Search results for "Nucleon"

Λ Decay Induced by Two Nucleons

1995

The decay of Λ hypernuclei induced by two nucleons is revised, along with its implications in the experimental determination of the ratio of neutron- to proton-stimulated Λ decay.

Electromagnetic interactions of nucleons and nuclei at low energy and momentum transfer

2005

A critical analysis on deeply bound kaonic states in nuclei and the KEK experiment

2008

We critically discuss the theoretical developments that led to predictions of very deeply bound kaon states and then revise the data of the KEK experiment from where claims for evidence of deeply bound kaon atoms in nuclei were made. We conclude that the peaks seen in the experiment correspond to the absorption of kaons by a pair of nucleons leading to Σp and Λp and leaving the daughter nucleus as a spectator. These conclusions have been reconfirmed by a recent experiment at FINUDA.

Quasi-deuteron effects at intermediate energies

2008

It has been shown that photon and pion reactions in certain energy regions are dominated by the absorption on correlated (n-p)-pairs. Therefore, calculations based on quasi-deuteron models describe rather well the present experimental results. However, with more accurate data out of the reactions (γ,np),(γ,N), (π,NN) and (π,N) performed so that the complete kinematics is known, the correlation function of nucleon pairs in nuclei can be studied a quantity very important for our understanding of the nuclear many body system. The dominance for absorption on pairs in reactions with a rather big mismatch in energy and momentum in the entrance channel compared with the exit channel of the reactio…

Virtual Compton Scattering at MAMI γ*p→ γ1p1

1999

The virtual Compton scattering (VCS) is the electron scattering on a proton which radiates a real photon before being detected. The new observables, called Generalized Polarizabilities (GP), extracted from this VCS at threshold can be understood as the deformation of the charge and current distributions of the proton [1]. These GP are functions of the mass of the virtual photon Q2. In real Compton scattering (Q2 = 0), some polarizabilities of the nucleon are already measured [2]. With the VCS, we will generalize these observables by measuring them at different values of Q2.

Deuteron Compton Scattering

1995

We have calculated deuteron Compton scattering below pion production threshold using different realistic NN potential models and explicit meson exchange current contributions. The gauge conditions for the current and two photon operators have been exploited extensively, so that our model fulfills the low energy theorems. Rescattering, meson exchange and nucleon substructure contributions are studied and compared with a previous calculation and recent experimental data.

The HypHI project at GSI and FAIR

2008

Even though both experimental and theoretical activities on hypernuclear physics have been extended by a number of international projects, direct measurements on hypernuclear magnetic moments and studies of hypernuclei at extreme isospins have never been performed. The international HypHI collaboration proposes to perform hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and FAIR in order to study neutron and proton rich hypernuclei and to measure directly hypernuclear magnetic moments. The project is divided into four phases. In the first Phase 0 experiment, the feasibility of precise hypernuclear spectroscopy with heavy ion beams will be demonstrated by o…

Decay Spectroscopy for Nuclear Astrophysics: β-delayed Proton Decay

2011

In several radiative proton capture reactions important in novae and XRBs, the resonant parts play the capital role. We use decay spectroscopy techniques to find these resonances and study their properties. We have developed techniques to measure beta- and beta-delayed proton decay of sd-shell, proton-rich nuclei produced and separated with the MARS recoil spectrometer of Texas A&M University. The short-lived radioactive species are produced in-flight, separated, then slowed down (from about 40 MeV/u) and implanted in the middle of very thin Si detectors. This allows us to measure protons with energies as low as 200 keV from nuclei with lifetimes of 100 ms or less. At the same time we measu…

Measurements of Elliptic and Triangular Flow in High-MultiplicityHe3+AuCollisions atsNN=200  GeV

2015

We present the first measurement of elliptic ($v_2$) and triangular ($v_3$) flow in high-multiplicity $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in $^{3}$He$+$Au and in $p$$+$$p$ collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the $^{3}$He$+$Au system. The collective behavior is quantified in terms of elliptic $v_2$ and triangular $v_3$ anisotropy coefficients measured with respect to their corresponding event planes. The $v_2$ values are comparable to those previously measured in $d$$+$Au collis…

Nucleon form factors with light Wilson quarks

2014

Jeremy Green∗,a† Michael Engelhardt,b Stefan Krieg,cd Stefan Meinel,a John Negele,a Andrew Pochinskya and Sergey Syritsyne aCenter for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA bDepartment of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA cBergische Universitat Wuppertal, D-42119 Wuppertal, Germany dIAS, Julich Supercomputing Centre, Forschungszentrum Julich, D-52425 Julich, Germany eLawrence Berkeley National Laboratory, Berkeley, California 94720, USA E-mail: green@kph.uni-mainz.de, engel@nmsu.edu, s.krieg@fz-juelich.de, smeinel@mit.edu, negele@mit.edu, avp@mit.edu,