Chicken pecking at new chickens

They are letting the chicks know where they stand in the pecking order, and it is normal.  If the behavior turns into 'hunting', then you might have a problem.  Just keep an eye out and remember that chickens are animals....they don't think "hey, maybe I'm being a bit harsh."  You'll probably notice that pecking happens when the chick enters the "personal space" of a bird that is already in the pecking order.

blood is not good, the chickens should be similar size, and there needs to escape places where they can get out of reach of the bigger hens.

It usually helps as well to pen the new chickens alongside the older ones for a week or so rather then just popping them in the pen with them.  That's a guaranteed fight.  I usually section off a part of the run for newbies and also put them in a wire dog crate inside the coop at night.  That way everybody can get used to seeing each other but the older ones can't attack.  I try to do all I can to avoid getting a serious, blood drawing pecking problem started.  Sometimes once they start they don't stop.

I have 8 hens - 7 pick on 1.  The one was injured by a cat and fully recovered, before anyone started laying.  All are 1 year old.  Recently I have applied a hen apron with shoulders and the thick, stinky no-peck stuff for her head.  Pecking seems to have increased, especially when it's bedtime.  I am getting 5 new chicks this week, and am thinking of placing the pecked one in with them in about a month or so, to help with her confidence and to provide a six-pack of chickens to join the originals, when they are big enough.  I would appreciate your thoughts on my ideas.  Thanks!
 

Oh - I should note that my hens get a variety of foods every day, stimulation from other critters, have way more room than I have in my house, get picked up and petted and gently chased, and get to roam truly free in a pasture, every night for about an hour.