@article{krivos_floyd_tang_morris_blatnik_clayton_cude-woods_holley_hooks_ito_et al._2024, title={Cerium doped yttrium aluminum perovskite scintillator as an absolute ultracold neutron detector}, volume={95}, ISSN={["1089-7623"]}, DOI={10.1063/5.0211059}, abstractNote={The upcoming UCNProBe experiment at Los Alamos National Laboratory will measure the beta decay rate of free neutrons with different systematic uncertainties than previous beam-based neutron lifetime experiments. We have tested a new 10B-coated Yttrium Aluminum Perovskite (YAP:Ce) scintillator and present its properties. The advantages of the YAP:Ce scintillator include its high Fermi potential, which reduces the probability for upscattering of ultracold neutrons (UCN), and its short decay time, which increases sensitivity at high counting rates. Birks’ coefficient of YAP:Ce was measured to be (5.56−0.30+0.05)×10−4 cm/MeV. The loss of light due to the 120 nm 10B-coating was measured to be about 60%, and the loss of light from YAP:Ce due to transmission through a deuterated polystyrene scintillator was about 50%. The efficiency for neutron capture on the 10B coating was (86.8 ± 2.6)%, and a measurement using UCN showed that the YAP:Ce crystal counted 8%–28% more UCN compared to a ZnS:Ag screen. The difference may be due to the uneven coating of 10B on the rough surface of ZnS:Ag.}, number={10}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, author={Krivos, M. and Floyd, N. C. and Tang, Z. and Morris, C. L. and Blatnik, M. and Clayton, S. M. and Cude-Woods, C. B. and Holley, A. T. and Hooks, D. E. and Ito, T. M. and et al.}, year={2024}, month={Oct} }
 @article{floyd_hassan_krivos_blatnik_cude-woods_clayton_holley_ito_johnson_liu_et al._2024, title={Scintillation characteristics of the EJ-299-02H scintillator}, volume={95}, ISSN={["1089-7623"]}, DOI={10.1063/5.0179451}, abstractNote={A study of the dead layer thickness and quenching factor of a plastic scintillator for use in ultracold neutron (UCN) experiments is described. Alpha spectroscopy was used to determine the thickness of a thin surface dead layer to be 630 ± 110 nm. The relative light outputs from the decay of 241Am and Compton scattering of electrons were used to extract Birks’ law coefficient, yielding a kB value of 0.087 ± 0.003 mm/MeV, consistent with some previous reports for other polystyrene-based scintillators. The results from these measurements are incorporated into the simulation to show that an energy threshold of (∼9 keV) can be achieved for the UCNProBe experiment. This low threshold enables high beta particle detection efficiency and the indirect measurement of UCN. The ability to make the scintillator deuterated, accompanied by its relatively thin dead layer, gives rise to unique applications in a wide range of UCN experiments, where it can be used to trap UCN and detect charged particles in situ.}, number={4}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, author={Floyd, N. and Hassan, Md. T. and Krivos, M. and Blatnik, M. and Cude-Woods, C. and Clayton, S. M. and Holley, A. T. and Ito, T. M. and Johnson, B. A. and Liu, C. -y. and et al.}, year={2024}, month={Apr} }
 @article{wong_hassan_burdine_chupp_clayton_cude-woods_currie_ito_liu_makela_et al._2023, title={Characterization of the new Ultracold Neutron beamline at the LANL UCN facility}, volume={1050}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2023.168105}, abstractNote={The neutron electric dipole moment (nEDM) experiment that is currently being developed at Los Alamos National Laboratory (LANL) will use ultracold neutrons (UCN) and Ramsey’s method of separated oscillatory fields to search for a nEDM. In this paper, we present measurements of UCN storage and UCN transport performed during the commissioning of a new beamline at the LANL UCN source and demonstrate a sufficient number of stored polarized UCN to achieve a statistical uncertainty of δdn=2×10−27 e cm in 5 calendar years of running. We also present an analytical model describing data that provides a simple parameterization of the input UCN energy spectrum on the new beamline.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Wong, D. K. -T. and Hassan, M. T. and Burdine, J. F. and Chupp, T. E. and Clayton, S. M. and Cude-Woods, C. and Currie, S. A. and Ito, T. M. and Liu, C. -Y. and Makela, M. and et al.}, year={2023}, month={May} }
 @article{lin_baldwin_blatnik_clayton_cude-woods_currie_filippone_fries_geltenbort_holley_et al._2023, title={Demonstration of sub-micron UCN position resolution using room-temperature CMOS sensor}, volume={1057}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2023.168769}, abstractNote={High spatial resolution of ultracold neutron (UCN) measurement is of growing interest to UCN experiments such as UCN spectrometers, UCN polarimeters, quantum physics of UCNs, and quantum gravity. Here we utilize physics-informed deep learning to enhance the experimental position resolution and to demonstrate sub-micron spatial resolutions for UCN position measurements obtained using a room-temperature CMOS sensor, extending our previous work (Kuk et al., 2021; Yue et al., 2023[2]) that demonstrated a position uncertainty of 1.5μm. We explore the use of the open-source software Allpix Squared to generate experiment-like synthetic hit images with ground-truth position labels. We use physics-informed deep learning by training a fully-connected neural network (FCNN) to learn a mapping from input hit images to output hit position. The automated analysis for sub-micron position resolution in UCN detection combined with the fast data rates of current and next generation UCN sources will enable improved precision for future UCN research and applications.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Lin, S. and Baldwin, J. K. and Blatnik, M. and Clayton, S. M. and Cude-Woods, C. and Currie, S. A. and Filippone, B. and Fries, E. M. and Geltenbort, P. and Holley, A. T. and et al.}, year={2023}, month={Dec} }
 @article{cude-woods_gonzalez_fries_bailey_blatnik_callahan_choi_clayton_currie_dawid_et al._2022, title={Fill and dump measurement of the neutron lifetime using an asymmetric magneto-gravitational trap}, volume={106}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.106.065506}, abstractNote={The past two decades have yielded several new measurements and reanalyses of older measurements of the neutron lifetime. These have led to a 4.4 standard deviation discrepancy between the most precise measurements of the neutron decay rate producing protons in cold neutron beams and the lifetime measured in neutron storage experiments. Measurements using different techniques are important for investigating whether there are unidentified systematic effects in any of the measurements . In this paper we report a new measurement using the Los Alamos asymmetric magneto-gravitational trap where the surviving neutrons are counted external to the trap using the fill and dump method. The new measurement gives a free neutron lifetime of Although this measurement is not as precise, it is in statistical agreement with previous results using in situ counting in the same apparatus.}, number={6}, journal={PHYSICAL REVIEW C}, author={Cude-Woods, C. and Gonzalez, F. M. and Fries, E. M. and Bailey, T. and Blatnik, M. and Callahan, N. B. and Choi, J. H. and Clayton, S. M. and Currie, S. A. and Dawid, M. and et al.}, year={2022}, month={Dec} }
 @article{gonzalez_fries_cude-woods_bailey_blatnik_broussard_callahan_choi_clayton_currie_et al._2021, title={Improved Neutron Lifetime Measurement with UCN τ}, volume={127}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.127.162501}, abstractNote={We report an improved measurement of the free neutron lifetime τ_{n} using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38×10^{6} surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ_{n} from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ_{n} measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ_{n}=877.75±0.28_{stat}+0.22/-0.16_{syst}  s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.}, number={16}, journal={PHYSICAL REVIEW LETTERS}, author={Gonzalez, F. M. and Fries, E. M. and Cude-Woods, C. and Bailey, T. and Blatnik, M. and Broussard, L. J. and Callahan, N. B. and Choi, J. H. and Clayton, S. M. and Currie, S. A. and et al.}, year={2021}, month={Oct}, pages={162501} }
 @article{kuk_cude-woods_chavez_choi_estrada_hoffbauer_holland_makela_morris_ramberg_et al._2021, title={Projection imaging with ultracold neutrons}, volume={1003}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2021.165306}, abstractNote={Ultracold neutron (UCN) projection imaging is demonstrated using a boron-coated back-illuminated CCD camera and the Los Alamos UCN source. Each neutron is recorded through the capture reactions with 10B. By direct detection at least one of the byproducts α, 7Li and γ (electron recoils) derived from the neutron capture and reduction of thermal noise of the scientific CCD camera, a signal-to-noise improvement on the order of 104 over the indirect detection has been achieved. Sub-pixel position resolution of a few microns is confirmed for individual UCN events. Projection imaging of test objects shows a spatial resolution less than 100μm by an integrated UCN flux one the order of 106 cm−2. The bCCD can be used to build UCN detectors with an area on the order of 1 m2. The combination of micrometer scale spatial resolution, low readout noise of a few electrons, and large area makes bCCD suitable for quantum science of UCN.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Kuk, K. and Cude-Woods, C. and Chavez, C. R. and Choi, J. H. and Estrada, J. and Hoffbauer, M. and Holland, S. E. and Makela, M. and Morris, C. L. and Ramberg, E. and et al.}, year={2021}, month={Jul} }
 @article{tang_watkins_clayton_currie_fellers_hassan_hooks_ito_lawrence_macdonald_et al._2021, title={Ultracold neutron properties of the Eljen-299-02D deuterated scintillator}, volume={92}, ISSN={["1089-7623"]}, DOI={10.1063/5.0030972}, abstractNote={In this paper, we report studies of the Fermi potential and loss per bounce of ultracold neutrons (UCNs) on a deuterated scintillator (Eljen-299-02D). These UCN properties of the scintillator enable its use in a wide variety of applications in fundamental neutron research.}, number={2}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, author={Tang, Z. and Watkins, E. B. and Clayton, S. M. and Currie, S. A. and Fellers, D. E. and Hassan, Md T. and Hooks, D. E. and Ito, T. M. and Lawrence, S. K. and MacDonald, S. W. T. and et al.}, year={2021}, month={Feb} }
 @article{sun_adamek_allgeier_bagdasarova_berguno_blatnik_bowles_broussard_brown_carr_et al._2020, title={Improved limits on Fierz interference using asymmetry measurements from the Ultracold Neutron Asymmetry (UCNA) experiment}, volume={101}, ISSN={2469-9985 2469-9993}, url={http://dx.doi.org/10.1103/PhysRevC.101.035503}, DOI={10.1103/PhysRevC.101.035503}, abstractNote={The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the β-decay asymmetry parameter, A₀, for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their β-decay electrons are detected with ≈4π acceptance into two detector packages which provide position and energy reconstruction. The experiment also has sensitivity to b_n, the Fierz interference term in the neutron β-decay rate. In this work, we determine b_n from the energy dependence of A₀ using the data taken during the UCNA 2011-2013 run. In addition, we present the same type of analysis using the earlier 2010 A dataset. Motivated by improved statistics and comparable systematic errors compared to the 2010 data-taking run, we present a new b_n measurement using the weighted average of our asymmetry dataset fits, to obtain b_n = 0.066±0.041_(stat)±0.024_(syst) which corresponds to a limit of −0.012 < b_n < 0.144 at the 90% confidence level.}, number={3}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Sun, X. and Adamek, E. and Allgeier, B. and Bagdasarova, Y. and Berguno, D. B. and Blatnik, M. and Bowles, T. J. and Broussard, L. J. and Brown, M. A.-P. and Carr, R. and et al.}, year={2020}, month={Mar} }
 @article{callahan_liu_gonzalez_adamek_bowman_broussard_clayton_currie_cude-woods_dees_et al._2019, title={Monte Carlo simulations of trapped ultracold neutrons in the UCNτ experiment}, volume={100}, ISSN={2469-9985 2469-9993}, url={http://dx.doi.org/10.1103/PhysRevC.100.015501}, DOI={10.1103/PhysRevC.100.015501}, abstractNote={In the UCN{\tau} experiment, ultracold neutrons (UCN) are confined by magnetic fields and the Earth's gravitational field. Field-trapping mitigates the problem of UCN loss on material surfaces, which caused the largest correction in prior neutron experiments using material bottles. However, the neutron dynamics in field traps differ qualitatively from those in material bottles. In the latter case, neutrons bounce off material surfaces with significant diffusivity and the population quickly reaches a static spatial distribution with a density gradient induced by the gravitational potential. In contrast, the field-confined UCN -- whose dynamics can be described by Hamiltonian mechanics -- do not exhibit the stochastic behaviors typical of an ideal gas model as observed in material bottles. In this report, we will describe our efforts to simulate UCN trapping in the UCN{\tau} magneto-gravitational trap. We compare the simulation output to the experimental results to determine the parameters of the neutron detector and the input neutron distribution. The tuned model is then used to understand the phase space evolution of neutrons observed in the UCN{\tau} experiment. We will discuss the implications of chaotic dynamics on controlling the systematic effects, such as spectral cleaning and microphonic heating, for a successful UCN lifetime experiment to reach a 0.01% level of precision.}, number={1}, journal={Physical Review C}, publisher={American Physical Society (APS)}, author={Callahan, Nathan and Liu, Chen-Yu and Gonzalez, Francisco and Adamek, E. and Bowman, J. D. and Broussard, L. and Clayton, S. M. and Currie, S. and Cude-Woods, C. and Dees, E. B. and et al.}, year={2019}, month={Jul} }
 @article{anghel_bailey_bison_blau_broussard_clayton_cude-woods_daum_hawari_hild_et al._2018, title={Solid deuterium surface degradation at ultracold neutron sources}, volume={54}, ISSN={1434-6001 1434-601X}, url={http://dx.doi.org/10.1140/epja/i2018-12594-2}, DOI={10.1140/epja/i2018-12594-2}, abstractNote={Solid deuterium (sD_2) is used as an efficient converter to produce ultracold neutrons (UCN). It is known that the sD_2 must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in the solid from which they are extracted into vacuum. Also the UCN transparency of the bulk sD_2 material must be high because crystal inhomogeneities limit the mean free path for elastic scattering and reduce the extraction efficiency. Observations at the UCN sources at Paul Scherrer Institute and at Los Alamos National Laboratory consistently show a decrease of the UCN yield with time of operation after initial preparation or later treatment (`conditioning') of the sD_2. We show that, in addition to the quality of the bulk sD_2, the quality of its surface is essential. Our observations and simulations support the view that the surface is deteriorating due to a build-up of D_2 frost-layers under pulsed operation which leads to strong albedo reflections of UCN and subsequent loss. We report results of UCN yield measurements, temperature and pressure behavior of deuterium during source operation and conditioning, and UCN transport simulations. This, together with optical observations of sD_2 frost formation on initially transparent sD_2 in offline studies with pulsed heat input at the North Carolina State University UCN source results in a consistent description of the UCN yield decrease.}, number={9}, journal={The European Physical Journal A}, publisher={Springer Nature}, author={Anghel, A. and Bailey, T. L. and Bison, G. and Blau, B. and Broussard, L. J. and Clayton, S. M. and Cude-Woods, C. and Daum, M. and Hawari, A. and Hild, N. and et al.}, year={2018}, month={Sep} }
 @article{morris_adamek_broussard_callahan_clayton_cude-woods_currie_ding_fox_hickerson_et al._2017, title={A new method for measuring the neutron lifetime using an in situ neutron detector}, volume={88}, ISSN={1089-7623}, url={http://dx.doi.org/10.1063/1.4983578}, DOI={10.1063/1.4983578}, abstractNote={In this paper, we describe a new method for measuring surviving neutrons in neutron lifetime measurements using bottled ultracold neutrons (UCN), which provides better characterization of systematic uncertainties and enables higher precision than previous measurement techniques. An active detector that can be lowered into the trap has been used to measure the neutron distribution as a function of height and measure the influence of marginally trapped UCN on the neutron lifetime measurement. In addition, measurements have demonstrated phase-space evolution and its effect on the lifetime measurement.}, number={5}, journal={REVIEW OF SCIENTIFIC INSTRUMENTS}, publisher={AIP Publishing}, author={Morris, C. L. and Adamek, E. R. and Broussard, L. J. and Callahan, N. B. and Clayton, S. M. and Cude-Woods, C. and Currie, S. A. and Ding, X. and Fox, W. and Hickerson, K. P. and et al.}, year={2017}, month={May}, pages={053508} }
 @article{pattie_adamek_brenner_brandt_broussard_callahan_clayton_cude-woods_currie_geltenbort_et al._2017, title={Evaluation of commercial nickel-phosphorus coating for ultracold neutron guides using a pinhole bottling method}, volume={872}, ISSN={1872-9576}, DOI={10.1016/j.nima.2017.07.051}, abstractNote={We report on the evaluation of commercial electroless nickel phosphorus (NiP) coatings for ultracold neutron (UCN) transport and storage. The material potential of 50~$\mu$m thick NiP coatings on stainless steel and aluminum substrates was measured to be $V_F = 213(5.2)$~neV using the time-of-flight spectrometer ASTERIX at the Lujan Center. The loss per bounce probability was measured in pinhole bottling experiments carried out at ultracold neutron sources at Los Alamos Neutron Science Center and the Institut Laue-Langevin. For these tests a new guide coupling design was used to minimize gaps between the guide sections. The observed UCN loss in the bottle was interpreted in terms of an energy independent effective loss per bounce, which is the appropriate model when gaps in the system and upscattering are the dominate loss mechanisms, yielding a loss per bounce of $1.3(1) \times 10^{-4}$. We also present a detailed discussion of the pinhole bottling methodology and an energy dependent analysis of the experimental results.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Pattie, R. W., Jr. and Adamek, E. R. and Brenner, T. and Brandt, A. and Broussard, L. J. and Callahan, N. B. and Clayton, S. M. and Cude-Woods, C. and Currie, S. A. and Geltenbort, P. and et al.}, year={2017}, month={Nov}, pages={64–73} }
 @article{wei_broussard_hoffbauer_makela_morris_tang_adamek_callahan_clayton_cude-woods_et al._2016, title={Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy}, volume={830}, ISSN={0168-9002}, url={http://dx.doi.org/10.1016/j.nima.2016.05.058}, DOI={10.1016/j.nima.2016.05.058}, abstractNote={Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15 $\mu$m has been achieved, which is equivalent to an UCN energy resolution below 2 pico-electron-volts through the relation $\delta E = m_0g \delta x$. Here, the symbols $\delta E$, $\delta x$, $m_0$ and $g$ are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. This method allows different types of UCN spectroscopy and other applications.}, journal={Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, publisher={Elsevier BV}, author={Wei, Wanchun and Broussard, L.J. and Hoffbauer, M.A. and Makela, M. and Morris, C.L. and Tang, Z. and Adamek, E.R. and Callahan, N.B. and Clayton, S.M. and Cude-Woods, C. and et al.}, year={2016}, month={Sep}, pages={36–43} }
 @article{wang_hoffbauer_morris_callahan_adamek_bacon_blatnik_brandt_broussard_clayton_et al._2015, title={A multilayer surface detector for ultracold neutrons}, volume={798}, DOI={10.1016/j.nima.2015.07.010}, abstractNote={A multilayer surface detector for ultracold neutrons (UCNs) is described. The top $^{10}$B layer is exposed to the vacuum chamber and directly captures UCNs. The ZnS:Ag layer beneath the $^{10}$B layer is a few microns thick, which is sufficient to detect the charged particles from the $^{10}$B(n,$\alpha$)$^7$Li neutron-capture reaction, while thin enough so that ample light due to $\alpha$ and $^7$Li escapes for detection by photomultiplier tubes. One-hundred-nm thick $^{10}$B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials and others. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparisons with other existing $^3$He and $^{10}$B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.}, journal={Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors, and Associated Equipment}, author={Wang, Z. H. and Hoffbauer, M. A. and Morris, C. L. and Callahan, N. B. and Adamek, E. R. and Bacon, J. D. and Blatnik, M. and Brandt, A. E. and Broussard, L. J. and Clayton, S. M. and et al.}, year={2015}, pages={30–35} }