# What is the $^{28}{\rm Si(}d,p)$ nuclear reaction?

I am reading about several processes in nuclear physics that put letters in parentheses next to the names of the isotopes.

Usually two letters, separated by a comma.

Besides $$d$$ and $$p$$, I have seen a (or alpha?) and n.

I first thought d and p stood for energy (sub)levels, but now I'm thinking p is proton, n is neutron, d is 'daughter' (nuclide?) Or deuterium? And a or 'alpha' is alpha particle....

Are these protons and neutrons and deuterons and such part of the initial reaction? Or end result?

$$\rm target (incoming, outgoing) residual$$
So your example, $$\rm^{28}Si(d,p)$$, suggests a silicon target exposed to a beam of deuterons (deuterium nuclei), where the particles which are detected after the interaction are protons. The mostly likely interpretation is neutron transfer,
$$\rm ^{28}Si + d \to p + {}^{29}Si$$
but there are other possibilities, too. Depending on the energies involved the $$\rm^{29}Si$$ nucleus might emit a gamma cascade, or re-emit the captured neutron, or fission. But if all you have is a proton detector, then you detect $$\rm^{28}Si(d,p)$$, and speculating about all the different final states occupies a long section in your paper.
This notation also allows you to talk about beam reactions independently of their targets. I did this already when I referred to your $$\rm(d,p)$$ as a "neutron transfer reaction." You will also find $$(n,\gamma)$$ for radiative neutron capture and $$\rm(n,f)$$ for neutron-induced fission.