M. Espirito Santo

The small angle tile calorimeter in the DELPHI experiment

Abstract The Small angle TIle Calorimeter (STIC) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with a so-called “shashlik” technique, gives a perfectly hermetic calorimeter and still allows for the insertion of tracking detectors within the sampling structure to measure the direction of the showering particle. A charged-particle veto system, composed of two scintillator layers, makes it possible to trigger on single photon events and provides e–γ separation. Results are presented from the extensive studies of these detectors in the CERN testbeams prior of installation and of the detector performance at LEP.

The DELPHI small angle tile calorimeter

The small angle tile Calorimeter (STIC) provides calorimetric coverage in the very forward region for the DELPHI experiment at the CERN LEP collider. A veto system composed of two scintillator layers allows one to trigger on single photon events and provides e-/spl gamma/ separation. We present here some results of extensive measurements performed on part of the calorimeter and the veto system in the CERN test beams prior to installation and report on the performance achieved during the 1994 LEP run. >

The silicon shower maximum detector for the STIC

The structure of a shashlik calorimeter allows the insertion of tracking detectors within the longitudinal sampling to improve the accuracy in the determination of the direction of the showering particle and the eπ separation ability. The new forward calorimeter of the DELPHI detector has been equipped with two planes of silicon pad detectors respectively after 4 and 7.4 radiation lengths. The novelty of these silicon detectors is that to cope with the shashlik readout fibers, they had to incorporate 1.4 mm holes every cm2. The detector consists of circular strips with a radial pitch of 1.7 mm and an angular granularity of 22.5°, read out by means of the MX4 preamplifier. The preamplifier is located at 35 cm from the silicon detector and the signal is carried by Kapton cables bonded to the detector. The matching to the MX4 input pitch of 44 μm was made by a specially developed fanin hybrid.

Percolation and high energy cosmic rays above 1017 eV

Abstract In this work we argue that in the interpretation of the energy dependence of the depth of the shower maximum and of the muon content in high energy cosmic ray showers ( E ≳ 10 17 eV ) , other variables besides the composition may play an important role, in particular those characterising the first (high energy) hadronic collisions. The role of the inelasticity, of the nature of the leading particle, and of the particle multiplicity are discussed. A consistent interpretation of existing data within a string percolation model implemented in a hybrid, one-dimensional simulation method is given.

A model for net-baryon rapidity distribution

AbstractIn nuclear collisions, a sizable fraction of the available energy is carried away by baryons. As baryon number is conserved, the net-baryon

Performance of the new high precision luminosity monitor of DELPHI

B-\bar{B}

Performance of a shashlik calorimeter at LEPII

retains information on the energy-momentum carried by the incoming nuclei. A simple and consistent model for net-baryon production in high energy proton–proton and nucleus–nucleus collisions is presented. The basic ingredients of the model are valence string formation based on standard PDFs with QCD evolution and string fragmentation via the Schwinger mechanism. The results of the model are presented and compared with data at different centre-of-mass energies and centralities, as well as with existing models. These results show that a good description of the main features of the net-baryon data is possible in the framework of a simplistic model, with the advantage of making the fundamental production mechanisms manifest.

Performance of the DELPHI small angle tile calorimeter

The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the “Shashlik” technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994–1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed.

A silicon pad shower maximum detector for a shashlik calorimeter

Abstract The Small Angle TIle Calorimeter (STIC) is a sampling lead-scintillator calorimeter, built with “shashlik’ technique. Results are presented from extensive studies of the detector performance at LEP.

The small angle tile calorimeter project in DELPHI

The DELPHI STIC detector is a lead-scintillator sampling calorimeter with wavelength shifting optical fibers used for light collection. The main goal of the calorimeter at LEP100 is to measure the luminosity with an accuracy better than 0.1%. The detector has been in operation since the 1994 LEP run. Presented here is the performance measured during the 1994-1995 LEP runs, with the emphasis on the achieved energy and space resolution, the long-term stability and the efficiency of the detector. The new bunch-trains mode of LEP requires a rather sophisticated trigger and timing scheme which is also presented. To control the trigger efficiency and stability of the calorimeter channels, a LED-based monitoring system has been developed.