Ultracold Metastable Calcium Ensembles, a Medium for Matter Wave   Amplification ?
  We propose an experimental implementation of matter wave amplification by optical pumping (MAO) with metastable calcium atoms. First experimental results indicate that pumping rates can be significantly higher than in previous experimental schemes and let it appear promising that the threshold condition for generation of degeneracy can be reached. 
J. Gruenert, G. Quehl, V. Elman and A. Hemmerich