I tried to do the measures without the strontium source, but the Alibava didn't cooperate with me.

First, it wasn't catching any events, then, I tried to put the Trigger on -20 and on -10. Nothing either..

Second, when I tried to restart the Alibava, it didn't open anymore. I used the comand sudo chmod a+rw/dev/ttyUSB0 and didn't work..

This message appeared: chmod: missing operand after ‘a+rw/dev/ttyUSB0’
                                      Try 'chmod --help' for more information.
Then, I give up.