Nonmodel fields - select_tag

Hi, I’m a ROR newbie and I’m trying to use a nonmodel field. Precisely,
I’m
trying to use the select_tag. Here’s what I’m doing:

in my view:
<%=select_tag(:place_sel, options_for_select(@places,
@params[:place_sel]))%>

in the controller, I try to get the selected item by doing this:

@tmp = @params[:place_sel]

and get nothing. What am I doing wrong?

Regards,
Rodrigo Lara