( Sometimes ( radioactivity ( ( is ( ( measured ( in ( counts ( per minute ) ) ) ) ( on ( a ( Geiger counter ) ) ) ) ) . ) ) )
(ROOT (S (ADVP (RB Sometimes)) (NP (NN radioactivity)) (VP (VBZ is) (VP (VBN measured) (PP (IN in) (NP (NP (NNS counts)) (PP (IN per) (NP (NN minute))))) (PP (IN on) (NP (DT a) (NNP Geiger) (NN counter))))) (. .)))
Sometimes radioactivity is measured in counts per minute on a Geiger counter.
(ROOT (S (NP (NP (DT The) (`` `) (NN counting) ('' ') (NN instrument)) (NP (NN geiger) (NN counter))) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB measure) (NP (NN radioactivity))))))) (. .)))