ALICE Trigger Oscilloscope

Quantum-ChromoDynamics (QCD) is the theory of the strong force and understanding its properties has been the focus of intense World-wide research over the past half century. QCD forms a major part of the Standard Model and its understanding is crucial in producing an overall theory to describe the properties of matter and the fundamental forces of nature including a grand unification theory to explain how the Universe evolved from the Big Bang.

The principal purpose of our research is to use ultra-relativistic heavy-ion interactions to study QCD at extreme energy densities. Theoretical models predict that under very extreme conditions of high energy densities the quarks, which are confined in normal nuclear matter, will be freed and nuclear matter will undergo a phase transition into a hot, dense plasma of free quarks and gluons known as a Quark-Gluon Plasma (QGP). It is thought that such a state of matter would have existed until about 10^-5 seconds after the Big Bang, after which time the Universe would have cooled sufficiently for protons and neutrons to form.

The physics aim of this research is to study the strong force under these extreme conditions and, in particular, explore the properties of this exotic state of matter. By studying the QGP, we hope to address the fundamental questions of quark confinement and how quarks gain a large effective mass in hadrons due to the strong force (accounting for 99% of atomic mass).

This field of research employs about two thousand physicists around the world and ALICE is the most sophisticated experiment ever built in the field, studying heavy-ion collisions at centre-of-mass energies over an order of magnitude greater than its nearest rival. It hence represents the pinnacle of research in this field.

The ALICE collaboration is now preparing for the second LHC upgrade scheduled to start in 2018. These upgrades are required to cope with the anticipated increase in lead beam luminosity which will increase beam intensities by an order of magnitude. The main motivation for the luminosity upgrade is to achieve a precise, quantitative understand of the properties of the QGP by focusing on rare probes both at low and high transverse momenta as well as on multi-dimensional analysis of such probes with respect to centrality, event plane, multi-particle correlations, etc.

The ALICE-Birmingham Group is playing a leading role in the ALICE Upgrade at the LHC (CERN), in particular we are responsible for the upgrade to the Central Trigger Processor (CTP) where we have recognised international leadership. This will enable us to continue to be responsible for the vital CTP and will position us to continue to play a leading role in the future. However, in order to develop the sophisticated trigger electronics and fast optical data transfers, we require a modern 16 GHz Oscilloscope, which we are applying for in this call. This bid will capitalise on the prior investment of STFC in the ALICE experiment by sustaining and enhancing the leadership role the UK plays.

The main beneficiaries of the activities related to this call will be experimentalists and theorists working in the field of hot Quantum Chromodynamics. They will directly benefit from the new insights that will arise out of the research, made possible by this upgrade. The results of the subsequent research will be disseminated in high impact journals, through conference talks and seminars so as to reach as wide an audience as possible. More broadly, both the technologies developed during the upgrade and the resulting research will also be of relevance to researchers in other fields, including other areas of nuclear physics, particle physics, astrophysics and cosmology. Some of the hardware developments related to the Birmingham design of the original ALICE trigger subsystem have already had impact, having being adopted by another experiment at CERN. Future developments that are foreseen in this proposal will potentially have relevance to a new generation of experiments planning to run in continuous data taking mode.

Another strand revolves around the public understanding of science. The research that is related to this proposal has the potential to capture the imagination and to inspire a new generation of scientists. The research programme which will arise from the ALICE upgrade is involved in studying matter as it would have existed a fraction of a second after the Big Bang. This aspect is relevant to the evolution of the Early Universe and the possible existence of (strange) quark matter stars. David Evans of the ALICE-Birmingham group has given over 90 public lectures over the past five years and been involved in many other public outreach events to school children, teachers, and members of the general public.