Measurement of the neutron life-time

Sosnovsky, A.N.; Spivak, P.E.; Prokofiev, Yu.A.; Kutikov, I.E.; Dobrinin, Yu.P.

doi:10.1016/0029-5582(59)90228-7

Cited by 58 publications

(6 citation statements)

References 6 publications

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“…6,8,10,12 In these experiments neutron decay recoil protons were accelerated electrostatically to 25 keV and counted with nearly 100% efficiency. The use of proton counting had the important advantage that protons could be stopped prior to detection by applying a small (800 V) potential.…”

Section: Previous Beam Lifetime Experimentsmentioning

confidence: 99%

Neutron Lifetime Experiments Using the Beam Method: Past, Present, and Future

Wietfeldt¹

2014

Next Generation Experiments to Measure the Neutron Lifetime

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The oldest method for measuring the neutron lifetime combines the rate of neutron decay in a slow neutron beam, found by counting the final state charged particles, with absolute determinations of the neutron flux and the effective decay volume to obtain the specific activity of the beam and hence the radioactive decay constant. This is known as the "beam method." The most recent beam neutron lifetime experiment 1 achieved an experimental uncertainty of 3.4 s, dominated by systematic limitations of the neutron flux measurement. Recent ultracold neutron "bottle" experiments have obtained uncertainties at or just below the 1 s level. The effort to reduce the neutron lifetime uncertainty to 0.1 s will benefit from both approaches because, while they are both challenged by difficult systematic effects at that level, the nature of these effects is very different for the two methods. We present a brief review of the principles and history of the beam method and outline a path for future beam experiments to improve the neutron lifetime uncertainty to 0.1 s and below.

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Section: Previous Beam Lifetime Experimentsmentioning

confidence: 99%

Neutron Lifetime Experiments Using the Beam Method: Past, Present, and Future

Wietfeldt¹

2014

Next Generation Experiments to Measure the Neutron Lifetime

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“…The method is still of interest and will be briefly reviewed below. The result by the Moscow group [9] was revised later on (see section 3.3.1). In a cloud chamber experiment D'Angelo [lo] observed individual tracks of decay electrons and achieved with t .…”

Section: Review Of Beam Experiments Determining the Neutron Lietimementioning

confidence: 99%

The lifetime of the free neutron

Schreckenbach

Mampe

1992

J. Phys. G: Nucl. Part. Phys.

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Abshad. We review the results and techniques of experiments on the lifetime of the free neutron. The present mean value is 887.4 (1.7) s at the 1 v confidence level. We further discuss the relevance of these results for other fields like weak interaction theory, neutrino physics. astrophysics and cosmology. 1231 '887.6 f 3.0 1989 UCN storage, Fomblin 1241 '893.6f5.3 1990 variable size p trap 1251 '888.4 f 2.9 1990 UCN gravitational trap 1261 '883.2 f 2.9 1990 UCN storage, Fomblin, variable temperature (271 Weighted mean of (*): 887.4 f 1.7 s

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“…In the first period, the results for the neutron lifetime exceeded 900 seconds. The so-called beam method measured a counting rate of protons or electrons from the decay of neutrons n → p + e − + ν in a neutron beam of a nuclear reactor [1], [2], [3]. For the second period, typical neutron lifetimes were less than 900 seconds.…”

Section: Introductionmentioning

confidence: 99%

“…Herewith, the shift in the estimates of the lifetime significantly exceeded the indicated experimental errors. In the case of [1] in 1959, the result was 1013 ± 26 seconds and was reduced in 1978 to the value of 877 ± 8 seconds [6] while repeating the basic scheme of the experiment. In the experiment [3] the result of 1980 was 937 ± 18 seconds, but 16 years later, the authors published their result [7] as equal to 889.2 ± 4.8 s. The averaging out all the results for the whole mentioned measurement period without any restriction leads to an average neutron lifetime of about 900 s.…”

Section: Introductionmentioning

confidence: 99%

Direct determination of neutron lifetime in $β$-decay

Vasiliev

2020

Preprint

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The neutron lifetime is determined for now most accurately by two methods -the so-called "beam method" and the method of neutron storage in a trap. The goal of this research is to obtain the neutron lifetime with a higher precision by eliminating the traditional systematic errors. A new feature is extracting the neutron lifetime only from the set of electron counting rates with their errors. The newly received neutron lifetime value is τ NT = 883.31 ± 0.02(stat.) ± 0.02(sys.) s.The obtained neutron lifetime is the weighted average of two lifetimes, defined for different subsets of neutrons providing the well-known effect of the asymmetry in the neutron βdecay. Simple calculations predict the values of these lifetimes and show their correspondence to the known asymmetry parameters of neutron decay. The arithmetic mean (central) value for the two newly introduced neutron lifetimes was determined. The resulting weighted value τ NT is in a good agreement with the lifetimes in the first and second methods in limits of their double errors, but exceeds them significantly in precision. In addition, estimates of the new lifetimes, which are called here as L-neutron lifetime and R-neutron lifetime, are fulfilled. The estimation results correspond to the known parameters of the neutron decay asymmetry.

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Measurement of the neutron life-time

Cited by 58 publications

References 6 publications

Neutron Lifetime Experiments Using the Beam Method: Past, Present, and Future

Neutron Lifetime Experiments Using the Beam Method: Past, Present, and Future

The lifetime of the free neutron

Direct determination of neutron lifetime in $β$-decay

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