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Search Results: 1 - 10 of 525358 matches for " G. M. Urciuoli "
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Softening and instability of natural slopes in highly fissured plastic clay shales
L. Picarelli, G. Urciuoli, A. Mandolini,M. Ramondini
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2006,
Abstract: Softening is often considered to be the main cause of first-time slides in OC clay, but so far the mechanics of softening has not been satisfactorily explained. Bearing on laboratory data and field observations about landslides in tectonized highly plastic clay shales of Italian Apennines, the paper describes a process of soil weakening that could explain some failures of natural slopes.
Models for photo- and electro-production of K^+ in view of new data
P. Bydzovsky,F. Cusanno,S. Frullani,F. Garibaldi,M. Iodice,M. Sotona,G. M. Urciuoli
Physics , 2003,
Abstract: Predictions of isobaric and Regge models are compared with the latest experimental data (Bonn,JLab) to select among the models those providing a satisfactory description of the data. Only the Saclay-Lyon and MAID models are in a reasonable agreement with both photo- and electro-production data ranging up to about 2.5 GeV.
16O(e,e'p) reaction at large missing energy
M. Iodice,E. Cisbani,R. De Leo,S. Frullani,F. Garibaldi,D. L. Groep,W. H. A. Hesselink,E. Jans,L. Lapikas,C. J. G. Onderwater,R. Perrino,J. Ryckebusch,R. Starink,G. M. Urciuoli
Physics , 2007, DOI: 10.1016/j.physletb.2007.08.034
Abstract: We investigate the origin of the strength at large missing energies in electron-induced proton knockout reactions. For that purpose the reaction 16O(e,e'p) was studied at a central value omega=210 MeV of the energy transfer, and two values of the momentum transfer: q=300, 400 MeV/c, corresponding to the "dip region". Differential cross sections were determined in a large range of missing energy (Em=0-140 MeV) and proton emission angle (gamma_pq =0-110 deg), and compared to predictions of a model that includes nucleon-nucleon short-range correlations and two-body currents. It is observed that, in the kinematic domain covered by this experiment, the largest contribution to the cross section stems from two-body currents, while short-range correlations contribute a significant fraction
p-Shell Hypernuclear Spectroscopy at JLab's Hall A and Future Prospects
F. Garibaldi,P. Bydzovsky,E. Cisbani,F. Cusanno,R. De Leo,S. Frullani,D. W. Highinbotham,M. Iodice,J. J. LeRose,P. Markowitz,G. M. Urciuoli,for the Hall A Collaboration
Physics , 2012,
Abstract: The first systematic study of 1p-shell and medium-heavy hypernuclei by electroproduction of strangeness has started at Jefferson Laboratory with the experiments E89-009, E94-107, E01-011, E05-115. The main results obtained in Hall A and future prospects of the investigation of hypernuclei at Jefferson Laboratory regarding the study of the angular dependence of electroproduction of strangeness and the possibility of performing the spectroscopy of 208^Tl_Lambda are reported here.
Weak charge form factor and radius of 208Pb through parity violation in electron scattering
C. J. Horowitz,Z. Ahmed,C. -M. Jen,A. Rakhman,P. A. Souder,M. M. Dalton,N. Liyanage,K. D. Paschke,K. Saenboonruang,R. Silwal,G. B. Franklin,M. Friend,B. Quinn,K. S. Kumar,J. M. Mammei,D. McNulty,L. Mercado,S. Riordan,J. Wexler,R. W. Michaels,G. M. Urciuoli
Physics , 2012, DOI: 10.1103/PhysRevC.85.032501
Abstract: We use distorted wave electron scattering calculations to extract the weak charge form factor F_W(q), the weak charge radius R_W, and the point neutron radius R_n, of 208Pb from the PREX parity violating asymmetry measurement. The form factor is the Fourier transform of the weak charge density at the average momentum transfer q=0.475 fm$^{-1}$. We find F_W(q) =0.204 \pm 0.028 (exp) \pm 0.001 (model). We use the Helm model to infer the weak radius from F_W(q). We find R_W= 5.826 \pm 0.181 (exp) \pm 0.027 (model) fm. Here the exp error includes PREX statistical and systematic errors, while the model error describes the uncertainty in R_W from uncertainties in the surface thickness \sigma of the weak charge density. The weak radius is larger than the charge radius, implying a "weak charge skin" where the surface region is relatively enriched in weak charges compared to (electromagnetic) charges. We extract the point neutron radius R_n=5.751 \pm 0.175 (exp) \pm 0.026 (model) \pm 0.005 (strange) fm$, from R_W. Here there is only a very small error (strange) from possible strange quark contributions. We find R_n to be slightly smaller than R_W because of the nucleon's size. Finally, we find a neutron skin thickness of R_n-R_p=0.302\pm 0.175 (exp) \pm 0.026 (model) \pm 0.005 (strange) fm, where R_p is the point proton radius.
Update of High Resolution (e,e'K^+) Hypernuclear Spectroscopy at Jefferson Lab's Hall A
F. Cusanno,A. Acha,P. Bydzovsky,C. C. Chang,E. Cisbani,C. W. De Jager,R. De Leo,S. Frullani,F. Garibaldi,D. W. Higinbotham,M. Iodice,J. J. LeRose,P. Markowitz,S. Marrone,M. Sotona,G. M. Urciuoli,for the Hall A Collaboration
Physics , 2009, DOI: 10.1016/j.nuclphysa.2010.01.185
Abstract: Updated results of the experiment E94-107 hypernuclear spectroscopy in Hall A of the Thomas Jefferson National Accelerator Facility (Jefferson Lab), are presented. The experiment provides high resolution spectra of excitation energy for 12B_\Lambda, 16N_\Lambda, and 9Li_\Lambda hypernuclei obtained by electroproduction of strangeness. A new theoretical calculation for 12B_\Lambda, final results for 16N_\Lambda, and discussion of the preliminary results of 9Li_\Lambda are reported.
Performance of the Two Aerogel Cherenkov Detectors of the JLab Hall A Hadron Spectrometer
S. Marrone,B. B. Wojtsekhowski,A. Acha,E. Cisbani,M. Coman,F. Cusanno,C. W. de Jager,R. De Leo,H. Gao,F. Garibaldi,D. W. Higinbotham,M. Iodice,J. J. LeRose,D. Macchia,P. Markowitz,E. Nappia,F. Palmisano,G. M. Urciuoli,I. van der Werf,H. Xiang,L. Y. Zhu
Physics , 2008, DOI: 10.1393/ncb/i2009-10743-5
Abstract: We report on the design and commissioning of two silica aerogel Cherenkov detectors with different refractive indices. In particular, extraordinary performance in terms of the number of detected photoelectrons was achieved through an appropriate choice of PMT type and reflector, along with some design considerations. After four years of operation, the number of detected photoelectrons was found to be noticeably reduced in both detectors as a result of contamination, yellowing, of the aerogel material. Along with the details of the set-up, we illustrate the characteristics of the detectors during different time periods and the probable causes of the contamination. In particular we show that the replacement of the contaminated aerogel and parts of the reflecting material has almost restored the initial performance of the detectors.
Investigation of the Exclusive 3He(e,e'pp)n Reaction
D. L. Groep,M. F. van Batenburg,Th. S. Bauer,H. P. Blok,D. J. Boersma,E. Cisbani,R. De Leo,S. Frullani,F. Garibaldi,W. Gloeckle,J. Golak,P. Heimberg,W. H. A. Hesselink,M. Iodice,D. G. Ireland,E. Jans,H. Kamada,L. Lapikas,G. J. Lolos,C. J. G. Onderwater,R. Perrino,A. Scott,R. Starink,M. F. M. Steenbakkers,G. M. Urciuoli,H. de Vries,L. B. Weinstein,H. Witala
Physics , 2000, DOI: 10.1103/PhysRevC.63.014005
Abstract: Cross sections for the 3He(e,e'pp)n reaction were measured over a wide range of energy and three- momentum transfer. At a momentum transfer q=375 MeV/c, data were taken at transferred energies omega ranging from 170 to 290 MeV. At omega=220 MeV, measurements were performed at three q values (305, 375, and 445 MeV/c). The results are presented as a function of the neutron momentum in the final-state, as a function of the energy and momentum transfer, and as a function of the relative momentum of the two-proton system. The data at neutron momenta below 100 MeV/c, obtained for two values of the momentum transfer at omega=220 MeV, are well described by the results of continuum-Faddeev calculations. These calculations indicate that the cross section in this domain is dominated by direct two-proton emission induced by a one-body hadronic current. Cross section distributions determined as a function of the relative momentum of the two protons are fairly well reproduced by continuum-Faddeev calculations based on various realistic nucleon-nucleon potential models. At higher neutron momentum and at higher energy transfer, deviations between data and calculations are observed that may be due to contributions of isobar currents.
Measurement of the Spectral Function of $^{40}$Ar through the $(e,e^\prime p)$ reaction
A. Ankowski,R. Beminiwattha,O. Benhar,D. G. Crabb,D. B. Day,F. Garibaldi,G. Garvey,D. Gaskell,C. Giusti,O. Hansen,D. W. Higinbotham,R. Holmes,C. M. Jen,X. Jiang,D. Keller,C. E. Keppel,R. Lindgren,J. M. Link,N. Liyanage,C. Mariani,A. Meucci,G. B. Mills,L. Myers,M. L. Pitt,O. A. Rondon,M. Sakuda,B. Sawatzky,P. A. Souder,G. M. Urciuoli,S. Wood,J. Zhang
Physics , 2014,
Abstract: The interpretation of the signals detected by high precision experiments aimed at measuring neutrino oscillations requires an accurate description of the neutrino-nucleus cross sections. One of the key element of the analysis is the treatment of nuclear effects, which is one of the main sources of systematics for accelerator based experiments such as the Long Baseline Neutrino Experiment (LBNE). A considerable effort is currently being made to develop theoretical models capable of providing a fully quantitative description of the neutrino-nucleus cross sections in the kinematical regime relevant to LBNE. The approach based on nuclear many-body theory and the spectral function formalism has proved very successful in explaining the available electron scattering data in a variety of kinematical conditions. The first step towards its application to the analysis of neutrino data is the derivation of the spectral functions of nuclei employed in neutrino detectors, in particular argon. We propose a measurement of the coincidence $(e,e^\prime p)$ cross section on argon. This data will provide the experimental input indispensable to construct the argon spectral function, thus paving the way for a reliable estimate of the neutrino cross sections. In addition, the analysis of the $(e,e^\prime p)$ data will help a number of theoretical developments, like the description of final-state interactions needed to isolate the initial-state contributions to the observed single-particle peaks, that is also needed for the interpretation of the signal detected in neutrino experiments.
Investigation of the Exclusive 3He(e,e'pp) Reaction
D. L. Groep,M. F. van Batenburg,Th. S. Bauer,H. P. Blok,D. J. Boersma,E. Cisbani,R. De Leo,S. Frullani,F. Garibaldi,W. Gloeckle,J. Golak,P. Heimberg,W. H. A. Hesselink,M. Iodice,D. G. Ireland,E. Jans,H. Kamada,L. Lapikas,G. J. Lolos,R. Perrino,A. Scott,R. Starink,M. F. M. Steenbakkers,G. M. Urciuoli,H. de Vries,L. B. Weinstein,H. Witala
Physics , 1999, DOI: 10.1103/PhysRevLett.83.5443
Abstract: Cross sections for the 3He(e,e'pp)n reaction were measured at an energy transfer of 220 MeV and three-momentum transfers q of 305, 375, and 445 MeV/c. Results are presented as a function of q and the final-state neutron momentum for slices in specific kinematic variables. At low neutron momenta, comparison of the data to results of continuum Faddeev calculations performed with the Bonn-B nucleon-nucleon potential indicates a dominant role for two-proton knockout induced by a one-body hadronic current.
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