Covering the Sphere by Equal Spherical Balls

We show that for any acute ϕ, there exists a covering of S d by spherical balls of radius ϕ such that no point is covered more than 400d ln d times. It follows that the density is of order at most d ln d, and even at most d ln ln d if the number of balls is polynomial in d. If the number of equal spherical balls is d + 3 then we determine the optimal arrangement.