A measurement of the K+ → e+v)(K+ → μ+v) branching ratio

The branching ratio $\text{R =}\text{Γ(}\text{K}{}^{\mathrm{+}}\text{→}\text{e}{}^{\mathrm{+}}\text{v)}\text{Γ(}\text{K}{}^{\mathrm{+}}\text{→ μ}{}^{\mathrm{+}}\text{v)}$ has been measured on the basis of 534 observed K⁺ → e⁺v decays. The K⁺ decay at rest; the momenta of the e⁺ and μ⁺ are measured in a magnetic spectrometer using multiwire driftchambers, and the electrons are identified in a gas Cerenkov counter. The result is R = (2.37 ± 0.17_× 10^?5. The value predicted for pure axial-vector interaction and μ-e-universality is R = 2.57 × 10^?5.     

Neubestimmung der absoluten Oszillatorenstärke der Eisen I-Resonanzlinieλ=3720 Å durch optische Doppelresonanz

The natural width of the strong Fe I spectral lineλ=3719,9 Å was determined in a double resonance experiment with an atomic beam as resonance cell and a hollow cathode as light source by the observation ofrf-induced magnetic dipole transitions between the Zeeman sublevels of the excited state in a weak static magnetic fieldH ₀. The optical line was isolated from disturbing neighbours in the same multiplet either roughly by an interference filter or strictly by a monochromator. From the widthΔν=5,35(14) MHz of the double resonance signal (monochromator value, including a small correction of 1.5% for the hyperfine structure of the 2.2% natural abundance of iron-57) the lifetimeτ of the (z ⁵ F ₅ ⁰ )-level is found to beτ=5,95 (16)×10^?8 sec. Thef-value of the transition to the ground state (a ⁵ D ₄) is calculated, by using the known relativef-values for the weak alternative transition possibilities to the (a ⁴ F ₅) and (a ⁵ F ₄) levels (λ=5012 and 5127 Å), to bef _λ3720=4,21 (11)×10^?2.     

The quasihole aspect of hole strength distributions in odd potassium and calcium isotopes

The ${}^{\mathrm{40,42,44,48}}\text{Ca}\text{(}\text{d}\text{, ρ)}{}^{\mathrm{39,41,43,47}}\text{K and}{}^{\mathrm{40,44}}\text{Ca(d, t)}{}^{\mathrm{39,43}}$ reactions have been studied at 52 MeV. Angular distributions have been taken and spectroscopic factors have been extracted by means of a DWBA analysis for states with excitation energies up to typically 10 MeV. Analog relations are proposed for mass-39 and mass-43 nuclei. A discussion of proton occupation numbers for various shells above and below the Fermi surface shows a substantial and about equal core excitation for ⁴²Ca and ⁴⁴Ca. Typically 70 % of the $\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ hole strengths have been located. The corresponding energy averaged strength distributions show quasihole structures whose widths are dominated by phonon-hole coupling to the first 2⁺ state in the target nucleus.     

Zur Deutung der Struktur der Bremsstrahl-Isochromate des Wolframs an der kurzwelligen Grenze

Ohlin's maximum of the tungsten isochromat may well be explained on the basis of the energy bands of tungsten calculated byManning andChodorow. The photons near the threshold voltage are then assumed to arise from transitions of the primary electrons to the unoccupied levels of the 5d and 6s bands. Using this explanation one has to drop, however, a selection rule formulated byNijboer, admitting only transitions to final s states. The validity of this ?s selection rule“ is critically examined. For a strict treatment one has to calculate the matrix elements connected with the transitions, using the exact wave functions of the tungsten crystal. These, however, are not known sufficiently. ThereforeNijboer appliedNedelsky's results for free-free transitions at the isolated atom to the transitions to bound states of the solid. Yet according to calculations made recently byGuggenberer the s selection rule is put into question even for free-free transitions. — A better approximation is obtained considering electron transitions from the continuum to the 5d and 6s states of the isolated atom. A calculation of the corresponding matrix elements is carried out. It shows that both kinds of transitions are of about the same probability at energies around 1 keV which are of special concern to us. Therefore it is allowed to use the 5d band for explaining the tungsten isochromat.     

Vanillin

Ohne Zusammenfassung     

Die Reaktion auf Guanidine, Harnstoff und Thioharnstoff mit Pentacyanoamminoferrat(III)

Ohne Zusammenfassung