tcs, same here. The best thing I've found so far is a Swedish group that reviewed children's helmets, using impacts at 21-27km/h (13-17mph). They did rate the Scott helmet highest for safety, but the hard data isn't available (or easily found - I'm google translating the pages)

Edit: Link here: http://www.folksam.se/testergodarad/sakeritrafiken/pacykelochtillfots/cykelhjalmstestbarn/1.110302