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Browsing by Author "Young, A. R."

Now showing 1 - 7 of 7
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    Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons
    Liu, J.; Mendenhall, M. P.; Holley, A. T.; Back, H. O.; Bowles, T. J.; Broussard, L. J.; Carr, Rachel E.; Clayton, S.; Currie, S.; Filippone, B. W.; Garcia, A.; Geltenbort, P.; Hickerson, K. P.; Hoagland, J.; Hogan, G. E.; Hona, B.; Ito, T. M.; Liu, C. Y.; Makela, M.; Mammei, R. R.; Martin, J. W.; Melconian, D.; Morris, C. L.; Pattie, R. W.; Galvan, A. P.; Pitt, M. L.; Plaster, B.; Ramsey, J. C.; Rios, R.; Russell, R.; Saunders, A.; Seestrom, S. J.; Sondheim, W. E.; Tatar, E.; Vogelaar, R. Bruce; VornDick, B.; Wrede, C.; Yan, H.; Young, A. R.; Ucna Collaboration (American Physical Society, 2010-10-29)
    A precise measurement of the neutron decay beta asymmetry A(0) has been carried out using polarized ultracold neutrons from the pulsed spallation ultracold neutron source at the Los Alamos Neutron Science Center. Combining data obtained in 2008 and 2009, we report A(0) = -0.119 66 +/- 0.000 89(-0.001 40)(+0.001 23), from which we determine the ratio of the axial- vector to vector weak coupling of the nucleon gA/gV = -1.275 90(-0.004 45)(+0.004 09).
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    First Measurement of the Neutron beta Asymmetry with Ultracold Neutrons
    Pattie, R. W.; Anaya, J.; Back, H. O.; Boissevain, J. G.; Bowles, T. J.; Broussard, L. J.; Carr, Rachel E.; Clark, D. J.; Currie, S.; Du, S.; Filippone, B. W.; Geltenbort, P.; Garcia, A.; Hawari, A.; Hickerson, K. P.; Hill, R.; Hino, M.; Hoedl, S. A.; Hogan, G. E.; Holley, A. T.; Ito, T. M.; Kawai, T.; Kirch, K.; Kitagaki, S.; Lamoreaux, S. K.; Liu, C. Y.; Liu, J.; Makela, M.; Mammei, R. R.; Martin, J. W.; Melconian, D.; Meier, N.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R.; Pichlmaier, A.; Pitt, M. L.; Plaster, B.; Ramsey, J. C.; Rios, R.; Sabourov, K.; Sallaska, A. L.; Saunders, A.; Schmid, R.; Seestrom, S. J.; Servicky, C.; Sjue, S. K. L.; Smith, D.; Sondheim, W. E.; Tatar, E.; Teasdale, W.; Terai, C.; Tipton, B.; Utsuro, M.; Vogelaar, R. Bruce; Wehring, B. W.; Xu, Y. P.; Young, A. R.; Yuan, J.; Ucna Collaboration (American Physical Society, 2009-01-09)
    We report the first measurement of an angular correlation parameter in neutron beta decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for similar to 30 s in a Cu decay volume. The interaction of the neutron magnetic dipole moment with a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage spin flipper and enter a decay volume, situated within a 1 T field in a 2 x 2 pi solenoidal spectrometer. We determine a value for the beta-asymmetry parameter A(0) = -0.1138 +/- 0.0046 +/- 0.0021.
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    A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment
    Holley, A. T.; Broussard, L. J.; Davis, J. L.; Hickerson, K.; Ito, T. M.; Liu, C. Y.; Lyles, J. T. M.; Makela, M.; Mammei, R. R.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R.; Pattie, R. W.; Rios, R.; Saunders, A.; Young, A. R. (AIP Publishing, 2012-07)
    The UCNA collaboration is making a precision measurement of the beta asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be (epsilon) over bar = 0.9985(4). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4732822]
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    Measurement of the neutron beta-asymmetry parameter A(0) with ultracold neutrons
    Plaster, B.; Rios, R.; Back, H. O.; Bowles, T. J.; Broussard, L. J.; Carr, Rachel E.; Clayton, S.; Currie, S.; Filippone, B. W.; Garcia, A.; Geltenbort, P.; Hickerson, K. P.; Hoagland, J.; Hogan, G. E.; Hona, B.; Holley, A. T.; Ito, T. M.; Liu, C. Y.; Liu, J.; Makela, M.; Mammei, R. R.; Martin, J. W.; Melconian, D.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R.; Pattie, R. W.; Galvan, A. P.; Pitt, M. L.; Ramsey, J. C.; Russell, R.; Saunders, A.; Schmid, R.; Seestrom, S. J.; Sjue, S.; Sondheim, W. E.; Tatar, E.; Tipton, B.; Vogelaar, R. Bruce; VornDick, B.; Wrede, C.; Xu, Y. P.; Yan, H.; Young, A. R.; Yuan, J.; Ucna Collaboration (American Physical Society, 2012-11-12)
    We present a detailed report of a measurement of the neutron beta-asymmetry parameter A(0), the parity-violating angular correlation between the neutron spin and the decay electron momentum, performed with polarized ultracold neutrons (UCN). UCN were extracted from a pulsed spallation solid deuterium source and polarized via transport through a 7-T magnetic field. The polarized UCN were then transported through an adiabatic-fast-passage spin-flipper field region, prior to storage in a cylindrical decay volume situated within a 1-T 2 x 2 pi solenoidal spectrometer. The asymmetry was extracted from measurements of the decay electrons in multiwire proportional chamber and plastic scintillator detector packages located on both ends of the spectrometer. From an analysis of data acquired during runs in 2008 and 2009, we report A(0) = -0.11966 +/- 0.00089(-0.00140)(+0.00123), from lambda = g(A)/g(V) = -1.27590 +/- 0.00239(-0.00377)(+0.00331). Complete details of the analysis are presented.
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    A new method for measuring the neutron lifetime using an in situ neutron detector
    Morris, C. L.; Adamek, E. R.; Broussard, L. J.; Callahan, N. B.; Clayton, S. M.; Cude-Woods, C.; Currie, S. A.; Ding, X.; Fox, W.; Hickerson, K. P.; Hoffbauer, M. A.; Holley, A. T.; Komives, A.; Liu, C. Y.; Makela, M.; Pattie, R. W., Jr.; Ramsey, J.; Salvat, D. J.; Saunders, A.; Seestrom, S. J.; Sharapov, E. I.; Sjue, S. K.; Tang, Z.; Vanderwerp, J.; Vogelaar, R. Bruce; Walstrom, P. L.; Wang, Z.; Wei, Wanchun; Wexler, J. W.; Womack, T. L.; Young, A. R.; Zeck, B. A. (2017-05)
    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. (C) 2017 Author(s).
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    Performance of the Los Alamos National Laboratory spallation-driven solid-deuterium ultra-cold neutron source
    Saunders, A.; Makela, M.; Bagdasarova, Y.; Back, H. O.; Boissevain, J. G.; Broussard, L. J.; Bowles, T. J.; Carr, Rachel E.; Currie, S. A.; Filippone, B. W.; Garcia, A.; Geltenbort, P.; Hickerson, K. P.; Hill, R. E.; Hoagland, J.; Hoedl, S. A.; Holley, A. T.; Hogan, G.; Ito, T. M.; Lamoreaux, Steve; Liu, Chen-Yu; Liu, J.; Mammei, R. R.; Martin, J.; Melconian, D.; Mendenhall, M. P.; Morris, C. L.; Mortensen, R. N.; Pattie, R. W., Jr.; Pitt, M.; Plaster, B.; Ramsey, J.; Rios, R.; Sallaska, A. L.; Seestrom, S. J.; Sharapov, E. I.; Sjue, S.; Sondheim, W. E.; Teasdale, W.; Young, A. R.; VornDick, B.; Vogelaar, R. Bruce; Wang, Z.; Xu, Yanping (AIP Publishing, 2013-01)
    In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the Monte Carlo code MCNPX and the UCN rates agree with our custom UCN Monte Carlo code. The source is shown to perform as modeled. The maximum delivered UCN density at the exit from the biological shield is 52(9) UCN/cc with a solid deuterium volume of similar to 1500 cm(3). (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770063]
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    Precision measurement of the neutron beta-decay asymmetry
    Mendenhall, M. P.; Pattie, R. W.; Bagdasarova, Y.; Berguno, D. B.; Broussard, L. J.; Carr, Rachel E.; Currie, S.; Ding, X.; Filippone, B. W.; Garcia, A.; Geltenbort, P.; Hickerson, K. P.; Hoagland, J.; Holley, A. T.; Hong, R.; Ito, T. M.; Knecht, A.; Liu, C. Y.; Liu, J. L.; Makela, M.; Mammei, R. R.; Martin, J. W.; Melconian, D.; Moore, S. D.; Morris, C. L.; Galvan, A. P.; Picker, R.; Pitt, M. L.; Plaster, B.; Ramsey, J. C.; Rios, R.; Saunders, A.; Seestrom, S. J.; Sharapov, E. I.; Sondheim, W. E.; Tatar, E.; Vogelaar, R. Bruce; VornDick, B.; Wrede, C.; Young, A. R.; Zeck, B. A.; Ucna Collaboration (American Physical Society, 2013-03-25)
    A new measurement of the neutron beta-decay asymmetry A(0) has been carried out by the UCNA Collaboration using polarized ultracold neutrons (UCNs) from the solid deuterium UCN source at the Los Alamos Neutron Science Center. Improvements in the experiment have led to reductions in both statistical and systematic uncertainties leading to A(0) = -0.11954(55)(stat)(98)(syst), corresponding to the ratio of axial-vector to vector coupling lambda = g(A)/g(V) = -1.2756(30).