Experimental results from a sandwich calorimeter using U absorbers and 0.25 m of Si active area

The electromagnetic section of a hadronic calorimeter, consisting of uranium absorbers and of silicon sampling units with an active area of 0.25 m², was investigated. The overall performance of the silicon detectors and especially developed associated electronics, seems to be stable and reliable. During a four-week run at the t₉, CERN-PS (Proton Synchrotron) electron beam (energies of 2 to 6 GeV), no variation of energy calibration of the calorimeter was observed. The energy resolution for electromagnetic showers was found to be about , where E is the energy of the incoming electron and τ is the number of radiation lengths of passive material interspaced between two active samplers, for a calorimeter depth of 15.6 X₀ (radiation lengths), with Si samplers depleted to 200 μm. The fiberglass supports of the silicon mosaics cause a reduction of energy response to electromagnetic showers. It can be exploited to equalize the response of a Si/U hadronic calorimeter to incoming electrons and hadrons.     

Study of a BGO calorimeter using electron and hadron beams from 1 to 50 GeV

A calorimeter of 25 bismuth germanate (BGO) crystals equipped with silicon photodiode readout has been tested at the CERN SPS in the energy range 1–50 GeV. The response for electrons has been shown to be linear in this energy range and the rms resolution obtained ( ) is approximately 1%, for E > 4 GeV. The electron/pion separation was found to be better than 1:500 in the energy range 1–20 GeV. Data on lateral and longitudinal shower development were compared with the results of a Monte Carlo simulation using the SLAC-EGS program and found to be in good agreement.     

The sat calorimeter of the DELPHI experiment at LEP; results of a module test

The construction of an electromagnetic calorimeter using scintillating plastic fibres and lead plates is described. The calorimeter is part of the Small Angle Tagger (SAT) of the DELPHI experiment at the LEP collider, recording high-energy electrons, positrons and photons. Results from a test of a module of similar construction are presented. The module was found to have a linear energy response when exposed to electrons of 10–70 GeV, with an energy resolution given by σ/E[%] = (1.16² + (11.4/√E[GeV])²)^1/2.     

A 4-inch silicon/tungsten calorimeter for p-p collider experiments

A 4-inch diameter silicon/tungsten sandwich calorimeter with 64 cm² in active area and 18 radiation lengths in depth has been constructed. The performance has been investigated for incoming electrons of 500 MeV to 4.5 GeV. The calorimeter shows a good linearity over the electron energy region and the energy resolution is well expressed by σ(rms)/E = 17√t/E%, where t represents the unit sampling thickness in radiation lengths and E the incident electron energy in GeV. The agreement between these results and a Monte Carlo simulation is quite satisfactory. The center of shower has been determined with the accuracy of better than 2 mm at energies exceeding 1 GeV.     

Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K⁰- system with an accuracy of 2 × 10⁻⁴ in the parameter e(ε′/ε). Decays in two π⁰'s will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of 3.5%/√E with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.     

A Si(Li)-Pb shower calorimeter for p-p collider experiments

A silicon/lead sandwich calorimeter with 38 cm² in active area and 10 radiation lengths in depth has been constructed. The performance has been investigated for incoming electrons of 250 to 750 MeV. The calorimeter shows a good linearity over the electron energy region and the energy resolution was well expressed by σ(rms)/E = (16.5 ± 0.5)/√E(GeV) %. Also, it is shown that the deposited energy and energy resolution do not change greatly even when the incident beam position is very close to the detector edge. The agreement between these results and a Monte Carlo simulation is quite satisfactory.     

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.     

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 CLAS forward electromagnetic calorimeter

The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab utilizes six iron-free superconducting coils to provide an approximately toroidal magnetic field. The six sectors are instrumented individually to form six independent spectrometers. The forward region (8°<θ<45°) of each sector is equipped with a lead–scintillator electromagnetic sampling calorimeter (EC), 16 radiation lengths thick, using a novel triangular geometry with stereo readout. With its good energy and position resolution, the EC is used to provide the primary electron trigger for CLAS. It is also used to reject pions, reconstruct π° and η decays and detect neutrons. This paper treats the design, construction and performance of the calorimeter.     

Analyses on the operating point dependence of the energy resolution with a Ti/Au TES microcalorimeter

We examined the performance of a single pixel Ti/Au transition-edge sensor (TES) calorimeter for incident X-ray energies of Al-K, Cr-K, and Fe-K, as a function of the TES resistance. We find that the energy resolution does not always degrade with increasing energy. The best energy resolution of 5.7±0.9 eV at 6.4 keV is obtained, which is possibly even better than the baseline width of 6.5±0.2 eV. Assuming that the noise level is determined by the noise spectrum NS(f;RR+dR(E)) considering the resistance change of dR(E), instead of NS(f;R) at the operating point, these results may be explained by the fact that the noise decreases at the higher TES resistance. The pulse variation appears to have a minimum at a certain resistance of R+dR(E)48 mΩ, and the best energy resolution for each line is obtained at such an operating point, respectively. The pulse variation could be enhanced when the fluctuation of the TES sensitivity is large at R+dR(E).     

CD: A double sided silicon strip detector for radioactive nuclear beam experiments

A very compact double sided silicon strip detector array is described, designed for use in reaction studies involving radioactive nuclear beams. It is small enough to fit inside a large solid angle γ-detector array and will enable Doppler-shift corrections at energies in the vicinity of the Coulomb barrier. The detector provides sufficient energy and time-of-flight resolution for the identification of light reaction products and can be set up to cover a substantial part of the scattering angular distribution with good resolution.

The device is available in thicknesses of up to 500 μm to stop all interesting reaction products. Moreover, a very thin (35–40 μm) variant of this detector is described that can be used as an energy loss detector in a ΔE−E telescope geometry followed by a detector that measures the residual energy. This provides additional particle identification capabilities, e.g. in light exotic nuclei induced reactions. First results from a commissioning run using a post-accelerated radioactive beam are presented.     

Performance of the ATLAS electromagnetic calorimeter barrel module 0

The construction and performance of the barrel pre-series module 0 of the future ATLAS electromagnetic calorimeter at the LHC is described. The signal reconstruction and performance of ATLAS-like electronics has been studied. The signal to noise ratio for muons has been found to be 7.11±0.07. An energy resolution of better than (sampling term) has been obtained with electron beams of up to 245 GeV. The uniformity of the response to electrons in an area of Δη×Δφ=1.2×0.075 has been measured to be better than 0.8%.     

Neutron energy spectrum measurements of neutron sources with an NE-213 spectrometer

The neutron energy spectra of the following sources were measured using a fast-neutron spectrometer with NE-213 liquid scintillator: ²⁵²Cf, Am-Be and T(d, n)⁴He from a Van de Graaff accelerator (400 keV). The measured proton recoil pulse-height data were unfolded using the FANTI code to obtain the neutron energy spectrum. The spectrometer gives neutron spectra in the range of 2–16 MeV, with 6% intrinsic efficiency and a resolution between 4% and 11%. The ²⁵²Cf neutron energy spectrum was measured and the results obtained showed good agreement with the spectrum usually published in the literature, which can be fitted by the expression N(E) =√E exp(− E/T) with the constant T = 1.42 MeV.     

A detector of superhard photons using aligned single crystals

The effects of considerable amplification of the pair production by photons and of radiation of charged particles in aligned single crystals are suggested to use for the creation of a comparatively simple ultrahigh-energy photon detector (ω < 100 GeV) with high angular resolution.     

Lead fluoride: An ultra-compact Cherenkov radiator for em calorimetry

We have tested the material PbF₂ and found that it is a Cherenkov radiator suitable for electromagnetic calorimetry. It has a density of 7.77 g/cm³, a radiation length of 0.93 cm, a refractive index of 1.8, and an optical cutoff at about 280 nm. An electromagnetic shower is 15% shorter longitudinally, and its apparent lateral extent has a 1/3 smaller radius in PbF₂ than in BGO. We have measured 1300 photoelectrons per GeV of deposited energy and have set an upper limit on the energy resolution of 5.1%/√E. The first measurements show PbF₂ to be much more radiation resistant than lead glass; also, when damaged, it almost fully recovers after a short exposure to UV light.     

Bearing strength of carbon epoxy laminates under static and dynamic loading

An experimental study has been carried out to investigate both the static and dynamic bearing strengths of a pinned-joint carbon epoxy composite plate with [0°/45°/−45°/90°]_S and [90°/45°/−45°/0°]_S stacking configurations. The static and dynamic experiments have been carried out according to the ASTM D953 standards and ASTM STP 749, respectively [ASTM D 953-D, Standard Test method for Bearing Strength of Plastics, ASTM Designation. 342; Joining of Composite Materials, ASTM STP 749, American Society for Testing and Materials (1981) 131]. The ratio of the edge distance to the pin diameter (E/D), and that of the width to the pin diameter (W/D) of the specimens were varied to obtain the static bearing strength and the S–N fatigue curve. The experiments show that the static bearing strengths reach their upper limit when E/D and W/D ratios are equal to or greater than 4 for both [0°/45°/−45°/90°]_S and [90°/45°/−45°/0°]_S stacking sequences. The fatigue strength, on the other hand, reduces by up to 65% as E/D and W/D ratios increase for both stacking configurations.     

CdSe band-splitting on thermal annealed films

Semiconducting polycrystalline CdSe thin films were prepared on glass substrates by chemical bath at 65 °C. As-deposited films grew in the metastable cubic sphalerite (S) crystalline structure with good stoichiometry. Upon thermal annealing (TA) in Ar+Se₂ atmosphere at different temperatures in the range 200–500 °C, the gradual phase transformation from cubic modification to hexagonal wurtzite (W) stable phase could be observed. From optical absorption measurements the fundamental energy band gap (E_g) and the second electronic transition (E_g+ΔE_g) were calculated for as-deposited and thermal annealed films. For TA350 °C, S-phase dominates the crystalline structure and only the spin orbit (ΔE_so) contribution to ΔE_g is present. Above 350 °C, the W-phase dominates and the energy splitting (ΔE_cf), owed to crystal field contribution and originated by the loss of lattice symmetry, should be added to ΔE_so in order to complete ΔE_g in the W-phase. The values ΔE_so=0.389±0.011 eV and ΔE_cf=0.048±0.018 eV were found from our analysis, and T_c=350 °C was here defined as the critical point of the phase transformation.     

The WiZard/CAPRICE silicon-tungsten calorimeter

A silicon-tungsten calorimeter has been developed to be flown in the WiZard/CAPRICE balloon borne experiment to measure the flux of antiprotons, positrons and light nuclei in the cosmic radiation. The calorimeter is composed of 8 x, y silicon sampling planes [active area (48 × 48) cm²] interleaved with 7 tungsten absorbers (7 radiation lengths); it provides the topology of the interacting events together with an independent measurement of the deposited energy. Details of the front-end electronics and of the read-out system are given and the overall performances during pre-flight ground operations are described as well.     

The use of CsI(Tl) scintillators with photodiode readout in heavy ion experiments

The performance of a ΔE−E telescope consisting of transmission silicon detector and CsI(Tl) scintillators with photodiode read out investigated in 46.7 MeV/u ¹²C induced reaction. The zero-crossing technique of pulse shape analysis has been employed to identify the light charged particles (p, d, t, ) with a low energy threshold, and a detector array composed of nine elements of CsI(Tl) scintillators with photodiode readout have been developed to measure the light charged particle interferometry in intermediate energy heavy ion induced reaction.     

ΔE−E Telescope systems for detecting charged particles produced with a “white” neutron beam

Highly stable ΔE−E telescope systems consisting of plastic scintillation detectors are operated as flux monitors in a “white” neutron beam between 15 and 50 MeV. Multiple telescope systems consisting of large area silicon ΔE detectors and NaI E detectors are set up in a scattering chamber to investigate charged particle reactions induced by fast neutrons up to 50 MeV.