Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments

Coakley, Kevin J.; Dewey, M. S.; Huber, M.; Huffer, C.R.; Huffman, P. R.; Marley, D. E.; Mumm, H. P.; O’Shaughnessy, C.; Schelhammer, K.W.; Thompson, A. K.; Yue, Andrew

doi:10.1016/j.nima.2015.12.064

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…The effect of poor cleaning was studied in the NIST trap [44][45][46]. The cleaning technique used was ramping down the radial magnetic field temporarily so that abovethreshold UCNs collide with material on the trap sidewall.…”

Section: Introductionmentioning

confidence: 99%

“…The cleaning technique used was ramping down the radial magnetic field temporarily so that abovethreshold UCNs collide with material on the trap sidewall. Detailed simulations show ramping to 30% of the initial field is required to ensure above-threshold UCNs are sufficiently cleaned from the trap (to reduce the storage time shift to < 1 s), but this reduces the initial number of well-trapped UCNs (E tot < U trap ) to 30% [46].…”

Section: Introductionmentioning

confidence: 99%

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Neutron lifetime measurements and effective spectral cleaning with an ultracold neutron trap using a vertical Halbach octupole permanent magnet array

et al. 2016

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Ultracold neutron (UCN) storage measurements were made in a trap constructed from a 1.3 T Halbach Octupole PErmanent (HOPE) magnet array aligned vertically, using the TES-port of the PF2 source at the Institut Laue-Langevin. A mechanical UCN valve at the bottom of the trap was used for filling and emptying. This valve was covered with Fomblin grease to induce non-specular reflections and was used in combination with a movable polyethylene UCN remover inserted from the top for cleaning of above-threshold UCNs. Loss due to UCN depolarization was suppressed with a minimum 2 mT bias field. Without using the UCN remover, a total storage time constant of (712 ± 19) s was observed; with the remover inserted for 80 s and used at either 80 cm or 65 cm from the bottom of the trap, time constants of (824 ± 32) s and (835 ± 36) s were observed. Combining the latter two values, a neutron lifetime of τn = (887 ± 39) s is extracted after primarily correcting for losses at the UCN valve. The time constants of the UCN population during cleaning were observed and compared to calculations based on UCN kinetic theory as well as Monte-Carlo studies. These calculations are used to predict above-threshold populations of ∼ 5%, ∼ 0.5% and ∼ 10 −12 % remaining after cleaning in the no remover, 80 cm remover and 65 cm remover measurements. Thus, by using a non-specular reflector covering the entire bottom of the trap and a remover at the top of the trap, we have established an effective cleaning procedure for removing a major systematic effect in high-precision τn experiments with magnetically stored UCNs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neutron lifetime measurements and effective spectral cleaning with an ultracold neutron trap using a vertical Halbach octupole permanent magnet array

et al. 2016

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Adiabatic expansion cooling of antihydrogen

Ahmadi,

Alves,

Baker

et al. 2024

Phys. Rev. Research

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Magnetically trapped antihydrogen atoms can be cooled by expanding the volume of the trap in which they are confined. We report a proof-of-principle experiment in which antiatoms are deliberately released from expanded and static traps. Antiatoms escape at an average trap depth of 0.08±0.01K (statistical errors only) from the expanded trap while they escape at average depths of 0.22±0.01 and 0.17±0.01K from two different static traps. (We employ temperature-equivalent energy units.) Detailed simulations qualitatively agree with the escape times measured in the experiment and show a decrease of 38% (statistical error<0.2%) in the mean energy of the population after the trap expansion without significantly increasing antiatom loss compared to typical static confinement protocols. This change is bracketed by the predictions of one-dimensional and three-dimensional semianalytic adiabatic expansion models. These experimental, simulational, and model results are consistent with obtaining an adiabatically cooled population of antihydrogen atoms that partially exchanged energy between axial and transverse degrees of freedom during the trap expansion. This result is important for future antihydrogen gravitational experiments which rely on adiabatic cooling, and it will enable antihydrogen cooling beyond the fundamental limits of laser cooling. Published by the American Physical Society 2024

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Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments

Cited by 2 publications

References 26 publications

Neutron lifetime measurements and effective spectral cleaning with an ultracold neutron trap using a vertical Halbach octupole permanent magnet array

Neutron lifetime measurements and effective spectral cleaning with an ultracold neutron trap using a vertical Halbach octupole permanent magnet array

Adiabatic expansion cooling of antihydrogen

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