selon ce site:
http://www.happybeertime.com/blog/2015/05/20/clarifier-biere...
But I'm no expert!

After fermentation is complete, the beer undergoes a 2 day rest period and is then “crashed” (cooled to 33 deg F). Crashing the beer causes the yeast to go dormant and begin to settle to the bottom of the fermenter. Thus begins the lagering phase. Our beers are lagered, or aged, from a few days to several months depending on style. During the lagering period the beer matures, allowing flavors to mellow and residual yeast to settle. Conditioning, or carbonating, follows the lagering phase. Carbon dioide can be injected into the conditioning tank to fine tune the residual carbonation created during fermentation. After lagering and conditioning steps are complete, the beer is packaged into kegs or cans.