( ( Since ( ( free neutrons ) ( ( are electrically ) neutral ) ) ) ( , ( they ( ( pass ( ( ( unhindered ( through ( ( the ( electrical fields ) ) ( within atoms ) ) ) ) and ) ( so ( constitute ( ( ( ( a ( penetrating form ) ) ( of radiation ) ) , ) ( ( ( interacting ( with matter ) ) ( almost exclusively ) ) ( through ( ( ( relatively rare ) collisions ) ( with ( atomic nuclei ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (JJ free) (NNS neutrons)) (VP (VBP are) (ADVP (RB electrically)) (ADJP (JJ neutral))))) (, ,) (NP (PRP they)) (VP (VBP pass) (S (VP (VP (JJ unhindered) (PP (IN through) (NP (NP (DT the) (JJ electrical) (NNS fields)) (PP (IN within) (NP (NNS atoms)))))) (CC and) (VP (ADVP (RB so)) (VBP constitute) (NP (NP (DT a) (JJ penetrating) (NN form)) (PP (IN of) (NP (NN radiation))) (, ,) (VP (VBG interacting) (PP (IN with) (NP (NN matter))) (ADVP (RB almost) (RB exclusively)) (PP (IN through) (NP (NP (ADJP (RB relatively) (JJ rare)) (NNS collisions)) (PP (IN with) (NP (JJ atomic) (NNS nuclei))))))))))) (. .)))
Since free neutrons are electrically neutral, they pass unhindered through the electrical fields within atoms and so constitute a penetrating form of radiation , interacting with matter almost exclusively through relatively rare collisions with atomic nuclei.
(ROOT (S (NP (NNS Neutrons)) (VP (VBP are) (ADVP (RB electrically)) (ADJP (JJ neutral))) (. .)))