Receive PHP parameters with jQuery ajax post

I am sending data via jQuery's .ajax method to my PHP file. Both files are on the same domain. The file making the post looks like this..

$('#pdf').click(function() {                    
    var proj_name = $('#proj_name').text();
    var date = $('#date').text();
    var req_comp_date = $('#req_comp_date').text();
    var status = $('#status').text();
    var secondUserID = $('#secondUserID').text();

    var postData = {
        "proj_name" : proj_name,
        "date" : date,
        "req_comp_date" : req_comp_date,
        "status" : status,
        "secondUserID" : secondUserID,
    };

    console.log(postData);

    $.ajax({
        type: "POST",
        url: "test.php",
        data: postData, 
        success: function(){
            alert(proj_name + ' ' + status);
            window.open("test.php"); 
        }
    });
});

And the PHP file getting the post data is...

//request parameters
$proj_name = $_POST['proj_name'];
$date = $_POST['date'];
$req_comp_date = $_POST['req_comp_date'];
$status = $_POST['status'];
$secondUserId = $_POST['secondUserId'];

echo 'postData: ' . var_dump($_POST);

if ($_POST)){
    echo $proj_name;
    echo $date;
    echo $req_comp_date;
    echo $status;
    echo $secondUserId;
} else {
    echo 'problem';
}

In my firebug console, I can see that the parameters posted with .ajax, but I cannot get the post via PHP. Can anyone help me out please? Thank you.