The initial beam diameter (4 mm) was reduced to 80 Î¼m. However, this spatial resolution is not high enough. To focus beam more, a small positron source should be fabricated. In this work, we developed a positron microbeam by a small source, a solid neon moderator, magnetic lenses and a SEM optics. In addition, a beam pulsing system was also developed which allows the positron annihilation lifetime spectroscopy (PALS) measurement.
The first American to orbit the Earth, John Glenn made history again when, at the age of 77, he became the oldest person to travel in space. But before he was nationally recognized as a hero, he had put his life on the line for his country many times.
Share your tributes to Sally Ride. Ride flew into orbit aboard the Space Shuttle Challenger in 1983 to become America's first woman in space. She took a second trip aboard the same shuttle one year later. The first woman in space was Soviet cosmonaut Valentina Tereshkova, who orbited the Earth 48 times in 1963.