Search results for "Absorption"

Results from the Real Photon Programme at MAMI

1995

The accelerator MAMI (Mainzer Mikrotron) with its excellent beam properties and its duty factor of 100% allows to apply coincidence techniques in intermediate energy nuclear physics, which has led to a variety of results with high precision. The real photon collaboration (A2) uses energy tagged bremsstrahlung photons with energies up to 800 MeV. We have results on total photon absorption (proton, deuteron, 3He and U), on Compton scattering (proton, 4He and 12C) and on meson production, especially on π°- and η-photoproduction. Double pion production on the proton and the deuteron was measured. The two and three body breakup of 3He was investigated as well as the reactions (γ,NN) and (γ, π ± …

Interpretation of the High-Energy ProcessesO16(γ,p0)N15andO16(γ,n0)O15

1978

Calculations based on a two-nucleon ($n\ensuremath{-}p$) absorption mechanism show that the form factor of the residual nucleus plays an important role in determining the shape of the photoproduction cross section in a wide energy range $60 \mathrm{MeV}l~{E}_{\ensuremath{\gamma}}l~300 \mathrm{MeV}$.

Modeling moderated proportional neutron counters using the Geant4 toolkit and the application to detection of fast neutron burst

2014

Total Absorption Study of Beta Decays Relevant for Nuclear Applications and Nuclear Structure

2014

Abstract An overview is given of our activities related to the study of the beta decay of neutron rich nuclei relevant for nuclear applications. Recent results of the study of the beta decay of 87,88 Br using a new segmented total absorption spectrometer are presented. The measurements were performed at the IGISOL facility using trap-assisted total absorption spectroscopy.

Periodic Motion for an Imperfect Solar Sail Near an Asteroid

2014

In this paper we consider the Hill 3-body problem with the extra effect of the solar radiation pressure as a model for the motion of a solar sail close to an asteroid. To model the sail’s acceleration, we include both reflectivity and absorption of the sail’s material. We describe the most relevant dynamical properties of the system for different reflectivity and absorption coefficients as well as different fixed sail orientations. We show families of periodic orbits, describe how they relate to the parameters of the sail and discuss their stability.

Theoretical study of resonant x-ray emission spectroscopy of Mn films on Ag.

2006

We report a theoretical study on resonant x-ray emission spectra (RXES) in the whole energy region of the Mn $L_{2,3}$ white lines for three prototypical Mn/Ag(001) systems: (i) a Mn impurity in Ag, (ii) an adsorbed Mn monolayer on Ag, and (iii) a thick Mn film. The calculated RXES spectra depend strongly on the excitation energy. At $L_3$ excitation, the spectra of all three systems are dominated by the elastic peak. For excitation energies around $L_2$, and between $L_3$ and $L_2$, however, most of the spectral weight comes from inelastic x-ray scattering. The line shape of these inelastic ``satellite'' structures changes considerably between the three considered Mn/Ag systems, a fact tha…

Relativistic corrections to the Drell-Hearn-Gerasimov sum rule in the constitutent quark model

1994

Relativistic corrections have been calculated for the Drell-Hearn-Gerasimov sum rule in the framework of the constituent-quark model. These corrections lead to additional absorption strength due to relativistic dipole currents in the case of a hyperfine interaction. The introduction of anomalous magnetic moments requires a subtraction of the dispersion integral at infinity. The additional effects of such anomalous moments, however, are numerically very small within the model.

Recent result from the A2 collaboration at MAMI

2016

The A2 Collaboration at the Mainz Microtron MAMI is measuring photon absorption cross section using circularly and linearly polarized photons up to energies of 1.6 GeV. The photons are produced in the ‘Bremsstrahlungs’ process, the energy is determined by a dedicated tagging system. The Crystal Ball-TAPS detector system with its high capability to cope with multi photon final states is used to acquire data with a variety of nonpolarized and spin polarized targets. Physical goals are the investigation of the nucleons excitation spectrum via single and double meson photoproduction and in addition a detailed determination of meson decays in precision experiments. We have started a program to m…

Diffusion of neutrons by a slab of moderating material: an application of the Monte Carlo Method

2004

An application of the Monte Carlo method to the diffusion of neutrons passing through a slab of a moderating material is presented. This method can be used as a tool to improve the student's comprehension of the statistical properties of many particle systems, showing the necessity of simulation procedures to obtain information on the expected results of real experiments. We have chosen a very simple example to illustrate it: the evaluation of the transmission, reflection and absorption probabilities of a monochromatic beam of neutrons diffusing through a slab of a moderator material. After a collision with a nucleus of the moderator the neutron may be either elastically scattered or captur…

Discovery of a Hard X‐Ray Source, SAX J0635+0533, in the Error Box of the Gamma‐Ray Source 2EG 0635+0521

1999

We have discovered an x-ray source, SAX J0635+0533, with a hard spectrum within the error box of the GeV gamma-ray source in Monoceros, 2EG J0635+0521. The unabsorbed x-ray flux is 1.2*10^-11 erg cm^-2 s^-1 in the 2-10 keV band. The x-ray spectrum is consistent with a simple powerlaw model with absorption. The photon index is 1.50 +/- 0.08 and we detect emission out to 40 keV. Optical observations identify a counterpart with a V-magnitude of 12.8. The counterpart has broad emission lines and the colors of an early B type star. If the identification of the x-ray/optical source with the gamma-ray source is correct, then the source would be a gamma-ray emitting x-ray binary.