Natural Xenon Research Articles

Searching for Two-Neutrino and Neutrinoless Double Beta Decay of ^{134}Xe with the PandaX-4T Experiment.

^{134}Xe is a candidate isotope for neutrinoless double beta decay (0νββ) search. In addition, the two-neutrino case (2νββ) allowed by the standard model of particle physics has not yet been observed. With the 656-kg natural xenon in the fiducial volume of the PandaX-4T detector, which contains 10.4% of ^{134}Xe, and its initial 94.9-day exposure, we have established the most stringent constraints on 2νββ and 0νββ of ^{134}Xe half-lives, with limits of 2.8×10^{22} yr and 3.0×10^{23} yr at 90%confidence level, respectively. The 2νββ (0νββ) limit surpasses the previously reported best result by a factor of 32 (2.7), highlighting the potential of large monolithic natural xenon detectors for double beta decay searches.

High-pressure xenon gas time projection chamber with scalable design and its performance around the Q value of 136Xe double-beta decay

Abstract We have been developing a high-pressure xenon gas time projection chamber (TPC) called AXEL (A Xenon ElectroLuminescence detector) to search for neutrinoless double-beta (0νββ) decay of 136Xe. The unique feature of this TPC is the electroluminescence light collection cell (ELCC), the part designed to detect ionization electrons. The ELCC is composed of multiple units, and one unit covers 48.5 cm2. A 180 L size prototype detector with 12 units, 672 channels, of the ELCC was constructed and operated with 7.6 bar natural xenon gas to evaluate the performance of the detector around a Q value of 136Xe 0νββ. The obtained FWHM energy resolution is $0.73 \pm 0.11\%$ at 1836 keV. This corresponds to $0.60 \pm 0.03\%$ to $0.70 \pm 0.21\%$ of the energy resolution at a Q value of 136Xe 0νββ. This result shows the scalability of the AXEL detector with the ELCC while maintaining a high energy resolution. Factors determining the energy resolution were quantitatively evaluated and the result indicates that further improvement is feasible. Reconstructed track images show distinctive structures at the endpoints of electron tracks, which will be an important feature in distinguishing 0νββ signals from gamma-ray backgrounds.

Pp solar neutrinos at DARWIN

The DARWIN collaboration recently argued that DARWIN (DARk matter WImp search with liquid xenoN) can collect, via neutrino--electron scattering, a large, useful sample of solar $pp$-neutrinos, and measure their survival probability with sub-percent precision. We explore the physics potential of such a sample in more detail. We estimate that, with 300 ton-years of data, DARWIN can also measure, with the help of current solar neutrino data, the value of $\sin^2\theta_{13}$, with the potential to exclude $\sin^2\theta_{13}=0$ close to the three-sigma level. We explore in some detail how well DARWIN can constrain the existence of a new neutrino mass-eigenstate $\nu_4$ that is quasi-mass-degenerate with $\nu_1$ and find that DARWIN's sensitivity supersedes that of all current and near-future searches for new, very light neutrinos. In particular, DARWIN can test the hypothesis that $\nu_1$ is a pseudo-Dirac fermion as long as the induced mass-squared difference is larger than $10^{-13}$ eV$^2$, one order of magnitude more sensitive than existing constraints. Throughout, we allowed for the hypotheses that DARWIN is filled with natural xenon or $^{136}$Xe-depleted xenon.

Production of xenon-135 from isotopically enriched xenon-134 and xenon-136 targets

Atmospheric radioxenon analyses conducted under the Comprehensive Test Ban Treaty Organization (CTBTO) necessitates the collection of air samples to quantify 135Xe, an indicator for nuclear explosions and reactor operations. Analytical instrument calibration for these analyses requires high quality, monoisotopic reference standards that are typically short lived, and therefore must be produced and shipped promptly to monitoring stations worldwide. The work described here outlines two methods to produce highly enriched 135Xe by irradiating stable monoisotopic targets by (1) neutron capture (n, ɣ) on monoisotopic 134Xe and (2) high energy photon irradiation (ɣ, n) of monoisotopic 136Xe. The targets were prepared by electromagnetic isotope separation of natural xenon. Results from each process were compared for 135Xe yield and purity.

Photostability of Oil-Coated and Stain-Coated Acetylated Hornbeam Wood against Natural Weather and Artificial Aging

Nine different environmentally friendly coatings were tested on natural and acetylated hornbeam wood, during natural weather exposure and xenon lamp irradiation. The coating performance of acetylated hornbeam, and the photostability properties of tested coatings were evaluated to offer suggestions regarding suitable and less-suitable coatings for the exterior use of acetylated hornbeam. On the one hand, acetylation decreased the coating absorbance of hornbeam. On the other hand, it made the wood more durable and dimensionally stable, all of which influences the outdoor performance of acetylated hornbeam. The color of acetylated hornbeam is not photostable; it brightens during photodegradation, and greys after leaching. For long-lasting color, acetylated hornbeam should be coated with dark pigmented stains and maintained regularly. Fungal degradation and cracking did not occur, but the wood is just as susceptible to wasp stripping as untreated hornbeam. In this study, 200-h-long xenon lamp irradiation resulted in a color similar to that caused by 1 month of weather exposure (April to May 2018, Sopron, Hungary).

Cosmogenic production of Ar37 in the context of the LUX-ZEPLIN experiment

We estimate the amount of $^{37}$Ar produced in natural xenon via cosmic ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth's surface. We then calculate the resulting $^{37}$Ar concentration in a 10-tonne payload~(similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea level production rate of $^{37}$Ar in natural xenon is estimated to be 0.024~atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1~tonne/month, the average $^{37}$Ar activity after 10~tonnes are purified and transported underground is 0.058--0.090~$\mu$Bq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic $^{37}$Ar will appear as a noticeable background in the early science data, while decaying with a 35~day half-life. This newly-noticed production mechanism of $^{37}$Ar should be considered when planning for future liquid xenon-based experiments.

Determination of Double Beta Decay Half-Life of 136Xe with the PandaX-4T Natural Xenon Detector.

Precise measurement of two-neutrino double beta decay (DBD) half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay. We report the measurement of DBD half-life of 136Xe using the PandaX-4T dual-phase Time Projection Chamber (TPC) with 3.7-tonne natural xenon and the first 94.9-day physics data release. The background model in the fiducial volume is well constrained in situ by events in the outer active region. With a 136Xe exposure of 15.5 kg-year, we establish the half-life as 2.27 ± 0.03(stat.) ± 0.10(syst.) × 1021 years. This is the first DBD half-life measurement with natural xenon and demonstrates the physics capability of a large-scale liquid xenon TPC in the field of rare event searches.

Projected sensitivity of the LUX-ZEPLIN experiment to the two-neutrino and neutrinoless double β decays of Xe134

The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double β decay of Xe134 is presented. LZ is a 10-tonne xenon time-projection chamber optimized for the detection of dark matter particles and is expected to start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass of natural xenon provides an exceptional opportunity to search for the double β decay of Xe134, for which xenon detectors enriched in Xe136 are less effective. For the two-neutrino decay mode, LZ is predicted to exclude values of the half-life up to 1.7×1024 years at 90% confidence level (CL) and has a three-sigma observation potential of 8.7×1023 years, approaching the predictions of nuclear models. For the neutrinoless decay mode LZ, is projected to exclude values of the half-life up to 7.3×1024 years at 90% CL.Received 19 May 2021Accepted 19 November 2021DOI:https://doi.org/10.1103/PhysRevC.104.065501©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDouble beta decayNeutrinoless double beta decayProperties90 ≤ A ≤ 149TechniquesSpectrometers & spectroscopic techniquesNuclear PhysicsParticles & Fields

Ventilation heterogeneity imaged by multibreath wash-ins of hyperpolarized 3 He and 129 Xe in healthy rabbits.

Multibreath imaging to estimate regional gas mixing efficiency is superior to intensity-based single-breath ventilation markers, as it is capable of revealing minute but essential measures of ventilation heterogeneity which may be sensitive to subclinical alterations in the early stages of both obstructive and restrictive respiratory disorders. Large-scale convective stratification of ventilation in central-to-peripheral directions is the dominant feature of observed ventilation heterogeneity when imaging a heavy/less diffusive xenon gas mixture; smaller-scale patchiness, probably originating from asymmetric lung function at bronchial airway branching due to the interaction of convective and diffusive flows, is the dominant feature when imaging a lighter/more diffusive helium gas mixture. Since detecting low regional ventilation is crucial for characterizing diseased lungs, our results suggest that dilution with natural abundance helium and imaging at higher lung volumes seem advisable when imaging with hyperpolarized 129 Xe; this will allow the imaging gas to reach slow-filling and/or non-dependent lung regions, which might otherwise be impossible to distinguish from total ventilation shunt regions. The ability to differentiate these regions from those of total shunt is worse with typical single-breath imaging techniques. The mixing of freshly inhaled gas with gas already present in the lung can be directly assessed with heretofore unachievable precision via magnetic resonance imaging of signal build-up resulting from multiple wash-ins of a hyperpolarized (HP) gas. Here, we used normoxic HP 3 He and 129 Xe mixtures to study regional ventilation at different spatial scales in five healthy mechanically ventilated supine rabbits at two different inspired volumes. To decouple the respective effects of density and diffusion rates on ventilation heterogeneity, two additional studies were performed: one in which 3 He was diluted with an equal fraction of natural abundance xenon, and one in which 129 Xe was diluted with an equal fraction of 4 He. We observed systematic differences in the spatial scale of specific ventilation heterogeneity between HP 3 He and 129 Xe. We found that large-scale, central-to-peripheral convective ventilation inhomogeneity is the dominant cause of observed heterogeneity when breathing a normoxic xenon gas mixture. In contrast, small-scale ventilation heterogeneity in the form of patchiness, probably originating from asymmetric lung function at bronchial airway branching due to interactions between convective and diffusive flows, is the dominant feature when breathing a normoxic helium gas mixture, for which the critical zone occurs more proximally and at an imageable spatial scale. We also showed that the existence of particular underventilated non-dependent lung regions when breathing a heavy gas mixture is the result of the density of that mixture - rather than, for example, its diffusion rate or viscosity. Finally, we showed that gravity-dependent ventilation heterogeneity becomes substantially more uniform at higher inspired volumes for xenon gas mixtures compared to helium mixtures.

Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of ^{136}Xe

The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of ^{136}Xe. Out of its 50 t total natural xenon inventory, 40 t will be the active target of a time projection chamber which thus contains about 3.6 t of ^{136}Xe. Here, we show that its projected half-life sensitivity is 2.4times {10}^{27},{hbox {year}}, using a fiducial volume of 5 t of natural xenon and 10 year of operation with a background rate of less than 0.2 events/(t cdot year) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in ^{136}Xe.

Influence of secondary oxide phases in enhancing the photocatalytic properties of alkaline earth elements doped LaFeO3 nanocomposites

An improvement in the photocatalytic activity of lanthanum ferrite was attempted by doping individual alkaline earth elements (Ba, Ca and Sr) in its La site and Mg in Fe site to get the desired energy band characteristics. All doped compositions of LaFeO3 were synthesised by sol-gel method. Structural studies show the formation of secondary oxide phases when calcined at 800 °C and phase pure compounds when calcined at 1100 °C. Optical studies reveal the capability of these perovskites to be visible light active and indicate that the bandgaps become narrower after doping alkaline earth elements. Photocatalytic activity was tested through Congo Red (CR) dye degradation studies and hydrogen evolution through water splitting. The results indicate that Mg doped LaFeO3 composite which was obtained after the calcination at 800 °C shows higher hydrogen evolution rate and the highest rate of Congo red (CR) dye degradation among all synthesised compositions of undoped and doped LaFeO3 under natural Xenon lamp irradiation. The possible mechanism of the photocatalytic activity is also proposed in this study.

Searching for neutrino-less double beta decay of 136Xe with PandaX-II liquid xenon detector * * Supported by grants from the Ministry of Science and Technology of China (2016YFA0400301, 2016YFA0400302), a Double Top-class grant from Shanghai Jiao Tong University, grants from National Science Foundation of China (11435008, 11505112, 11525522, 11775142, 11755001), grants from the Office of Science and Technology, Shanghai Municipal

We report the Neutrino-less Double Beta Decay (NLDBD) search results from PandaX-II dual-phase liquid xenon time projection chamber. The total live time used in this analysis is 403.1 days from June 2016 to August 2018. With NLDBD-optimized event selection criteria, we obtain a fiducial mass of 219 kg of natural xenon. The accumulated xenon exposure is 242 kg·yr, or equivalently 22.2 kg·yr of 136Xe exposure. At the region around 136Xe decay Q-value of 2458 keV, the energy resolution of PandaX-II is 4.2%. We find no evidence of NLDBD in PandaX-II and establish a lower limit for decay half-life of 2.1 yr at the 90% confidence level, which corresponds to an effective Majorana neutrino mass eV. This is the first NLDBD result reported from a dual-phase xenon experiment.

A thermally polarized 129 Xe phantom for quality assurance in multi-center hyperpolarized gas MRI studies.

Hyperpolarized 129 Xe MR is increasingly being adopted worldwide, but no standards exist for assessing or comparing performance at different 129 Xe imaging centers. Therefore, we sought to develop a thermally polarized xenon phantom assembly, approximating the size of a human torso, along with an associated imaging protocol to enable rapid quality-assurance imaging. MR-compatible pressure vessels, with an internal volume of 5.85 L, were constructed from pressure-rated, engineering grade PE4710 high-density polyethylene. They were filled with a mixture of 61% natural xenon and 39% oxygen to approximately 11.6 bar and placed in a loader shell filled with a 0.56% saline solution to mimic the human chest. Imaging employed a 2D spoiled gradient-echo sequence using non-slice-selective excitation (TR/TE = 750/6.13 ms, flip angle = 74°, FOV = 40 × 440 mm, matrix = 64 × 32, bandwidth = 30 Hz/pixel, averages = 4), resulting in a 1.6 min acquisition. System characterization and imaging were performed at 8 different MRI centers. At 3 Telsa, 129 Xe in the pressure vessels was characterized by T1 = 580.5 ± 8.3 ms, linewidth = 0.21 ppm, and chemical shift = +10.2 ppm. The phantom assembly was used to obtain transmit voltage calibrations and 2D and 3D images across multiple coil and scanner configurations at 8 sites. Across the 5 sites that employed a standard flexible chest coil, the SNR was 12.4 ± 1.8. The high-density polyethylene pressure vessels filled with thermally polarized xenon and associated loader shell combine to form a phantom assembly that enables spectroscopic and imaging acquisitions that can be used for testing, quality assurance, and performance tracking-capabilities essential for standardizing hyperpolarized 129 Xe MRI within and across institutions.

Proton-induced spallation of mercury and xenon targets for neutron flux produced between CEM03.01 and INCL4-ABLA spallation packages

Accelerator-Driven Subcritical (ADS) reactors are one of the pathways considered for the incineration of minor actinides. They use a proton beam accelerator up to a GeV energy, bombarding a spallation target, usually made of a material of high atomic number (W, Pb, Ta or U). The neutrons generated during the spallation reactions are then multiplied. The main goal of this study is to make a comparison between two models of physical packages via the Monte Carlo code MCNP6. The first package is the INCL4-ABLA and the second one is the CEM03.01, and we have deduced the best package according to the neutron production rate. In this study, we are interested in two cylindrical targets of natural mercury and xenon 20cm in height and 20 in diameter and a proton beam varies from 0.1 to 1.5 GeV.

Proton-induced spallation of mercury and xenon targets for neutron flux produced between CEM03.01 and INCL4-ABLA spallation packages

Accelerator-Driven Subcritical (ADS) reactors are one of the pathways considered for the incineration of minor actinides. They use a proton beam accelerator up to a GeV energy, bombarding a spallation target, usually made of a material of high atomic number (W, Pb, Ta or U). The neutrons generated during the spallation reactions are then multiplied. The main goal of this study is to make a comparison between two models of physical packages via the Monte Carlo code MCNP6. The first package is the INCL4-ABLA and the second one is the CEM03.01, and we have deduced the best package according to the neutron production rate. In this study, we are interested in two cylindrical targets of natural mercury and xenon 20cm in height and 20 in diameter and a proton beam varies from 0.1 to 1.5 GeV.

Feasibility study of large-scale production of iodine-125 at the high temperature engineering test reactor

The feasibility of a large-scale iodine-125 production from natural xenon gas at high-temperature gas-cooled reactors (HTGRs) was investigated. A high-temperature engineering test reactor (HTTR), which is located in Japan at Oarai-machi Research and Development Center, was used as a reference HTGR reactor in this study. First, a computer code based on a Runge-Kutta method was developed to calculate the quantities of isotopes arising from the neutron irradiation of natural xenon gas target. This code was verified with a good agreement with a reference result. Next, optimization of irradiation planning was carried out. As results, with 4 days of irradiation and 8 days of decay, the 125I production could be maximized and the 126I contamination was within an acceptable level. The preliminary design of irradiation channels at the HTTR was also optimized. The case with 3 irradiation channels and 20-cm diameter was determined as the optimal design, which could produce approximately 1.8 × 105GBq/y of 125I production.

Neutrino physics with DARWIN

DARWIN (DARk matter WImp search with liquid xenoN) will be a multi-ton dark matter detector with the primary goal of exploring the entire experimentally accessible parameter space for weakly interacting massive particles (WIMPs) over a wide mass-range. With its 40 tonne active liquid xenon target, low-energy threshold and ultra-low background level, DARWIN can also search for other rare interactions. Here we present its sensitivity to low-energy solar neutrinos and to neutrinoless double beta decay. In a low-energy window of 2-30 keV a rate of 105/year, from pp and 7Be neutrinos can be reached. Such a measurement, with 1% precision will allow testing neutrinos models. DARWIN could also reach a competitive half-life sensitivity of 8.5 · 1027 y to the neutrinoless double beta decay (0νββ) of 136Xe after an exposure of 140 t×y of natural xenon. Nuclear recoils from coherent scattering of solar neutrinos will limit the sensitivity to WIMP masses below 5 GeV/c2, and the event rate from 8B neutrinos would range from a few to a few tens of events per tonne and year, depending on the energy threshold of the detector. Deviations from the predicted but yet unmeasured neutrino flux would be an indication for physics beyond the Standard Model

Development of NEW, towards the first physics results of NEXT

The NEXT ββ0ν experiment will use a high-pressure gas electroluminescent TPC to search for the decay of Xe-136. The development, construction and installation of NEXT-WHITE (NEW), the first radio-pure version of NEXT, will take place this year at Laboratorio Subterráneo de Canfranc. NEW will run initially using 10 kg of natural xenon during which time NEXT technology will be validated and the topological reconstruction algorithms refined. Moreover, the background model will be benchmarked using data. A second run will use enriched xenon and will make a first measurement of the two neutrino channel (ββ2ν) by NEXT. This poster will present the various technical aspects of the detector detailing the radio-pure solutions for a low backgorund experiment and the low noise, high resolution measurement of both energy and position.

Measurement of cosmogenic radioactive products in xenon and copper

Rare events searches, such as direct dark matter detection or neutrinoless double beta decay (0vββ) observation, using liquid xenon as target and detection medium require ultralow background to fully exploit the physics potential. Cosmogenic activation of the detector components, and even more importantly, of the xenon itself might have undesired impact on the background and the final sensitivity of the experiment. Since no measurement of cosmogenic activation of xenon was present in literature so far, we performed such a measurement exposing of a natural xenon sample to the cosmic radiation at the Jungfraujoch research station at an altitude of 3470 m above sea level for 245 days. This study was complemented with a ultra pure copper sample that was activated together with the xenon. We directly observed, with gamma-ray spectrometry, the production of 7Be, 101Rh, 125Sb, 126I and 127Xe in xenon, out of which only 125 Sb could potentially lead to a background relevant for multi-ton scale direct dark matter search. The production rates for five out of eight radioactive isotopes in copper are in good agreement with the only dedicated measurement present in literature. The production rates measured for both samples were compared with the predictions obtained with commonly used software packages. The latter showed a systematic under-estimation, especially for xenon.

Optimal Glass-Forming Solvent Brings Sublimation Dynamic Nuclear Polarization to 129Xe Hyperpolarization Biomedical Imaging Standards

In addition to the dedicated spin exchange optical pumping (SEOP) technique, an alternative method to produce hyperpolarized xenon gas using dynamic nuclear polarization (DNP) followed by a sublimation procedure was proposed. The challenge associated with sublimation DNP is to obtain solid-state samples with the required homogeneity following the incorporation of xenon into a glass-forming solvent. We show that the maximum achievable 129Xe polarization strongly depends on the xenon concentration dissolved in the solvent and the properties of the solvent itself. Using a 5 T home-built polarizer, the 129Xe spins in natural abundance xenon were polarized up to 30% in about 90 min at 1.15 ± 0.05 K. The gas was subsequently extracted to perform 129Xe MRI in a distant 9.4 T rodent scanner. We demonstrate that by careful optimization of the sample preparation, sublimation DNP can be used to hyperpolarize 129Xe at a polarization level and in quantities that are sufficiently large for biomedical applications.