NMR Measurements for Solid Polarized Targets at Jefferson Lab

Maxwell, James

doi:10.22323/1.346.0102

Cited by 3 publications

(3 citation statements)

References 12 publications

(12 reference statements)

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“…The microwave frequency was fixed approximately halfway between the normal frequencies for positive and negative polarizations. Additional details can be found in Ref [11].…”

Section: Test Resultsmentioning

confidence: 99%

Magnetic Field Requirements for the CLAS12 Polarized Target

Lagerquist¹

2020

Proceedings of the 18th International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2019)

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Upcoming spin structure experiments in Hall B at Jefferson Lab will employ a new dynamically polarized target inside the CLAS12 detector system. Protons and deuterons in irradiated NH 3 and ND 3 will be polarized at 1 K using the 5 T field of the CLAS12 solenoidal magnet. For optimum polarization, the field uniformity requirements are around 100 ppm over the volume of the target sample. I will discuss methods to improve field uniformity utilizing thin superconducting shim coils integrated within the 1 K refrigerator. I will also demonstrate that this method to adjust the 5 T field also enables the simultaneous opposite polarization of two adjacent target cells.

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“…The microwave frequency was fixed approximately halfway between the normal frequencies for positive and negative polarizations. Additional details can be found in Ref [11].…”

Section: Test Resultsmentioning

confidence: 99%

Magnetic Field Requirements for the CLAS12 Polarized Target

Lagerquist¹

2020

Proceedings of the 18th International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2019)

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“…Our second objective is to revisit cold circuit NMR techniques, which were used briefly for deuteron runs in JLab's Hall B polarized target [7] using static capacitors that did not allow remote tuning. We have added varactor diodes to allow remote tuning of the capacitance [8], and have been assessing their use not only for deuterons, but for protons as well. Tests of cold circuit NMR methods using in the CLAS12 polarized target refrigerator [9] have given unforeseen results.…”

Section: Developmentmentioning

confidence: 99%

Developing New Q-meters for NMR Measurements of Polarized Solids

Maxwell¹

2020

Proceedings of the 18th International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2019)

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Enhanced polarization of target nuclei can be measured via the complex impedance of a resonant circuit coupled to the target while sweeping the circuit through the nuclear Larmor frequency, observing the absorption or emission of energy by the spins in the material. For decades, solid polarized targets at Jefferson Lab have relied upon continuous-wave Nuclear Magnetic Resonance polarization measurements using Liverpool Q-meter systems. These Liverpool Q-meters are no longer produced, and replacing the aging components is becoming increasingly difficult. The polarized target group at Bochum has produced replacement Q-meters in the Liverpool style using modern components, and we are following their example while researching improvemnts to the technique. We discuss our efforts to produce improved Q-meters for upcoming experiments utilizing solid polarized targets in Jefferson Lab's Hall B.

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“…While revolutionary for its time with its introduction of phase-sensitive detection and proven reliable performance over 4 decades, the Liverpool Q-meter can no longer be manufactured according to the original design [6], as many RF components become obsolete. Due to the high demand and reduced availability, several groups (including our team) have worked on designing a system which would replace the Liverpool Q-meter and potentially add extra functionality [7,8]. Some of the SpinQuest specific requirements with respect to polarization measurements include: (i) ability to resolve polarization changes in the material along the beam direction, which would require operating up to nine NMR channels not including spares; (ii) ability to resolve polarization degradation during the ∼ 5 s long beam spill, which requires faster data acquisition for improved NMR statistics; (iii) addressing NMR signal degradation due to the hall's radiation environment and thus increased length of the resonant cable.…”

Section: Liverpoool Q-metermentioning

confidence: 99%

A New Target Polarization Measurement System for the Fermilab Polarized Drell-Yan SpinQuest Experiment

Yurov¹,

McGaughey²,

Mirabal-Martinez³

2020

Proceedings of the 18th International Workshop on Polarized Sources, Targets, and Polarimetry — PoS(PSTP2019)

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The Liverpool Q-meters were developed in the late 70s and became a de facto industry standard for NMR-based polarization measurements of polarized solid targets. However, it is becoming increasingly more difficult to produce the required number of q-meter channels as the components have become obsolete. The Los Alamos National Laboratory (LANL) group has developed a new NMR-based polarization measuring system following the basic Liverpool design. The new Q-meter will have multiple improvements, such as remote tuning and compact design. These improvements present opportunities for achieving a higher figure of merit for experiments exploiting polarized solid targets by potentially increasing the accuracy of the polarization measurements. The new LANL Q-meter is intended to be used in Fermilab SpinQuest/E1039 experiment which is part of the continuing worldwide effort to shed light on the nucleon spin composition puzzle. The current status of this work is presented.

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NMR Measurements for Solid Polarized Targets at Jefferson Lab

Cited by 3 publications

References 12 publications

Magnetic Field Requirements for the CLAS12 Polarized Target

Magnetic Field Requirements for the CLAS12 Polarized Target

Developing New Q-meters for NMR Measurements of Polarized Solids

A New Target Polarization Measurement System for the Fermilab Polarized Drell-Yan SpinQuest Experiment

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