Ties to nothing

[Tim Sawyer]

In percussion music, it is normal to have a tie to nothing after a cymbal 
note, to indicate that the cymbal should be left to ring.

Can anyone help me achieve this effect in lilypond 2.0.3 (lilypond book if 
that makes any difference)?

This is what I want to do but it doesn't print the final tie line:

\begin[20pt]{lilypond}
  \score
  {
    \notes
    {
      \time 4/4
      \property Staff.TimeSignature \set #'style = #'()
      \clef bass
      \stemUp
     b1:32~b4 r4 r2 b1:32~b4~r4 r2 \bar "|."
    }
  }
\end{lilypond}

Thanks,

Tim.