Investigation of titanium and polyethylene as UCN absorber materials with AbEx

Picker, R.; Altarev, I.; Amos, P.; Franke, B.; Geltenbort, P.; Gutsmiedl, E.; Hartmann, F. J.; Mann, A.; Materne, S.; Müller, A.; Paul, S.; Stoepler, R.; Wirth, H. F.

doi:10.1016/j.nima.2009.07.089

Cited by 6 publications

(10 citation statements)

References 8 publications

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“…At the same time, the fully moderated flux spectrum has Maxwellian shape with the average energy of 53±4 meV at room temperature. Our conclusion contradicts obviously with the value E = 10 − 13 meV [7,8], obtained in an essentially the same kind of the experiment although with a different 3 He detector, with a PE sample and by the analysis in a frame of Maxwellian approximation. This situation induced us to reanalyze data [7,8] using the MCNP code with the input describing geometry and conditions of the measurement [8].…”

contrasting

confidence: 91%

“…Recent reviews [1,2] highlight the use of UCN in nuclear and particle physics, cosmology and gravity. In particular, an importance of study of the upscattering spectrum temperature and rates for neutron lifetime measurements is emphasized in [3]. Authors of Ref.[4] discuss using UCN upscattering techniques in solid state and surfaces studies with the view that the rather limited UCN intensity available at existing UCN sources will be overcome with more powerful next generation UCN sources.…”

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confidence: 99%

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confidence: 99%

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Upscattering of ultracold neutrons from the polymer [C6H12]n

Sharapov¹,

Morris²,

Makela³

et al. 2013

Phys. Rev. C

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It is generally accepted that the main cause of ultracold neutron (UCN) losses in storage traps is upscattering to the thermal energy range by hydrogen adsorbed on the surface of the trap walls. However, the data on which this conclusion is based are poor and contradictory. Here we report a measurement, performed at the Los Alamos National Laboratory UCN source, of the average energy of the flux of upscattered neutrons after the interaction of UCN with hydrogen bound in the semicrystalline polymer PMP (trade name TPX), [C 6 H 12 ] n . Our analysis, performed with the MCNP code which applies the neutron-scattering law to UCN upscattered by bound hydrogen in semicrystalline polyethylene, [C 2 H 4 ] n , leads us to a flux average energy value of 26 ± 3 meV, in contradiction to previously reported experimental values of 10 to 13 meV and in agreement with the theoretical models of neutron heating implemented in MCNP.

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Upscattering of ultracold neutrons from the polymer [C6H12]n

Sharapov¹,

Morris²,

Makela³

et al. 2013

Phys. Rev. C

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“…A toroidal arrangement of electromagnetic coils provides a 60-120 G ambient field to prevent UCN depolarization. UCNs with E ≳ 38 neV are then removed ("cleaned") [28][29][30]34] during a period t clean ¼ 50 s; they are either up-scattered by horizontal polyethylene sheets, or captured by 10 B-coated-ZnS surfaces via the capture reaction…”

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confidence: 99%

Improved Neutron Lifetime Measurement with UCNτ

et al. 2021

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We report an improved measurement of the free neutron lifetime τ n using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38 × 10 6 surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ n from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ n measurements and by performing a global likelihood fit to all data while selfconsistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ n ¼ 877.75 AE 0.28 stat þ 0.22= − 0.16 syst s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.

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“…A toroidal arrangement of electromagnetic coils provides a 60 − 120 G ambient field to prevent UCN depolarization. UCN with E 38 neV are then removed ("cleaned") [27][28][29]33] during a period t clean = 50 s; they are either up-scattered by horizontal polyethylene sheets, or captured by 10 B-coated-ZnS surfaces via the capture reaction 10 B+n → α+ 7 Li. The cleaners are then retracted, and UCN are stored in the trap for t store varying from 20 to 1550 s. The surviving neutrons are then counted by the primary 10 B-coated-ZnS scintillator UCN counter [28] over time interval t count = 210 s. The primary detector collects the n-capture-induced ZnS scintillation light in an array of wavelength shifting fibers, which route the light to two PMTs.…”

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Improved neutron lifetime measurement with UCN$τ$

Gonzalez,

Fries,

Cude-Woods

et al. 2021

Preprint

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We report an improved measurement of the free neutron lifetime τn using the UCNτ apparatus at the Los Alamos Neutron Science Center. We counted a total of approximately 38 × 10 6 surviving ultracold neutrons (UCN) after storing in UCNτ 's magneto-gravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τn from three blinded, independent analyses by both pairing long and short storage-time runs to find a set of replicate τn measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τn = 877.75±0.28 stat +0.22/−0.16 syst s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.

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Investigation of titanium and polyethylene as UCN absorber materials with AbEx

Cited by 6 publications

References 8 publications

Upscattering of ultracold neutrons from the polymer [C6H12]n

Upscattering of ultracold neutrons from the polymer [C6H12]n

Improved Neutron Lifetime Measurement with UCNτ

Improved neutron lifetime measurement with UCN$τ$

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