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Ray, D.

Publications and source records attributed to Ray, D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Design of a high voltage delivery system for noble liquid time projection chambers

Noble liquid time projection chambers (TPCs) are a leading technology in the detection of ionizing radiation, particularly in applications such as accelerator neutrino physics, dark matter detection, and neutrinoless double beta decay. This work addresses the design considerations for implementing stable high voltage (HV) systems within large noble liquid TPCs, with a focus on the nEXO experiment. Utilizing insights from prior HV research and experimental investigations, we outline factors influencing HV stability and discuss design choices to improve stability and prevent electrical discharges. A novel HV delivery system concept is presented, tailored for the nEXO TPC, which incorporates these design considerations while also meeting the stringent radiopurity requirements of the nEXO neutrinoless double beta decay search. These design considerations and their specific implementation towards a HV delivery system offer guidance to future experiments applying high voltage in noble liquid environments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Ultra-sensitive radon assay using an electrostatic chamber in a recirculating system

Rare event searches such as neutrinoless double beta decay and Weakly Interacting Massive Particle detection require ultra-low background detectors. Radon contamination is a significant challenge for these experiments, which employ highly sensitive radon assay techniques to identify and select low-emission materials. This work presents the development of ultra-sensitive electrostatic chamber (ESC) instruments designed to measure radon emanation in a recirculating gas loop, for future lower background experiments. Unlike traditional methods that separate emanation and detection steps, this system allows continuous radon transport and detection. This is made possible with a custom-built recirculation pump. A Python-based analysis framework, PyDAn, was developed to process and fit time-dependent radon decay data. Radon emanation rates are given for various materials measured with this instrument. A radon source of known activity provides an absolute calibration, enabling statistically-limited minimal detectable activities of 20 µBq. These devices are powerful tools for screening materials in the development of low-background particle physics experiments.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Overcoming photobleaching in imaging of single barium atoms in a solid xenon matrix

Neutrinoless double beta decay is one of the most sensitive probes for new physics beyond the Standard Model of particle physics. One of the isotopes under investigation is 136 Xe, which would double beta decay into 136 Ba. Detecting the single 136 Ba daughter provides a sort of ultimate tool in the discrimination against backgrounds. Previous work demonstrated the ability to perform single atom imaging of Ba atoms in a single-vacancy site of a solid xenon matrix. In this paper, the effort to identify signal from individual barium atoms is extended to Ba atoms in a hexa-vacancy site in the matrix and is achieved despite increased photobleaching in this site. Abrupt fluorescence turn-off of a single Ba atom is also observed. Significant recovery of fluorescence signal lost through photobleaching is demonstrated upon annealing of Ba deposits in the Xe ice. Following annealing, it is observed that Ba atoms in the hexa-vacancy site exhibit antibleaching while Ba atoms in the tetra-vacancy site exhibit bleaching. This may be evidence for a matrix site transfer upon laser excitation. Our findings offer a path of continued research toward tagging of Ba daughters in all significant sites in solid xenon.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

The Beta-decay Paul Trap Mk IV: Design and commissioning

Here, the Beta-decay Paul Trap is an open-geometry, linear trap used to measure the decays of 8 Li and 8 B to search for a tensor contribution to the weak interaction. In the latest 8 Li measurement of Burkey et al. (2022), β scattering was the dominant experimental systematic uncertainty. The Beta-decay Paul Trap Mk IV reduces the prevalence of β scattering by a factor of 4 through a redesigned electrode geometry and the use of glassy carbon and graphite as electrode materials. The trap has been constructed and successfully commissioned with 8 Li in a new data campaign that collected 2.6 million triple coincidence events, an increase in statistics by 30% with 4 times less β scattering compared to the previous 8 Li data set.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Precise mass measurements of A = 133 isobars with the Canadian Penning Trap: Resolving the Q β − anomaly at 133Te

We report precision mass measurements of 133 Sb 133g,m Te, and 133g,m I, produced at CARIBU at Argonne National Laboratory's ATLAS facility and measured using the Canadian Penning Trap mass spectrometer. These masses clarify an anomaly in the 133 Te β-decay. The masses reported in the 2020 Atomic Mass Evaluation (M. Wang et al., 2021) produce Q B - ( 133 Te)=2920(6) keV; however, the highest-lying 133 I level populated in this decay is observed at E i = 2935.83(15) keV, resulting in an anomalous Q$^i_B-$ = -16(6)keV. Our new measurements give Q B - ( 133 Te)=2934.8(11) keV, a factor of five more precise, yielding Q$^i_B$ = -1.0(12) keV, a 3σ shift from the previous results. This resolves this anomaly, but indicates further anomalies in our understanding of the structure of this isotope.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Investigating the effects of precise mass measurements of Ru and Pd isotopes on machine learning mass modeling

Atomic masses are a foundational quantity in our understanding of nuclear structure, astrophysics, and fundamental symmetries. The longstanding goal of creating a predictive global model for the binding energy of a nucleus remains a significant challenge, however, and prompts the need for precise measurements of atomic masses to serve as anchor points for model developments. We present precise mass measurements of neutron-rich Ru and Pd isotopes performed at the Californium Rare Isotope Breeder Upgrade facility at Argonne National Laboratory using the Canadian Penning Trap mass spectrometer. The masses of 108 Ru, 110 Ru, and 116 Pd were measured to a relative mass precision $\delta$⁢$m/m$ ≈ 10 -8 via the phase-imaging ion-cyclotron-resonance technique, and represent an improvement of approximately an order of magnitude over previous measurements. Further, these mass data were used in conjunction with the physically interpretable machine learning (PIML) model, which uses a mixture density neural network to model mass excesses via a mixture of Gaussian distributions. The effects of our new mass data on a Bayesian-updating of a PIML model are presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Improved Tensor Current Limit from 8 B 𝛽 Decay Including New Recoil-Order Calculations

A precision measurement of the 𝛽 + decay of 8 B was performed using the Beta-decay Paul Trap to determine the 𝛽−𝜈 angular correlation coefficient 𝑎 𝛽⁢𝜈 . The experimental results were combined with new ab initio symmetry-adapted no-core shell-model calculations to yield the second-most precise measurement from Gamow-Teller decays, 𝑎 𝛽⁢𝜈 = −0.3345 ± 0.001⁢9 stat ± 0.002⁢1 syst . This value agrees with the standard model value of −1/3 and improves uncertainties in 8 B by nearly a factor of 2. By combining results from 8 B and 8 Li , a tight limit on tensor current coupling to right-handed neutrinos was obtained. A recent global evaluation of all other precision 𝛽 decay studies suggested a nonzero value for right-handed neutrino coupling in contradiction with the standard model at just above 3⁢𝜎. Finally, the present results are of comparable sensitivity and do not support this finding.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Direct Mass Measurements to Inform the Behavior of 128m $\mathrm{Sb}$ in Nucleosynthetic Environments

Nuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The β-decaying isomer 128m Sb was identified as potentially impactful since the β-decay pathway along the A = 128 isobar funnels into this state bypassing the ground state. Here we report the first direct mass measurements of the 128 Sb isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25) keV and -84608.8(21) keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of 128m Sb in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Determination of the $^8\mathrm{B}$ neutrino energy spectrum using trapped ions

We report the β + decay of 8 B provides the dominant source of solar neutrinos above 2 MeV. Consequently, experiments that detect neutrinos from the sun require an accurate determination of the 8 B neutrino energy spectrum. In this work, the β -decay Paul trap surrounded by double-sided silicon strip detectors was utilized to precisely measure the decay products of trapped 8 B ions. The results were used to determine the 8 Be final-state distribution and to reconstruct the neutrino energy spectrum. This measurement using trapped ions is the first of its kind and puts the neutrino energy spectrum on much firmer footing by discriminating between recently reported values for the maximum of the final-state distribution.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Precise $\textit{Q}$-value measurements of 112,113 Ag and 115 Cd with the Canadian Penning trap for evaluation of potential ultralow $\textit{Q}$-value $\textit{β}$ decays

Background: An ultralow $\textit{Q}$-value $\textit{β}$ decay can occur from a parent nuclide to an excited nuclear state in the daughter such that $Q_{\text{UL}}$ 1 keV. These decay processes are of interest for nuclear $\textit{β}$-decay theory and as potential candidates in neutrino mass determination experiments. To date, only one ultralow $\textit{Q}$-value $\textit{β}$ decay has been observed—that of 115 In with $Q_β$ = 147(10) eV. A number of other potential candidates exist, but improved mass measurements are necessary to determine if these decay channels are energetically allowed and, in fact, ultralow. Purpose: To perform precise $\textit{β}$-decay $\textit{Q}$-value measurements of 112,113 Ag and 115 Cd and to use them in combination with nuclear energy level data for the daughter isotopes 112,113 Cd and 115 In to determine if the potential ultralow $\textit{Q}$-value $\textit{β}$-decay branches of 112,113 Ag and 115 Cd are energetically allowed and 1 keV. Method: The Canadian Penning Trap at Argonne National Laboratory was used to measure the cyclotron frequency ratios of singly charged 112,113 Ag and 115 Cd ions with respect to their daughters 112,113 Cd and 115 In. From these measurements, the ground-state to ground-state $\textit{β}$-decay $\textit{Q}$ values were obtained. Results: The 112 Ag → 112 Cd, 113 Ag → 113 Cd, and 115 Cd → 115 In $\textit{β}$-decay $\textit{Q}$ values were measured to be $Q_β$( 112 Ag) = 3990.16(22) keV, $Q_β$( 113 Ag) = 2085.7(4.6) keV, and $Q_β$( 115 Cd) = 1451.36(34) keV. These results were compared to energies of excited states in 112 Cd at 3997.75(14) keV, 113 Cd at 2015.6(2.5) and 2080(10) keV, and 115 In at 1448.787(9) keV, resulting in precise $Q_{\text{UL}}$ values for the potential decay channels of –7.59(26) keV, 6(11) keV, and 2.57(34) keV, respectively. Conclusion: The potential ultralow $\textit{Q}$-value decays of 112 Ag and 115 Cd have been ruled out. 113 Ag is still a possible candidate until a more precise measurement of the 2080(10) keV, 1/2+ state of 113 Cd is available. In the course of this work we have found the ground state mass of 113 Ag reported in the 2020 Atomic Mass Evaluation [Wang et al., Chin. Phys. C 45, 030003 (2021)] to be lower than our measurement by 69(17) keV (a 4σ discrepancy).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Improved Limit on Tensor Currents in the Weak Interaction from Li 8 β Decay

Here, the electroweak interaction in the standard model is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this Letter, we present the most precise measurement of tensor currents in the low-energy regime by examining the $β-\bar{ν}$ correlation of trapped 8 Li ions with the Beta-decay Paul Trap. We find $a_{β\barν}$ = - 0.3325 ± 0.0013 stat ± 0.0019 syst at 1σ for the case of coupling to right-handed neutrinos (C T = -C$^{'}_{T}$), which is consistent with the standard model prediction.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Searching for the origin of the rare-earth peak with precision mass measurements across Ce–Eu isotopic chains

A nuclear mass survey of rare-earth isotopes has been conducted with the Canadian Penning Trap mass spectrometer using the most neutron-rich nuclei thus far extracted from the CARIBU facility. Here, we present a collection of 12 nuclear masses determined with a precision of ≤ 10 keV/c 2 for Z = 58-63 nuclei near N = 100. Independently, a detailed study exploring the role of nuclear masses in the formation of the r-process rare-earth abundance peak has been performed. Employing a Markov chain Monte Carlo (MCMC) technique, mass predictions of lanthanide isotopes have been made which uniquely reproduce the observed solar abundances near A = 164 under three distinct astrophysical outflow conditions. We demonstrate that the mass surface trends thus far mapped out by our measurements are most consistent with MCMC mass predictions given an r process that forms the rare-earth peak during an extended (n, γ) ⇌ (γ, n) equilibrium.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Few-femtosecond resolved imaging of laser-driven nanoplasma expansion

Abstract The free expansion of a planar plasma surface is a fundamental non-equilibrium process relevant for various fields but as-yet experimentally still difficult to capture. The significance of the associated spatiotemporal plasma motion ranges from astrophysics and controlled fusion to laser machining, surface high-harmonic generation, plasma mirrors, and laser-driven particle acceleration. Here, we show that x-ray coherent diffractive imaging can surpass existing approaches and enables the quantitative real-time analysis of the sudden free expansion of laser-heated nanoplasmas. For laser-ionized SiO 2 nanospheres, we resolve the formation of the emerging nearly self-similar plasma profile evolution and expose the so far inaccessible shell-wise expansion dynamics including the associated startup delay and rarefaction front velocity. Our results establish time-resolved diffractive imaging as an accurate quantitative diagnostic platform for tracing and characterizing plasma expansion and indicate the possibility to resolve various laser-driven processes including shock formation and wave-breaking phenomena with unprecedented resolution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Gaussian mixture model clustering algorithms for the analysis of high-precision mass measurements

The development of the phase-imaging ion-cyclotron resonance (PI-ICR) technique for use in Penning trap mass spectrometry (PTMS) increased the speed and precision with which PTMS experiments can be carried out. In PI-ICR, data sets of the locations of individual ion hits on a detector are created showing how ions cluster together into spots according to their cyclotron frequency. Ideal data sets would consist of a single, 2D-spherical spot with no other noise, but in practice data sets typically contain multiple spots, non-spherical spots, or significant noise, all of which can make determining the locations of spot centers non-trivial. A method for assigning groups of ions to their respective spots and determining the spot centers is therefore essential for further improving precision and confidence in PI-ICR experiments. Here, we present the class of Gaussian mixture model (GMM) clustering algorithms as an optimal solution. We show that on simulated PI-ICR data, several types of GMM clustering algorithms perform better than other clustering algorithms over a variety of typical scenarios encountered in PI-ICR. The mass spectra of 163Gd, 163 mGd, 162 Tb, and 162 mTb measured using PI-ICR at the Canadian Penning trap mass spectrometer were checked using GMMs, producing results that were in close agreement with the previously published values.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

High intensity x-ray interaction with a model bio-molecule system: double-core-hole states and fragmentation of formamide

Formamide, a simple model bio-molecule (HCONH 2 ), is irradiated with high intensity, ultrashort pulses from an x-ray free electron laser. Ionic fragments resulting from photoionization and subsequent decay processes are recorded, as well as the electronic signature of the different inner shell ionization events that can take place during the x-ray pulses. Additionally, the formation of double-core-hole states, where a second inner shell electron is removed before the first core hole has been refilled is observed in the electron spectra, recorded at all three sites (C, N, O) of the molecule. The individual ionization potentials are compared with results of ab initio calculations at different level of theory. Based on our results, future opportunities for advanced studies of inner-shell-induced electronic and nuclear dynamics are explored.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Spin-trap isomers in deformed, odd-odd nuclei in the light rare-earth region near $N=98$

Masses of neutron-rich, odd-odd Pm, Eu, and Tb nuclei near N = 98 were measured using the Canadian Penning Trap mass spectrometer at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility. High-resolution mass measurements yielded the discovery of spin-trap isomers at N = 97 in Tb 162 , and in the N = 99 isotones of Pm 160 and Tb 164 . Furthermore, no evidence of long-lived isomers were observed at N = 95 in Eu 158 , at N = 97 in Pm 158 , nor at N = 101 in Eu 164 and Tb 166 . Here, these experimental observations are compared to results from multiquasiparticle blocking calculations.

150 ≤ A ≤ 189↗
DOE OSTI2020

Possibility of 14 C cluster as a building block of medium-mass nuclei

The possibility of the 14 C cluster being a basic building block of medium-mass nuclei is discussed. Although α cluster structures have been widely discussed in the light N ≈ Z mass region, the neutron-to-proton ratio deviates from unity in the nuclei near β-stability line and in neutron-rich nuclei. Thus, more neutron-rich objects with N > Z could become the building blocks of cluster structures in such nuclei. The 14 C nucleus is strongly bound and can be regarded as such a candidate. In addition, the path to the lowest shell-model configuration at short relative distances is closed for the 14 C+ 14 C structure, contrary to the case of the 12 C+ 12 C structure; this allows an appreciable separation distance between the 14 C clusters. The recent development of the antisymmetrized quasicluster model (AQCM) allows us to utilize a j j-coupling shell-model wave function for each cluster in a simplified way. The AQCM results for the 14 C+ 14 C structure in 28 Mg are compared with the ones of cranked relativistic mean field (CRMF) calculations. Although theoretical frameworks of these two models are quite different, they give similar results for the nucleonic densities and rotational properties of the structure under investigation. The existence of a linear chain three- 14 C cluster structure in 42 Ar has also been predicted in AQCM. Furthermore, these results confirm the role of the 14 C cluster as a possible building block of cluster structures in medium-mass nuclei.

20 ≤ A ≤ 38↗