Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout

We propose a depth-of-interaction (DOI)-encoding method to extract continuous DOI information using a single-layer scintillation crystal array with single-ended readout for cost-effective high-resolution positron emission tomography (PET). DOI information is estimated by different light dispersions along the x- and y-directions tailored by the geometric shape of reflectors around the crystals. The detector module comprised a 22 × 22 array of unpolished LGSO crystals (2.0 × 2.0 × 20 mm3). A multi-anode photomultiplier tube with 64 anodes measured light dispersion in the crystal array. Gain non-uniformity of each anode was corrected by an analogue gain compensation circuit. DOI information was determined from peaks in the x and y anode-signal distributions normalized by the total energy of the distribution. Average DOI resolution (full width at half maximum, FWHM) over all crystals and depths was estimated to be 4.2 mm. Average energy resolution from the 2 to 18 mm DOI positions was 11.3% ± 0.79%, with 13% difference in photo-peak positions. Average time resolutions (FWHM) were 320–356 ps. Energy, time and DOI resolutions were uniform over all crystal positions except at the array's edge. This DOI-PET detector shows promise for applications that require high resolution and sensitivity at low cost.

Source:IOPscience

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Prediction of four, six or eight ears in drawn cups of single-crystal aluminum sheets

The new single crystal criterion developed by Cazacu, Revil and Chandola (2017) was implemented in a finite-element (FE) code and applied to forming of single-crystal cups of aluminum. Drawing simulations were conducted for circular single-crystal blanks of three different orientations: {100}〈001〉, {111} and [112] using the same set of parameters for the single-crystal yield criterion. A strong influence of anisotropy (single-crystal orientation) on the earing profile is found. While for the {100}〈001〉 orientation it is predicted that four ears develop, for the {111} and [112] crystal orientations six and eight ears are predicted, respectively. The FE simulation results are consistent with experimental observations of Tucker (1961).

Source:IOPscience

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Organic single-crystal TFT

Rubrene single-crystal TFT (thin-film transistor) made on a kapton substrate using rubrene single crystal grown by physical vapor transport remains unaffected by bending up to a radius of 9.4 mm. BPEA {9,10-bis(phenylethynyl) anthracene} single crystal TFT fabricated on polyimide film shows good endurance to bending. The difficulty of precise placement of crystals at defined locations is avoided by making OTS (octadecyltriethoxysilane) domains on source/drain electrode pattern using an OTS-inked stamp, from where the organic crystals can be selectively grown. CuPc {copper(II) phthalocyanine} and F16CuPc (copper hexadecafluorophthalocyanine) single crystal TFTs are transferred to a gold wire to make a complementary inverter circuit.

Source:IOPscience

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Optical non-linearities by Z-scan measurements, thermal characterization of single crystal: 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate

Single crystals of 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate were grown by slow evaporation technique at room temperature by using ethanol as solvent. Single crystal X-ray diffraction study elucidated that the crystal structure of8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate belongs to monoclinic crystal system with space group P21/n. The solid state physical parameters have been also determined for the grown crystal from the single crystal data. The cut-off wavelength and optical band gap energy of grown crystal was found to be 420 nm and 2.67 eV respectively.Thermogravimetric and differential thermal analysis reveals that the 8-hydroxyquinolinium 3-carboxy-4-hydroxy benzene sulfonate monohydrate single crystal is thermally stable up to 144˚C without any weight loss. The mechanical properties of the grown crystal were studied by Vickers microhardness technique and it is found that 8-hydroxyquinolinium 3-carboxy-4-hydroxybenzene sulfonate monohydrate belongs to hard material category. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and non

Source:IOPscience

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