A. D'Angelo - Academia.edu (original) (raw)

Papers by A. D'Angelo

Research paper thumbnail of Neutral Pion Production from Deuterium at the Legs Facility

Electromagnetic Interactions in Nuclear and Hadron Physics - Proceedings of the International Symposium, 2002

Abstract: Neutral pion photoproduction from a liquid deuterium target was measured in the energy ... more Abstract: Neutral pion photoproduction from a liquid deuterium target was measured in the energy region near 300 MeV at the LEGS facility of Brookhaven National Laboratory. The inclusive cross sections from deuterium are in agreement with measurments from Mainz, ...

Research paper thumbnail of Compton scattering at GRAAL

Gdh 2002: Proceedings of the Second International Symposium on the Gerasimov-Drell-Hearn Sum Rule and the Spin Structure of the Nucleon, 2003

At the GRAAL facility, a polarised and tagged {vec gamma } ray beam is produced in the energy ran... more At the GRAAL facility, a polarised and tagged {vec gamma } ray beam is produced in the energy range from 500 MeV up to 1500 MeV. Preliminary results of beam polarization asymmetries for Compton scattering on the proton are presented. These very precise measurements cover the angular range 30°-150°, providing stringent constraints to theoretical models.

Research paper thumbnail of Charged particle detection at GRAAL

Radiation Effects and Defects in Solids, 2009

Experimental results on proton and charged pion detection obtained from a study of the ??+ n??? p... more Experimental results on proton and charged pion detection obtained from a study of the ??+ n??? p+ ????? reaction are reported in detail. Data have been collected using the tagged and linearly polarized photon beam, impinging on a deuterium target, and the large solid ...

Research paper thumbnail of Measurement of the nucleon structure function in the nuclear medium and evaluation of its moments

Nuclear Physics A, 2010

We report on the measurement of inclusive electron scattering off a carbon target performed with ... more We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W ≈ 2.4 GeV with four-momentum transfers Q 2 ranging from 0.2 to 5 (GeV/c) 2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q 2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F 2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q 2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F 2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainties, to be smaller with respect to the deuteron case for n < 7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.

Research paper thumbnail of Measurement of πphotoproduction on the proton from 550 to 1500 MeV at GRAAL

The European Physical Journal A, 2005

Research paper thumbnail of Electrons on the HDice target: results and analysis of test runs at JLab in 2012

Proceedings of XVth International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2013), 2014

Research paper thumbnail of Polarization observable measurements for γp → K+Λ and γp → K+Σfor energies up to 1.5 GeV

The European Physical Journal A, 2007

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Research paper thumbnail of The graal experiment: Beam polarization asymmetries in pseudoscalar meson photoproduction

Czechoslovak Journal of Physics, 1999

Research paper thumbnail of Vertex identification of events in photonuclear reactions by cylindrical multiwire proportional chambers

Radiation Effects and Defects in Solids, 2009

In the framework of investigation of meson photo-production on proton and neutron in a deuterium ... more In the framework of investigation of meson photo-production on proton and neutron in a deuterium target at the GRAAL experiment, we present a method to identify the vertex of interaction when in reaction products there are at least two charged particles, by the information provided by the cylindrical multiwire proportional chambers. By this device, we are able to obtain the direction of charged particles that leave the target after a photo-production reaction. For each charged particle, the device provides the coordinates of two points in the laboratory reference system, and the z-axis represents the beam direction. We calculate the trajectory of each charged particle and its cross point, representing the vertex of the reaction.

Research paper thumbnail of Simultaneous Photoproduction of η and π0 Mesons on the Proton

Physical Review Letters, 2008

Research paper thumbnail of Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

Acta Physica Polonica B, 2015

The workshops focus on the development of amplitude analysis tools for meson and baryon spectrosc... more The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the

Research paper thumbnail of Induced polarization of Λ(1116) in kaon electroproduction with CLAS

Research paper thumbnail of Near-threshold photoproduction of ϕ mesons from deuterium

Physics Letters B, 2011

We report the first, kinematically-complete measurement of the differential cross section of φmes... more We report the first, kinematically-complete measurement of the differential cross section of φmeson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K + and K − near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections dσ dt for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on φ-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.

Research paper thumbnail of Differential cross section measurement of η photoproduction on the proton from threshold to 1100 MeV

Physics Letters B, 2002

Measurement of the differential cross section for the reaction p(γ, ηp) is presented from thresho... more Measurement of the differential cross section for the reaction p(γ, ηp) is presented from threshold to 1100 MeV photon laboratory energy. The experiment has been performed using the GRAAL facility in Grenoble. For the first time, the region of the S11(1535) resonance is fully covered, allowing a precise extraction of its width. Above 900 MeV, s-wave dominance disappears while p and d-waves take over. A discussion about their origin is given, suggesting unexpected contribution from vector meson exchange or the need for "missing" resonances.

Research paper thumbnail of Precise measurement of Σ beam asymmetry for positive pion photoproduction on the proton from 550 to 1100 MeV

Physics Letters B, 2000

S beam asymmetries for p q photoproduction on the proton have been measured in the energy range 5... more S beam asymmetries for p q photoproduction on the proton have been measured in the energy range 550-1100 MeV over a wide angular range. The statistical and systematic errors of the data are much lower than in previous measurements, due to the high polarization of the photon beam and the cylindrical geometry of the 4p detector. Our results confirm the

Research paper thumbnail of Beam asymmetry Σ in meson photo-production at GRAAL

Research paper thumbnail of Taladon: a polarized and tagged gamma ray beam

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1991

Nuclear Instruments and Methods m Physics Research A305 (1991) 19-24 North-Holland 19 Taladon: a ... more Nuclear Instruments and Methods m Physics Research A305 (1991) 19-24 North-Holland 19 Taladon: a polarized and tagged gamma ray beam D. Babusci, E. Cima, M. lannarelli and E. Turri INFN, Laboratory Naztonali di Frascati, PO Box 13, I-00044 Frascati, Italy F. Basti ...

Research paper thumbnail of Performances of frozen-spin polarized HD targets for Nucleon spin experiments

Research paper thumbnail of Beam asymmetry Σ measurements of π^{-} photoproduction on neutrons

Physical Review C, 2010

The -beam asymmetry in the photoproduction of negative pions on quasi-free neutrons in a deuteriu... more The -beam asymmetry in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval 700-1500 MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.

Research paper thumbnail of Simultaneous Photoproduction of η and π0 Mesons on the Proton

Physical Review Letters, 2008

The analysis of the p ! 0 p reaction has been performed using data from the GRAAL experiment. The... more The analysis of the p ! 0 p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S 11 1535 and 1700 are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the 1700 excitation, followed by the decay into 1232, is found to be dominant.

Research paper thumbnail of Neutral Pion Production from Deuterium at the Legs Facility

Electromagnetic Interactions in Nuclear and Hadron Physics - Proceedings of the International Symposium, 2002

Abstract: Neutral pion photoproduction from a liquid deuterium target was measured in the energy ... more Abstract: Neutral pion photoproduction from a liquid deuterium target was measured in the energy region near 300 MeV at the LEGS facility of Brookhaven National Laboratory. The inclusive cross sections from deuterium are in agreement with measurments from Mainz, ...

Research paper thumbnail of Compton scattering at GRAAL

Gdh 2002: Proceedings of the Second International Symposium on the Gerasimov-Drell-Hearn Sum Rule and the Spin Structure of the Nucleon, 2003

At the GRAAL facility, a polarised and tagged {vec gamma } ray beam is produced in the energy ran... more At the GRAAL facility, a polarised and tagged {vec gamma } ray beam is produced in the energy range from 500 MeV up to 1500 MeV. Preliminary results of beam polarization asymmetries for Compton scattering on the proton are presented. These very precise measurements cover the angular range 30°-150°, providing stringent constraints to theoretical models.

Research paper thumbnail of Charged particle detection at GRAAL

Radiation Effects and Defects in Solids, 2009

Experimental results on proton and charged pion detection obtained from a study of the ??+ n??? p... more Experimental results on proton and charged pion detection obtained from a study of the ??+ n??? p+ ????? reaction are reported in detail. Data have been collected using the tagged and linearly polarized photon beam, impinging on a deuterium target, and the large solid ...

Research paper thumbnail of Measurement of the nucleon structure function in the nuclear medium and evaluation of its moments

Nuclear Physics A, 2010

We report on the measurement of inclusive electron scattering off a carbon target performed with ... more We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W ≈ 2.4 GeV with four-momentum transfers Q 2 ranging from 0.2 to 5 (GeV/c) 2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q 2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F 2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q 2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F 2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainties, to be smaller with respect to the deuteron case for n < 7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.

Research paper thumbnail of Measurement of πphotoproduction on the proton from 550 to 1500 MeV at GRAAL

The European Physical Journal A, 2005

Research paper thumbnail of Electrons on the HDice target: results and analysis of test runs at JLab in 2012

Proceedings of XVth International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2013), 2014

Research paper thumbnail of Polarization observable measurements for γp → K+Λ and γp → K+Σfor energies up to 1.5 GeV

The European Physical Journal A, 2007

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Research paper thumbnail of The graal experiment: Beam polarization asymmetries in pseudoscalar meson photoproduction

Czechoslovak Journal of Physics, 1999

Research paper thumbnail of Vertex identification of events in photonuclear reactions by cylindrical multiwire proportional chambers

Radiation Effects and Defects in Solids, 2009

In the framework of investigation of meson photo-production on proton and neutron in a deuterium ... more In the framework of investigation of meson photo-production on proton and neutron in a deuterium target at the GRAAL experiment, we present a method to identify the vertex of interaction when in reaction products there are at least two charged particles, by the information provided by the cylindrical multiwire proportional chambers. By this device, we are able to obtain the direction of charged particles that leave the target after a photo-production reaction. For each charged particle, the device provides the coordinates of two points in the laboratory reference system, and the z-axis represents the beam direction. We calculate the trajectory of each charged particle and its cross point, representing the vertex of the reaction.

Research paper thumbnail of Simultaneous Photoproduction of η and π0 Mesons on the Proton

Physical Review Letters, 2008

Research paper thumbnail of Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

Acta Physica Polonica B, 2015

The workshops focus on the development of amplitude analysis tools for meson and baryon spectrosc... more The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the

Research paper thumbnail of Induced polarization of Λ(1116) in kaon electroproduction with CLAS

Research paper thumbnail of Near-threshold photoproduction of ϕ mesons from deuterium

Physics Letters B, 2011

We report the first, kinematically-complete measurement of the differential cross section of φmes... more We report the first, kinematically-complete measurement of the differential cross section of φmeson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K + and K − near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections dσ dt for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on φ-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.

Research paper thumbnail of Differential cross section measurement of η photoproduction on the proton from threshold to 1100 MeV

Physics Letters B, 2002

Measurement of the differential cross section for the reaction p(γ, ηp) is presented from thresho... more Measurement of the differential cross section for the reaction p(γ, ηp) is presented from threshold to 1100 MeV photon laboratory energy. The experiment has been performed using the GRAAL facility in Grenoble. For the first time, the region of the S11(1535) resonance is fully covered, allowing a precise extraction of its width. Above 900 MeV, s-wave dominance disappears while p and d-waves take over. A discussion about their origin is given, suggesting unexpected contribution from vector meson exchange or the need for "missing" resonances.

Research paper thumbnail of Precise measurement of Σ beam asymmetry for positive pion photoproduction on the proton from 550 to 1100 MeV

Physics Letters B, 2000

S beam asymmetries for p q photoproduction on the proton have been measured in the energy range 5... more S beam asymmetries for p q photoproduction on the proton have been measured in the energy range 550-1100 MeV over a wide angular range. The statistical and systematic errors of the data are much lower than in previous measurements, due to the high polarization of the photon beam and the cylindrical geometry of the 4p detector. Our results confirm the

Research paper thumbnail of Beam asymmetry Σ in meson photo-production at GRAAL

Research paper thumbnail of Taladon: a polarized and tagged gamma ray beam

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1991

Nuclear Instruments and Methods m Physics Research A305 (1991) 19-24 North-Holland 19 Taladon: a ... more Nuclear Instruments and Methods m Physics Research A305 (1991) 19-24 North-Holland 19 Taladon: a polarized and tagged gamma ray beam D. Babusci, E. Cima, M. lannarelli and E. Turri INFN, Laboratory Naztonali di Frascati, PO Box 13, I-00044 Frascati, Italy F. Basti ...

Research paper thumbnail of Performances of frozen-spin polarized HD targets for Nucleon spin experiments

Research paper thumbnail of Beam asymmetry Σ measurements of π^{-} photoproduction on neutrons

Physical Review C, 2010

The -beam asymmetry in the photoproduction of negative pions on quasi-free neutrons in a deuteriu... more The -beam asymmetry in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval 700-1500 MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.

Research paper thumbnail of Simultaneous Photoproduction of η and π0 Mesons on the Proton

Physical Review Letters, 2008

The analysis of the p ! 0 p reaction has been performed using data from the GRAAL experiment. The... more The analysis of the p ! 0 p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S 11 1535 and 1700 are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the 1700 excitation, followed by the decay into 1232, is found to be dominant.