To determine the total cross section and absolute luminosity in the ATLAS detector at the LHC via pp scattering under very small angles, a dedicated sub-detector called ALFA has been made. Several performance evaluation tests including a test beam campaign lead to improvements of the detector system capabilities both before and after the installation at the LHC in winter 2010-2011.

The ALFA detector system was commissioned, optimized and integrated into ATLAS making it possible to trigger full ATLAS detector with ALFA. Already In 2011 this allowed for a measurement of the total cross section at center of mass energy 7 TeV using special high β* beam optics. The measurement was later repeated and extended at center of mass energy 8 TeV.

A major conceptual upgrade of the ALFA trigger system was made in the winter shutdown 2011-2012 which potentially doubled the data taking time useful for physics in all runs after.

Beam induced heating (impedance heating) was observed on the ALFA detectors and tests revealed that the detectors were in danger of overheating with massive degradation as a consequence. A short term solution was found and implemented and the implementation of a long term solution by minimization of the impedance losses is ongoing.