There's a detailed and informative article about the design of the New Horizons probe on the British Interplanetary Society site at [1]. An even more detailed description of the science payload can be found at [2].

[1] http://www.bis-space.com/2015/07/13/14875/inside-new-horizon...

[2] http://www.boulder.swri.edu/pkb/ssr/ssr-payload-overview.pdf