With the use of an on-line isotope separator, Tm149 (T1/2=0.90.2 s) was identified in Ni58 bombardments of Mo94. Seven rays were observed to follow the isotopes (++electron capture) decay, including the 111.3-keV transition known from Erm149 isomeric decay to be the d3/2 (111.3 keV)s1/2 (0.0 keV) ray in Er149. In addition to the previously known levels at 111.3 (d3/2) and 741.5 (h11/2) keV in Er149, our data establish three other excited states, at 907.4 ((5/2+), 1066.2 ((7/2-), and 1482.9 ((9/2-, (11/2-) keV. Coincidences observed between Er K x rays and protons in the A=149 mass chain show that Tm149 is a -delayed proton precursor.
ASJC Scopus subject areas
- Nuclear and High Energy Physics