how to access session from next to previous page

how to access session from next to previous page

I am in trouble.in my login page i am using ajax.a pop come in my page for
login an after authentication using ajax it returns to the same calling
page.i am using session for tracking my login.but when i reload the page
the session expires which i dont want.i need only session should expires
when we close browser.How is it possible to?
part of code i used(from top to bottom)
request code
<?php
error_reporting(E_ALL);
ini_set('display_errors','1');
?>
<?php session_start();
if(isset($_SESSION["manager"]))
{
echo'<script>document.getElementById("accordion").style.display="block";</script>';
}
?>
response code
<?php
error_reporting(E_ALL);
ini_set('display_errors','1');
?>
<?php
if(isset($_GET["uname"])&&isset($_GET["upass"])){
$manager=preg_replace('#[^A-Za-z0-9]#i','',$_GET["uname"]);
$password=preg_replace('#[^A-Za-z0-9]#i','',$_GET["upass"]);
include"connect_to_mysql.php";
$sql=mysql_query("SELECT username FROM login WHERE username='$manager'
AND password='$password' LIMIT 1");
$existCount=mysql_num_rows($sql);
if($existCount==1){
/*while($row=mysql_fetch_array($sql)){
$id=$row["id"];
}*/
//$_SESSION["id"]=$id;
$_SESSION["manager"]=$manager;
$_SESSION["password"]=$password;
echo("success");
}
else
{
echo("fail");
}
}
?>