Search results for "absorption."

Determination of helium number densities in high-frequency electrodeless plasma

2010

Abstract The number densities of He first excited states 2 3 S 1 , 2 1 S 0 , 2 3 P 0,1,2 , and 2 1 P 0 were measured by absorption and self-absorption methods. The emission lines in the range 290–730 nm were used to determine the number densities of He metastable and resonant states of inductively coupled high-frequency electrodeless lamps filled with helium at pressure 0.1 Torr. The obtained number densities of helium metastable levels 2 3 S 1 and 2 1 S 0 are 2×10 12 and 3×10 11  cm −3 , respectively. For the 2 3 P 0,1,2 and 2 1 P 0 levels the determined number densities are ten times smaller than that of the metastable levels. Values of number densities from measurements using both method…

Photonuclear reactions at intermediate energies

2008

Starting from basic couplings of the photons to mesons, nucleons and isobars a microscopic manybody theory is developped which allows one to evaluate different photonuclear reactions at intermediate energies. The theory is applied to obtain the total photonuclear cross section and the separation between γ absorption and (γ, π) reaction channels.

TAS measurements for reactor physics and nuclear structure

2011

In this contribution we will present recent total absorption measurements of the beta decay of neutron‐rich nuclei performed at the IGISOL facility of the Univ. of Jyvaskyla. In the measurements the JYFL Penning Trap was used as a high resolution isobaric separator. The total absorption technique will be described and the impact of recent results in the fields of reactor physics (decay heat calculations) and nuclear structure will be discussed.

Physics at MAMI

2008

The Mainz Microtron MAMI has delivered a high quality electron beam with maximum energy of 880MeV for many years. Recently the MAMI C stage with its maximum energy of 1.5GeV was put into operation successfully and is delivering beam routinely now. The A1 collaboration is doing electron scattering experiments with a “Three Spectrometer Setup”. A first experiment using the MAMI C beam to measure the “Recoil polarisation and beam-recoil double polarisation of eta electroproduction on the proton in the region of the S11(1535) resonance” has been finished. A new, very compact magnetic spectrometer (KaoS) suitable especially for the detection of kaons is being installed now. The A2 collaboration …

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…