Search results for "Absorption cross section"
showing 5 items of 15 documents
Total photofission cross section for 238U as a substitute for the photon absorption cross section in the energy range of the first baryon resonances
1992
Abstract The total photofission cross section σγ, F for 238U has been measured as a substitute for the total photon absorption cross section σtot in the energy range of the first baryon resonances (50⩽Eγ⩽800 MeV). The experiments were performed at the tagging facility of the new 855 MeV Mainz Microton MAMI B using monochromatic photons and a sophisticated 4π-arrangement of position sensitive fragment detectors. The measured cross section agrees in the Δ-resonance region with previous results and the so-called universal curve αtot/A. In the energy region of the D13-resonance near 710 MeV resonancelike structure could be observed as is seen for the free proton.
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.
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 …
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…
Fluorine laser-induced silicon hydride SiH groups in silica
2007
Abstract Formation and destruction of silicon hydride (Si–H) groups in silica by F 2 laser irradiation and their vacuum ultraviolet (VUV) optical absorption was examined by infrared (IR) and VUV spectroscopy. Photoinduced creation of Si–H groups in H 2 -impregnated oxygen deficient silica is accompanied by a growth of infrared absorption band at 2250 cm −1 and by a strong increase of VUV transmission at 7.9 eV. Photolysis of Si–H groups by 7.9 eV photons in this glass was not detected when the irradiation was performed at temperature 80 K. However, a slight destruction of Si–H groups under 7.9 eV irradiation was observed at the room temperature. This finding gives a tentative estimate of VU…