Phys. J. A, 53(6), 118–5pp.
Abstract: We study nuclear effects in the deuteron in the deep inelastic regime using the newest available data. We put special emphasis on their Q(2) dependence. The study is carried out using a scheme which parameterizes, in a simple manner, these effects by changing the proton and neutron stucture functions in medium. The result of our analysis is compared with other recent proposals. We conclude that precise EMC ratios cannot be obtained without considering the nuclear effects in the deuteron.
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Sakai, S., Oset, E., & Ramos, A. (2018). Triangle singularities in B- -> K- pi- D(s0)+ and B- -> K- pi- D(s1)+. Eur. Phys. J. A, 54(1), 10–14pp.
Abstract: We study the appearance of structures in the decay of the B- into K-pi D--(s0)+ (2317) and K-pi D--(s1)+ (2460) final states by forming invariant mass distributions of pi D--(s0)+ and pi D--(s1)+ pairs, respectively. The structure in the distribution is associated to the kinematical triangle singularity that appears when the B- -> K- K*(0) D-0 (B- -> K- K*(0) D*(0)) decay process is followed by the decay of the K*(0) into pi(-) K+ and the subsequent rescattering of the K+ D-0 (K+ D*(0)) pair forming the D-s0(+) (2317) (D-s1(+) (2460)) resonance. We find this type of non-resonant peaks at 2850MeV in the invariant mass of pi D--(s0) pairs from B- -> K- pi(-) D-s0(+) (2317) decays and around 3000MeV in the invariant mass of pi D--(s1)+ pairs from B- -> K- pi(-) D-s1(+)(2460) decays. By employing the measured branching ratios of the B- -> K- K*(0) D-0 and B- -> K- K*(0) D*(0) decays, we predict the branching ratios for the processes B- into K-pi D--(s0)+ (2317) K-pi D--(s1)+ (2460), in the vicinity of the triangle singularity peak, to be about 8 x 10(-6) and 1 x 10(-6), respectively. The observation of this reaction would also give extra support to the molecular picture of the D-s0(+)(2317) and D-s1(+)(2460).
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