( ( When ( ( a ( radioactive nucleus ) ) ( emits ( ( an electron ) ( -LRB- ( ( beta decay ) -RRB- ) ) ) ) ) ) ( , ( it ( ( ( is ( in fact ) ) ( ( ( ( a neutron ) ( within ( ( the nucleus ) ( that ( ( transforms ( into ( a proton ) ) ) ( by ( emitting ( a W ) ) ) ) ) ) ) ) - ) ( which ( ( , ( soon ( after , ) ) ) ( decays ( into ( an ( electron ( anti-neutrino pair ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT a) (JJ radioactive) (NN nucleus)) (VP (VBZ emits) (NP (NP (DT an) (NN electron)) (PRN (-LRB- -LRB-) (NP (JJ beta) (NN decay)) (-RRB- -RRB-)))))) (, ,) (NP (PRP it)) (VP (VBZ is) (ADVP (IN in) (NN fact)) (NP (NP (DT a) (NN neutron)) (PP (IN within) (NP (NP (DT the) (NN nucleus)) (SBAR (WHNP (WDT that)) (S (VP (VBZ transforms) (PP (IN into) (NP (DT a) (NN proton))) (PP (IN by) (S (VP (VBG emitting) (NP (DT a) (NNP W)))))))))) (: -) (SBAR (WHNP (WDT which)) (S (PRN (, ,) (ADVP (RB soon)) (PP (IN after)) (, ,)) (VP (VBZ decays) (PP (IN into) (NP (DT an) (JJ electron) (JJ anti-neutrino) (NN pair)))))))) (. .)))
When a radioactive nucleus emits an electron ( beta decay ), it is in fact a neutron within the nucleus that transforms into a proton by emitting a W- which, soon after, decays into an electron anti-neutrino pair.
(ROOT (S (NP (NP (DT The) (NN electron)) (VP (VBN released) (PP (IN during) (NP (JJ beta) (NN decay))))) (VP (VBZ is) (RB not) (NP (NP (DT an) (JJ orbital) (NN electron)) (PP (CC but) (NP (NP (DT an) (NN electron)) (SBAR (WHNP (WP$ whose) (NNS origin)) (S (VP (VBD was) (PP (IN in) (NP (DT the) (NN nucleus)))))))))) (. .)))