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.
Glenn was one of America's first and most celebrated astronauts and had a long public career that included two space flights, 24 years as a senator from Ohio and a run for the presidency. He was born July 18, 1921. He will go down in history as the first American to orbit the earth, one of the original seven Mercury astronauts. On Feb. 20, 1962, he climbed into his Friendship 7 capsule, lifted off from Cape Canaveral in Florida, circled the earth three times in five hours â and became a national hero. Zero G, and I feel fine, he said from his spacecraft.