Abstracts

Coulter, John S.

doi:10.1093/ptj/29.6.276a

Cited by 3 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The drop in 3 He polarization for the hybrid cell was also observed to be consistent with the drop in P A . The magnitude of these effects is much larger than expected given earlier study of ionization effects produced by an -particle beam [19]. Measurements over several decades of neutron flux show that the increased spin-relaxation rate approximately scales with n p , which would be consistent with the recombination-limited equilibrium concentration of electrons or ions.…”

mentioning

confidence: 61%

“…Since ÿ does not change appreciably, the most likely cause is a drop of P A , possibly due to ionization effects induced by the neutron-beam. Ionization effects on both ÿ and P A were observed in work with a 180 particlenA beam of 18 MeV particles [19]. Those observations led to the development of the double cell now ubiquitous in SEOP-based polarized 3 He targets for electron scattering [20]; however, we expected these effects to be negligible for 3 He cells in neutron beams, where the ionization energy loss is 100 -10 000 times less at ILL and LANSCE, respectively.…”

mentioning

confidence: 98%

See 1 more Smart Citation

Neutron Beam Effects on Spin-Exchange-PolarizedHe3

et al. 2008

View full text Add to dashboard Cite

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal spin-exchange-polarized 3He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3He polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at Los Alamos Neutron Science Center and Institute Laue-Langevin. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as sqrt[phi_{n}], where phi_{n} is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the concentration of electron-ion pairs but is much larger than expected from earlier work.

show abstract

mentioning

confidence: 61%

mentioning

confidence: 98%

Neutron Beam Effects on Spin-Exchange-PolarizedHe3

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Measurements over several decades of neutron flux show that the increased spin relaxation rate approximately scales with √ φ n , which would be consistent with the recombination-limited equilibrium concentration of one or more ion species. The magnitude of this effect is much larger than expected given earlier study of ionization effects produced by an alpha-particle beam [19]. At ILL's PF1B, the world's highest flux cold neutron beam for fundamental physics, P A was reduced by about 20% in a potassium-rubidium hybrid cell pumped by high-power narrowed diode laser arrays.…”

mentioning

confidence: 75%

“…Since Γ does not change appreciably, the most likely cause is a drop of P A , possibly due to ionization effects induced by the neutron beam. Ionization effects on both Γ and P A were observed in work with a 180 particle-nA beam of 18 MeV alpha particles [19]. Those observations led to the development of the double cell now ubiquitous in SEOP based polarized 3 He targets for electron scattering [20]; however we expected these effects to be negligible for 3 He cells in neutron beams, where the ionization energy loss is 100 to 10,000 times less.…”

mentioning

confidence: 97%

Neutron Beam Effects on Spin Exchange Polarized He-3

Sharma,

Babcock,

Andersen

et al. 2008

Preprint

View full text Add to dashboard Cite

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal-spin-exchange polarized 3 He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3 He polarization and was attributed to a decrease of alkalimetal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data reveal a new alkali-metal spinrelaxation mechanism that approximately scales as √ φ n , where φn is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the recombinationlimited ion concentration, but is much larger than expected from earlier work.

show abstract

“…35,36 Depolarization is caused by atomic ions, 3 He + , and molecular ions, 3 He 2 + , created by beam ionization. Depolarization of the 3 He by charged-particle beam irradiation has been considered previously.…”

Section: Target Polarization Calibrationmentioning

confidence: 99%

Spin-exchange optically pumped polarized He3 target for low-energy charged particle scattering experiments

Katabuchi¹,

Buscemi²,

Cesaratto³

et al. 2005

Review of Scientific Instruments

View full text Add to dashboard Cite

We have constructed, tested, and calibrated a polarized 3 He target system which facilitates p-3 He elastic scattering at proton energies as low as 2 MeV. This system consists of a target cell placed in a uniform B field inside a scattering chamber and an external optical pumping station utilizing Rb spin exchange. Computer-controlled valves allow polarized 3 He gas to be transferred quickly between the optical pumping station and the spherical Pyrex target cell, which has Kapton film covering apertures for the passing beam and the scattering particles. The magnetic field required to maintain 3 He polarization in the target cell is created with a compact, shielded sine-theta coil. Target gas polarimetry is accomplished using nuclear magnetic resonance and calibrated using the known analyzing power of ␣-3 He scattering.

show abstract

Abstracts

Cited by 3 publications

References 0 publications

Neutron Beam Effects on Spin-Exchange-PolarizedHe3

Neutron Beam Effects on Spin-Exchange-PolarizedHe3

Neutron Beam Effects on Spin Exchange Polarized He-3

Spin-exchange optically pumped polarized He3 target for low-energy charged particle scattering experiments

Contact Info

Product

Resources

About