I think you'll probably have to define the term "Preparator" a bit
more, and the context of your query.
 
Most of the museums I am familiar with have well defined divisions
based upon discipline, and each division has its own technical
people (titles very with division).  The term "preparator" is commonly
applied to vertebrate paleontology technical folk, and somewhat less
so to the biological folk, but I am not aware of a museum which has a
_separate_ department of "preparators" of any sort.
 
Gregory Brown
Chief Preparator, Vertebrate Paleontology
University of Nebraska State Museum