arXiv subjects

J. Runge

Publications and source records attributed to J. Runge.

36 records · Page 2Linked to original sources

arXiv2022

The COHERENT Experimental Program

The COHERENT experiment located in Neutrino Alley at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory (ORNL), has made the world's first two measurements of coherent elastic neutrino-nucleus scattering (CEvNS), on CsI and argon, using neutrinos produced at the SNS. The COHERENT collaboration continues to pursue CEvNS measurements on various targets as well as additional studies of inelastic neutrino-nucleus interactions, searches for accelerator-produced dark matter (DM) and physics beyond the Standard Model, using the uniquely high-quality and high-intensity neutrino source available at the SNS. This white paper describes primarily COHERENT's ongoing and near-future program at the SNS First Target Station (FTS). Opportunities enabled by the SNS Second Target Station (STS) for the study of neutrino physics and development of novel detector technologies are elaborated in a separate white paper.

hep-ex↗

arXiv2022

Simulating the neutrino flux from the Spallation Neutron Source for the COHERENT experiment

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is a pulsed source of neutrons and, as a byproduct of this operation, an intense source of pulsed neutrinos via stopped-pion decay. The COHERENT collaboration uses this source to investigate coherent elastic neutrino-nucleus scattering and other physics with a suite of detectors. This work includes a description of our Geant4 simulation of neutrino production at the SNS and the flux calculation which informs the COHERENT studies. We estimate the uncertainty of this calculation at about 10% based on validation against available low-energy pion production data.

hep-ex↗

arXiv2021

Quenching factor measurements of neon nuclei in neon gas

The NEWS-G collaboration uses Spherical Proportional Counters (SPCs) to search for weakly interacting massive particles (WIMPs). In this paper, we report the first measurements of the nuclear quenching factor in neon gas at \SI{2}{bar} using an SPC deployed in a neutron beam at the TUNL facility. The energy-dependence of the nuclear quenching factor is modelled using a simple power law: $α$E$_{nr}^β$; we determine its parameters by simultaneously fitting the data collected with the detector over a range of energies. We measured the following parameters in Ne:CH$_{4}$ at \SI{2}{bar}: $α$ = 0.2801 $\pm$ 0.0050 (fit) $\pm$ 0.0045 (sys) and $β$ = 0.0867 $\pm$ 0.020 (fit) $\pm$ 0.006(sys). Our measurements do not agree with expected values from SRIM or Lindhard theory. We demonstrated the feasibility of performing quenching factor measurements at sub-keV energies in gases using SPCs and a neutron beam.

physics.ins-det↗

arXiv2021

Quenching Factor consistency across several NaI(Tl) crystals

Testing the DAMA/LIBRA annual modulation result independently of dark matter particle and halo models has been a challenge for twenty years. Using the same target material, NaI(Tl), is required and presently two experiments, ANAIS-112 and COSINE-100, are running for such a goal. A precise knowledge of the detector response to nuclear recoils is mandatory because this is the most likely channel to find the dark matter signal. The light produced by nuclear recoils is quenched with respect to that produced by electrons by a factor that has to be measured experimentally. However, current quenching factor measurements in NaI(Tl) crystals disagree within the energy region of interest for dark matter searches. To disentangle whether this discrepancy is due to intrinsic differences in the light response among different NaI(Tl) crystals, or has its origin in unaccounted for systematic effects will be key in the comparison among the different experiments. We present measurements of the quenching factors for five small NaI(Tl) crystals performed in the same experimental setup to control systematics. Quenching factor results are compatible between crystals and no clear dependence with energy is observed from 10 to 80 keVnr.

astro-ph.IM↗

arXiv2021

Search for Majoron-emitting modes of $^{136}$Xe double beta decay with the complete EXO-200 dataset

A search for Majoron-emitting modes of the neutrinoless double-beta decay of $^{136}$Xe is performed with the full EXO-200 dataset. This dataset consists of a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr, and includes data with detector upgrades that have improved the energy threshold relative to previous searches. A lower limit of T$_{1/2}^{\rm{^{136}Xe}}>$4.3$\cdot$10$^{24}$ yr at 90\% C.L. on the half-life of the spectral index $n=1$ Majoron decay was obtained, a factor of 3.6 more stringent than the previous limit from EXO-200, corresponding to a constraint on the Majoron-neutrino coupling constant of $|\langle g_{ee}^{M}\rangle|$$<(0.4$-$0.9)\cdot10^{-5}$. The lower threshold and the additional data taken resulted in a factor 8.4 improvement for the $n=7$ mode compared to the previous EXO search. This search provides the most stringent limits to-date on the Majoron-emitting decays of $^{136}$Xe with spectral indices $n=1,2,3,$ and 7.

hep-ex↗

arXiv2021

The unusually high dark matter concentration of the galaxy group NGC 1600

We investigate the properties of the dark matter (DM) halo surrounding the nearby galaxy group NGC 1600. Through the use of deep (252 ks) Chandra observations and 64.3 ks of XMM-Newton observations, we construct surface brightness profiles in multiple energy bands in order to perform hydrostatic equilibrium analysis of the hot plasma within NGC 1600. Regardless of the DM model profile assumed, we measure a halo concentration (c$_{200}$) that is an extreme, positive outlier of the $Λ$CDM c$_{200}$-M$_{200}$ relation. For a typical NFW DM profile, we measure c$_{200}\!=\!26.7\pm1.4$ and M$_{200}\!=\!(2.0\pm0.2)\times10^{13}$ M$_\odot$; assuming a similar halo mass, the average concentration expected is c$_{200}=6-7$ for the theoretical $Λ$CDM c-M relation. Such a high concentration is similar to that of well-known fossil groups MRK 1216 and NGC 6482. While NGC 1600 exhibits some properties of a fossil group, it fails to meet the X-ray luminosity threshold of L$_X>5\times10^{41}$ erg s$^{-1}$. Whether or not it is considered a fossil group, the high concentration value makes it part of a select group of galaxy groups.

astro-ph.GA↗

arXiv2021

A detailed study of the bridge of excess X-ray emission between the galaxy clusters Abell 2029 and Abell 2033

We examine Suzaku, XMM-Newton, and Chandra observations of the Abell 2029/2033 system to investigate the nature of a bridge of X-ray emission joining the two galaxy clusters. By modelling the contributions from the outskirts of the two clusters, and excluding the emission from the southern infalling group and the background group LOS9, we find a significant excess of X-ray emission between the two clusters at the level of 6.5-7.0$σ$, depending on the choice of model, that cannot be explained by the overlap of the clusters. This excess component to the surface brightness is consistent with being emission from a filament with roughly 1.0 Mpc wide. The derived emission measure for the gas associated with the filament yields an average gas density of $3.7^{+1.0}_{-0.7} \times 10^{-5}$ cm$^{-3}$, corresponding roughly to 160 times the mean baryon density of the Universe. The Suzaku X-ray spectrum of the excess emission indicates that it is significantly colder ($1.4_{-0.5}^{+0.7}$ keV) than the cluster outskirts emission from the two clusters ($\sim$ 5 keV), statistically consistent with the temperature expected from the hottest and densest parts of the warm-hot intergalactic medium (WHIM). The geometry, density, and temperature are similar to those found from X-ray studies of the Abell 222/223 filament.

astro-ph.CO↗

arXiv2021

A D$_{2}$O detector for flux normalization of a pion decay-at-rest neutrino source

We report on the technical design and expected performance of a 592 kg heavy-water-Cherenkov detector to measure the absolute neutrino flux from the pion-decay-at-rest neutrino source at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The detector will be located roughly 20 m from the SNS target and will measure the neutrino flux with better than 5% statistical uncertainty in 2 years. This heavy-water detector will serve as the first module of a two-module detector system to ultimately measure the neutrino flux to 2-3% at both the First Target Station and the planned Second Target Station of the SNS. This detector will significantly reduce a dominant systematic uncertainty for neutrino cross-section measurements at the SNS, increasing the sensitivity of searches for new physics.

physics.ins-det↗

arXiv2021

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 $3σ$ 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.

nucl-ex↗

arXiv2021

Probing within the Bondi radius of the ultramassive black hole in NGC 1600

We present deep (250 ks) Chandra observations of the nearby galaxy group NGC 1600, which has at its centre an ultramassive black hole (17$\pm$1.5 billion M$_{\odot}$). The exceptionally large mass of the black hole coupled with its low redshift makes it one of only a handful of black holes for which spatially resolved temperature and density profiles can be obtained within the Bondi radius with the high spatial resolution of Chandra. We analyzed the hot gas properties within the Bondi accretion radius R$_B$=1.2" - 1.7"= 0.38 - 0.54 kpc. Within a $\sim\!3$ kpc radius, we find two temperature components with statistical significance. Both the single temperature and two temperature models show only a very slight rise in temperature towards the centre, and are consistent with being flat. This is in contrast with the expectation from Bondi accretion for a temperature profile which increases towards the centre, and appears to indicate that the dynamics of the gas are not being determined by the central black hole. The density profile follows a relatively shallow $ρ\propto~r^{-[0.61\pm0.13]}$ relationship within the Bondi radius, which suggests that the true accretion rate on to the black hole may be lower than the classical Bondi accretion rate.

astro-ph.GA↗

arXiv2021

Development of a $^{83\mathrm{m}}$Kr source for the calibration of the CENNS-10 Liquid Argon Detector

We report on the preparation of and calibration measurements with a $^{83\mathrm{m}}$Kr source for the CENNS-10 liquid argon detector. $^{83\mathrm{m}}$Kr atoms generated in the decay of a $^{83}$Rb source were introduced into the detector via injection into the Ar circulation loop. Scintillation light arising from the 9.4 keV and 32.1 keV conversion electrons in the decay of $^{83\mathrm{m}}$Kr in the detector volume were then observed. This calibration source allows the characterization of the low-energy response of the CENNS-10 detector and is applicable to other low-energy-threshold detectors. The energy resolution of the detector was measured to be 9$\%$ at the total $^{83\mathrm{m}}$Kr decay energy of 41.5 keV. We performed an analysis to separately calibrate the detector using the two conversion electrons at 9.4 keV and 32.1 keV

physics.ins-det↗

arXiv2020

COHERENT Collaboration data release from the first detection of coherent elastic neutrino-nucleus scattering on argon

Release of COHERENT collaboration data from the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) on argon. This release corresponds with the results of "Analysis A" published in Akimov et al., arXiv:2003.10630 [nucl-ex]. Data is shared in a binned, text-based format representing both "signal" and "backgrounds" along with associated uncertainties such that the included data can be used to perform independent analyses. This document describes the contents of the data release as well as guidance on the use of the data. Included example code in C++ (ROOT) and Python show one possible use of the included data.

nucl-ex↗

arXiv2020

Measurement of the scintillation and ionization response of liquid xenon at MeV energies in the EXO-200 experiment

Liquid xenon (LXe) is employed in a number of current and future detectors for rare event searches. We use the EXO-200 experimental data to measure the absolute scintillation and ionization yields generated by $γ$ interactions from $^{228}$Th (2615~keV), $^{226}$Ra (1764~keV) and $^{60}$Co (1332~keV and 1173~keV) calibration sources, over a range of electric fields. The $W$-value that defines the recombination-independent energy scale is measured to be $11.5~\pm~0.5$~(syst.)~$\pm~0.1$~(stat.) eV. These data are also used to measure the recombination fluctuations in the number of electrons and photons produced by the calibration sources at the MeV-scale, which deviate from extrapolations of lower-energy data. Additionally, a semi-empirical model for the energy resolution of the detector is developed, which is used to constrain the recombination efficiency, i.e., the fraction of recombined electrons that result in the emission of a detectable photon. Detailed measurements of the absolute charge and light yields for MeV-scale electron recoils are important for predicting the performance of future neutrinoless double beta decay detectors.

physics.ins-det↗

arXiv2020

Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden non-unique $β$-decay transition $^{137}\textrm{Xe}(7/2^-)\to\,^{137}\textrm{Cs}(7/2^+)$. The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultra-low background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal-to-background ratio of more than 99-to-1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden non-unique $β$-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

nucl-ex↗

arXiv2019

Sensitivity of the COHERENT Experiment to Accelerator-Produced Dark Matter

The COHERENT experiment is well poised to test sub-GeV dark matter models using low-energy recoil detectors sensitive to coherent elastic neutrino-nucleus scattering (CEvNS) in the $π$-DAR neutrino beam produced by the Spallation Neutron Source. We show how a planned 750-kg liquid argon scintillation detector would place leading limits on scalar light dark matter models, over two orders of magnitude of dark matter mass, for dark matter particles produced through vector and leptophobic portals in the absence of other effects beyond the standard model. The characteristic timing structure of a $π$-DAR beam allows a unique opportunity for constraining systematic uncertainties on the standard model background in a time window where signal is not expected, enhancing expected sensitivity. Additionally, we discuss future prospects, further increasing the discovery potential of CEvNS detectors. Such methods would test the calculated thermal dark matter abundance for all couplings $α'\leq1$ within the vector portal model over an order of magnitude of dark matter masses.

hep-ex↗

arXiv2019

Search for Neutrinoless Double-Beta Decay with the Complete EXO-200 Dataset

A search for neutrinoless double-beta decay ($0νββ$) in $^{136}$Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between $0νββ$ and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4$\pm$3.0% and the energy resolution of the detector at the Q-value of $^{136}$Xe $0νββ$ has been improved from $σ/E=1.23\%$ to $1.15\pm0.02\%$ with the upgraded detector. Accounting for the new data, the median 90% confidence level $0νββ$ half-life sensitivity for this analysis is $5.0 \cdot 10^{25}$ yr with a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr. No statistically significant evidence for $0νββ$ is observed, leading to a lower limit on the $0νββ$ half-life of $3.5\cdot10^{25}$ yr at the 90% confidence level.

hep-ex↗

arXiv2019

First Constraint on Coherent Elastic Neutrino-Nucleus Scattering in Argon

Coherent elastic neutrino-nucleus scattering (CEvNS) is the dominant neutrino scattering channel for neutrinos of energy $E_ν< 100$ MeV. We report a limit for this process using data collected in an engineering run of the 29 kg CENNS-10 liquid argon detector located 27.5 m from the Oak Ridge National Laboratory Spallation Neutron Source (SNS) Hg target with $4.2\times 10^{22}$ protons on target. The dataset yielded $< 7.4$ observed CEvNS events implying a cross section for the process, averaged over the SNS pion decay-at-rest flux, of $<3.4 \times 10^{-39}$ cm$^{2}$, a limit within twice the Standard Model prediction. This is the first limit on CEvNS from an argon nucleus and confirms the earlier CsI non-standard neutrino interaction constraints from the collaboration. This run demonstrated the feasibility of the ongoing experimental effort to detect CEvNS with liquid argon.

hep-ex↗

arXiv2004

The Infati Data

The ability to perform meaningful empirical studies is of essence in research in spatio-temporal query processing. Such studies are often necessary to gain detailed insight into the functional and performance characteristics of proposals for new query processing techniques. We present a collection of spatio-temporal data, collected during an intelligent speed adaptation project, termed INFATI, in which some two dozen cars equipped with GPS receivers and logging equipment took part. We describe how the data was collected and how it was "modified" to afford the drivers some degree of anonymity. We also present the road network in which the cars were moving during data collection. The GPS data is publicly available for non-commercial purposes. It is our hope that this resource will help the spatio-temporal research community in its efforts to develop new and better query processing techniques.

cs.DB↗