Measurements of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mover accent="true"><mml:mi mathvariant="bold">H</mml:mi><mml:mo>→</mml:mo></mml:mover><mml:mover accent="true"><mml:mi mathvariant="bold">D</mml:mi><mml:mo>→</mml:mo></mml:mover><mml:mo stretchy="false">(</mml:mo><mml:mover accent="true"><mml:mi>γ</mml:mi><mml:mo>→</mml:mo></mml:mover><mml:mo>,</mml:mo><mml:mi>π</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math>and Implications for the Convergence of the Gera

Hoblit, S.; Sandorfi, A. M.; Ardashev, K.; Bade, C.; Bartalini, O.; Blecher, M.; Caracappa, A.; D’Angelo, A.; Salvo, R. Di; Fantini, A.; Gibson, Christopher J.; Glückler, H.; Hicks, K.; Hönig, A.; Kageya, T.; Khandaker, M.; Kistner, O. C.; Kizilgul, S.; Kucuker, S.; Lehmann, A.; Lowry, M.; Lucas, M.; Mahon, J.; Miceli, L.; Moricciani, D.; Norum, B.; Pap, M.; Preedom, B. M.; Seyfarth, H.; Schaerf, C.; Ströher, H.; Thorn, C.; Whisnant, C. S.; Wang, K.; Wei, X.

doi:10.1103/physrevlett.102.172002

Cited by 30 publications

(26 citation statements)

References 21 publications

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“…1 Targets are now being prepared for an experimental program at Jefferson Laboratory to study nucleon resonances from polarized neutrons. 1 Targets are now being prepared for an experimental program at Jefferson Laboratory to study nucleon resonances from polarized neutrons.…”

Section: A Motivationmentioning

confidence: 99%

Measuring the relative concentration of H2 and D2 in HD gas with gas chromatography

Whisnant

Hansen

Kelley

2011

Review of Scientific Instruments

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Frozen-spin polarized hydrogen deuteride (HD) targets are being prepared for photonuclear experiments at Jefferson Lab. The targets are frozen HD gas. To polarize and achieve the required spin-lattice relaxation times, the targets are made from high purity HD gas in which the residual H(2) and D(2) concentrations are known. To determine these residual concentrations, a gas chromatograph is used. The separation of the gas components is done in a column cooled to ≈120 K by immersing it in a mixture of liquid nitrogen and isopentane and using neon as the carrier gas. The different hydrogen isotopes have different transit times through the column and their arrival is registered by a thermal conductivity detector. The peaks in the chromatograms are fit using an exponentially modified Gaussian line shape to extract the areas of these peaks. The ratios of areas are corrected for differences in thermal conductivity to give the relative concentrations. Here, H(2) and D(2) concentrations on the order of a few percent have been measured with uncertainties of less than ± 5%. The linear response of the system is confirmed to within about ± 6.3%.

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Section: A Motivationmentioning

confidence: 99%

Measuring the relative concentration of H2 and D2 in HD gas with gas chromatography

Whisnant

Hansen

Kelley

2011

Review of Scientific Instruments

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“…In turn, this means that our analysis is at the classical limit in the frame of the Compton model, and, thus, using the Thomson model is justified. On the other hand, it is worth recalling that polarized photon beams can be obtained by Compton scattering on electrons having initial energies of the order of GeV (Hoblit et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Polarization effects in collisions between very intense laser beams and relativistic electrons

Popa

2012

Laser Part. Beams

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The interaction between laser and relativistic electron beams is a promising source of very energetic X rays. We present an accurate model for the collisions between very intense linearly polarized laser beams, corresponding to relativistic parameters of the order of unity or greater, and electrons having energies up to 100 MeV. Our approach uses only one approximation, namely it neglects the radiative corrections. We consider the two cases in which the laser field polarization is either perpendicular or parallel to the plane defined by the directions of propagation of the laser beam and electron beam, and calculate accurately the properties of the σ and π polarized scattered beams. The angle between the directions of the laser and electron beams, denoted by θ L , is allowed to have arbitrary values, so that the widely analyzed 180°and 90°geometries, in which the two beams collide, respectively, head on and perpendicularly, are particular cases. We prove that the polarization properties of the scattered beam depend on the angle θ L . By varying this angle, the polarization of the scattered beam can be varied between the two limit configurations in which the electromagnetic field of the scattered beam is σ or π polarized with respect to the scattering plane. Our theoretical results are in good agreement with experimental results published in literature. Our model shows that current technologies can be used to produce hard harmonics of the scattered radiations. These harmonics can have relatively high intensities comparable to the intensities of the first harmonics, and energies higher than 1 MeV. Our results lead to the possibility to realize an adjustable photon source with both the energy and polarization of the scattered radiations accurately controlled by the value of the θ L angle.

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“…Experiments with polarized targets are essential to unravel the amplitudes in meson photo-production. First proposed in 1967 [1] and first used in photo-production experiments only recently [2], this type of polarized target has many attractive features for such measurements, but its operation is considerably more complex than that of a conventional polarized target. Several commercial cryostats and magnet systems are used in the production process, as well as two specially designed and constructed devices.…”

Section: Introductionmentioning

confidence: 99%

A cryostat to hold frozen-spin polarized HD targets in CLAS: HDice-II

Lowry

Bass

D’Angelo

et al. 2016

Nuclear Instruments and Methods in Physics Research Section A:

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The design, fabrication, operation, and performance of a He-3/4 dilution refrigerator and superconducting magnet system for holding a frozen-spin polarized hydrogen deuteride target in the Jefferson Laboratory CLAS detector during photon beam running is reported. The device operates both vertically (for target loading) and horizontally (for target bombardment). The device proves capable of maintaining a base temperature of 50 mK and a holding field of 1 T for extended periods. These characteristics enabled multi-month polarization lifetimes for frozen spin HD targets having proton polarization of up to 50% and deuteron up to 27%. (C) 2016 Elsevier B.V. All rights reserved

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Measurements ofH→D→(γ→,π)and Implications for the Convergence of the Gera

Cited by 30 publications

References 21 publications

Measuring the relative concentration of H2 and D2 in HD gas with gas chromatography

Measuring the relative concentration of H2 and D2 in HD gas with gas chromatography

Polarization effects in collisions between very intense laser beams and relativistic electrons

A cryostat to hold frozen-spin polarized HD targets in CLAS: HDice-II

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