Search results for "Photodisintegration"
showing 10 items of 37 documents
Study of three-nucleon mechanisms in the photodisintegration of 3He
1997
Abstract The cross section of the 3He(γ,pp)n reaction has been measured for the first time over a wide photon energy and proton angular range (200 MeV ≤ Eγ ≤ 800 MeV; 20° ≤ ϑplab ≤ 160°) using the large acceptance detector DAPHNE at the tagged photon facility of the MAMI microtron in Mainz. The wide kinematical coverage of the measurement has allowed a detailed analysis of three-nucleon absorption mechanisms. A model developed by Laget explains the main characteristics of the data in the Δ resonance region.
Introduction to the Discussion Session on Photo- and Electrodisintegration of the Deuteron
1992
This session is exclusively devoted to the electromagnetic break-up of the deuteron. It reflects the fact that notwithstanding its long history deuteron photo- and electrodisintegration is still an active and interesting field of research (for a recent review on photodisintegration see [1]). The purpose of this introduction is — on the one hand — to put the various contributions to this session into a general perspective and — on the other hand — to supply complimentary material of interesting recent experimental results which is of relevance to the general theme.
Photoreactions with tensor-polarized deuterium target at VEPP–3
2011
We give an overview of the activity in studying photoprocesses on a tensor-polarized deuterium target, which is carried out at the VEPP–3 electron storage ring. Recent experimental results on tensor asymmetries in two-body deuteron photodisintegration at the photon energy up to 500 MeV, and in coherent pion photoproduction on deuteron are presented. Plans to upgrade the facility and future experiments are discussed. Further progress is connected with the installation of a tagging system for almost-real photons. This would allow us to extend the measurements of polarization observables in photonuclear reactions on deuteron up to a photon energy of 1.5 GeV and permit to perform double polariz…
Electro- and photodisintegration of deuterium
1978
Deuteron break-up by inelastic electron scattering or photoabsorption is discussed with emphasis on effects from meson exchange currents and isobar configurationgurations.
THE R-PROCESS: SUPERNOVAE AND OTHER SOURCES OF THE HEAVIEST ELEMENTS
2007
Rapid neutron capture in stellar explosions is responsible for the heaviest elements in nature, up to Th , U and beyond. This nucleosynthesis process, the r-process, is unique in the sense that a combination of nuclear physics far from stability (masses, half-lives, neutron-capture and photodisintegration, neutron-induced and beta-delayed fission and last but not least neutrino-nucleus interactions) is intimately linked to ejecta from astrophysical explosions (core collapse supernovae or other neutron star related events). The astrophysics and nuclear physics involved still harbor many uncertainties, either in the extrapolation of nuclear properties far beyond present experimental explorat…
Ab initio calculation of Li7 photodisintegration
2004
The Li7 total photoabsorption cross section is calculated microscopically. As nucleon-nucleon interaction the semi-realistic central AV4' potential with S- and P-wave forces is taken. The interaction of the final 7-nucleon system is fully taken into account via the Lorentz Integral Transform (LIT) method. For the calculation of the LIT we use expansions in hyperspherical harmonics (HH) in conjunction with the HH effective interaction (EIHH) approach. The convergence of the LIT expansion is discussed in detail. The calculated cross section agrees quite well with the available experimental data, which cover an energy range from threshold up to 100 MeV.
Photodisintegration of the deuteron in the Δ-resonance region
1993
Abstract Photodisintegration of the deuteron in the Δ-resonance region is calculated treating the final state interaction within a N N−NΔ coupled channel approach including explicit pion degrees of freedom. For the electromagnetic interaction the nucleonic one-body current, meson exchange currents and the direct Δ-excitation are taken into account. The γN Δ-coupling is fixed in accordance with the M 1+ ( 3 2 ) multipole amplitude for pion photoproduction on the nucleon. The resulting total cross section underestimates the experimental data for photon energies below 340 MeV, whereas a good agreement is achieved by uaing a modified γN Δ-coupling effectively including the nonresonant Born term…
Polarization observables in deuteron photodisintegration below 360 MeV
2010
High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.
On the Gerasimov-Drell-Hearn sum rule for the deuteron
1997
The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit integration up to a photon energy of 550 MeV including contributions from the photodisintegration channel and from coherent and incoherent single pion production as well. The photodisintegration channel converges fast enough in this energy range and gives a large negative contribution, essentially from the $^1S_0$ resonant state near threshold. Its absolute value is about the same size than the sum of proton and neutron GDH values. It is only partially cancelled by the single pion production contribution. But the incoherent channel has not reached convergence at 550 MeV.
Photoemission of protons from4He in theΔ-resonance region
1996
High resolution proton energy spectra from the4He(γ,p) reaction have been measured with tagged photons in the range Eγ = 130−525 MeV using the large Mainz NaI(T1) spectrometer atΘplab=37.1°. Three separate reaction channels were identified, viz.4He(γ,p)t two-body breakup,4He photodisintegration via two-nucleon photon absorption processes and the quasifree pion production channel. Differential cross sections are presented for each of these channels as a function of photon energy. The sum of the two-nucleon photon absorption and the quasifree pion production differential cross sections, in the CM system, resembles that of the corresponding free-nucleon differential cross section when Fermi mo…