A measurement of the neutron lifetime using the method of storage of ultracold neutrons and detection of inelastically up-scattered neutrons

Arzumanov, Sergei S.; Bondarenko, L. N.; Chernyavsky, S. M.; Geltenbort, P.; Морозов, В. И.; Nesvizhevsky, V. V.; Panin, Yu. N.; Strepetov, A. N.

doi:10.1016/j.physletb.2015.04.021

Cited by 125 publications

(141 citation statements)

References 21 publications

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“…Since our measured storage-time constants are significantly shorter than the neutron lifetime, the μ and η values are not altered significantly by a change of the neutron lifetime of several seconds [91][92][93][94][95].…”

Section: B the Wall Loss Parameter ηmentioning

confidence: 84%

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

et al. 2017

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At Institut Laue-Langevin (ILL) and Paul Scherrer Institute (PSI), we have measured the losses and depolarization probabilities of ultracold neutrons on various materials: (i) nickel-molybdenum alloys with weight percentages of 82/18, 85/15, 88/12, 91/9, and 94/6 and natural nickel Ni100, (ii) nickel-vanadium NiV93/7, (iii) copper, and (iv) deuterated polystyrene (dPS). For the different samples, storage-time constants up to ∼460 s were obtained at room temperature. The corresponding loss parameters for ultracold neutrons, η, varied between 1.0 × 10 −4 and 2.2 × 10 −4 . All η values are in agreement with theory except for dPS, where anomalous losses at room temperature were established with four standard deviations. The depolarization probabilities per wall collision β measured with unprecedented sensitivity varied between 0.7 × 10 −6 and 9.0 × 10 −6 . Our depolarization result for copper differs from other experiments by 4.4 and 15.8 standard deviations. The β values of the paramagnetic NiMo alloys over molybdenum content show an increase of β with increasing Mo content. This is in disagreement with expectations from literature. Finally, ferromagnetic behavior of NiMo alloys at room temperature was found for molybdenum contents of 6.5 at.% or less and paramagnetic behavior for more than 8.7 at.%. This may contribute to solving an ambiguity in literature.

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Section: B the Wall Loss Parameter ηmentioning

confidence: 84%

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

et al. 2017

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“…[43,44]. The diagonal bands are derived from neutron lifetime measurements and are separated into neutron beam [31,32] and UCN bottle experiments, which consist of material bottle storage [34][35][36][37][38] and magnetic bottle storage [33]. The V ud band (horizontal) comes from superallowed 0 + → 0 + nuclear β-decay measurements [39].…”

Section: Resultsmentioning

confidence: 99%

New result for the neutron β -asymmetry parameter A0 from UCNA

Brown¹,

Dees²,

Adamek³

et al. 2018

Phys. Rev. C

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Background:The neutron β-decay asymmetry parameter A 0 defines the angular correlation between the spin of the neutron and the momentum of the emitted electron. Values for A 0 permit an extraction of the ratio of the weak axial-vector to vector coupling constants, λ ≡ g A /g V , which under assumption of the conserved vector current hypothesis (g V = 1) determines g A . Precise values for g A are important as a benchmark for lattice QCD calculations and as a test of the standard model. Purpose: The UCNA experiment, carried out at the Ultracold Neutron (UCN) source at the Los Alamos Neutron Science Center, was the first measurement of any neutron β-decay angular correlation performed with UCN. This article reports the most precise result for A 0 obtained to date from the UCNA experiment, as a result of higher statistics and reduced key systematic uncertainties, including from the neutron polarization and the characterization of the electron detector response. Methods: UCN produced via the downscattering of moderated spallation neutrons in a solid deuterium crystal were polarized via transport through a 7 T polarizing magnet and a spin flipper, which permitted selection of either spin state. The UCN were then contained within a 3-m long cylindrical decay volume, situated along the central axis of a superconducting 1 T solenoidal spectrometer. With the neutron spins then oriented parallel or anti-parallel to the solenoidal field, an asymmetry in the numbers of emitted decay electrons detected in two electron detector packages located on both ends of the spectrometer permitted an extraction of A 0 .

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“…Its 1 s uncertainty is far greater than the 0.1 s sensitivity required for new physics searches, and is dominated by the ∼ 8 s discrepancy between the two methods. Although earlier experiments have been reanalyzed [73,74,75] since the present best resulted τ n = 878.5(8) s [76], the discrepancy could not yet be resolved. We note that the most precise 'magnetic storage' experiment [77] is not included in the PDG average.…”

Section: The Neutron Lifetime Puzzlementioning

confidence: 66%

Cold and Ultra-cold Neutrons as Probes of New Physics

Konrad¹,

Abele²

2017

Proceedings of the 26th International Nuclear Physics Conference — PoS(INPC2016)

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Despite the great success of the Standard Model, many key questions in particle physics, astrophysics, and cosmology are unanswered. In particular, more than 95 % of the universe consists of unknown dark matter and dark energy. Today, a major goal of particle physics is to look for evidence of new physics beyond the Standard Model. Collider searches for new physics are well suited to the direct production of new high-mass particles, whereas low-energy precision experiments search for traces that new particles leave in known processes. Direct and indirect evidence of new physics are highly complementary. High-precision experiments with extremely slow, cold and ultra-cold neutrons address some of the unanswered questions, for instance, on the nature of the fundamental forces and underlying symmetries, the origin, evolution, and fate of the universe, or on the nature of the gravitational force at very small distances. For example, the limit on the electric dipole moment of the neutron constrains the CP violating phases, the lifetime of the neutron determines the relative helium abundance in the universe, and neutrons bouncing over a mirror probe dark matter and dark energy. New facilities and technological developments now give window for significant improvement in precision by one to two orders of magnitude. In this paper, we will give an overview of current and planned facilities and experiments, as well as an overview of some of the applications of neutrons to astrophysics, cosmology, and physics beyond the Standard Model.

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A measurement of the neutron lifetime using the method of storage of ultracold neutrons and detection of inelastically up-scattered neutrons

Cited by 125 publications

References 21 publications

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

Losses and depolarization of ultracold neutrons on neutron guide and storage materials

New result for the neutron β -asymmetry parameter A0 from UCNA

Cold and Ultra-cold Neutrons as Probes of New Physics

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