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Ladies and gentlemen,
Does anybody know what a BSRI is for?
I figured out the following:

• From the pictures in the Elogbook, it appears to be a device that splits a beam through two slits and makes pictures of the interference pattern.
• It looks like it operates on light (it says lambda=560 nm, which is green).
• I cannot figure out from the picture where this light comes from.
• When I googled it, I got a link to an article saying "double diffractive cross section measurement in the forward direction", but I can't get to the article.
• From the title, I would guess this devices is a new way to measure the beam cross section.

It may be a device that measures the beam position, intensity or some other parameter indirectly
through synchroton radiation.

It stands for Beam Synchrotron Radiation Interferometry. Is is a test set-up to extract the beam size from the BSRT light without some of the inherent errors in the normal system.