Copyright law does not apply to names. You do however have two possible options to help protect the name of your band. Firstly, you could register the name of the band with the Companies Registration Office and should anyone else try to register this name they will be told of your existence.
You could also register your name as a trade mark or service mark and this can be done through the Patents Office. This would in effect stop anyone trading under this name in Ireland. You would also need to register this name for the rest of Europe and the World.
For more comprehensive information regarding both of these processes and the associated costs involved you should contact these offices directly.
On such matters it is recommended that you seek independent legal advice.