Development of a Precision Neutron Lifetime Measurement PDF Download

Author: Christopher Martin O'Shaughnessy
Publisher:
ISBN:
Category :
Languages : en
Pages : 161

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Author: Liang Yang
Publisher:
ISBN:
Category : Magnetic traps
Languages : en
Pages : 432

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Author: Susan J Seestrom
Publisher: World Scientific
ISBN: 9814571687
Category : Science
Languages : en
Pages : 193

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There is a great interest in improving the limits on neutron lifetime to the level of a precision of 0.1 s. The neutron lifetime is both an important fundamental quantity as well as a parameter influencing important processes such as nucleosynthesis (Helium production in the early universe) and the rate of energy production in the Sun.Aiming to create a roadmap of R&D for a next generation neutron lifetime experiment that can be endorsed by the North American neutron community, the focus of the workshop was on experiments using traps that utilize ultracold neutrons and confinement by a combination of magnetic and/or gravitational interaction in order to avoid systematic uncertainties introduced by neutron interactions with material walls. The papers in this volume summarize the limitations of present experiments, the discussion of new experiments in planning stage, and the discussion of systematic effects that must be addressed to achieve a lifetime measurement at an accuracy of 0.1 second.Cover image courtesy of Elena Fernández, Los Alamos National Laboratory.

Author: Francisco Gonzalez (Physicist)
Publisher:
ISBN:
Category : Beta decay
Languages : en
Pages : 0

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Because it lacks an electric charge, the neutron is a useful probe of the electroweak framework of the Standard Model (SM), which describes the process as a particle undergoes radioactive decay. Neutrons are the simplest example of B-decay, which provides a unique suite of tests for fundamental parameters of electroweak theory.The neutron lifetime, rn, can be used in conjunction with its other decay properties to extract Vud. This can then be combined with other particle decays to investigate the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. By itself, neutron b-decay can be used to study the origins of matter in the universe, and even hunt for new novel decay modes. The UCNr experiment, at Los Alamos National Laboratory (LANL), is the world's most precise measurement of the neutron lifetime. UCNt traps Ultracold Neutrons (UCN) in a bottle of permanent magnets for periods of time longer than the neutron lifetime. This work presents the results of two calendar years of UCNr data taking, resulting in a lifetime with both statistical and systematic uncertainties below 0.3 s. The analysis has utilized new methods to minimize the uncertainties due to backgrounds and initial estimation of the number of trapped UCN. A suite of Monte Carlo simulations, in conjunction with data-driven measurements, have been used to demonstrate the loss rates of UCN in UCNr are below the statistical precision of the experiment. This analysis leads to a blinded lifetime result with uncertainties on rn of -+0.26 +0.21/−0.16s, or a relative precision of 4 x 10−4.

Author: Andrew Tsung-Tse Yue
Publisher:
ISBN:
Category :
Languages : en
Pages : 173

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The reported lifetime in an in-beam neutron lifetime experiment performed at NIST was [tau]n̳ = (886.3 ± 3.4) s [Nico et al., 2005b]. The largest source of uncertainty was the efficiency of the neutron flux monitor (0.3% relative uncertainty). The flux monitor operates by counting charged particles produced when neutrons impinge on a 6Li foil. Its efficiency was calculated from the 6Li thermal neutron cross section, the solid angle subtended by the charged particle detectors, and the amount of neutron-absorbing material present on the foil. An absolute black neutron detector for cold neutron beams has been developed to measure the efficiency without the need to know these quantities. The flux monitor efficiency is measured to a precision of 0.052% using this direct calibration technique. This calibration removes the largest barrier to a 1 s neutron lifetime measurement with the beam technique. It is hoped that this data can also be used to re-evaluate the current NIST neutron lifetime value, reduce its uncertainty, and remove the dependence on evaluated nuclear data files. There is also the possibility for a direct measurement of the 6Li thermal neutron cross section.

Author: Kim Ulrike Roß
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author:
Publisher: DIANE Publishing
ISBN: 9781422328552
Category :
Languages : en
Pages : 6

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Author: United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development
Publisher:
ISBN:
Category : Energy development
Languages : en
Pages : 1854

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Author: United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development
Publisher:
ISBN:
Category : Energy development
Languages : en
Pages : 2038

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Author:
Publisher: DIANE Publishing
ISBN: 9781422328569
Category :
Languages : en
Pages : 6

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