Two Proton Emission with Electromagnetic Probes

A model to study two-proton emission from nuclei induced by electromagnetic probes is developed. The process is due to one-body electromagnetic operators, acting together with short-range correlations, and two-body $\Delta$ currents. The model includes all the diagrams containing a single correlation function. The sensitivity of the cross section to the details of the correlation function is studied by using realistic and schematic correlations. Results for the $^{16}$O nucleus are presented.Comment: 9 pages, 8 figures, Contribution to the 6th. Workshop on "Electromagnetic Induced Two-Hadron Emission",Pavia, 200

Photo-emission of two protons from nuclei

The photo-emission of two protons from the $^{12}$C, $^{16}$O and $^{40}$Ca nuclei is investigated. Aim of the work is the study of the possibilities offered by this probe to obtain information about the characteristics of the short-range correlations. We have also evaluated the effects of the two-body $\Delta$-currents which, in this processes, compete with those produced by the short-range correlations. Our results show that ($\gamma$,pp) processes could be more useful than (e,e'pp) for the study of the short-range correlations.Comment: 21 pages, 15 figures, 3 table

Finite-range simple effective interaction including tensor terms

ACKNOWLEDGMENTS Useful discussions with F. Stancu are warmly acknowledged. P. Bano acknowledges the support from MANF Fellowship of UGC, India. T.R.R. gives sincere thanks to Professor B. Behera for meaningful discussions. M.C. and X.V. were partially supported by Grants No. PID2020-118758GBI00 and No. CEX2019-000918-M (through the “Unit of Excellence María de Maeztu 2020-2023” award to ICCUB) from the Spanish MCIN/AEI (DOI 10.13039/501100011033). The work of L.M.R. was partly supported by the Spanish MINECO Grant No. PGC2018-094583-B-I00. M.A. has been partially supported by the Spanish MINECO Grant No. PID2019-104888GB-I00.An existing parametrization of the simple effective interaction (SEI) that is able to reproduce the experimentally known crossing between the 2p3/2 and 1f5/2 single-particle (s.p.) proton levels in neutron-rich Ni isotopes has been generalized. We have added a short-range tensor force in order to describe the observed gaps between the 1h11/2 and 1g7/2s.p. proton levels in the Sn isotopic chain and between the 1i13/2 and 1h9/2s.p. neutron levels in N=82 isotones without compromising the good agreement with the splittings in the Ni isotopes. Different scenarios where tensor effects are relevant are considered with the new interaction and its predictions are compared with results from other mean-field models and experimental data where available.MANF Fellowship of UGCUniversity Grants Commission CEX2019-000918-M, PID2020-118758GB-I00Ministerio de Economía y Competitividad PGC2018-094583-B-I00, PID2019-104888GB-I00Agencia Estatal de InvestigaciónInstituto de Ciencias del Cosmos, Universitat de Barcelona (ICCUB

Una breve storia della radioterapia. A brief history of radiotherapy

Questo articolo delinea le pietre miliari dello sviluppo della radioterapia sin dai suoi inizi. In particolare, descrive come alcune delle differenti tecniche sviluppate e usate in più di 100 anni di storia sono diventate prassi comune: dalle molteplici applicazioni dei raggi X, utilizzati solo pochi mesi dopo la loro scoperta, che hanno definito l'inizio delle radiazioni ionizzanti nella terapia contro il cancro, fino alla più recente adroterapia. Sono citate le persone che hanno reso possibili questi sviluppi

Tensor and tensor-isospin terms in the effective Gogny interaction

We discuss the need of including tensor terms in the effective Gogny interaction used in mean-field calculations. We show in one illustrative case that, with the usual tensor term that is employed in the Skyrme interaction (and that allows us to separate the like-nucleon and the neutron-proton tensor contributions), we can describe the evolution of the N=28 neutron gap in calcium isotopes. We propose to include a tensor and a tensor-isospin term in finite-range interactions of Gogny type. The parameters of the two tensor terms allow us to treat separately the like-nucleon and the neutron-proton contributions. Two parameterizations of the tensor terms have been chosen to reproduce different neutron single-particle properties in the 48Ca nucleus and the energy of the first 0- state in the 16O nucleus. By employing these two parameterizations we analyze the evolution of the N=14, 28, and 90 neutron energy gaps in oxygen, calcium and tin isotopes, respectively. We show that the combination of the parameters governing the like-nucleon contribution is crucial to correctly reproduce the experimental (where available) or shell-model trends for the evolution of the three neutron gaps under study.Comment: 20 pages, 6 figures. Accepted for publication in Physical Review

Effect of short- and long-range correlations on neutron skins of various neutron-rich doubly magic nuclei

We study the effects of correlations beyond the independent particle model in the evaluation of neutron skins of various neutron-rich doubly magic nuclei.We consider short- and long-range correlations to take into account the presence of the strongly repulsive core of the bare nucleon-nucleon interaction and collective nuclear phenomena, respectively. Despite the strong sensitivity on the structure of the nucleus considered, our results indicate that, in general, correlations increase the values of the neutron skins.Junta de Andalucia FQM387Spanish Government PID2019-104888GB-I00European Commissio

Effective tensor forces and neutron rich nuclei

We study the effects of the tensor term of the effective nucleon-nucleon interaction on nuclear excited states. Our investigation has been conducted by using a self-consistent Random Phase Approximation approach. We investigate various nuclei in different regions of the isotopes chart. Results for a set of calcium isotopes are shown.Comment: 4 pages, 4 figures, 1 table Proc. 10th International Spring Seminar on Nuclear Physics New Quests in Nuclear Structure, Vietri Sul Mare, May 21-25, 201

Characterizing the human postural control system using detrended fluctuation analysis

AbstractDetrended fluctuation analysis is used to study the behaviour of the time series of the position of the center of pressure, output from the activity of a human postural control system. The results suggest that these trajectories present a crossover in their scaling properties from persistent (for high frequencies, short-range time scale) to anti-persistent (for low frequencies, long-range time scale) behaviours. The values of the scaling exponent found for the persistent parts of the trajectories are very similar for all the cases analysed. The similarity of the results obtained for the measurements done with both eyes open and both eyes closed indicate either that the visual system may be disregarded by the postural control system, while maintaining quiet standing, or that the control mechanisms associated with each type of information (visual, vestibular and somatosensory) cannot be disentangled with this technique