How to add jquery click event to gRaphael graphics?

3gwebtrain

I made a chart using g.Raphael:

$(function(){
    var r = Raphael("pieChart"),
            pie = r.piechart(320, 240, 100, [55, 20, 13, 32, 5, 1, 2, 10]);

            r.text(320, 100, "Interactive Pie Chart").attr({ font: "20px sans-serif" });
            $(pie.sector).click(function(){
                alert('hi');//not work!
            })

})

Later I added the click event to pie.sector, but my event is not work… any one know the right way to handle gRaphael with jQuery?