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Abstract: The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing a low-pressure gas TPC for detecting WIMP-nucleon interactions. DMTPC detectors use optical readout with CCD cameras to search for the daily modulation of the directional signal of the dark matter wind. An analysis of several charge readout channels has been developed to obtain additional information about ionization events in the detector. In order to reach sensitivities required for the WIMP detection, the detector needs to minimize backgrounds from electron recoils. This article shows that by using the readout of charge signals in addition to CCD readout, a preliminary statistics-limited 90% C.L. upper limit on the γ and e − rejection factor of 5.6 × 10−6 is obtained for energies between 40 keVee and 200 keVee. [Copyright &y& Elsevier]

Abstract: While petroleum-derived polymers persist for many years after disposal, biopolymers inclined to degrade in bioactive environments. Moreover biopolymers are suitable to be reinforced by natural fibres, which behave as biodegradable fillers into a biodegradable matrix, to improve their mechanical performance. Among the biodegradable polymers, starch-based biopolymers are ones of the most intensity studied. Starch-based biopolymers are produced by blending thermoplastic starch with synthetic polymers resulting in different biopolymer morphology and final properties. In this work, lignocellulosic fibres from hemp core raw material were used as reinforcement of starch-based biopolymer and the final mechanical properties evaluated. Due to the similar chemical characteristics of both composite components, no one coupling agent was used to improve the biocomposite stress transfer. Hemp core fibres were obtained by means of a semi-chemical pulp process and biocomposites from starch-based biopolymer comprising 10, 20 and 30wt% of reinforcement were prepared. The interfacial shear strength of the obtained composites, determined from Kelly–Tyson model, demonstrated the good quality at fibre–matrix interface for this type of composites. [Copyright &y& Elsevier]