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).     

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.     

Scintillation ring hodoscope with WLS fiber readout

A simple tracking system for measuring the K⁺ decay vertex along the beam axis in the T-Violation Experiment (E246) at KEK is described. It consists of 32 grooved BC408 plastic scintillator rings with embedded Y11 wavelength-shifting (WLS) optical fibers. Both ends of each multi-clad WLS fiber are directly viewed by a green-extended photomultiplier. Light yield of 46 photoelectrons per minimum ionizing particle in the 5 mm thick ring has been achieved. This configuration gives 1.7 mm position resolution determined purely by the 6 mm width of each ring. Time resolution of 1.0 ns and detection efficiency of 98.4% were obtained.     

An electromagnetic calorimeter with scintillator strips and wavelength shifter readout

We have built an electromagnetic calorimeter of the lead scintillator sandwich type. The dimensions of the lead plates are 20 × 60 cm² and their thickness 6 mm. A scintillator layer consists of 12 strips, 20 × 5 cm² and 2.5 mm thick. Each strip is read out using wavelength shifting plates at both sides. The mechanical stability of the module is provided by tie-rods and spacers. We have tested it in a 1 to 5 GeV electron beam. The influence of rods and spacers of various shapes and sizes on the uniformity of response and energy resolution is investigated.     

An electromagnetic calorimeter with wavelength shifting fiber readout

We investigate the response of an electromagnetic calorimeter using wavelength shifting fibers for the readout. The calorimeter is a sandwich of lead and scintillator plates and the fibers are inserted into holes perpendicular to the plates. We study in particular light yield, uniformity of response and energy resolution. We also present a Monte Carlo interpretation of our experimental results.     

Performance of a BGO calorimeter with photodiode readout and with photomultiplier readout at energies up to 10 GeV

Bismuth germanate (BGO) calorimeter arrays, consisting of up to 12 elements of 30 × 30 × 200 mm³ have been tested at the CERN PS with pions and electrons of up to 10 GeV/c momentum, and at SIN with pions, electrons and protons up to 450 MeV/c. Both photomultiplier (PM) and photodiode (PD) readouts were used. Accurate calibration in the 100 MeV energy range was achieved with stopping protons, stopping pions and minimum ionizing pions. With 212 MeV electrons and PM readout, a time resolution of the BGO signal of 640 ps fwhm has been measured. The energy resolution for electrons above 1 GeV (PD readout) was found to be roughly constant at σ/E ～ 1%. This is consistent with a negligible intrinsic resolution for BGO at these energies, after taking into account shower leakage and PD noise. For electrons of 92 and 200 MeV, we obtained (PM readout) energy resolutions close to the theoretical limit given by photon statistics and shower leakage. The electron/hadron separation was better than 1:500 over the energy range of 0.5 to 10 GeV, and improved to better than 1:1000 after a simple pattern cut. The energy deposition of the e.m. showers, both laterally and longitudinally (rear leakage), was found to be in agreement at the 0.1% level with Monte Carlo calculations using the SLAC-EGS program.     

The response of a CsI(Tl) scintillator with photodiode readout to light particles and heavy ions

The response of a small (1 cm³) CsI(Tl) crystal coupled to a silicon photodiode to light particles and heavy ions has been investigated using proton, alpha and oxygen beams in the energy range 10–25 MeV/n.Pulse-height resolution of 1.2 and 2.9% [fwhm] have been measured for 98 MeV ⁴He and 278 MeV ¹⁶O. The use of CsI(Tl)-photodiode assembly in nuclear physics experiments with intermediate energy heavy-ions beams is envisaged     

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.     

Load–displacement behavior of glass fiber/epoxy composite plates with circular cut-outs subjected to compressive load

An experimental study of the behavior of woven glass fiber/epoxy composite laminated panels under compression is presented. Compression tests were performed on to 16 fiber-glass laminated plates with and without circular cut-outs using the compressed machine. The maximum load of failure for each of the glass-fiber/epoxy laminated plates under compression has been determined experimentally. A parametric study was performed as well to investigate the effects of varying the centrally located circular cut-out sizes and fiber angle-ply orientations on to the ultimate load. The experimental work revealed that as the cut-out size increases, the maximum load of the composite plate decreases. Also, it has been observed that cross-ply laminates possess the greatest ultimate load as compared to other types of ply stacking sequences and orientations.     

Structural characterization of lead–bismuth eutectic corrosion of stainless steel by ultrasonic and metallographic analysis

Metallic test coupons subjected to corrosion in a lead–bismuth eutectic (LBE) were analyzed by both ultrasound and scanning electron microscope (SEM). The advantages and disadvantages of each method are given, and the possibility of using ultrasound as a screening process for SEM is presented. Visual data from each method are given, and the data derived from each method are compared and contrasted. Use of both ultrasound and SEM is recommended for future analysis of corrosion coupons, and development of a better methodology will increase the portion of the analysis workload obtainable by ultrasound.     

Displacement‐based finite elements with nodal integration for Reissner–Mindlin plates

An assumed‐strain finite element technique is presented for shear‐deformable (Reissner–Mindlin) plates. The weighted residual method (reminiscent of the strain–displacement functional) is used to enforce weakly the balance equation with the natural boundary condition and, separately, the kinematic equation (the strain–displacement relationship). The a priori satisfaction of the kinematic weighted residual serves as a condition from which strain–displacement operators are derived via nodal integration, for linear triangles, and quadrilaterals, and also for quadratic triangles. The degrees of freedom are only the primitive variables: transverse displacements and rotations at the nodes. A straightforward constraint count can partially explain the insensitivity of the resulting finite element models to locking in the thin‐plate limit. We also construct an energy‐based argument for the ability of the present formulation to converge to the correct deflections in the limit of the thickness approaching zero. Examples are used to illustrate the performance with particular attention to the sensitivity to element shape and shear locking. Copyright © 2009 John Wiley & Sons, Ltd.     

Vibration and buckling of rectangular composite plates with variable fiber spacing

This is a summary of the first known work which analyzes the structural behavior of composite plates having nonuniformly spaced fibers. The present investigation is limited to single layer composites having parallel fibers. This results in a plate which is macroscopically orthotropic, but nonhomogeneous. The free vibrations and buckling of such plates subjected to inplane boundary loadings are studied. A plane elasticity problem must first be solved to determine the inplane stresses caused by the applied boundary loading, and these stresses become input to the vibration and buckling problem. Both problems are dealt with by the Ritz method. Numerical results are obtained for six nonuniform distributions of E-glass, graphite and boron fibers in epoxy matrices in simply supported, square plates. The redistributions are seen to increase the buckling load by as much as 38%, and the fundamental frequency by as much as 21%.     

eXtended finite element methods for thin cracked plates with Kirchhoff–Love theory

A modelization of cracked plates under bending loads in the XFEM framework is addressed. The Kirchhoff–Love model is considered. It is well suited for very thin plates commonly used for instance in aircraft structures. Reduced HCT and FVS elements are used for the numerical discretization. Two kinds of strategies are proposed for the enrichment around the crack tip with, for both of them, an enrichment area of fixed size (i.e. independant of the mesh size parameter). In the first one, each degree of freedom inside this area is enriched with the nonsmooth functions that describe the asymptotic displacement near the crack tip. The second strategy consists in introducing these functions in the finite element basis with a single degree of freedom for each one. An integral matching is then used in order to ensure the ??¹ continuity of the solution at the interface between the enriched and the non‐enriched areas. Finally, numerical convergence results for these strategies are presented and discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimization and kinetics of electroless Ni–P–B plating of quartz optical fiber

The preparation of Ni–P–B coatings on surface of quartz optical fibers was carried out using electroless plating method. The effects of the concentrations of nickel chloride, sodium hypophosphite, potassium borohydride, ethylenediamine, cadmium sulfate and temperature on the quality of Ni–P–B coatings were investigated by orthogonal experiment and their optimal values were determined to be: 0.1 mol L⁻¹, 0.094 mol L⁻¹, 0.185 mol L⁻¹, 0.36 mol L⁻¹, 5.68 × 10⁻⁴ mol L⁻¹ and 90 °C, respectively. The effect of coarsening time of the naked fiber on the quality of Ni–P–B coatings was also researched and the optimal coarsening time was determined to be 15 min. Stereomicroscope, Scanning Electron Microscope and X-ray diffractometer were used to characterize the apparentness, morphology and structure of the prepared Ni–P–B coatings. Inductively Coupled Plasma-Atomic Emission Spectroscopy, Thermal Shock Method and Gravimetric Analysis Method were employed to analyze the composition, force of adhesion and solderability of the coatings, respectively. The results showed that a Ni–P–B coating with low surface roughness, good strength of adhesion, low resistivity and good solderability was successfully prepared. The kinetic models (Ni–P–B deposition rate equations) of the process were established as . The theoretical values calculated by the models were proved to be basically consistent with the practical measurements through experimental verification.     

A new hybrid-mixed variational approach for Reissner–Mindlin plates. The MiSP model

A valuable variational approach for plate problems based on the Reissner–Mindlin theory is presented. The new MiSP (Mixed Shear Projected) approach is based on the Hellinger–Reissner variational principle, with a particular representation of transversal shear forces and transversal shear strains. The approximations of the shear forces are derived from those of the bending moments using the corresponding equilibrium relations. The shear strains are defined in terms of the edge tangential strains that are projected on the element degrees of freedom. Two finite elements are developed on the MiSP approach basis: 3-node triangular element MiSP3 and 4-node quadrilateral element MiSP4. Both elements can be considered as the most simple among the existent mixed elements. A modified MiSP model with a derived 4-node element is also presented. Numerical experiments are presented which show that the MiSP elements do not exhibit shear locking and give excellent results for thick and thin plates. They also pass the patch test for a general triangle and quadrilateral. © 1998 John Wiley & Sons, Ltd.     

Refined global–local higher‐order theory and finite element for laminated plates

Based on completely three‐dimensional elasticity theory, a refined global–local higher‐order theory is presented as enhanced version of the classical global–local theory proposed by Li and Liu (Int. J. Numer. Meth. Engng. 1997; 40 :1197–1212), in which the effect of transverse normal deformation is enhanced. Compared with the previous higher‐order theory, the refined theory offers some valuable improvements these are able to predict accurately response of laminated plates subjected to thermal loading of uniform temperature. However, the previous higher‐order theory will encounter difficulty for this problem. A refined three‐noded triangular element satisfied the requirement of C¹ weak‐continuity conditions in the inter‐element is also presented. The results of numerical examples of moderately thick laminated plates and even thick plates with span/thickness ratios L/h = 2 are given to show that in‐plane stresses and transverse shear stresses can be reasonably predicted by the direct constitutive equation approach without smooth technique. In order to accurately obtain transverse normal stresses, the local equilibrium equation approach in one element is employed herein. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparative investigation of tungsten inert gas and friction stir welding characteristics of Al–Mg–Sc alloy plates

Al–Mg–Sc alloy plates were welded by FSW and TIG welding. The effect of welding processes on mechanical properties of Al–Mg–Sc welded joints was analyzed based on optical microscopy, transmission electron microscopy, tensile testing and Vickers microhardness measurements. The results show that the mechanical properties of FSW welded joint are much better than those of TIG welded joint; the strength coefficient of FSW joint is up to 94%. Moreover, tensile strength and yield strength of FSW joint are 19% and 31% higher than those of TIG joint, respectively, which are attributed to the preservation of cold working microstructures in the process of FSW. Due to the low welding temperature during FSW process and the excellent thermal stability of Al₃(Sc, Zr) particles, the cold working microstructures can be well preserved. In addition, the FSW joint have asymmetric microstructures and mechanical properties, which are not observed in TIG welded joint.     

A scintillating tile/fiber system for a high-energy calorimeter with high light yield and uniform longitudinal and transverse response

We have performed R&D for a tile/fiber calorimeter system. Using a multi-turn wave-length-shifting (WLS) fiber, the response of tile/fiber system was made uniform to within 2.5% over a tile. The response uniformity with respect to the tile size, which varies from 80 mm to 200 mm square, was controlled to within 3% (r.m.s.) by changing the WLS fiber length. Using a Hamamatsu R329 photomultiplier tube, the average light yield was greater than 2.5 photoelectrons per minimum ionizing particle.     

Computation of the limit load and elasto–plastic bending of thin plates

We use the mixed equilibrium finite element method of Hellan–Herrmann,^1-5 for solving the problem of elasto–plastic bending and limit load for a thin plate. We give also some results for the elastic case, for which exact solutions are known.