# what is wrong in this reaction?

\documentclass{article}
\usepackage[version=4]{mhchem}
\usepackage{siunitx}
\usepackage{isotope}
\begin{document}
\section{Decay mode of  \ce{Be isotope}}

$\ce{^4_2Be -> [5x10^3}{ns}][{1.37 MeV}] ^4_2He + 2p^+}$\\
\end{document}


I read a error that a $is missing or plus. any solution? • What output would you expect? Currently, there seems to be a mismatch between { and }. Oct 16, 2019 at 14:58 • Correct suggestion of the user leandriis. This MWE works correctly: \documentclass{article} \usepackage[version=4]{mhchem} \usepackage{siunitx} \usepackage{isotope} \begin{document} \section{Decay mode of \ce{Be isotope}}$\ce{^4_2Be -> [\num{5e3} {ns}][{1.37 MeV}] ^4_2He + 2p^+}$\end{document}. For siunitx package I have read to page 4: \num{5e3}. Oct 16, 2019 at 15:01 ## 3 Answers The one apparent error is a missing opening brace in [5x10^3}{ns}]. But there are other things: • 5x10^3}{ns} should be \SI{5e3}{ns} or \SI{5e3}{\nano\second} or at least $5\times10^3\,\mathrm{ns}$ • {1.37 MeV} should be \SI{1.37}{MeV} or \SI{1.37}{\mega\electronvolt} or at least $1.37\,\mathrm{MeV}$ • \ce{Be isotope} should be \ce{Be} isotope • -> [ should be ->[ (the blank is wrong there) • the math mode around $\ce{...}$ isn't necessary • \\ at the end of the line is wrong Full example: \documentclass{article} \usepackage[version=4]{mhchem} \usepackage{siunitx} \begin{document} \section{Decay mode of \ce{Be} isotope} \ce{^4_2Be ->[\SI{5e3}{\nano\second}][\SI{1.37}{\mega\electronvolt}] ^4_2He + 2p^+} \end{document}  • sorry to ask again: and antiparticle like anti-neutino? i can use heparticle? and yes, your version work very good. thank you for your help Oct 16, 2019 at 16:05 Possibly "\SI{" is missing: \documentclass{article} \usepackage[version=4]{mhchem} \usepackage{siunitx} \usepackage{isotope} \begin{document} \section{Decay mode of \ce{Be isotope}}$\ce{^4_2Be ->[ \SI{5e3}{ns}][{1.37 MeV}] ^4_2He + 2p^+}$\\ \end{document}  • Ops :-) excuse me. You have beat me for 5 sec. :-) I delete my answer and put a comment. Oct 16, 2019 at 15:01 If you want to use the hepparticles package, you have either to use its syntax, e.g. \HepParticle{p}{}{+} for a proton, or write a shortcut such as \newcommand{\Pproton}{\HepParticle{p}{}{+}}  in your preamble in order to use it elsewhere in your document. That was not the case from your screenshot (and please take the time to write code in your question). A few more thing : • as mhchem does not need to be enclosed in a math environment, you can ditch the $, it will make your code lighter;
• the way you write it, it might take less effort to stick with mhchem;
• also, should it not be beryllium-6 that undergoes that decay ?
• I use this only to see if it work, is not offical work. it still not working. I try many things I'm out of ideas. Oct 16, 2019 at 15:39
• I had forgotten a \ for the \HepParticle. Corrected, it works fine for me. Oct 16, 2019 at 15:46