The extended use of tracking information at the trigger level in the LHC is crucial for the trigger and data acquisition (TDAQ) system to fulfill its task. Precise and fast tracking is important to identify specific decay products of the Higgs boson or new phenomena, as well as to distinguish the contributions coming from the many collisions that occur at every bunch crossing. However, track reconstruction is among the most demanding tasks performed by the TDAQ computing farm; in fact, complete reconstruction at full Level-1 trigger accept rate (100 kHz) is not possible. In order to overcome this limitation, the ATLAS experiment is planning the installation of a dedicated processor, the Fast Tracker (FTK), which is aimed at achieving this goal. The FTK is a pipeline of high performance electronics, based on custom and commercial devices, which is expected to reconstruct, with high resolution, the trajectories of charged-particle tracks with a transverse momentum above 1 GeV, using the ATLAS inner tracker information. Pattern recognition and the track parameter extraction are expected to be performed in roughly 100 µs, allowing all the high level trigger selections to use the tracks provided by FTK in order to build high quality and robust triggering.

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A measurement of the rate of prompt diphoton production in jjp collisions at fi = 1800 GeV using the CDF detector is presented. The background from non-prompt sources is estimated using a sample of single photon candidate events. The results are compared to a next-to-leading order calculation by Bailey, et al. Both background and signal take on particular significance as an indicator of our ability to estimate the backgrounds affecting LHC low mass Higgs to diphoton searches.