Promatranje blizih nukleona u jezgrama visokoenergijskim probama

Recently, we measured the reaction 12C(p,2p+n) and studied the correlation between the momenta of the struck target proton and the backward recoil neutron. We intend to continue this line of research and to measure the C(e,e\u27p+N) reaction at TJNAF (approved experiment E97-106). Two permanent magnetic spectrometers will be used to measure the (e,e\u27p) part of the reaction. We plan to add a third arm, consisting of a series of scintillation counters, to measure neutrons and protons in coincidence with the outgoing high momentum electron and proton. We choose kinematical conditions that will allow us to determine the fraction of (e,e\u27p) events which are associated with NN short-range correlations, as a function of the momentum of the proton in the nucleus. It will also allow us to compare between pn and pp correlated pairs in nuclei.Nedavno smo mjerili reakciju 12C(p,2p+n) i proučavali korelacije među impulsima udarenog protona u meti i unatrag odbijenog neutrona. Ta ćemo istraživanja nastaviti mjerenjima reakcije C(e,e’p+N) u TJNAF (odobreno mjerenje E97-106). Rabit će se dva spektrometra s trajnim magnetima za mjerenje dijela reakcije (e,e’p). Predviđa se treća mjerna grana s nizom scintilacijskih detektora radi sudesnog mjerenja neutrona i protona s izlaznim elektronom i protonom velikih impulsa. Odabiru se kinematički uvjeti koji dozvoljavaju određivanje udjela (e,e’p) dogođaja u svezi s kratkodosežnim NN korelacijama u jezgri u ovisnosti o impulsu protona u jezgri. To će omogućiti i usporedbu koreliranih parova pn i pp u jezgrama

Promatranje blizih nukleona u jezgrama visokoenergijskim probama

Recently, we measured the reaction 12C(p,2p+n) and studied the correlation between the momenta of the struck target proton and the backward recoil neutron. We intend to continue this line of research and to measure the C(e,e\u27p+N) reaction at TJNAF (approved experiment E97-106). Two permanent magnetic spectrometers will be used to measure the (e,e\u27p) part of the reaction. We plan to add a third arm, consisting of a series of scintillation counters, to measure neutrons and protons in coincidence with the outgoing high momentum electron and proton. We choose kinematical conditions that will allow us to determine the fraction of (e,e\u27p) events which are associated with NN short-range correlations, as a function of the momentum of the proton in the nucleus. It will also allow us to compare between pn and pp correlated pairs in nuclei.Nedavno smo mjerili reakciju 12C(p,2p+n) i proučavali korelacije među impulsima udarenog protona u meti i unatrag odbijenog neutrona. Ta ćemo istraživanja nastaviti mjerenjima reakcije C(e,e’p+N) u TJNAF (odobreno mjerenje E97-106). Rabit će se dva spektrometra s trajnim magnetima za mjerenje dijela reakcije (e,e’p). Predviđa se treća mjerna grana s nizom scintilacijskih detektora radi sudesnog mjerenja neutrona i protona s izlaznim elektronom i protonom velikih impulsa. Odabiru se kinematički uvjeti koji dozvoljavaju određivanje udjela (e,e’p) dogođaja u svezi s kratkodosežnim NN korelacijama u jezgri u ovisnosti o impulsu protona u jezgri. To će omogućiti i usporedbu koreliranih parova pn i pp u jezgrama

Color Transparency at COMPASS - Feasibility Study

We examine the potential of the COMPASS experiment at CERN to study color transparency via exclusive vector meson production in hard muon-nucleus scattering. It is demonstrated that COMPASS has high sensitivity to test this important prediction of perturbative QCD.Comment: Expanded version of the talk presented at the Workshop on "Nucleon Structure and Meson Spectroscopy", Dubna, Russia, 10-11 October 200

Color Transparency at COMPASS via Exclusive Coherent Vector Meson Production

We examine the potential of the COMPASS experiment at CERN to study color transparency via exclusive coherent vector meson production in hard muon-nucleus scattering. It is demonstrated that COMPASS has high sensitivity to test this important prediction of perturbative QCD.Comment: Contribution to Proceedings of 2002 Praha Advanced Study Institute "Symmetries and Spin" Workshop, Praha-SPIN-2002, July 2002, Prague, Czech Republic. File has 13 pages, four figures. Conference site is http://mfinger.home.cern.ch/mfinger/praha200

Nuclear Density Dependence of In-Medium Polarization

It is shown that polarization transfer measurements $(\vec{e},e'\vec{p})$ on a specific target nucleus can provide constraints on the ratio of the in-medium electric to magnetic form factor. Thereby one exploits the fact that proton knockout from single-particle levels exhibit a specific sensitivity to the effective nuclear density. It is shown that in $^{12}$C the effective nuclear density for $s$-shell knockout is about twice as high as for $p$-shell knockout. With current model predictions for the in-medium form factors, one obtains measurable modifications of the order of 5% in the ratios of the double polarization observables between those single-particle levels

Nucleon-Nucleon Correlations, Short-Lived Excitations, and the Quarks Within

This article reviews our current understanding of how the internal quark structure of a nucleon bound in nuclei differs from that of a free nucleon. The interpretation of measurements of the European Muon Collaboration (EMC) effect for valence quarks, a reduction in the deep inelastic scattering cross-section ratios for nuclei relative to deuterium, and its possible connection to nucleon-nucleon short-range correlations (SRCs) in nuclei are focused on. This review and new analysis (involving the amplitudes of non-nucleonic configurations in the nucleus) of the available experimental and theoretical evidence shows that there is a phenomenological relation between the EMC effect and the effects of SRCs that is not an accident. The influence of strongly correlated neutron-proton pairs involving highly virtual nucleons is responsible for both effects. These correlated pairs are temporary high-density fluctuations in the nucleus in which the internal structure of the nucleons is briefly modified. This conclusion needs to be solidified by the future experiments and improved theoretical analyses that are discussed herein

Nucleon-Nucleon Correlations, Short-Lived Excitations, and the Quarks Within

This article reviews our current understanding of how the internal quark structure of a nucleon bound in nuclei differs from that of a free nucleon. The interpretation of measurements of the European Muon Collaboration (EMC) effect for valence quarks, a reduction in the deep inelastic scattering cross-section ratios for nuclei relative to deuterium, and its possible connection to nucleon-nucleon short-range correlations (SRCs) in nuclei are focused on. This review and new analysis (involving the amplitudes of non-nucleonic configurations in the nucleus) of the available experimental and theoretical evidence shows that there is a phenomenological relation between the EMC effect and the effects of SRCs that is not an accident. The influence of strongly correlated neutron-proton pairs involving highly virtual nucleons is responsible for both effects. These correlated pairs are temporary high-density fluctuations in the nucleus in which the internal structure of the nucleons is briefly modified. This conclusion needs to be solidified by the future experiments and improved theoretical analyses that are discussed herein