You've created an infinite loop. [L] does not mean "stop right here and proceed directly to the page". It means "go back to the beginning of the list of Apache modules and start over, this time using the 'target' as your new 'pattern'".
Fortunately there are, at a rough estimate, 70,000 earlier posts discussing rewrites, redirects, the role of a RewriteCond, and the appropriate ordering of rules.
Now, about that