High-Energy Physics - Signal Processing Systems - page 143

systems are discussed several times throughout this chapter. For a more general
discussion of FPGA-based DSP platforms, see [ 43 ] .
Although the initial CMS Level-1 Trigger used some programmable hardware, at
the time of its design performance considerations limited many components to using
fixed-function electronics [ 51 ] . The flexibility provided by the limited amounts of
programmable hardware should allow for some modifications to the system over
the initial LHC's planned lifetime. However, a significant proposed LHC upgrade,
commonly referred to as the Super Large Hadron Collider (SLHC) project, will
require a redesign of the triggering systems for the experiments. This redesign is
projected to replace most of the remaining ASICs with reconfigurable hardware,
increasing system flexibility.
The purpose of the SLHC upgrade is to boost the LHC's luminosity by an
order of magnitude, with a corresponding increase in collision rate. This could
allow the accelerator to continue to make new discoveries years after the original
experiments have run their course [ 30 ] . Naturally, increasing the collision event rate
places significant strain on the triggering system, since this system is responsible for
performing the first-pass analysis of the event data. Higher luminosities will mean
that each collision event will produce more particles that must be analyzed by the
triggering system and will make it more difficult to isolate sensor readings from
adjacent particles in a phenomenon known as pile-up. The existing Level-1 Trigger
hardware and algorithms are insufficient to handle the SLHC's increased particle
pile-up, and must thus be upgraded [ 47 , 50 ] . The design problems of this upgrade
provide examples of the challenges of modern system design for HEP applications.

3 Characteristics of High-Energy Physics Applications

Although every HEP system is different, many of them share certain high-level
technical and design-oriented characteristics. Understanding the unique features
of HEP applications is key to designing signal processing systems for these
applications.

3.1 Technical Characteristics

Many of the technical challenges of HEP systems derive from their extreme scale.
This scale gives rise to several important technical characteristics of HEP applica-
tions, discussed here using concrete examples from the CMS Trigger introduced in
Sect. 2.2 .