Showing papers by "Achim Richter published in 1981"
TL;DR: In this paper, the quenching of M1 transitions is discussed within the framework of an effective magnetic transition operator renormalized by virtual Δ(1232)-hole excitations.
60 citations
TL;DR: In this article, the distribution of E1 and E2 strength in the region of excitation energy E x = 8−12MeV was investigated and it was shown that the E1 strength is very fragmented and the EWSR strength amounts to (10 +7 −6 )% and (29 +11 −8 )% in the investigated energy region, respectively.
25 citations
TL;DR: In this article, the mixed E2/M1 transitions from the 3 2 + ground states to the first excited case 1 2 + states in 39K. and 41K were studied by low momentum transfer inelastic electron scattering.
14 citations
TL;DR: A broad structure at EX ≈ 9 MeV in 140Ce which hitherto had been interpreted as the M1 giant resonance was shown to consist of an accumulation of Jπ = 2− states with a total strength of about 6 × 103 μK2fm2 as discussed by the authors.
12 citations
TL;DR: In this paper, measured M1 ground state transition strengths over a wide range of nuclei are used for a determination of the paramagnetic susceptibility of a given nuclei, and the diamagnetic susceptibility can at present only be estimated.
9 citations
TL;DR: In this paper, the K-shell fluorescence yield of Al, Ca, V and Mn has been measured by bombarding thin solid targets of 0.5 − 4.0μg/cm2 on 6 − 10μg /cm2 carbon backing with relativistic electrons of 30 and 60 MeV and by simultaneous detection of the x-ray and Auger yield by means of a Si(Li) detector and an electrostatic electron spectrometer.
Abstract: The K-shell fluorescence yield of Al, Ca, V and Mn has been measured by bombarding thin solid targets of 0.5–4.0μg/cm2 on 6–10μg/cm2 carbon backing with relativistic electrons of 30 and 60 MeV and by simultaneous detection of the x-ray and Auger yield by means of a Si(Li) detector and an electrostatic electron spectrometer, respectively. While the values obtained for25Mn (ωK=0.310−0.020+0.023) and23V(ωK=0.252−0.018+0.020) agree within their accuracy with known experimental and theoretical data, are the values of20Ca (ωK=0.127−0.011+0.013) and13Al(ωK=0.027±0.005) lower than experimental or recommended empirical values.
6 citations
01 Jan 1981
TL;DR: In this article, the authors describe how inelastic electron scattering can be used to study rather elementary problems of nuclear structure which in part may have some far-reaching consequences on fundamental questions of mesonic degrees of freedom in nuclear physics.
Abstract: In these two lectures, I shall describe how inelastic electron scattering can be used to study rather elementary problems of nuclear structure which in part may have some far-reaching consequences on fundamental questions of mesonic degrees of freedom in nuclear physics. Because of the limited time available and for pedagogical reasons (I have been told explicitely by the organizers of this school to lecture for young graduate students in nuclear physics) I confine myself to (e,e′) on nuclei at low momentum transfer. This means that we will discuss electric and magnetic transitions of low multipolarity (λ = 1 and 2) in light and heavy nuclei. I will illustrate this subject by a few selected examples of some very recent work at the Darmstadt electron linear accelerator (DALINAC). The formalism and also often even the physics problems are basically the same in electron scattering at higher energies where nuclear transitions of high multipolarity are studied. Therefore we loose little by staying in the realm of (e,e′) at low momentum transfer but gain by its conceptional simplicity and direct connection to problems of nuclear structure. In all nuclear structure aspects we will rely on the shell model to be discussed by Joe McGrory1 at this school.
3 citations
01 Dec 1981
TL;DR: In this article, cross sections for the production of evaporation residues in a fusion reaction were extracted from measurements of cross-sections for elastic, quasi-elastic and deep inelastic scattering of 40Ar projectiles on 40Ca target nuclei at incident energies ELAB=191, 236 and 272 MeV.
Abstract: Cross sections for the production of evaporation residues in a fusion reaction have been extracted from measurements of cross sections for elastic, quasi-elastic and deep inelastic scattering of40Ar projectiles on40Ca target nuclei at incident energies ELAB=191, 236 and 272 MeV. The extracted data are compared with the predictions of a one-body window-friction model including a neck configuration in the interaction phase between the projectile and target nuclei. Furthermore, the results for the40Ar+40Ca system are compared to those obtained in the similarly mass-symmetric system40Ca+40Ca where directly measured evaporation residue data are available.
1 citations
TL;DR: The retardation of magnetic multipole strength distributions (specifically M1 and M2) in heavy nuclei by inelastic electron electron scattering is attributed mainly to a mesonic renormalization of the nuclear spin current as discussed by the authors.
1 citations
01 Jan 1981
TL;DR: In this article, the measurements of K and L-shell ionization by relativistic electron impact were extended to search for the density effect produced by the polarization of the atoms inside the target close to the path of the electrons, and investigate the question of a possible energy dependence of the K-shell fluorescence yield and to study effects caused by multiple ionization.
Abstract: The measurements of K- and L-shell ionization by relativistic electron impact1 have been extended to search for the density effect produced by the polarization of the atoms inside the target close to the path of the electrons, to investigate the question of a possible energy dependence of the K-shell fluorescence yield and to study effects caused by multiple ionization.