Are there positions for recently graduated bachelor or masters students with a record of research to work as a researcher before committing to their PhD?
TCS has a culture of post-doc positions for recent PhD graduates to do research before attempting to apply for a faculty position. Is there a similar mechanism in place for Bachelor or Masters students to do research before applying for a Ph.D? In particular, if they have a research record already (say a few published papers). I have heard of such positions, but usually they are through your current or future supervisor. Are there other options in industry or at universities/research-centers that are more formal than these personal connections?
The goal of such a position is to work within your field or at an institute you are considering for PhD before committing to it for a longer term.
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Edit:
After a number of answers, I'd like to emphasize the interest is in having an analogue to a post-doc in that it is purely (or almost completely) a research position. Programs where you take courses to ready for a PhD application are not interesting, since the goal is not to prepare yourself for a PhD application as much as it is to do research to make sure research is what you want to do for the long term.