I have this XML:

```
<root>
  <experiment accessCount="1" downloadCount="1">alfa</experiment>
  <experiment accessCount="1" downloadCount="1">beta</experiment>
</root>

```

And I would like to detect if the node experiment with value alfa exists.
But this PHP code is returning to me all values. 

```
    $this->xml = simplexml_load_file("data/stats.xml") or die("Error: Cannot create object");
    $node = $this->xml->xpath("/root[experiment='alfa']");

```

Where am I wrong?