Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature

Abstract

The 1996 data taking of the SMC experiment used polarized protons to measure the spin dependent structure function g 1 of the proton. Three liters of solid granular ammonia were irradiated at the Bonn electron linac in order to create the paramagnetic radicals which are needed for polarizing the protons. Proton polarizations of (90 2:5) % were routinely reached. An analysis based on a theoretical line-shape for spin-1 systems with large quadrupolar broadening was developed which allowed the nitrogen polarization in the ammonia to be determined with a 10 % relative error. The measured quadrupolar coupling constant of 14 N agrees well with earlier extrapolated values. The polarization of the nitrogen nuclei was measured as a function of the proton polarization in order to provide a test of the equal spin temperature (EST) hypothesis. It was found to be closely valid under the dynamic nuclear polarization conditions with which the protons are polarized. Large deviations from EST could be induced by cross relaxing the proton and nitrogen spin systems at low elds. Nitrogen polarizations up to 40% were reached by these means.

The double spin asymmetry of nitrogen in elastic and quasielastic kinematics from a solid ammonia dynamically polarized target

“…In a work by B. Adeva et al [14] the nitrogen asymmetry in a similar ammonia target was measured relative to the proton asymmetry and compared to a calculation based on the EST model. A substantial 14 N polarization level of about 10% was reported for the highly polarized target,in agreement with the EST model.…”

“…Keller [27]. The nitrogen polarization level was calculated with respect to the proton polarization based on the EST model as calculated by Adeva et al [14].…”

“…10 cannot be used. B. Adeva et al [14] and O. A. Rondon [15] used shell model approximations to determine the nitrogen asymmetry relative to the proton asymmetry.…”

“…Previous works has shown that the spin 1 + 14 N is also polarized in the process to approximately 10%, and hence contributes a nontrivial background to scattering asymmetry experiments [13][14][15][16]. Specifically, experiments that utilize the asymmetry of the scattering cross section as a probe of the nucleon structure must take into account the asymmetry contribution by the polarized nitrogen nuclei.…”

Search for Exotic Gluonic States in the Nucleus via Polarized Deep Inelastic Scattering

“…Much in the same way that proton polarization is enhanced using the high polarization of electrons in DNP, the polarization of nitrogen in 14 NH 3 or lithium in LiH may be enhanced using the high polarization of proton spins from DNP. Significant polarization in nitrogen has been achieved by the SMC collaboration using cross-relaxation between the different spin species [10]. Nitrogen polarization of 40% was reached by altering the magnetic field to bring the proton and nitrogen spin reservoirs into thermal contact.…”