3He neutron spin filter at ILL

Heil, W.; Andersen, K.H.; Hofmann, D.; Humblot, H.; Kulda, J.; Lelièvre-Berna, E.; Schärpf, O.; Tasset, F.

doi:10.1016/s0921-4526(97)00511-5

Cited by 25 publications

(31 citation statements)

References 24 publications

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“…An equivalent method of determining the neutron polarization without flipping the neutron spins is to reverse the 3 He polarization and measure the transmission of one neutron spin state through both 3 He polarization states [22]. The 3 He polarization is flipped by AFP.…”

Section: Neutron Polarization Measurementsmentioning

confidence: 99%

Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized 3He neutron spin-filter

Musgrave

Baeßler

Balascuta

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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Accurately measuring the neutron beam polarization of a high flux, large area neutron beam is necessary for many neutron physics experiments. The Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) is a pulsed neutron beam that was polarized with a supermirror polarizer for the NPDGamma experiment. The polarized neutron beam had a flux of ∼ 10 9 neutrons per second per cm 2 and a cross sectional area of 10×12 cm 2 . The polarization of this neutron beam and the efficiency of a RF neutron spin rotator installed downstream on this beam were measured by neutron transmission through a polarized 3 He neutron spin-filter. The pulsed nature of the SNS enabled us to employ an absolute measurement technique for both quantities which does not depend on accurate knowledge of the phase space of the neutron beam or the 3 He polarization in the spin filter and is therefore of interest for any experiments on slow neutron beams from pulsed neutron sources which require knowledge of the absolute value of the neutron polarization. The polarization and spin-reversal efficiency measured in this work were done for the NPDGamma experiment, which measures the parity violating γ-ray angular distribution asymmetry with respect to the neutron spin direction in the capture of polarized neutrons on protons. The experimental technique, results, systematic effects, and applications to neutron capture targets are discussed.

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Section: Neutron Polarization Measurementsmentioning

confidence: 99%

Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized 3He neutron spin-filter

Musgrave

Baeßler

Balascuta

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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“…By using crossed super-mirror polarizers (Petoukhov et al, 2003) a neutron polarization larger than 99.5 % is obtained over the full cross-section of the neutron beam (6 × 20 cm 2 ). The neutron polarization is determined with a new polarimeter which is based on spin-dependent neutron absorption in polarized 3 He and which yields a precision of about 0.1 % (Heil et al, 1998;Zimmer et al, 1999). Following these upgrades a new high-precision determination of the A-parameter is being prepared with the PERKEO-II set-up (Fig.…”

Section: B Neutron β Asymmetry Parametermentioning

confidence: 99%

Tests of the standard electroweak model in nuclear beta decay

2006

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We review the current status of precision measurements in allowed nuclear beta decay, including neutron decay, with emphasis on their potential to look for new physics beyond the standard electroweak model. The experimental results are interpreted in the framework of phenomenological model-independent descriptions of nuclear beta decay as well as in some specific extensions of the standard model. The values of the standard couplings and the constraints on the exotic couplings of the general beta decay Hamiltonian are updated. For the ratio between the axial and the vector couplings we obtain C A /C V = −1.26992(69) under the standard model assumptions. Particular attention is devoted to the discussion of the sensitivity and complementarity of different precision experiments in direct beta decay. The prospects and the impact of recent developments of precision tools and of high intensity low energy beams are also addressed.

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“…An experimental implementation with neutrons would be difficult because it would involve putting a QZE set-up inside an interferometer in order to measure phase. We therefore restrict ourselves to a gedanken experiment based on the use of 3 He as a neutron polarization filter [17]. It is well known [18] that Helium 3 is "black" to neutrons but polarized 3 He only absorbs one spin state of a neutron beam-hence acts as a 50% absorber of a beam; the rest of it emerges fully polarized.…”

Section: A Gedanken Experimentsmentioning

confidence: 99%

Berry phase from a quantum Zeno effect

et al. 1999

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We exhibit a specific implementation of the creation of geometrical phase through the state-space evolution generated by the dynamic quantum Zeno effect. That is, a system is guided through a closed loop in Hilbert space by means a sequence of closely spaced projections leading to a phase difference with respect to the original state. Our goal is the proposal of a specific experimental setup in which this phase could be created and observed. To this end we study the case of neutron spin, examine the practical aspects of realizing the ‘projections’, and estimate the difference between the idealized projections and the experimental implementation

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3He neutron spin filter at ILL

Cited by 25 publications

References 24 publications

Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized 3He neutron spin-filter

Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized 3He neutron spin-filter

Tests of the standard electroweak model in nuclear beta decay

Berry phase from a quantum Zeno effect

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