Measurement of the resolution of a combined hodoscope calorimeter at 18 GeV and 38 GeV

The energy and spatial resolution of a combined detector consisting of the Cherenkov photon calorimeter GAMS-2000 and the modular hadron calorimeter MHC-100 has been studied at 18.5 and 38 GeV incident pion energies at the IHEP accelerator. The energy resolution of the combined setup is substantially improved by applying a correction based on the analysis of the lateral development of hadron showers in GAMS and MHC. It is shown that the parameters of the correction depend only weakly on the hadron energy. The influence of the gap between both photon and hadron calorimeters on the combined detector characteristics is of less importance with increasing energy.     

Some characteristics of plastic streamer tubes

The operating characteristics of plastic streamer tubes chosen as a detector of the DELPHI-LEP hadron calorimeter are described. The work has been performed using a set-up specially designed to investigate a hadron calorimeter prototype on a beam of the Dubna synchrophasotron. The apparatus operated on-line with an ES-1040 computer.     

The limited streamer tubes of the SLD

A large hadron calorimeter and muon tracking device using plastic streamer tubes has been constructed in the iron flux-return structure for the SLD detector at SLAC. Various studies of the operating characteristics of the streamer tubes of this system are presented. Emphasis is placed on the tracking capabilities of the device and on the optimization of the high voltage and readout electronics.     

A combined photon-hadron hodoscope calorimeter

The energy and spatial resolution and other characteristics of a combined detector permitting simultaneous detection of a large number of photons and hadrons has been studied in a 200 GeV/c hadron beam at the CERN SPS. The detector consists of the GAMS-4000 spectrometer (4096 lead-glass cells) and a modular hadron calorimeter MHC-200 located behind it (240 total-absorption sandwich counters). A new method for adding the signals from the two calorimeters, which takes into account the difference in the development of hadron showers in photon and hadron calorimeters, has been developed. It permits substantial improvement of the energy resolution of the combined detector. The hadron coordinates are defined with a precision of several millimeters and the energy resolution is typical for steel-scintillator sandwiches with a wavelength-shifter readout. The effect of the gap between the photon and the hadron calorimeters has also been studied.     

On quality requirements to the barium fluoride crystals

This report summarizes the quality requirements to the barium fluoride (BaF₂) crystals for constructing a high precision electromagnetic calorimeter at future hadron colliders. The basic property of BaF₂ crystals and the design and performance of a BaF₂ calorimeter are presented. The emphasis of the discussion is in the radiation resistance of the current production BaF₂ crystals. An approach to implement optical bleaching in situ is also presented. By using optical bleaching current production quality BaF₂ crystals could serve as an excellent candidate to construct a precision calorimeter at future hadron colliders.     

The xenon olive detector for the next generation colliders

We propose a fast detector with high resolution and fine granularity, consisting of a xenon electromagnetic shower counter and a TMS-uranium hadron calorimeter. Both are linear in energy, insensitive to radiation damage and have good spatial resolution in 3-dimensional space in order to measure di-electron and di-jet masses at the next generation high luminosity colliders.     

Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method ATLAS

This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within ±1% of the true values and the fractional energy resolution is

Full-size image

. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74±0.04 and agrees with the prediction that e/h>1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.     

A simple model of hadron calorimeters

A simple model of hadron calorimeter response is examined. It is found that not only must a hadron calorimeter be compensated in order to achieve linearity, but also that the intrinsic hadron and electromagnetic resolutions must be equal if the calorimeter resolution is to be independent of energy and have a Gaussian distribution.     

A hadron-blind detector

The development of highly efficient solid photocathodes, compatible with high-gain gaseous detectors, has opened the possibility to build threshold Cherenkov counters with a good hadron rejection, with a minimum amount of matter, and a time resolution of the order of the nanosecond. We discuss the properties of a hadron-blind detector, with a granularity of a few millimetres. The study of the background sources shows that a rejection power of the order of 99% can be achieved for high-energy hadrons. It permits instantaneous multi-hadron rejection and, combined to a fast electromagnetic calorimeter, can ensure on-line electron selection, even when they are produced close to hadronic jets. It could permit the operation of lepton-tracking detectors in a magnetic field, in very high hadronic backgrounds.     

A uranium scintillator calorimeter with plastic-fibre readout

We have developed a method for reading out scintillator plates in a compact calorimeter using embedded wavelength-shifting fibres coupled to photomultipliers. A test calorimeter using this technique, with uranium plates as the passive medium, was placed in test beams of 1 to 80 GeV. Results on resolution, uniformity, and electron-pion discrimination are presented, as well as a discussion of compensation (the near-equality of electron and hadron responses).     

Results from a CsI(Tl) test calorimeter with photodiode readout between 1 and 20 GeV

Results from a test with a CsI(Tl) calorimeter will be presented. The purpose was to evaluate the use of CsI(Tl) for high resolution electromagnetic calorimetry. A resolution of about 1% has been measured between 4 and 20 GeV. A very high electron/hadron separation of > 1 : 1000 has been observed. Prospects and limitations for large scale applications will be discussed.     

Test of a prototype of the ZEUS backing calorimeter

We have studied the performance of a high resolution uranium-scintillator calorimeter followed by a much coarser backing calorimeter, made out of iron plates interleaved with planes of limited streamer tubes. The test results, obtained at the CERN-SPS hadron beam, show that the backing calorimeter can be used either to veto events with significant energy leakage from the uranium calorimeter or to correct for the energy. In both cases the energy resolution of the combined calorimeters improves significantly compared to the uranium calorimeter alone.     

Pion muon identification in the ALEPH detector using the discriminant analysis

This paper illustrates the application of Discriminant Analysis to the separation between π's and μ's through the energy measurement and tracking capability of a hadron calorimeter followed by a system of chambers. For data taken in a test run with π and μ beams of 5–10–20 GeV, Discriminant Analysis provides an identification level of about 99.5%, very close to the physical limit corresponding to sail-through pions. The extension of the method to the case of the whole ALEPH detector and Z⁰ events is also discussed, with the aid of a Monte Carlo program.     

A high-granularity scintillator calorimeter readout with silicon photomultipliers

We report on the design, construction and performance of a prototype for a high-granularity tile hadronic calorimeter for a future international linear collider detector. Scintillating tiles are read out via wavelength-shifting fibers that guide the scintillation light to a novel photodetector, the silicon photomultiplier. A prototype has been tested using a positron test beam at DESY. The results are compared with a reference prototype calorimeter equipped with multichannel vacuum photomultipliers. Detector calibration, noise, linearity and stability are discussed, and the energy response in a 1–6 GeV positron beam is compared with simulations. The present results demonstrate that the silicon photomultiplier is well-suited as photodetectors in calorimeters and thus has been selected for the construction of a calorimeter prototype to operate in hadron beams.     

Metallic Magnetic Calorimeters for Particle Detection

The principles and theory of operation of a magnetic calorimeter, made of a dilute concentration of paramagnetic ions in a metallic host, is discussed in relation to the use of such a device as a detector of x-rays. The response of a calorimeter to the absorption of energy depends upon size, heat capacity, temperature, magnetic field, concentration of spins and interactions among them. The conditions that optimize the performance of a calorimeter are derived. Noise sources, especially that due to thermodynamic fluctuations of the electrons in the metal, are analyzed. Measurements have been made on detectors in which Er serves as the paramagnetic ion and Au as the host metal. The measured resolution of a detector with a heat capacity of 10^–12 J/K was 12 eV at 6 keV. In a detector suitable for use with hard x-rays up to 200 keV a resolution of 120 eV was obtained. Calculations indicate that the performance of both detectors can be improved by an order of magnitude. At temperatures below 50 mK, the time response of the Au : Er calorimeters to an energy deposition indicates the presence of an additional heat capacity, which we interpret as arising from the quadruple splitting of the Au nuclei in the electric field gradients introduced by the presence of the Er ions.     

Simulation and measurements of the response of an air ionisation chamber exposed to a mixed high-energy radiation field

CERN's radiation protection group operates a network of simple and robust ionisation chambers that are installed inside CERN's accelerator tunnels. These ionisation chambers are used for the remote reading of ambient dose rate equivalents inside the machines during beam-off periods. This Radiation Protection Monitor for dose rates due to Induced Radioactivity ('PMI', trade name: PTW, Type 34031) is a non-confined air ionisation plastic chamber which is operated under atmospheric pressure. Besides its current field of operation it is planned to extend the use of this detector in the Large Hadron Collider to measure radiation under beam operation conditions to obtain an indication of the machine performance. Until now, studies of the PMI detector have been limited to the response to photons. In order to evaluate its response to other radiation components, this chamber type was tested at CERF, the high-energy reference field facility at CERN. Six PMI detectors were installed around a copper target being irradiated by a mixed hadron beam with a momentum of 120 GeV c(-1). Each of the chosen detector positions was defined by a different radiation field, varying in type and energy of the incident particles. For all positions, detailed measurements and FLUKA simulations of the detector response were performed. This paper presents the promising comparison between the measurements and simulations and analyses the influence of the different particle types on the resulting detector response.     

A concept for a hadron calorimeter with photodiode readout

A concept for a hadron calorimeter will be described. The calorimeter is a scintillator sandwich type with WLS-bars and photodiode readout. Emphasis is put on compactness, high stability, easy fabrication, and safety.     

Beam test of the CsI(Tl) calorimeter for the BELLE detector at the KEK-B factory

We studied the performance of a prototype electromagnetic calorimeter for the BELLE detector at the KEK proton synchrotron for an energy range of 0.25–3.5 GeV. The prototype consisted of an array of 6 × 5 CsI(Tl) crystals with 30 cm length (16.2 radiation lengths) and about 6 cm × 6 cm cross section. The scintillation light of each CsI(Tl) crystal was read out by two large-area PIN photodiodes and charge-sensitive preamplifiers attached at the rear face of the crystal. We measured the energy and position resolution for electrons and the e/π separation for two sets of matrix configurations: one corresponded to the center and the other to the edge of the barrel calorimeter. The overall performance measured by the test proves that the prototype calorimeter is satisfactory for the use in the BELLE detector.     

The segmentation of hadron calorimeters

Optimization of the segmentation of large hadron calorimeters is important in order to obtain good resolution for jet physics at minimum construction cost for the next generation of high energy experiments. The principles of the segmentation of hadron calorimeters are discussed. As an example, the Monte Carlo optimization of the segmentation of the L3 hadron calorimeter barrel at CERN is described. Comparisons of results for the reconstructed jet shapes show that the optimum number ADC channels is about 20K for the readout of 450K wires of the proportional chambers. The matching between the sandwiched φ towers and Z towers is the dominant factor for angular resolution. Based on these Monte Carlo simulations, an optimized tower structure is obtained.     

The CDF plug upgrade electromagnetic calorimeter: test beam results

The CDF Plug Upgrade calorimeter, which fully exploits the tile–fiber technique, was tested at the Fermilab meson beamline. The calorimeter was exposed to positron, positively charged pion and positive muon beams with energies in the range of 5–230 GeV. The energy resolution of the electromagnetic calorimeter to the positron beam is consistent with the design value of , where E is the energy in units of GeV and represents sum in quadrature. The non-linearity for positrons is studied in an energy range of 11–181 GeV. It is important to incorporate the response of the preshower detector, the first layer of the electromagnetic calorimeter which is readout separately, into that of the calorimeter to reduce the non-linearity to 1% or less. The energy scale is about 1.46 pC/GeV with HAMAMATSU R4125 operated typically at a gain of 2.5×10⁴. The response non-uniformity over the surface of a tower of the electromagnetic calorimeter is found to be about 2% with 57 GeV positrons. Studies of several detailed detector characteristics are also presented.