25 Search Results

The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on ${}_{40}\mathrm{Ar}$ and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called “brems flipping,” as well as the burst direction from anmore » ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE’s burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage.« less

Here, the effect of ion kinetic energy on gas phase ion reactivity with ICP-MS/MS was investigated in order to explore tuning strategies for interference removal. The collision/reaction gases CO₂, N₂O and O₂ were used to observe the ion product distribution for 48 elements using an Agilent tandem ICP-MS (ICP-MS/MS) as a function of reaction gas flow rate (pressure) and ion kinetic energy. The kinetic energy of the incident ion was varied by adjusting the octopole bias (V_oct). The three gases all form oxides (MO⁺) as the primary product with differing reaction enthalpies that result in distinct differences in the ionmore » energies required for reaction with product ion distributions that vary with Voct. Consequently, by varying the ion kinetic energy (i.e., V_oct), differences in interference reactivity can be used to achieve maximum separation. Three practical application examples were reported to demonstrate how the ion kinetic energy can be varied to achieve the ideal ion product distribution for interference resolution: CO₂ for the removal of ²³⁸U in Pu analyses, CO₂ for the removal of ⁴⁰Ar¹⁶O vs. ⁵⁶Fe, and O₂ for the removal of Sm in Eu analyses, analogous to Pu/Am. The results demonstrate how the starting ion energy defined by V_oct is an important factor to fully leverage the utility of any given reaction gas to remove interferences in the mass spectrum using ICP-MS/MS.« less

Dust particulate fallout on materials in use for rare-event searches is a concerning source of radioactive backgrounds due to the presence of the naturally occurring radionuclides ⁴⁰K, ²³²Th, ²³⁸U, and their progeny in dust. Much effort is dedicated to inform radioactive backgrounds from dust and evaluate the efficacy of mitigation procedures. A great portion of such effort relies on fallout models and assumed dust composition. Here, in this work, an ICP-MS based methodology was employed for a direct determination of fallout rates of radionuclides and stable isotopes of interest from dust particulate at the SNOLAB facility. Hosted in an activemore » mine, the SNOLAB underground laboratory strives to maintain experimental areas at class 2000 cleanroom level. This work validates the mitigation procedures in place at SNOLAB and informs dust backgrounds during laboratory activities. Fallout rates of major constituents of the local rock were measured two to three orders of magnitude lower in the clean experimental areas compared to non-clean transition areas from the mine to the laboratory. An increase of approximately two orders of magnitude in the fallout rate of stable Pb isotopes was determined in an experimental area during activities involving handling of Pb bricks. Increased ⁴⁰K, ²³²Th, and ²³⁸U fallout rates were measured in clean experimental areas during activities generating particulate.« less

Carbonyl sulfide (OCS) was used as a reaction gas to investigate gas phase metal (M⁺) ion-molecule reactions using the Agilent 8900 inductively coupled plasma tandem mass spectrometer (ICP-MS/MS) to yield insight on how this gas may be used to remove isobaric interferences in analytical measurements. The experimental work was paired with density functional theory (DFT) calculations of the reaction enthalpy to predict whether M⁺ will react with OCS. A multi-element standard containing 46 elements ranging from 9 to 208 u was analyzed in the presence and absence of OCS. When a reaction was observed, the dominant product was the sulfidemore » (MS⁺). Oxide products were also observed for many M⁺ but formation was less efficient with OCS than previously observed with other reaction gases. This is likely due to the weaker OC-S bond that makes MS⁺ formation more favorable. Increasing the flow rate from 0.1 to 0.2 mL/min (corresponding to a change in reaction gas pressure from 0.35 to 0.53 Pa (2.6 to 4.0 mTorr)) generally resulted in greater MS⁺ production, including the secondary product MS₂⁺ for a few cations. The early lanthanide series ions (La⁺, Ce⁺, Pr⁺ and Nd⁺) produced greater quantities of MO⁺ at the higher pressure, although MS⁺ products were still the dominant product. The DFT-predicted reaction enthalpies were consistent with the observed sulfide formation, with an accuracy >90%; however, model predictions were less accurate for the minor and higher order products (< 77% for MO⁺). Finally, the work presented here continues a systematic study of ion-molecule reactions in ICP-MS/MS to understand and develop new and novel ways to analyze complex mixtures with minimal pre-analysis treatment.« less

Intrinsic ⁴⁰K radioactive backgrounds from impurities of natural K in liquid scintillation cocktails have previously been demonstrated to limit their use in ultra-sensitive applications. Here, this work explores two methodologies in parallel for the reduction of ⁴⁰K backgrounds in the cocktails, and lays the groundwork for use in ultra-sensitive applications. In one method, alternative low-K liquid scintillation matrix constituents were identified and in the other, a simple purification method for single components and finished cocktails was developed. Both methods were verified via ICP-MS analysis. Liquid scintillation counting of selected purified cocktails demonstrated background reduction, improved stability, and enhanced performance. Themore » best performing purified cocktail was also counted on a custom-built ultra-low background liquid scintillation counter, with results below the detector background.« less

The Pandora Software Development Kit and algorithm libraries provide pattern-recognition logic essential to the reconstruction of particle interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at ProtoDUNE-SP, a prototype for the Deep Underground Neutrino Experiment far detector. ProtoDUNE-SP, located at CERN, is exposed to a charged-particle test beam. This paper gives an overview of the Pandora reconstruction algorithms and how they have been tailored for use at ProtoDUNE-SP. In complex events with numerous cosmic-ray and beam background particles, the simulated reconstruction and identification efficiency for triggered test-beam particles is above 80% formore » the majority of particle type and beam momentum combinations. Specifically, simulated 1 GeV/c charged pions and protons are correctly reconstructed and identified with efficiencies of 86.1$$\pm 0.6$$% and 84.1$$\pm 0.6$$%, respectively. The efficiencies measured for test-beam data are shown to be within 5% of those predicted by the simulation.« less

The mass concentrations of ²³²Th and ²³⁸U in several 3D printing filaments and printed polymer parts are reported as measures of their radiopurity. In order to minimize background signals in rare event physics detectors, radiopure polymers are necessary as dielectric and structural materials in their construction. New data are reported for polyvinylidene fluoride (PVDF), polyphenylene sulfide (PPS), and two forms of polyetherimide (PEI, branded ULTEM 1010 and 9085). Data for starting filaments and both simple and complex printed parts are reported. PVDF filaments and simple printed beads, were found to have values of approximately 30 and 50 pg g^-1 formore » ²³²Th and ²³⁸U, respectively, while a more complex spring clip part had slightly elevated ²³²Th levels of 65 pg g^-1, with ²³⁸U remaining at 50 pg g^-1. PPS filament was found to have concentrations of 270 and 710 pg g^-1 for ²³²Th and ²³⁸U, respectively, and were not chosen to be printed as those levels were already higher than other material options. ULTEM 1010 filaments and printed complex spring clip parts were found to have concentrations of around 5 and 7 pg g^-1 for ²³²Th and ²³⁸U, respectively, illustrating no significant contamination from the printing process. ULTEM 9085 filaments were found to have concentrations of around 9 and 5 pg g^-1 for ²³²Th and ²³⁸U, respectively, while the printed complex spring clip part was found to have slightly elevated concentrations of 25 and 7 pg g^-1 for ²³²Th and ²³⁸U, respectively. All these results were obtained using a novel dry ashing method in crucibles constructed of ultralow background electroformed copper or, when applicable, microwave assisted wet ashing digestion. Samples and process blanks were spiked with ²²⁹Th and ²³³U as internal standards prior to dry/wet ashing and determinations were made by inductively coupled plasma mass spectrometry (ICP-MS). In order to maintain high radiopurity levels, pre-cleaning the filaments before printing and post-cleaning the parts is recommended, although the printing process itself has shown to contribute very minute amounts of radiocontaminants.« less

The rapid development of general-purpose computing ongraphics processing units (GPGPU) is allowing the implementationof highly-parallelized Monte Carlo simulation chains for particlephysics experiments. This technique is particularly suitable forthe simulation of a pixelated charge readout for time projectionchambers, given the large number of channels that this technologyemploys. Here we present the first implementation of a fullmicrophysical simulator of a liquid argon time projectionchamber (LArTPC) equipped with light readout and pixelated chargereadout, developed for the DUNE Near Detector. The software isimplemented with an end-to-end set of GPU-optimizedalgorithms. The algorithms have been written in Python andtranslated into CUDA kernels using Numba, a just-in-timemore » compilerfor a subset of Python and NumPy instructions. The GPUimplementation achieves a speed up of four orders of magnitudecompared with the equivalent CPU version. The simulation of thecurrent induced on 10^3 pixels takes around 1 ms on the GPU,compared with approximately 10 s on the CPU. The results of thesimulation are compared against data from a pixel-readout LArTPCprototype.« less

We report the performance of LSC cocktails in ultra-sensitive applications was evaluated. Backgrounds from radioactive contaminations in commercially available and in-house developed liquid scintillation cocktails were measured and compared to the predicted background levels of the ultra-low background liquid scintillation counter. Through the ICP-MS assay of the cocktails and their constituents, potassium impurities in the surfactant component were identified as a significant source of background, potentially limiting the use of LSC counting in ultra-sensitive applications. This work lays the groundwork for future research towards ultrapure LSC cocktails for ultrasensitive LSC counting

Regretfully, the author list of the original paper did not contain the members of the groups being responsible for the HPGe screening, Radon emanation measurement and ICPMS surface characterization works. As the work performed is to be considered more than “just service work”, the authors together with the members of these groups have decided to amend the authors list. At publication the following authors were not included in the author list: • From Pacific Northwest National Laboratory, Richland, WA, U.S.A.: E.W. Hoppe, I.J. Arnquist, K.P. Hobbs, A.D. French, M.L. diVacri • From INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi,more » Italy: M. Laubenstein • From M. Smoluchowski Institute of Physics, Jagiellonian University, 30-348 Krakow, Poland: G. Zuzel The metadata of the present erratum are already correct.« less