Affine Wa(A4), Quaternions, and Decagonal Quasicrystals

We introduce a technique of projection onto the Coxeter plane of an arbitrary higher dimensional lattice described by the affine Coxeter group. The Coxeter plane is determined by the simple roots of the Coxeter graph I2 (h) where h is the Coxeter number of the Coxeter group W(G) which embeds the dihedral group Dh of order 2h as a maximal subgroup. As a simple application we demonstrate projections of the root and weight lattices of A4 onto the Coxeter plane using the strip (canonical) projection method. We show that the crystal spaces of the affine Wa(A4) can be decomposed into two orthogonal spaces whose point groups is the dihedral group D5 which acts in both spaces faithfully. The strip projections of the root and weight lattices can be taken as models for the decagonal quasicrystals. The paper also revises the quaternionic descriptions of the root and weight lattices, described by the affine Coxeter group Wa(A3), which correspond to the face centered cubic (fcc) lattice and body centered cubic (bcc) lattice respectively. Extensions of these lattices to higher dimensions lead to the root and weight lattices of the group Wa(An), n>=4 . We also note that the projection of the Voronoi cell of the root lattice of Wa(A4) describes a framework of nested decagram growing with the power of the golden ratio recently discovered in the Islamic arts.Comment: 26 pages, 17 figure

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Effects of radiation and their consequences for the performance of the forward calorimeters in the CMS experiment

The experiments at the Large Hadron Collider (LHC) will have to deal with unprecedented radiation levels. In the large-rapidity regions, close to the beam pipe, these levels reach megagrays per year. The detectors to be installed in these regions, the HF Calorimeters, are designed to operate under these conditions, In this paper, we describe the results of studies in which a prototype calorimeter was exposed to radiation of the type and intensity expected at the LHC. These studies made it possible to estimate the effects of this radiation on the response and the resolution of the calorimeter as a function of time during LHC operation

Energy resolution and the linearity of the CMS forward quartz fibre calorimeter pre-production-prototype (PPP-1)

The first pre-production-prototype (PPP-I) of the quartz fibre calorimeter of the CMS detector has been tested at CERN. The calorimeter consists of quartz fibres embedded in an iron matrix. Results are presented on the energy resolution and on the signal uniformity of the prototype for electrons and pion's and the signal uniformity and linearity

Energy Resolution and the Linearity of the CMS Forward Quartz Fiber Calorimetry Pre-Production-Prototype (PPP-I)

The first pre-production-prototype (PPP-I) of the quartz fiber calorimeter of the CMS detector has been tested at CERN.The calorimeter consists of quartz fibers embedded in an iron matrix. Results are presented on the energy resolution of the prototype for electron and pions and the signal uniformity and linearity

On the differences between high-energy proton and pion showers and their signals in a non-compensating calorimeter

We present the results of experimental studies of hadron showers in a copper:quartz-fiber calorimeter, based on the detection of Cherenkov light. These studies show that there are very significant differences between the signals from protons and pions at the same energies. In the energy range between 200 and 375 GeV, where these studies were performed, the calorimeter's response to protons was typically 10% smaller than the response to pions. On the other hand, the energy resolution was about 25% better for protons. In addition, the protons had a Gaussian line shape, whereas the pion response curve was asymmetric. These differences can be understood from the requirements of baryon number conservation in the shower development. They are expected to be present in any non-compensating calorimeter, to a degree determined by the e/h value