Final Scientific/Technical Report for "Forward Angle Physics at CMS"

Abstract

CMS will be used to study the reaction products from nuclear collisions of lead with lead at energies of 1100 TeV and also collisions between lighter elements. CMS is a huge detector array at the LHC (Large Hadron Collider), now under construction at CERN in Geneva, Switzerland. The emphasis in this work will be on the far-forward angles (close to the beam line) which has the highest density of products and for which the Univ. of Iowa group has made major contributions to the design and construction of the detectors (CMS-HF, CMS-ZDC). With a detailed knowledge of all of the forward detectors, this group is uniquely prepared to distinguish real physics from effects caused by peculiarities of the detectors. The work included finishing the detectors and getting them into operation and preparing to study data after the LHC restarts in 2010. The Iowa group also continued to develop improved detectors for use with upgrades to CMS and for other applications. The available energy is almost 30 times that from gold + gold at the present RHIC facility. The new energy regime will open a new window on hot and dense matter physics. The higher energy lengthens the lifetime of a quark gluon plasma and provides additional probes for studying this new form of matter. For example, there is abundant production of jets and heavy quarks with a large cross section for J/{Psi} and {Upsilon} production. The three states of the {Upsilon} are clearly resolved by CMS. The different 'melting' for members of the {Upsilon} family provides information about the nuclear medium. The much wider range of Q{sup 2} and x allow a major extension of the measurements at RHIC. This large increase in energy provides more than just an extension of RHIC results to higher energy. It is expected to reveal a wealth of new phenomena. This will be the first time that sufficient energy is available to produce in the laboratory the strange and poorly understood objects found in high-energy cosmic ray events. The largest system available in cosmic rays is iron on oxygen. Lead on lead is totally new. It is only possible to record a small fraction of the output of CMS. With its intimate knowledge of the forward detectors, the Iowa group needs to have a part in decisions about the selection of events to be saved. Otherwise, events that should have the highest priority may be discarded at the trigger level and lost forever.