• The first continuous flow-type equipment in the world developed for spin-polarized xenon gas production.
• The equipment can increase ten thousand times the signal sensitivity of NMR.
• The equipment can make instantaneous imaging of the cavity gases.
• High precision and fast imaging of the blood flow in the brain is expected to contribute to the prevention of cerebral infarction.

The Photonics Research Institute of the National Institute of Advanced Industrial Science and Technology (AIST), in cooperation with Toyoko Kagaku Co., Ltd. (Toyoko Kagaku), has succeeded in development of continuous flow-type equipment for spin-polarized xenon production based on the flow-type spin-polarized xenon production technology developed by AIST. This technology will lead to the development of medical equipment for instantaneous high precision diagnosis of the lung functions, and will represent a significant advance in technology for preventive diagnosis of brain infarction as it provides a highly accurate and fast imaging of the blood flow in the brain.

• This is the first equipment for continuous flow production of spin-polarized xenon, developed for practical use. To date, the equipment for spin-polarized xenon production has been of reservoir type using a container of Pyrex glass with a capacity of one liter. In this equipment, small pieces of the alkaline metal rubidium (Rb) and xenon gas with pressure of around 3 atmospheres are sealed in a cylinder cell of 70 mm diameter and 150 mm length made of Pyrex glass with a flat window for irradiation. The cell is heated to 100 Åé in a magnetic field of around 100 G and irradiated by semiconductor laser light of 795 nm in wavelength, circularly polarized through a quarter-wave plate. After 20 minutes, spin-polarized xenon gas is produced with a polarization rate of 5%. So far, the produced gas has been used for experiments by being extracted little by little from the valve attached to the cell.
• The equipment newly developed by AIST makes it possible to attain continuous production of spin-polarized xenon with high productivity.
  
  Based on the fundamental aspects of the production of spin-polarized xenon, AIST has thoroughly investigated the structure and materials for the cell. In this equipment, to increase the laser adsorption coefficient, heating temperatures at the polarization cell are set at 200 to 400^oC, the vapor pressure of Rb increases, and the irradiation cell gap is set at 1 mm, resulting in equipment with high polarization rate and high production per unit of time (Patents No. Hei-11-309126 and No. Hei-11-248809).
• Taking advantage of the high productivity, this technology will become the base for expanding the range of applications for spin-polarized gas.
  
  In terms of simultaneous increase of polarization rate and production per unit of time, the equipment here developed is more advanced than similar equipment developed in Europe and America. Thus, the technology is expected to accelerate practical uses of medical equipment that makes it possible to carry out instantaneous diagnostic of lung functions and of medical technologies for diagnosis and prevention of cerebral infarction based on high-accuracy and high speed imaging of the blood flow in the brain. The possibility of producing polarized xenon gas on demand will make the use of MRI equipment much easier. Moreover, the application fields will extend beyond the field of medical applications to various measurements, e.g., the pore size distribution and the dynamic gas analysis in porous materials such as catalysts, as well as the imaging of pithy tissue in firebricks for blast furnaces.

Results will be presented at the 49th Conference of Applied Physics to be held at the Shonan Campus of Tokai University from March 27 to March 30, 2002.