Question

What practical applications does particle physics have?

Answer 1

Well, it depends on your definition of "practical".

Explanation:

...If we take "practical" to mean "usable for the creation of devices, technologies, or mechanisms that function in the real world", then you can start with:

nuclear reactors
nuclear weapons

...now, allowing that not everyone would accept the desirability or utility of the above two applications, you can also add:

MRI scanners in medicine
Materials science
Electrical power transmission
Computing
Medicine development

...and many others. A quick web search will return many results.