Absorber materials for low-energy neutrons—Theoretical and experimental studies

Brose, D.; Geltenbort, P.; Plonka-Spehr, C.; Reichert, T.-H.

doi:10.1016/j.nima.2011.11.046

Cited by 6 publications

(4 citation statements)

References 12 publications

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“…Since U opt < 0 and W ≈ 0 for these materials, the previous expression is not valid. Instead, μ for this class of materials, assuming kinetic theory, is [59]:…”

Section: Fig 4 (Color Online)mentioning

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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“…Since U opt < 0 and W ≈ 0 for these materials, the previous expression is not valid. Instead, μ for this class of materials, assuming kinetic theory, is [59]:…”

Section: Fig 4 (Color Online)mentioning

confidence: 99%

“…If v 2 z /2 > gh PE , then the UCN reaches the remover and (v z − v 2 z − 2gh PE )/g is added to the survival time. The loss probability is calculated using the equations for PE derived in [59] (i.e., the E k⊥ version of Eq. 7).…”

Section: Interpretation Of Trap Cleaningmentioning

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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“…It is therefore useful to study a measurement procedure without monitoring but using the fixed horizontal absorber described above. In experiments using UCNs, a wide range of materials can be used as absorbers [16]. Titanium was chosen from a constructive point of view.…”

Section: Simulation Without Monitoring But With the Absorbermentioning

confidence: 99%

Monte Carlo simulations of a neutron lifetime experiment with a big gravitational trap

Fomin

Serebrov

2019

EPJ Web Conf.

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A Monte Carlo model was developed for our current neutron lifetime experiment using storage of ultracold neutrons (UCN) in a big gravitational trap. The model allows us to calculate neutron trajectories in the given geometry, taking into account gravity, and has been used in simulations that reproduce all stages of the experiment. The simulation was proven able to reproduce the time-dependence of the detected neutron count rates. For investigation of systematic effects, the value of the neutron lifetime resulting from the simulation of the experimental procedure was compared to the value entered as an input parameter. In particular, the systematic uncertainty associated with the method of calculating the effective UCN collision frequency in the trap was found not to exceed 0.1 s. In addition, calculations showed that up to 1% uncoated area of the copper trap has a negligible influence on the neutron lifetime result.

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“…В экспериментах с УХН широко применяются по-глотители нейтронов из разных материалов [8]. В экс-перименте с гравитационной ловушкой вставка пово-рачивается в положение вверх или вниз, но остается неподвижной при заданном типе измерений (со вставкой или без вставки).…”

Section: использование поглотителя в экспериментеunclassified

Моделирование Эксперимента По Измерению Времени Жизни Нейтрона С Большой Гравитационной Ловушкой Ультрахолодных Нейтронов С Поглотителем

Фомин¹,

Серебров²

2017

Журнал Технической Физики

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Absorber materials for low-energy neutrons—Theoretical and experimental studies

Cited by 6 publications

References 12 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

Monte Carlo simulations of a neutron lifetime experiment with a big gravitational trap

Моделирование Эксперимента По Измерению Времени Жизни Нейтрона С Большой Гравитационной Ловушкой Ультрахолодных Нейтронов С Поглотителем

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