Demonstration of surface electron rejection with interleaved germanium detectors for dark matter searches

The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two 210 Pb sources producing ∼130 beta decays/hr. In ∼800 live hours, no events leaked into the 8–115 keV signal region, giving upper limit leakage fraction 1.7 × 10−5 at 90% C.L., corresponding to < 0.6 surface event background in the future 200-kg SuperCDMS SNOLAB experiment

Rational guidelines for the two-step scalability of enzymatic polycondensation: experimental and computational optimization of the enzymatic synthesis of poly(glycerolazelate)

8si: The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to a Design of Experiment approach that allowed to understand the effect of the experimental variables on monomer conversion, M n and regioselectivity of acylation of glycerol. The chemometric analysis showed that after 24h the reaction proceeds regardless of the presence of the enzyme. Accordingly, the biocatalyst was removed after a first step of synthesis and the chain elongation continued at 80°C. That allowed the removal of the biocatalyst and the preservation of its activity: pre-requites for efficient applicability at industrial scale. The experimental study, combined with docking based computational analysis, provided rational guidelines for the optimization of the regioselective acylation of glycerol. Overall, the process was scaled up to 73.5 g of monomer. The novelty of the present study stays in the rigorous control of the reaction conditions and of the integrity of the immobilized biocatalyst, thus avoiding any interference of free enzyme or fines released in the reaction mixture.  The quantitative analysis of the effect of the experimental conditions and the overcoming of the major technical bottlenecks for the scalability of enzymatic polycondensation opens new scenarios for its industrial exploitation.noneopenTodea, Anamaria; Fortuna, Sara; Ebert, Cynthia; Asaro, Fioretta; Tomada, Stefano; Cespugli, Marco; Hollan, Fabio; Gardossi, LuciaTodea, Anamaria; Fortuna, Sara; Ebert, Cynthia; Asaro, Fioretta; Tomada, Stefano; Cespugli, Marco; Hollan, Fabio; Gardossi, Luci

Search for Low-Mass Weakly Interacting Massive Particles with SuperCDMS

We report a first search for weakly interacting massive particles (WIMPs) using the background rejection capabilities of SuperCDMS. An exposure of 577 kg days was analyzed for WIMPs with mass <30  GeV/c2, with the signal region blinded. Eleven events were observed after unblinding. We set an upper limit on the spin-independent WIMP-nucleon cross section of 1.2×10−42  cm2 at 8  GeV/c2. This result is in tension with WIMP interpretations of recent experiments and probes new parameter space for WIMP-nucleon scattering for WIMP masses <6  GeV/c2

Search for low-mass weakly interacting massive particles with SuperCDMS.

We report a first search for weakly interacting massive particles (WIMPs) using the background rejection capabilities of SuperCDMS. An exposure of 577 kg days was analyzed for WIMPs with mass &lt;30  GeV/c(2), with the signal region blinded. Eleven events were observed after unblinding. We set an upper limit on the spin-independent WIMP-nucleon cross section of 1.2×10(-42)  cm(2) at 8  GeV/c(2). This result is in tension with WIMP interpretations of recent experiments and probes new parameter space for WIMP-nucleon scattering for WIMP masses &lt;6  GeV/c(2)