G. La Commare

Track reconstruction with a central two-shell scintillating fibre tracker (SFT)

Abstract We present a track reconstruction algorithm designed for the scintillating fibre tracker (SFT), having in view the upgrade of the L3 detector for LEP-II. This algorithm can also be applied for particle tracking at future hadron colliders. The tracking elements are polystyrene fibres of 60 μm diameter, which are arranged as fused coherent bundles into fibre layers. We study in particular a tracking setup, which consists of two concentric cylindrical shells each of 8 mm thickness, placed at r = 18.7 cm and r = 31.4 cm radius from the collider axis. The tracking reconstruction algorithm was tested with Monte Carlo generated e+ e− events at 185 GeV c.m. energy and comparing them with the reconstructed events. It achieves for particle momenta above 0.2 GeV/c a track reconstruction efficiency of nearly 100% for primary charged tracks with less than 1% contribution of ghost tracks. The average error on the reconstructed momenta for single tracks is around 3% and the average error on the reconstructed total momentum per event is around 6%.

Results on lead/scintillating fibres calorimetry

Abstract In the framework of the LAA project at CERN, the RD25 R&D group has built a fully projective, integrated electromagnetic and hadronic, lead/scintillating fibres compensating calorimeter prototype. The prototype consists of 41 modules, each made of a straight (or electromagnetic) and two wedged (or hadronic) sections, with a lead to fibres ratio of 4 to 1 in volume. We describe in this paper the performances of the calorimeter exposed to high energy electron and pion beams: results are presented on electromagnetic and hadronic energy resolution, position resolution and particle/particle separation in space. Prototype construction required the development of a technology, also described in this paper, which is directly scalable to the construction of a 4 π detector, intended to measure, localize and identify particles in a multi-TeV hadron collider experiment.

Neural networks for Higgs search

SummaryWe describe an approach to the heavy-Higgs (mH=750 GeV) search by means of a neural network (NN) in pp collisions at

SUD: an advanced set-up descriptor for complex multi-TeV experiments

\sqrt s = 16

Heavy higgs search with hadron supercolliders up to √s=200 TeV

, TeV (LHC), 40 TeV (SSC) and 200 TeV (ELN/Eloisatron). The mechanisms we considered for Higgs production are gluon fusion and vector boson fusion, letting the H0 decay through the channel H0→Z0Z0→μ+μ-μ+μ-. The overall background to the Higgs signal was assumed to consist of the QCD continuum production of Z0 pairs, where each Z0 was forced to decay into muons. Using Monte Carlo simulated events at each energy, we trained a neural network to distinguish signal from background and evaluated its performances as an event classifier. The results are promising and indicate that neural networks could be efficiently used for event selection in future experiments at super-high energy.

An entity relationship approach to the event and detector monte carlo simulation in high-energy physics

SummaryPurpose of this note is to propose a search for typical signatures produced by charginos, neutralinos and sleptons on the basis of two supergravity model predictions, at the highest e+ e− energy which will be available with LEP-II. The typical signatures are of two main classes: i) «pure leptonic» states; ii) «mixed lepton-jets» states. The «pure leptonic» states consist of acoplanardi-leptons with «leading» and «non-leading» leptonic components plusmulti-di-lepton states. All with at least two missing momenta. The «mixed lepton-jets» states contain at least two jets and one or three leptons plus missing momenta. All these final states represent clear signatures for SUSY. Cross-sections and branching ratios are computed using two «local» supersymmetry models:i.e. the minimalSU(5) supergravity and theSU(5)×U(1) supergravity. The corresponding numbers of «pure leptonic» and of «mixed lepton-jets» final states are computed. We also discuss the upgrading needed in an experimental set-up at LEP-II especially suited for the detection of the supersymmetry signals expected on the basis of the two supergravity models quoted. These models are at present the most reliable in terms of physically sound assumptions.

A ‘Super Monte Carlo’ for Multi-TeV Physics Simulation

SummaryWe have defined a new Entity-Relationship (ER) database, called SUD (Set-Up Descriptor), which contains all the information needed to describe any kind of High Energy Physics apparatus for Monte Carlo simulation and real data analysis. SUD has been implemented using the ADAMO database management system. Different programs can access the data and their mutual relationships in a user-friendly way, via standard FORTRAN calls. As an example of application, the database has been interfaced with the GEANT tracking program.