Unexpected reduction of rf spin resonance strength for stored polarized deuterons.

The ratio $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ of the deuteron's measured rf spin resonance's strength, $\varepsilon _{FS }$, obtained by fitting spin-flipping data to the Froissart-Stora equation, to the $^{\ast }\varepsilon _{Bdl}$ calculated from our rf magnet's $\smallint $\textit{Bdl} was about 7 times smaller than predicted. We studied this discrepancy using a 1.85 GeV/c vertically polarized deuteron beam stored in COSY in J\"{u}lich, Germany, by sweeping the frequency of an rf-dipole through an rf-induced spin resonance. We studied the dependence of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ on the beam size, the momentum spread $\Delta p$/$p$, the distance from a 1$^{st}$-order intrinsic spin resonance and the frequency sweep range $\Delta $f. We found no dependence on the beam size, $\Delta p$/$p$ or $\Delta $f. We saw a strong enhancement of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ with a hyperbolic dependence on the distance from the intrinsic resonance. This did not explain the reduction of $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ far from the intrinsic resonance. Thus, this small $\varepsilon _{FS}$/$^{\ast }\varepsilon _{Bdl}$ ratio may be due to some unexpected behavior of relativistic spin-1 deuterons in an rf dipole. (Supported by the German BMBF Science Ministry.)