A removable cryogenic window for transmission of light and neutrons

Butterworth, James; Brome, C. R.; Huffman, P. R.; Mattoni, C. E. H.; McKinsey, D. N.; Doyle, John M.

doi:10.1063/1.1149211

Cited by 7 publications

(4 citation statements)

References 6 publications

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“…There are three vacuum windows that are each made from 20 mil (508 µm) thick Teflon perfluoroalkoxy flouropolymer (PFA) film [21,7]. Teflon-PFA is manufactured without metallic contaminants that could activate and produce background activation.…”

Section: Neutron Entrance Windowsmentioning

confidence: 99%

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

et al. 2014

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The cryogenic design and performance of an apparatus used to magnetically confine ultracold neutrons (UCN) is presented. The apparatus is part of an effort to measure the beta-decay lifetime of the free neutron and is comprised of a high-current superconducting magnetic trap that surrounds ∼ 21 l of isotopically pure 4 He cooled to approximately 250 mK. A 0.89 nm neutron beam can enter the apparatus from one end of the magnetic trap and a light collection system allows visible light generated within the helium by decays to be transported to detectors at room temperature. Two cryocoolers are incorporated to reduce liquid helium consumption.

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Section: Neutron Entrance Windowsmentioning

confidence: 99%

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

et al. 2014

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“…Cold (0.89 nm) neutrons enter the trapping region through a series of Teflon (vacuum) and beryllium (thermal) windows on the dewar. [9][10][11] Interlocking tubes of boron nitride (BN) surround the beam and shield the dewar from scattered neutrons to minimize backgrounds from neutroninduced activation. Near the front window of the helium cell the BN is coated with graphite to reduce light scattering.…”

Section: Apparatusmentioning

confidence: 99%

Measuring the Neutron Lifetime with Magnetically Trapped Ultracold Neutrons

Mumm

Huber

Yue

et al. 2014

Next Generation Experiments to Measure the Neutron Lifetime

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We describe an experiment to measure the neutron lifetime using a technique with a set of systematic uncertainties largely different than those of previous measurements. 1 In this approach, ultracold neutrons (UCN) are produced by inelastic scattering of cold (0.89 nm) neutrons in a reservoir of superfluid 4 He. 2 These neutrons are then confined using a three-dimensional magnetic trap. As the trapped neutrons beta decay, the energetic electrons produced in the decay generate scintillations in the liquid He; 3,4 each decay is detectable with nearly 100 % efficiency. The neutron lifetime can be directly determined by measuring the scintillation rate as a function of time.

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“…Neutrons enter the trapping region through a series of perfluoroalkoxy (PFA) Teflon/beryllium windows on the dewar [13]. Interlocking tubes of boron nitride (BN) surround the beam and shield the dewar from scattered neutrons to minimize backgrounds from neutron-induced activation.…”

Section: Newly Developed Apparatusmentioning

confidence: 99%

Measuring the neutron lifetime using magnetically trapped neutrons

O’Shaughnessy

Golub

Schelhammer

et al. 2009

Nuclear Instruments and Methods in Physics Research Section A:

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The neutron beta-decay lifetime plays an important role both in understanding weak interactions within the framework of the Standard Model and in theoretical predictions of the primordial abundance of 4 He in Big Bang Nucleosynthesis. In previous work, we successfully demonstrated the trapping of ultracold neutrons (UCN) in a conservative potential magnetic trap. A major upgrade of the apparatus is nearing completion at the National Institute of Standards and Technology Center for Neutron Research (NCNR). In our approach, a beam of 0.89 nm neutrons is incident on a superfluid 4 He target within the minimum field region of an Ioffe-type magnetic trap. A fraction of the neutrons is downscattered in the helium to energies < 200 neV, and those in the appropriate spin state become trapped. The inverse process is suppressed by the low phonon density of helium at temperatures less than 200 mK, allowing the neutron to travel undisturbed. When the neutron decays the energetic electron ionizes the helium, producing scintillation light that is detected using photomultiplier tubes. Statistical limitations of the previous apparatus will be alleviated by significant increases in field strength and trap volume resulting in twenty times more trapped neutrons.

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A removable cryogenic window for transmission of light and neutrons

Abstract: A demountable, superfluid-tight window for the transmission of neutrons and light has been developed. A fluorocarbon polymer ͑Teflon͒ film is both the window and sealing gasket. Transmission of blue light and bursting pressure are measured for films of varying thicknesses.

Cited by 7 publications

References 6 publications

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

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

Measuring the Neutron Lifetime with Magnetically Trapped Ultracold Neutrons

Measuring the neutron lifetime using magnetically trapped neutrons

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