Detection system for neutron β decay correlations in the UCNB and Nab experiments

Broussard, L. J.; Zeck, B. A.; Adamek, Evan; Baeßler, S.; Birge, N.; Blatnik, M.; Bowman, J. D.; Brandt, Aaron; Brown, Michael; Burkhart, J.; Callahan, Nathan; Clayton, S. M.; Crawford, Christopher; Cude-Woods, C.; Currie, Scott; Dees, Eric; Ding, X.; Fomin, N.; Frlež, E.; Fry, J. R.; Gray, F.; Hasan, S.; Hickerson, K. P.; Hoagland, J.; Holley, A. T.; Ito, T. M.; Klein, A.; Li, H.; Liu, C.-Y.; Makela, M.; McGaughey, P. L.; Mirabal-Martinez, J.; Morris, C. L.; Ortiz, Joseph D.; Pattie, R. W.; Penttilä, S. I.; Plaster, B.; Počanić, D.; Ramsey, J.; Salas-Bacci, A.; Salvat, Daniel; Saunders, Alexander; Seestrom, S.J.; Sjue, Sky; Sprow, Aaron; Tang, Z.; Vogelaar, R. B.; VornDick, B.; Wang, ‪Zhehui; Wei, Wanchun; Wexler, J.; Wilburn, W. S.; Womack, Tanner L.; Young, A. R.

doi:10.1016/j.nima.2016.12.030

Cited by 14 publications

(8 citation statements)

References 67 publications

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“…This was the first production UCN source based on superthermal UCN production. As the only operational UCN source in the US and as one of the two multi-experiment UCN facilities in the world (along with the ILL turbine source), it has provided UCN to various experiments including the UCNA [16][17][18][19][20], UCNB [32], and UCNτ [14] experiments as well as development efforts for the nEDM and Nab experiments at SNS [32,33].…”

mentioning

confidence: 99%

Performance of the upgraded ultracold neutron source at Los Alamos National Laboratory and its implication for a possible neutron electric dipole moment experiment

Ito¹,

Adamek²,

Callahan³

et al. 2018

Phys. Rev. C

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The ultracold neutron (UCN) source at Los Alamos National Laboratory (LANL), which uses solid deuterium as the UCN converter and is driven by accelerator spallation neutrons, has been successfully operated for over 10 years, providing UCN to various experiments, as the first production UCN source based on the superthermal process. It has recently undergone a major upgrade. This paper describes the design and performance of the upgraded LANL UCN source. Measurements of the cold neutron spectrum and UCN density are presented and compared to Monte Carlo predictions. The source is shown to perform as modeled. The UCN density measured at the exit of the biological shield was 184(32) UCN/cm 3 , a four-fold increase from the highest previously reported. The polarized UCN density stored in an external chamber was measured to be 39(7) UCN/cm 3 , which is sufficient to perform an experiment to search for the nonzero neutron electric dipole moment with a one-standard-deviation sensitivity of σ(dn) = 3 × 10 −27 e·cm.

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mentioning

confidence: 99%

Performance of the upgraded ultracold neutron source at Los Alamos National Laboratory and its implication for a possible neutron electric dipole moment experiment

Ito¹,

Adamek²,

Callahan³

et al. 2018

Phys. Rev. C

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“…Electron backscattering and energy reconstruction has been studied within the collaboration, and remains an important topic of continued study. The initial characterization of the detectors at the Triangle Universities Nuclear Laboratory (TUNL) proton accelerator showed a dead layer of 100 nm and a resolution near 3 kV [23,24], meeting the needs of the Nab experiment. Another recent update of the Nab detectors and electronics can be found here [25].…”

Section: Measurement Principlesmentioning

confidence: 99%

The Nab experiment: A precision measurement of unpolarized neutron beta decay

et al. 2019

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Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axialvector to vector coupling constants in the standard model, λ = g A /g V , through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter a with a precision of δa/a = 10 −3 and the Fierz interference term b to δb = 3 × 10 −3 in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio λ with a precision of δλ/λ = 0.03% that will allow an evaluation of V ud and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects. *

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“…Central to the success of the experiment is the detection system, which must directly detect both the proton and electron in coincidence with excellent timing and energy resolution. The specified performance, in particular 40 ns rise times of the recorded waveforms and 3 keV full-width halfmaximum energy resolution, has been demonstrated using thick, large area, highly segmented silicon detectors and a 24 channel prototype preamplification system, including coincidence detection of neutron decay protons and electrons [8,9]. The detectors, electronics, and data acquisition system for the upper detection system in Nab will be floated to a potential of −30 kV to boost the proton's energy so that it can penetrate past the 100 nm thick dead layer of the silicon.…”

Section: The Nab Experiments Overviewmentioning

confidence: 99%

“…A −30 kV accelerating potential is sufficient to achieve an uncertainty of <100 ppm/keV. The dead layer can vary due to residual gas cryopumping on the detector as observed in [9] but this effect is negligible in Nab with the high vacuum achieved in spectrometer tests of 5 × 10 −10 Torr. The uniformity of the dead layer and the actual trigger efficiency for protons will be studied using a proton source [11].…”

Section: Systematics In Detectionmentioning

confidence: 99%

Using Nab to determine correlations in unpolarized neutron decay

et al. 2018

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The Nab experiment will measure the ratio of the weak axial-vector and vector coupling constants λ = g A /g V with precision δλ/λ ∼ 3 × 10 −4 and search for a Fierz term b F at a level ∆b F < 10 −3 . The Nab detection system uses thick, large area, segmented silicon detectors to very precisely determine the decay proton's time of flight and the decay electron's energy in coincidence and reconstruct the correlation between the antineutrino and electron momenta. Excellent understanding of systematic effects affecting timing and energy reconstruction using this detection system are required. To explore these effects, a series of ex situ studies have been undertaken, including a search for a Fierz term at a less sensitive level of ∆b F < 10 −2 in the beta decay of 45 Ca using the UCNA spectrometer.

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Detection system for neutron β decay correlations in the UCNB and Nab experiments

Cited by 14 publications

References 67 publications

Performance of the upgraded ultracold neutron source at Los Alamos National Laboratory and its implication for a possible neutron electric dipole moment experiment

Performance of the upgraded ultracold neutron source at Los Alamos National Laboratory and its implication for a possible neutron electric dipole moment experiment

The Nab experiment: A precision measurement of unpolarized neutron beta decay

Using Nab to determine correlations in unpolarized neutron decay

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