Zend session and zend auth

I have made a login system through zend auth here is the code

// userAuthentication
   public function authAction(){
       $request     = $this->getRequest();
       $registry    = Zend_Registry::getInstance();
       $auth        = Zend_Auth::getInstance(); 
       $DB = $registry['DB'];
           $authAdapter = new Zend_Auth_Adapter_DbTable($DB);
               $authAdapter->setTableName('user')
                            ->setIdentityColumn('user_name')
                            ->setCredentialColumn('user_password');

      $username = $request->getParam('username');
      $password = $request->getParam('password');
      $authAdapter->setIdentity($username);
      $authAdapter->setCredential($password);
      $result = $auth->authenticate($authAdapter);

      if($result->isValid()){
           $data = $authAdapter->getResultRowObject(null,'password');
           $auth->getStorage()->write($data);
           $this->_redirect('/login/controlpannel');
       }else{
           $this->_redirect('/login/login');
        }
  }

This work fine now. There is user_id (column) in user (table) where there are username and password too. I need to get that specific user_id from this table which just login and put it in session through

$user_session = new Zend_Session_Namespace('user_session');
$user_session->username = $username;
$user_id->user_id       = $user_id;

so that I can query some info against this $user_id and pass the result into view (name) controlpanel

Get user id from storage :

$userInfo = Zend_Auth::getInstance()->getStorage()->read();

echo $userInfo->user_id;