2p→1sX-Ray Transitions inπ-Mesonic Atoms

Abstract

We have measured the 2/> -Is 7r-mesonic and muonic x-ray energies and widths for Z (atomic number) =3 (lithium) through 12 (magnesium) in order to study the effect of the nucleus on 7r-mesonic x-ray energy levels. The search for the tf-mesonic 2p -Is x ray in higher Z elements is difficult because of the low yields and large natural linewidths of the x rays. As Z increases, the yield decreases because of nuclear capture from the 2p state, and the x-ray line is broadened because of fast nuclear capture from the Is state.Our use of solid-state germanium and silicon detectors allowed the measurement of xray energies with high resolution. Optimum resolution was obtained by using both silicon and germanium detectors to exploit the relative advantages of each detector. The silicon detector had a better resolution (1.2 keV) than germanium (2.5 keV), but it had a lower efficiency for energies above 70 keV. Electronic shifts in gain were minimized by using two digital gain stabilizers to stabilize the lower and upper end of the energy window. All targets were at least 95% isotopically pure except magnesium, for which we used the naturally occurring element, and B 10

Pionic and Muonic X Rays in Liquid Helium

“…Both the direction and magnitude of this shift are consistent with the nuclear force effect predicted by Deser et al 6 (0.102 keV) and by Bethe and de Hoffmann 7 (0.10 keV, using the value of Jenkins et al 8 for the local nuclear potential V 0 ).…”

2p→1sPionic Transition

“…More recently solidstate detectors have been used and these data are in good agreement with the later measurements of West except for the width of the Be 9 line which was not analyzed properly. 4 In our analysis, we have taken only the solidstate detector measurements because of their higher resolution in this energy range. The higher resolution not only allows more accurate measurement but it also helps to separate out the muonic and nuclear y transitions in the spectra which are close in energy to the pionic lines and which complicate the analysis of these lines.…”

“…Unfortunately, such a method predicts 2 a strong interaction width for the Is level in Na 23 which is off by a factor of 5. Indeed, whereas Brueckner 3 predicted that the widths should vary roughly as Z 4 , there is strong evidence 4 " 7 that the widths level off in the region of fluorine.…”

The Quest for Pionic and Kaonic Nuclear Bound Systems Following Yukawa and Tomonaga

“…33) Since then, a great amount of experimental data, not only on pionic atoms but also on other exotic atoms, has been accumulated, as reviewed by Batty, Friedman and Gal. 34) The systematics of the strong-interaction shift in the pionic 1s states in light nuclei indicate that the s-wave part of the optical potential is repulsive.…”