Design and performance of a cryogenic apparatus for magnetically trapping ultracold neutrons

Huffman, P. R.; Coakley, Kevin J.; Doyle, John M.; Huffer, C.R.; Mumm, H. P.; O’Shaughnessy, C.; Schelhammer, K.W.; Seo, P. N.; Yang, L.

doi:10.1016/j.cryogenics.2014.09.008

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…Another advantage of high current magnets is a smaller inductance which allows faster ramping of magnetic fields. This was very important in experiments with ultra-cold neutrons 21 . The high-current approach was used in the octupole magnet of the ALPHA collaboration for trapping antihydrogen 12 where the nominal operating current was 1 kA.…”

Section: Design Considerationsmentioning

confidence: 99%

“…The high-current approach was used in the octupole magnet of the ALPHA collaboration for trapping antihydrogen 12 where the nominal operating current was 1 kA. High currents require special cryogenic solutions for the current leads and strongly complicate the cryostat construction 21 . This approach is difficult to realize for small labs and desk-top experiments.…”

Section: Design Considerationsmentioning

confidence: 99%

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A large octupole magnetic trap for research with atomic hydrogen

Ahokas,

Semakin,

Järvinen

et al. 2021

Preprint

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We describe the design and performance of a large magnetic trap for storing and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K. Aiming at a large volume of the trap we implemented the octupole configuration of linear currents (Ioffe bars) for the radial confinement, combined with two axial pinch coils and a 3 T solenoid for the cryogenic H dissociator. The octupole magnet consists of eight race-track segments which are compressed towards each other with magnetic forces. This provides a mechanically stable and robust construction with a possibility of replacement or repair of each segment. A maximum trap depth of 0.54 K (0.8 T) was reached, corresponding to an effective volume of 0.5 liters for hydrogen gas at 50 mK. This is an order of magnitude larger than ever used for trapping atoms.

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Section: Design Considerationsmentioning

confidence: 99%

Section: Design Considerationsmentioning

confidence: 99%

A large octupole magnetic trap for research with atomic hydrogen

Ahokas,

Semakin,

Järvinen

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The first of such experiments was the use of a magnetic storage ring called NESTOR at the UCN facility of the Institut Laue-Langevin (ILL) in France, which gave a lifetime value of 877 ± 10 s [33]. An Ioffe-type design of magnetic traps was installed at NIST as the first three-dimensional magnetic trap of UCNs [67,68]. More magnetic traps have since been built using small permanent magnets to form Halbach arrays, combined with solenoid fields to confine UCNs.…”

Section: Evaluation Of Neutron Lifetime Measurementsmentioning

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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“…The first three-dimensional magnetic trap of UCNs, designed in 1994 [74] and later operated at NIST [67,68], was also similar in size to both HOPE and τ SPECT. But it applied a very unique Ioffe-type design, consisting of a large magnetic quadrupole to trap UCNs radially and a pair of solenoids to trap them axially, as shown in Fig.…”

Section: Anomalies In Magnetic Trapsmentioning

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

Design and performance of a cryogenic apparatus for magnetically trapping ultracold neutrons

Cited by 6 publications

References 18 publications

A large octupole magnetic trap for research with atomic hydrogen

A large octupole magnetic trap for research with atomic hydrogen

Neutron lifetime anomaly and mirror matter theory

Neutron lifetime anomaly and mirror matter theory

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