LHC Report: Intensity ramp-up

The first stable beams at 4 TeV were declared on Thursday, 5 April with 3 bunches per beam. This marked the start of the intensity ramp-up, which aims to get back up to 1380 bunches per beam as quickly as is safely possible.

The next couple of days saw fills with 47, 84 and 264 bunches per beam and on Sunday, 8 April the move was made to 624 bunches. With the squeeze to 60 cm in place, 624 bunches with reasonably high bunch intensities of around 1.3 to 1.4 x10¹¹ protons per bunch have already yielded respectable peak luminosities of up to 2.5 x10³³ cm^-2s^-1. Following a lot of hard work during the Christmas technical stop, machine availability is very good at the moment.

The ramp-up in the number of bunches is accompanied by a series of checks aimed to make sure the machine protection systems and operational procedures are in a good enough shape to safely deal with the beam intensity. 624 bunches at 4 TeV already represents an energy over 50 MJ and serious damage potential.

The next few days should see a steady increase to 840, 1092 and finally 1380 bunches per beam as the operations team commissions high intensity operation in preparation for some sustained production running. The schedule includes a 7-week running period for physics. This is preceded by a 3-day machine development period and a 5-day technical stop starting on Friday, 20 April.

by Mike Lamont for the LHC Team