A Study of the Mechanism of Micropore Filling. I. Molecular Sieve Effects

The adsorptive properties of two microporous carbons and a microporous silica have been investigated and compared using argon and benzene. The micropore volumes determined using the Theory for Volume filling of Micropores (TVFM) agreed to within 40/o of the total micropore volumes determined from the a8 method of pore analysis. Adsorption data of argon at 77 °K and benzene at 298 °K on the microporous carbons were interpreted in terms of the Dubinin-Astakhov and Dubinin-Radushkevich equations, and Weibull and Gaussian distributions of the adsorption free energy with pore volume, respectively. The Weibull distribution was found to apply better than the Gaussian distribution, although variations from linear D-A plots occurred. The adsorption data on the silica sample were best interpreted as a two-term D-R equation. Plots of the distribution of adsorption energy with pore volume of the silica sample for each term of the D-R equation and their effective contribution to the cumulative distribution curve gave conclusive evidence of the ordering of the adsorption process within micropores of varying dimensions

A Study of the Mechanism of Micropore Filling. I. Molecular Sieve Effects

The adsorptive properties of two microporous carbons and a microporous silica have been investigated and compared using argon and benzene. The micropore volumes determined using the Theory for Volume filling of Micropores (TVFM) agreed to within 40/o of the total micropore volumes determined from the a8 method of pore analysis. Adsorption data of argon at 77 °K and benzene at 298 °K on the microporous carbons were interpreted in terms of the Dubinin-Astakhov and Dubinin-Radushkevich equations, and Weibull and Gaussian distributions of the adsorption free energy with pore volume, respectively. The Weibull distribution was found to apply better than the Gaussian distribution, although variations from linear D-A plots occurred. The adsorption data on the silica sample were best interpreted as a two-term D-R equation. Plots of the distribution of adsorption energy with pore volume of the silica sample for each term of the D-R equation and their effective contribution to the cumulative distribution curve gave conclusive evidence of the ordering of the adsorption process within micropores of varying dimensions

Observation of Coherent Elastic Neutrino-Nucleus Scattering

The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.7-sigma confidence level, using a low-background, 14.6-kg CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions. Improved constraints on non-standard neutrino interactions with quarks are derived from this initial dataset

First Measurement of Coherent Elastic Neutrino-Nucleus Scattering on Argon

We report the first measurement of coherent elastic neutrino-nucleus scattering (\cevns) on argon using a liquid argon detector at the Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer \cevns over the background-only null hypothesis with greater than $3\sigma$ significance. The measured cross section, averaged over the incident neutrino flux, is (2.2 $\pm$ 0.7) $\times$10$^{-39}$ cm$^2$ -- consistent with the standard model prediction. The neutron-number dependence of this result, together with that from our previous measurement on CsI, confirms the existence of the \cevns process and provides improved constraints on non-standard neutrino interactions.Comment: 8 pages, 5 figures with 2 pages, 6 figures supplementary material V3: fixes to figs 3,4 V4: fix typo in table 1, V5: replaced missing appendix, V6: fix Eq 1, new fig 3, V7 final version, updated with final revision

Search for nucleon decays with EXO-200

A search for instability of nucleons bound in $^{136}$Xe nuclei is reported with 223 kg$\cdot$yr exposure of $^{136}$Xe in the EXO-200 experiment. Lifetime limits of 3.3$\times 10^{23}$ and 1.9$\times 10^{23}$ yrs are established for nucleon decay to $^{133}$Sb and $^{133}$Te, respectively. These are the most stringent to date, exceeding the prior decay limits by a factor of 9 and 7, respectively

Sensitivity and discovery potential of the proposed nEXO experiment to neutrinoless double beta decay

The next-generation Enriched Xenon Observatory (nEXO) is a proposed experiment to search for neutrinoless double beta ($0\nu\beta\beta$) decay in $^{136}$Xe with a target half-life sensitivity of approximately $10^{28}$ years using $5\times10^3$ kg of isotopically enriched liquid-xenon in a time projection chamber. This improvement of two orders of magnitude in sensitivity over current limits is obtained by a significant increase of the $^{136}$Xe mass, the monolithic and homogeneous configuration of the active medium, and the multi-parameter measurements of the interactions enabled by the time projection chamber. The detector concept and anticipated performance are presented based upon demonstrated realizable background rates.Comment: v2 as publishe

Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector

Results from a search for neutrinoless double-beta decay (0νββ) of Xe136 are presented using the first year of data taken with the upgraded EXO-200 detector. Relative to previous searches by EXO-200, the energy resolution of the