Presenting a nuclear reaction in LaTeX

\documentclass{article}
\usepackage[version=4]{mhchem}
\begin{document}
\section{The discovery of \ce{^4_2He}}
$\ce{^4_2He + ^27_13Al -> ^31_15P -> ^30_15P + ^1_0n}$

\sffamily Works also with text fonts (\ce{^4_2He}).
\end{document}

For a special nuclear reaction in LaTeX, I have taken a particular reaction here into this link https://www.physicsforums.com/threads/latex-help-for-nuclear-reactions.14912/ using isotope package. I use often this solution just as alternative to mhchem package.

EDIT: --> for the comment of the user @mhchem.

\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{sectsty}
\allsectionsfont{\bfseries}
\usepackage{isotope}
\usepackage{xcolor}

\begin{document}

Text mode: \textcolor{red}{\isotope[4][2]{He}} or normal without color \isotope[4][2]{He} and also for the section.
\section{The discovery of \isotope[4][2]{He}}

In math-mode you can have the same thing:

$\isotope[4][2]{He}+\isotope[27][13]{Al}\rightarrow\isotope[31][15]{P}\rightarrow\isotope[30][15]{P}+\isotope[1][0]{n}$
\end{document}

ADDENDUM:

Also isotope package can have a bold formula in the section in text mode.

\documentclass[12pt]{article}

\usepackage{sectsty}
\allsectionsfont{\bfseries\boldmath}
\usepackage{isotope}

\begin{document}

\section{The discovery of \isotope[4][2]{He}}

\end{document}