Data acquisition system for dark matter detectors

Progress in Ge detector technology has resulted in ultralow backgrounds of less than 0.3 counts keV^–1 kg^–1 d^–1 at energies between 5 and 12 keV, and less than 1.0 counts kev^–1 kg^–1 d^–1 for energies between 3 and 5 keV. Coupled with good energy resolution, 0.4 keV FWHM at 10 keV, this allows searches for DM particles with m 8 GeV/c².Electromagnetic interference and acoustical pick-up are the main sources of background in the best Ge detectors. These problems are even more important in cryogenic WIMP detectors under development. A PC-based on line pulse shape analysis system is presented which permits rejection of about 95% percent of the EMI/ acoustical background. The hardware uses a low cost, commercially available digital storage oscilloscope. The software consists of about 20,000 lines of code in Pascal and assembly language. We tested this system using a low radioactive background Ge-system on the Earth's surface. For low energy events (27 keV photons) this system permits improvement in the background from 0.1 cpm to 2 cpd.     

Enhancing design-for-test for active analog filters by using CLP(ℜ)

We describe a computer-aided approach to automatic fault isolation in active analog filters which enhances the design-for-test (DFT) methodology proposed by Soma (1990). His primary concern was in increased controllability and observability while the fault isolation procedure was sketched only in general terms. We operationalize and extend the DFT methodology by using CLP() to model analog circuits and by a model-based diagnosis approach to implement a diagnostic algorithm. CLP() is a logic programming language which combines symbolic and numeric computation. The diagnostic algorithm uses different DFT test modes and results of voltage measurements for different frequencies and computes a set of suspected components. Ranking of suspected components is based on a measure of (normalized) standard deviations from predicted mean values of component parameters. The diagnosis is performed incrementally, in each step reducing the set of potential candidates for the detected fault. Case studies show encouraging results in isolation of soft faults of a given low-pass biquad filter.     

Optimization of Boundary Scan Tests Using FPGA-Based Efficient Scan Architectures

This paper presents a method for optimization of board-level scan test with the help of reconfigurable scan-chains (RSCs) implemented in a programmable logic of FPGA. Despite that the RSC concept is a well-known solution for scan-based test time reduction, the usage of RSC may lead to un-acceptable hardware overhead. In our work, we are targeting a completely new approach of exploiting on-board FPGA resources that being unconfigured are typically available during the manufacturing test phase for carrying out tests using temporarily implemented virtual RSC structures. As the allocated FPGA logic is re-claimed for functional use after the test is finished, the presented method delivers all the advantages of RSCs at no extra hardware cost. Experimental results show that the proposed virtual RSCs can fit into all available commercial FPGAs providing a significant test time reduction in comparison with state-of-the-art Boundary Scan test tecnique.     

Dealing with Zero Flows in the Simulation of Water Distribution Networks with Low-Resistance Pipes Using the Global Gradient Algorithm

Water Resources Management - This paper shows that the zero flow treatment algorithm and the convergence criteria of EPANET 2.2, the latest version of the EPANET 2 open-source software package, may...     

Hydrides under High Pressure

Journal of Superconductivity and Novel Magnetism - The experimental discovery of the highest, up to 0 degree Celsius, superconducting transition temperatures T $$_c$$ in the class of so-called...     

Light-induced ultrafast proton-coupled electron transfer responsible for H2 evolution on silver plasmonics

Light-driven proton-coupled electron transfer (PCET) reactions on nanoplasmonics would bring temporal control of their reactive pathways, in particular, prolong their charge separation state. Using a silver nano-hybrid plasmonic structure, we observed that optical excitation of Ag-localized surface plasmon instigated electron injection into TiO₂ conduction band and oxidation of isopropanol alcoholic functionality. Femtosecond transient infrared absorption studies show that electron transfer from Ag to TiO₂ occurs in ca. 650?fs, while IPA molecules near the Ag surface undergo an ultrafast bidirectional PCET step within 400?fs. Our work demonstrates that ultrafast PCET reaction plays a determinant role in prolonging charge separation state, providing an innovative strategy for visible-light photocatalysis with plasmonic nanostructures.     

New method for controlled synthesis of polylactide block copolymers: organoborane/p-quinone system and reversible-deactivation radical polymerization

We developed a new approach to obtain polylactide hybrid block copolymers with vinyl monomers (styrene, methyl methacrylate, methyl acrylate) through the realization of a reaction sequence using triethylborane and various p-quinones. The method offered includes two stages. In the first stage, a chain-transfer agent was obtained by borylation of the terminal hydroxyl groups of polylactide. The second stage was vinyl monomer radical polymerization in the presence of p-quinone accompanied by S_H2-substitution at the boron atom.1,4-Naphthoquinone, 2,3-dimethyl-1,4-benzoquinone, duroquinone and 2,5-di-tert-butyl-1,4-benzoquinone were used as synthetic polymer chain growth mediators. It is shown that 1,4-naphthoquinone and 2,3-dimethyl-1,4-benzoquinone, similar in their characteristics, are effective agents providing the realization of reversible-deactivation radical polymerization. Realization of reversible-deactivation radical polymerization was proved with the analysis of the kinetics of block copolymerization, molecular weight characteristics and compositional homogeneity of block copolymers as well as its further capability to elongate the polymer chain. Synthesized block copolymers have a high thermal stability compared to the initial borylated polylactide. © 2021 Society of Industrial Chemistry.     

Formation of branched polyethylenes by ethylene homopolymerization using LNiBr2 homo- and heterogeneous precatalysts: Interpretation of the polymer structures in comparison with commercial LLDPE

Comparative data on the micro-structures and properties of branched polyethylenes (BPE) produced via ethylene homopolymerization over homogeneous N,N-α-diimine LNiBr₂ complexes with different ligand composition (AlEt₂Cl as a cocatalyst) and corresponding supported catalysts LNiBr₂/SiO₂(Al) (Al[iso-Bu]₃ as a cocatalyst) are presented. Noticeable differences were observed between micro-structures of BPEs obtained using homo- and heterogeneous LNiBr₂ complexes as catalysts. Supported catalysts produce BPEs with the majority of methyl branches (17–18 CH₃(1000 C)⁻¹ characterized by different molecular masses (1800–210 kg mol⁻¹) and molecular weight distributions (M_w[M_n]⁻¹ = 5.9 and 2.6). Thermal and mechanical properties of these BPE samples obtained over supported Ni catalysts are similar to those of commercial LLDPE samples prepared with metallocene and Ziegler-Natta catalysts.