Vibrational Character ofPd104and a Spectroscopic Study ofPd104by Pickup Reactions

The ${\mathrm{Pd}}^{105}(d, t){\mathrm{Pd}}^{104}$ and ${\mathrm{Ag}}^{107}(p, \alpha ){\mathrm{Pd}}^{104}$ pickup reactions were studied at bombarding energies of 17 and 12 MeV, respectively. Tritons were detected by nuclear emulsions in an Enge split-pole spectrograph with 5-7-keV resolution, and 43 ($d, t$) angular distributions were measured for transitions to low-lying levels in ${\mathrm{Pd}}^{104}$. Comparison of the ($d, t$) data with distorted-wave Born-approximation (DWBA) calculations predominantly led to $l=0, 2, \mathrm{and} 4$ assignments and yielded spectroscopic factors and quantitative estimates for single-neutron state occupancies. A previously postulated doublet at 1.33 MeV was resolved as a nearly degenerate triplet, in agreement with the two-phonon description for collective vibrations. Further evidence for the vibrational structure of the low-lying levels of ${\mathrm{Pd}}^{104}$ might be furnished by the well-isolated multiplet near 1.80 MeV, which may contain some or all of the members of the three-phonon quintet. In the ($p, \alpha$) experiment, cross sections were found to be very small ($p, \alpha$) angular distributions are given for the four strongest groups below 2 MeV. Very good agreement between the experimental results and $j$-dependent DWBA calculations based on a triton-cluster transfer mechanism supports the interpretation that direct pickup is the dominant ($p, \alpha$) reaction process in this mass and energy region.