Experiments with ultracold neutrons - first 50 years

Pokotilovski, Yu. N.

doi:10.48550/arxiv.1805.05292

Cited by 3 publications

(7 citation statements)

References 99 publications

(130 reference statements)

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“…If UCNs are prepared at a much higher temperature than their kinetic energies, the corresponding Maxwell-Boltzmann velocity distribution will be proportional to v 2 in this extreme case. Therefore the mean velocity of UCNs can be calculated from v = 3 4 v max in the extreme case or v < 3 4 v max in more realistic cases when more energetic neutrons will oscillate more frequently, resulting in a softer energy spectrum. From the trap dimensions of UCNτ , the UCN mean free path of l ∼ 75 cm can be estimated.…”

Section: Explanation Of Neutron Lifetime Anomaly and Ckm Unitarity Pu...mentioning

confidence: 99%

Neutron lifetime anomaly and mirror matter theory

Tan¹

2023

Preprint

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This paper reviews the puzzles in modern neutron lifetime measurements and related unitarity issues in the CKM matrix. It is not a comprehensive and unbiased compilation of all historic data and studies, but rather a focus on compelling evidence leading to new physics. In particular, the largely overlooked nuances of different techniques applied in material and magnetic trap experiments are clarified. Further detailed analysis shows that the ``beam'' approach of neutron lifetime measurements is likely to give the ``true'' $\beta$-decay lifetime, while discrepancies in ``bottle'' measurements indicate new physics at play. The most feasible solution to these puzzles is a newly proposed ordinary-mirror neutron ($n-n'$) oscillation model under the framework of mirror matter theory. This phenomenological model is reviewed and introduced, and its explanations of the neutron lifetime anomaly and possible non-unitarity of the CKM matrix are presented. Most importantly, various new experimental proposals, especially lifetime measurements with small\slash narrow magnetic traps or under super-strong magnetic fields, are discussed in order to test the surprisingly large anomalous signals that are uniquely predicted by this new $n-n'$ oscillation model.

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Section: Explanation Of Neutron Lifetime Anomaly and Ckm Unitarity Pu...mentioning

confidence: 99%

Neutron lifetime anomaly and mirror matter theory

Tan¹

2023

Preprint

View full text Add to dashboard Cite

show abstract

“…However, these resonant conditions are not easy to realize. For example, the matter density has to be in the range of about 10 2 -10 3 g/cm 3 , which is only possible in the dense interior of a star, or super-strong magnetic fields around 50-200 T are required.…”

Section: Phenomenological Model Of N − N Oscillationsmentioning

confidence: 99%

“…[1,2] and a historic note from Ref. [3]). Considering that the sole known decay mode of neutrons is β decay, one would have thought that tremendous technological advances over the years would make it easy to measure the neutron lifetime.…”

Section: Introductionmentioning

confidence: 99%

Neutron Lifetime Anomaly and Mirror Matter Theory

Tan

2023

Universe

View full text Add to dashboard Cite

This paper reviews the puzzles in modern neutron lifetime measurements and related unitarity issues in the CKM matrix. It is not a comprehensive and unbiased compilation of all historic data and studies, but rather a focus on compelling evidence leading to new physics. In particular, the largely overlooked nuances of different techniques applied in material and magnetic trap experiments are clarified. Further detailed analysis shows that the “beam” approach of neutron lifetime measurements is likely to give the “true” β-decay lifetime, while discrepancies in “bottle” measurements indicate new physics at play. The most feasible solution to these puzzles is a newly proposed ordinary-mirror neutron (n−n′) oscillation model under the framework of mirror matter theory. This phenomenological model is reviewed and introduced, and its explanations of the neutron lifetime anomaly and possible non-unitarity of the CKM matrix are presented. Most importantly, various new experimental proposals, especially lifetime measurements with small/narrow magnetic traps or under super-strong magnetic fields, are discussed in order to test the surprisingly large anomalous signals that are uniquely predicted by this new n−n′ oscillation model.

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“…In fact, the neutron lifetime puzzle is more complicated than the 1% discrepancy between the two approaches mentioned above. A long-standing anomalous loss effect from solid walls of a material UCN trap has been observed and has puzzled the UCN community for many decades [3,13]. According to quantum mechanics, total reflection of UCNs from walls, which are made of good clean trapping materials such as beryllium, should be ideal, at least at low enough temperatures, for storage of UCNs.…”

Section: B More Puzzles In Neutron Lifetime and Ckm Unitaritymentioning

confidence: 99%

“…The neutron lifetime puzzle has been an evolving and complicated issue since high precision lifetime measurements of 3 seconds in uncertainties began in the late 1980s (see review from Refs [1,2] and a historic note from Ref. [3]). Considering that the sole known decay mode of neutrons is β decay, one would have thought that tremendous technological advances over the years would make it easy to measure the neutron lifetime.…”

mentioning

confidence: 99%

Neutron lifetime anomaly and mirror matter theory

Tan¹

2023

Preprint

View full text Add to dashboard Cite

This paper reviews the puzzles in modern neutron lifetime measurements and related unitarity issues in the CKM matrix. It is not a comprehensive and unbiased compilation of all historic data and studies, but rather a focus on compelling evidence leading to new physics. In particular, the largely overlooked nuances of different techniques applied in material and magnetic trap experiments are clarified. Further detailed analysis shows that the "beam" approach of neutron lifetime measurements is likely to give the "true" β-decay lifetime, while discrepancies in "bottle" measurements indicate new physics at play. The most feasible solution to these puzzles is a newly proposed ordinary-mirror neutron (n − n ) oscillation model under the framework of mirror matter theory. This phenomenological model is reviewed and introduced, and its explanations of the neutron lifetime anomaly and possible non-unitarity of the CKM matrix are presented. Most importantly, various new experimental proposals, especially lifetime measurements with small/narrow magnetic traps or under superstrong magnetic fields, are discussed in order to test the surprisingly large anomalous signals that are uniquely predicted by this new n − n oscillation model.

show abstract

Experiments with ultracold neutrons - first 50 years

Cited by 3 publications

References 99 publications

Neutron lifetime anomaly and mirror matter theory

Neutron lifetime anomaly and mirror matter theory

Neutron Lifetime Anomaly and Mirror Matter Theory

Neutron lifetime anomaly and mirror matter theory

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