The large particle count (LPC) in a CMP slurry is the concentration of tail particles typically > 0.5 µm or 1 µm.
Some scientists define the LPC >0.5 µm, others >1.0 µm. An official size cut off has not been standardized yet.
LPC data from the AccuSizer FX
The LPC has been proven to be an effective control parameter to avoid scratches on surfaces, reducing yield.