Three-dimensional imaging of spin polarization of alkali-metal vapor in optical pumping cells

Abstract

We present detailed images of the Rb polarization in a high-pressure optical pumping cell. Images taken at high magnetic field strengths (≈37 G) yield precise information on the relative occupation probability of the hyperfine Zeeman sublevels. Low-field (⩽4 G) images yield very high resolution (less than 1 mm) maps of the spatial distribution of the Rb polarization. For optical pumping in the presence of high-pressure buffer gases, the measured populations of the hyperfine magnetic sublevels are shown to be well described by a spin temperature, even though the Rb–Rb spin exchange rate is much smaller than the rates of optical pumping or electron-randomizing Rb–Xe collisions in the buffer gas.

Experimental studies of rubidium absolute polarization at high temperatures

“…In order to optimize the Rb ͑and thus Xe͒ polarization, a low-cost and compact polarization imaging device was developed which enables measurement of the distribution of the absolute Rb polarization in the pumping cell. The methodology and first experimental results of absolute Rb polarization imaging in high-pressure optical pumping cells at a temperature of Tϭ100°C were recently published by Baranga et al 9 and Young et al 10 Spin exchange optical pumping at temperatures higher than 100°C causes the spin exchange rate between Rb and Xe to be larger and therefore the time required to polarize Xe atoms is significantly shorter.Experimental results of the absolute 85 Rb polarization in high pressure optical pumping cells for temperatures up to 180°C are presented. The measured, volume-averaged absolute Rb polarization sets a limit on the maximum achievable Xe nuclear polarization at high temperatures.…”

Measurement of rubidium and xenon absolute polarization at high temperatures as a means of improved production of hyperpolarized 129Xe

“…This paper presents a method for the measurement of the absolute rubidium and xenon polarization achievable, in situ. The physics of absolute polarization imaging of alkaline atoms at temperatures up to 100°C has been published recently by Young et al 22 and Baranga et al 19 In this contribution we show experimental results of both the absolute 85 Rb and 129 Xe polarization in high pressure optical pumping cells for higher temperatures up to 180°C. Furthermore, we studied the penetration of light from a broadband pumping laser into the cell in the regime of high Rb number densities (n Rb b10 14 cm…”

“…The low-field NMR apparatus also allows the measurement of protons in water thereby enabling the determination of the absolute Xe polarization in situ. The two diagnostic devices, which are low-cost devices, are further developments of systems recently published by Young et al 22 Baranga et al 19 and Saam et al…”

Gradient-echo 3D imaging of Rb polarization in fiber-coupled atomic magnetometer

“…Conventional NMR-inspired and non-conventional methods have already been demonstrated for imaging distributions of atomic spins in vapors: 2D imaging with the projection reconstruction method [1], 2D optical imaging with gradient slice selection [2], imaging of Rb polarization by applying a one-dimensional gradient and light-beam profiling with a photo-diode [3]. Optical measurements allow fast image generation, since only one excitation is needed to obtain the image of a slice, but require a special optical configuration.…”