Measuring gas temperature during spin-exchange optical pumping process

作者：Normand E; Jiang C Y; Brown D R; Robertson L; Crow L; Tong X

来源：10th International Conference on Polarised Neutrons for Condensed Matter Investigations, PNCMI 2014, China,Tibet Autonomous Region,Ali, 2014-09-15 to 2014-09-19.

DOI：10.1088/1742-6596/711/1/012012

• 3 He polarization
• Direct measurement
• Experimental methods
• Indirect measurements
• Neutron transmission
• Oven temperature
• Spin exchange optical pumping
• Spin relaxation

The gas temperature inside a Spin-Exchange Optical Pumping (SEOP) laser-pumping polarized3He cell has long been a mystery. Different experimental methods were employed to measure this temperature but all were based on either modelling or indirect measurement. To date there has not been any direct experimental measurement of this quantity. Here we present the first direct measurement using neutron transmission to accurately determine the number density of3He, the temperature is obtained using the ideal gas law. Our result showed a surprisingly high gas temperature of 380°C, compared to the 245°C of the3He cell wall temperature and 178°C of the optical pumping oven temperature. This experiment result may be used to further investigate the unsolved puzzle of the "X-factor"in the SEOP process which places an upper bound to the3He polarization that can be achieved. Additional spin relaxation mechanisms might exist due to the high gas temperature, which could explain the origin of the X-factor.

• 出版日期2016
• 单位Oak Ridge National Laboratory