IANAE, but it seems like the pinch point is the temp where the difference between your cooling fluid and instrument temperature is the lowest. in other words, t

IANAE, but it seems like the pinch point is the temp where the difference between your cooling fluid and instrument temperature is the lowest. in other words, this is where your cooling efficiency is lowest. This is probably doubly tricky at such low temperatures because the low average energy makes it difficult to even cool it further to begin with, never mind how cool the rest of your cooling systems need to be to actually sustain such low temperatures of your cooling brine to begin with. It took months to cool the instruments to these temperatures, but it could have taken even longer.