Hadronic Energy Scale Research Articles

Hadronic Energy Scale Calibration of Calorimeters in Space Using the Moon’s Shadow

Hadronic Energy Scale Calibration of Calorimeters in Space Using the Moon’s Shadow

Controlling quark mass determinations non-perturbatively in three-flavour QCD

The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.

Combined Forward Calorimetry Option for Phase II CMS Endcap Upgrade

Traditionally, EM and HAD compartments are thought to be separate and are often optimized individually. However, it is possible to optimize a robust and economical combined calorimeter system for myriad physics objectives. By employing event-by-event compensation afforded by the dual-readout technique, we have shown that excellent jet performance can be attained with a longitudinally un-segmented calorimeter that is calibrated only with electrons. In addition, the linear hadronic energy scale renders complex off-line correction schemes unnecessary. The proposed replacement of the CMS EE and HE calorimeters with a single Combined Forward Calorimeter (CFC) shows excellent jet performance complemented by good EM object detection. In this paper, we give brief snapshots on basic design criteria, timing characteristics of Cherenkov and scintillation pulses, trigger generation criteria and performance under high radiation fields. Although CMS has recently chosen different technologies for its endcap calorimetry in Phase II, the concepts developed here are likely to remain valuable for some time to come.

Reconstruction of the jet hadronic energy scale in the ATLAS calorimeter system

The precision of the final jet energy scale is a fundamental ingredient for important physics measurements, like the top-quark mass, or even for new discoveries (SUSY). The ATLAS calorimeter requirements in terms of uniformity and resolution have been achieved and verified in many years of tests on beam at CERN. The key issues for the jet reconstruction and calibration in ATLAS (agreement between test beam data and the Geant 4 predictions, clustering strategies, reconstruction and calibration algorithms) will be briefly discussed and reviewed.

Intercalibration of the longitudinal segments of a calorimeter system

Three different methods of setting the hadronic energy scale of a longitudinally segmented calorimeter system are compared with each other. The merits of these methods have been studied with testbeam data from the CDF Plug Upgrade Calorimeter. It turns out that one of the (commonly used) calibration methods introduces a number of undesirable side effects, such as an increased hadronic signal nonlinearity and trigger biases resulting from the fact that the reconstructed energy of hadrons depends on the starting point of their showers. These problems can be avoided when a different calibration method is used. The results of this study are applied to determine the e/ h values of the calorimeter and its segments.

Precision calibration of the NuTeV calorimeter

NuTeV is a neutrino–nucleon deep-inelastic scattering experiment at Fermilab. The detector consists of an iron-scintillator sampling calorimeter interspersed with drift chambers, followed by a muon toroidal spectrometer. We present determinations of response and resolution functions of the NuTeV calorimeter for electrons, hadrons, and muons over an energy range from 4.8 to 190 GeV. The absolute hadronic energy scale is determined to an accuracy of 0.43%. We compare our measurements to predictions from calorimeter theory and GEANT3 simulations.

From current to constituent quarks: A renormalization-group-improved Hamiltonian-based description of hadrons

A model which combines the perturbative behavior of QCD with low-energy phenomenology in a unified framework is developed. This is achieved by applying a similarity transformation to the QCD Hamiltonian which removes interactions between the ultraviolet cutoff and an arbitrary lower scale. Iteration then yields a renormalization-group-improved effective Hamiltonian at the hadronic energy scale. The procedure preserves the standard ultraviolet behavior of QCD. Furthermore, the Hamiltonian evolves smoothly to a phenomenological low-energy behavior below the hadronic scale. This method has the benefit of allowing radiative corrections to be directly incorporated into nonperturbative many-body techniques. It is applied to Coulomb gauge QCD supplemented with a low-energy linear confinement interaction. A nontrivial vacuum is included in the analysis via a Bogoliubov-Valatin transformation. Finally, the formalism is applied to the vacuum gap equation, the quark condensate, and the dynamical quark mass.