[en] A systematic study of the performance of the Resistive Plate Chambers as a function of the bakelite temperature is presented. The current, the rate and the efficiency were measured in the temperature range 22-40 deg. C. The values of the relative humidity during the data taking were in the range 40-60%. Measurements show a strong dependence of the efficiency on bakelite temperature

[en] An attractive feature of ⁶Li containing fluorescence materials that determines their potential application in radiation detection is the capture reaction with slow (∼< 100 keV) neutrons: ⁶Li + n = ⁴He + ³H + 4.8MeV. The use of ⁶Li-salicylate (LiSal, LiC₆H₅O₃) for thermal neutron detection was previously studied in liquid and polycrystalline scintillators. The studies showed that both liquid and polycrystalline LiSal scintillators could be utilized in pulse shape discrimination (PSD) techniques that enable separation of neutrons from the background gamma radiation. However, it was found that the efficiency of neutron detection using LiSal in liquid solutions was severely limited by its low solubility in commonly used organic solvents like, for example, toluene or xylene. Better results were obtained with neutron detectors containing the compound in its crystalline form, such as pressed pellets, or microscopic-scale (7-14 micron) crystals dispersed in various media. The expectation drown from these studies was that further improvement of pulse height, PSD, and efficiency characteristics could be reached with larger and more transparent LiSal crystals, growth of which has not been reported so far. In this paper, we present the first results on growth and characterization of relatively large, a cm-scale size, single crystals of LiSal with good optical quality. The crystals were grown both from aqueous and anhydrous (methanol) media, mainly for neutron detection studies. However, the results on growth and structural characterization may be interesting for other fields where LiSal, together with other alkali metal salicylates, is used for biological, medical, and chemical (as catalyst) applications

[en] A rapid solid-liquid reaction mechanism has been used to form A15 Nb₃Sn in the liquid-infiltration processed NbSn wire. Small, equiaxed A15 grains across the fine reacted filaments of 0.2-1.0 μm thickness were revealed with the transmission electron microscopy studies. A uniform Sn concentration near the stoichiometry was found in the A15 region. High inductive T /SUB c/ 's of 17.9K with sharp transition widths (<0.3K) and excellent overall J /SUB c/ 's of 10⁴ A/cm² at 19T and 4.2K were achieved. Mechanical properties of the reacted wire are no worse than those of typical commercial bronze-process Nb₃Sn conductors, and epsilon /SUB irrev/ is slightly higher

[en] Ceramic and single crystal Lutetium Aluminum Garnet scintillators exhibit energy resolution with bialkali photomultiplier tube detection as good as 8.6% at 662 keV. Ceramic fabrication allows production of garnets that cannot easily be grown as single crystals, such as Gadolinium Aluminum Garnet and Terbium Aluminum Garnet. Measured scintillation light yields of Cerium-doped ceramic garnets indicate prospects for high energy resolution

[en] This paper measures the sample to sample variation in the light yield non-proportionality of NaI:Tl, and so explores whether this is an invariant characteristic of the material or whether it is dependent on the chemical and physical properties of tested sample. In this work we report on the electron response of nine crystals of NaI(Tl), differing in shape, volume, age, manufacturer and quality. The non-proportionality has been measured at the SLYNCI facility in the energy range between 3.5 to 460 keV. The Scintillation Light Yield Non-proportionality Characterization Instrument (SLYNCI) is a next generation Compton Coincidence device, explicitly designed to study the 'non-proportionality' of the electron response in scintillators and the contribution of this effect to the intrinsic energy resolution. We also discuss the gamma response, x-ray excited emission spectra and decay times for the nine crystals, in order to provide a complete characterization of their physical properties and determine whether the mechanism of scintillation varies between samples

[en] Thin-film heterostructures of Bi₄Ti₃O₁₂/Bi₂Sr₂CuO_6+x and Bi₄Ti₃O₁₂/YBCO were grown on single crystals of SrTiO₃, LaAlO₃, and MgAl₂O₄ by pulsed laser deposition. X-ray diffraction studies show the presence of the c-axis orientation only, while Rutherford backscattering experiments show the composition to be close to the Bi₄Ti₃O₁₂ stoichiometry. The films are ferroelectric and exhibit a symmetric hysteresis loop. The remnant polarization was 1.0 μC/cm², while the coercive field was 2.0 x 10⁵ V/cm. These films look promising for the fabrication of lattice-matched, epitaxial ferroelectric film/electrode heterostructures for memory applications

[en] We present the synthesis and the physical properties of new ternary molybdenum chalcogenides MMo₆X₈ (M = In, Tl; X = S, Se) that cannot be made by the usual high-temperature techniques (except for InMo₆S₈). These materials were obtained by diffusion of the ternary element into the binary phase Mo₆X₈ at a relatively low temperature (430 ⁰C and 520 ⁰C for the sulfides and selenides, respectively). They crystallize in the rhombohedral space group R3 (C₃⁴) with (a/sub r/ = 6.78 A, α/sub r/ = 89.86⁰) when M = In and X = Se and with (a/sub r/ = 6.57 A, α/sub r/ = 88.45⁰) and (a/sub r/ = 6.836 A, α/sub r/ = 88.35⁰) when M = Tl and X = S and Se, respectively. TlMo₆Se₈ presents a large temperature-dependent paramagnetism and begins superconducting at 12.2 K, the highest value ever observed in the selenide Chevrel phases, while that of TlMo₆S₈ is lower, 8.7 K. The susceptibility of InMo₆Se₈ reveals the existence of two first-order transitions that have considerable hysteresis, while only one transition without hysteresis is observed for InMo₆S₈. The absence of superconductivity down to 1.5 K has been confirmed for this last compound, while the homolog selenide begins superconducting at 8.2 K

[en] The Central Neutron Detector, a recently constructed scintillator barrel which is used in CLAS12 at Jefferson Lab to detect 0.2–1 GeV neutrons at backwards angles, is here described. The motivations and R&D tests leading to its final design, based on three radial layers of coupled paddles with one-side light readout by photomultipliers plus “U-turn” lightguides on the other side, are outlined. The performance of the detector, evaluated from cosmic-ray tests and simulations, which satisfies the physics requirements, is reported.

[en] We studied the performances of the LaBr₃:Ce scintillator when optically coupled to NaI:Tl and CsI:Na in a Phoswich detector for the R and D phase of the gamma ray calorimeter PARIS (Photon Array for the studies with Radioactive Ion and Stable beams). This detector has the purpose to measure γ-energies in a wide range (100 keV–40 MeV), and it will be used principally as a part of the SPIRAL2 instrumentation at GANIL. In this communication we report on the study of the light yield and energy resolution for gamma detection realized by coupling the phoswiches with various photomultiplier tubes, providing different characteristics. We were interested in investigating the possible degradation of the scintillation light produced by the LaBr₃:Ce due to the presence of NaI:Tl/CsI:Na crystals, before being detected on the photocathode. For this purpose we realized all the measurements employing a standard ADC and QDC read-out system leading the possibility to perform a gate-based event selection. In this study we measured an energy resolution of 4.6% with an uncollimated ¹³⁷Cs source for a 50.8×50.8×50.8 mm³ LaBr₃:Ce coupled to a 50.8×50.8×152.4 mm³ NaI:Tl. This value is 30% bigger than the energy resolution measured for a 50.8×50.8×101.6 mm³ stand-alone LaBr₃:Ce but still in the specifications for the PARIS collaboration physics list.

[en] Raman scattering measurements of the Esub(g) and Tsub(2g) optical phonons in V³Si, Nb³Sn, V³Ge, Cr³Si, V³Pt, and Nb³Pt are presented and discussed in terms of interaction with interband electronic excitations. Data on superconducting Nb³Sn is presented and modifications to the phonon spectral function and the spectrum of Raman active interband electronic excitations in the superconducting state are discussed. (orig.)