Search for excited states in $^{101}$Sn

Single-particle excitations near closed shells are critical in understanding nuclear structure. Single-particle energies in the doubly-magic self-conjugate $^{100}$Sn nucleus are not known. Studies of nuclei around $^{100}$Sn are at the current sensitivity limit. A search for gamma-ray transitions in $^{101}$Sn, which contains only one neutron outside of the $^{100}$Sn core, was carried out at the Argonne Tandem-Linac Accelarator System. $^{101}$Sn nuclei were produced using the $^{46}$Ti($^{50}$Cr,3n)$^{101}$Sn reaction with a cross section of about 50 nb. Beta-delayed protons with energies and decay times consistent with previous $^{101}$Sn decay studies were observed in a Double-Sided Si Strip Detector at the focal plane of the Argonne Fragment Mass Analyzer. In-beam gamma rays were detected in the GAMMASPHERE array of Ge detectors and were correlated with $^{101}$Sn beta-delayed protons. Implications of the $^{101}$Sn gamma-ray spectrum for the structure of $^{101}$Sn, $^{100}$Sn and neighboring nuclei will be discussed.