Showing papers by "Achim Richter published in 1979"
01 Sep 1979
TL;DR: In this article, the authors measured K-, L and M-shell ionization cross sections for 23 elements, 12≦Z≦92, after bombardment with relativistic electrons, 15≦E fixme065MeV, by means of high resolution semiconductor detectors and a recently developed gas-scintillation proportional counter.
Abstract: K-, L andM-shell ionization cross sections have been measured for 23 elements, 12≦Z≦92, after bombardment with relativistic electrons, 15≦E
065MeV, by means of high resolution semiconductor detectors and a recently developed gas-scintillation proportional counter. For constant electron bombarding energyE
0 the ionization cross sections follow a power law dependence,σ∽Z
−α, and forE
0=50MeV we deducedα =2.45±0.02 for theK shell andα=3.00 ±0.09 for theL shell. The observedZ dependence exhibits significant systematic deviations from theoretical predictions which exceed the experimental values up to 15 % at lowZ elements for theK shell and on the average about 11% for theL andM shell. The same behaviour of too low experimental values, i.e. an overestimation by the theory, is observed for the energy dependence of the cross sections for all shells. A scaling behaviour describing theZ andE
0 dependence for allK-, L andM-shell data points is observed which also predicts the experimental values by other groups at lower and higher energies correctly. The comparsion of the measuredLΒ/Lα, andLγ/Lα intensity ratios for highZ elements with the values obtained by other groups in the energy range 0.3≦E0≦1,000 MeV exhibits an increase with bombarding energy that cannot merely be explained by the energy dependence of the subshellionization cross sections for theL shell. An attempt to explain this effect with the change of the Coster-Kronig transition probability is described.
74 citations
TL;DR: In this paper, an ususually strong magnetic dipole transition from the ground state to a state at Ex = 10.319 MeV in 40Ca has been observed in high-resolution inelastic electron scattering, contrary to expectations from the pure independent particle shell model.
49 citations
TL;DR: In this paper, high resolution inelastic electron scattering at low momentum transfer yields the precise location of states with J π, T = 1 +, 1 in 28 Si at excitation energies E x = 10594, 10725, 10901, 11445 and 12331 MeV.
32 citations
TL;DR: In this article, the principle of detailed balance has been tested in the reactions 27 Al (p, α 0 ) 24 Mg (Q = 1.600 MeV ) and 27 Al(Q = −1.35−1.52 MeV ).
16 citations
TL;DR: In this article, the Lβ/Lα branching ratio after L-shell ionization with relativistic electrons for three heavy elements (79Au, 82Pb and 83Bi) exhibit a distinct increase of about 14% as function of bombarding energy in the range E0 = 0.3−900 MeV.
12 citations
TL;DR: In this article, the experimental data were compared with the ordinary and the generalized Fresnel models and a Woods-Saxon potential with an energy independent set of parameters (V R = −21.76 MeV, r OR = 1.37 fm, a R = 0.45 fm; W 1 = −13.36 fm).
12 citations
TL;DR: In this article, the angular distribution and energy loss of reaction fragments as well as the charge spread of the element distribution are reported for strongly damped collisions of 40Ar on 40Ca at energies Elab = 191, 236 and 272 MeV.
5 citations
01 Jan 1979
TL;DR: In this paper, the main design characteristics of a proposed superconducting recyclotron for electrons with a variable energy from 1o to a maximum of 13o MeV, a duty cycle of 1oo% and an energy spread of 2▪10−4 at maximum energy.
Abstract: We describe the main design characteristics of a proposed superconducting recyclotron for electrons with a variable energy from 1o to a maximum of 13o MeV, a duty cycle of 1oo% and an energy spread of 2▪10−4 at maximum energy. The 3 GHz superconducting accelerating units, which are the main building blocks for the 4o MeV linac and the 1o MeV injector, are of a design which is expected to be free of electron multipacting. The design energy gradient of these units is 5 MeV/m. First experimental results on single cell accelerating cavities of the proposed spherical shape are given.
3 citations
TL;DR: In this article, the validity of the Born approximation for the elastic scattering of charged particles at sub-Coulomb energies is examined, and the nuclear contributions to α-208Pb and 16O- 208Pb elastic angular distributions at energies below the Coulomb barrier tend to cancel predicted effects due to the vacuum polarization potential.