Effects of spatial sensitivity on mass sensing with bulk acoustic mode resonators

The spatial sensitivity of bulk acoustic mode resonators can influence calibrations when they are implemented as accurate mass sensors of surface-bound particles. A new spatial sensitivity model based on images of the resonator surface is introduced from early principles. The adsorption of particles was studied empirically by repeatedly drying particle laden droplets on the surface of two 3.14 MHz bulk acoustic mode resonators. Theoretical and experimental results were compared to identify three scenarios over the course of consecutive droplet evaporation with varying spatial sensitivity influences. Examining different surface treatments for the resonators revealed the hydrophilic surface to have a higher rate of particle stacking and conglomeration.ATZ thanks the Natural Sciences and Engineering Research Council of Canada, the Sir Winston Churchill Society of Edmonton, and the Cambridge Trust for funding of the PhD degree.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.sna.2015.11.00

Extending the lifetime of resonant atmospheric particulate mass sensors with solvent rinses

The cleaning of a collection-based sensor extends its lifetime and reduces its effective cost. Existing cleaning regimes for silicon-based devices typically require access to large laboratory equipment. A simple cleaning method based on solvent rinses is presented here for the application of microresonator atmospheric particulate mass sensors. The suggested approach is intended for scenarios with limited access to laboratory equipment. Two piezoelectric resonator topologies (in-plane bulk mode and out-of-plane flexural) collected particles via impaction for an hour before rinsing. The solvent rinses reset the resonant frequency and quality factor of each resonator to within 0.4% and 10% of their original values, respectively. Subsequent mass collections were largely repeatable despite fluctuations in particle concentration and deposition location. The presented method provides a straightforward but effective cleaning method for soluble particulate removal. A physical cleaning method is required after substantial insoluble particle adsorption

Particulate Mass Sensing with Piezoelectric Bulk Acoustic Mode Resonators

Current portable particle detection instruments typically rely on optical methods which are limited to 100 nm diameter particles. Microfabricated bulk acoustic resonators, when used as mass balances, could take particle detection below this limit. This study examines the collection of particles onto piezoelectric bulk acoustic mode resonators from gaseous flow using classical impaction. Collection of both polystyrene latex alpha-pinene secondary organic aerosol particles was examined in terms of frequency shift and collection efficiency. A new experimental setup was introduced which allows for adjusting major impactor, resonator, and aerosol properties. Preliminary results show the setup works for both particles while the saturation limit was not reached within an hour despite highly elevated particle concentrations.Conference sponsors: IEEE, UFF

Particulate mass sensing with piezoelectric bulk acoustic mode resonators

© 2016 IEEE.Current portable particle detection instruments typically rely on optical methods which are limited to 100 nm diameter particles. Microfabricated bulk acoustic resonators, when used as mass balances, could take particle detection below this limit. This study examines the collection of particles onto piezoelectric bulk acoustic mode resonators from gaseous flow using classical impaction. Collection of both polystyrene latex particles and α-pinene secondary organic aerosol particles was examined in terms of frequency shift and collection efficiency. A new experimental setup was introduced which allows for adjusting major impactor, resonator, and aerosol properties. Preliminary results show the setup works for both particles while the saturation limit was not reached within an hour despite highly elevated particle concentrations

A new processing scheme for ultra-high resolution direct infusion mass spectrometry data

High resolution, high accuracy mass spectrometry is widely used to characterise environmental or biological samples with highly complex composition enabling the identification of chemical composition of often unknown compounds. Despite instrumental advancements, the accurate molecular assignment of compounds acquired in high resolution mass spectra remains time consuming and requires automated algorithms, especially for samples covering a wide mass range and large numbers of compounds. A new processing scheme is introduced implementing filtering methods based on element assignment, instrumental error, and blank subtraction. Optional post-processing incorporates common ion selection across replicate measurements and shoulder ion removal. The scheme allows both positive and negative direct infusion electrospray ionisation (ESI) and atmospheric pressure photoionisation (APPI) acquisition with the same programs. An example application to atmospheric organic aerosol samples using an Orbitrap mass spectrometer is reported for both ionisation techniques resulting in final spectra with 0.8% and 8.4% of the peaks retained from the raw spectra for APPI positive and ESI negative acquisition, respectively.This work was supported by the European Research Council (ERC starting grant 279405) and by the U.K. Natural Environment Research Council (NERC grant NE/H52449X/1). ATZ thanks the Natural Sciences and Engineering Research Council of Canada, the Sir Winston Churchill Society of Edmonton, and the Cambridge Trust for PhD funding. IK was supported by a M. Curie Intra-European fellowship (project no. 254319

Cross section ratio and angular distributions of the reaction p + d -> 3He + eta at 48.8 MeV and 59.8 MeV excess energy

We present new data for angular distributions and on the cross section ratio of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q = 59.8 MeV. The data have been obtained at the WASA-at-COSY experiment (Forschungszentrum J\"ulich) using a proton beam and a deuterium pellet target. While the shape of obtained angular distributions show only a slow variation with the energy, the new results indicate a distinct and unexpected total cross section fluctuation between Q = 20 MeV and Q = 60 MeV, which might indicate the variation of the production mechanism within this energy interval.Comment: 9 pages, 9 figure

ABC Effect in Basic Double-Pionic Fusion --- Observation of a new resonance?

We report on a high-statistics measurement of the basic double pionic fusion reaction $pn \to d\pi^0\pi^0$ over the energy region of the so-called ABC effect, a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The measurements were performed with the WASA detector setup at COSY. The data reveal the ABC effect to be associated with a Lorentzian shaped energy dependence in the integral cross section. The observables are consistent with a resonance with $I(J^P) =0(3^+)$ in both $pn$ and $\Delta\Delta$ systems. Necessary further tests of the resonance interpretation are discussed

Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay

We reconstruct the rare decays $B^+ \to K^+\mu^+\mu^-$, $B^0 \to K^{*}(892)^0\mu^+\mu^-$, and $B^0_s \to \phi(1020)\mu^+\mu^-$ in a data sample corresponding to $4.4 {\rm fb^{-1}}$ collected in $p\bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ by the CDF II detector at the Fermilab Tevatron Collider. Using $121 \pm 16$ $B^+ \to K^+\mu^+\mu^-$ and $101 \pm 12$ $B^0 \to K^{*0}\mu^+\mu^-$ decays we report the branching ratios. In addition, we report the measurement of the differential branching ratio and the muon forward-backward asymmetry in the $B^+$ and $B^0$ decay modes, and the $K^{*0}$ longitudinal polarization in the $B^0$ decay mode with respect to the squared dimuon mass. These are consistent with the theoretical prediction from the standard model, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the $B^0_s \to \phi\mu^+\mu^- decay and measure its branching ratio${\mathcal{B}}(B^0_s \to \phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}$using$27 \pm 6$signal events. This is currently the most rare$B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let

A Search for Dark Higgs Bosons

Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the Standard Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots for b/w printin

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO