The Photomagnetoelectric Effect in Mercury Iodide
In order to investigate the transport properties of mercury iodide, measurements of photomagnetoelectric (PME) effect and photoconductivity (PC) have been carried out. The experimental results show the presence of trapping phenomena and a strong dependence of carrier lifetimes on the light injection level. The obtained values of the lifetimes are in the range 10-7-10-6 s.
High‐resolution Hgl2 x‐ray spectrometers
Several high‐resolution HgI2 x‐ray detectors have been made from single crystals grown from the vapor phase. Hole and electron transport properties and detector electrical characteristics are described. Measured mobility‐lifetime product for electrons is 8×10−5 cm2/V with a μe of 3 cm2/V sec. The mean energy per electron‐hole pair is 4.33 eV at 122 keV. Detectors up to 1 mm3 are described, and a resolution as low as 850 eV at 300 °K in air has been obtained for 5.9‐keV x rays, which suggests possible x‐ray flourescence detection applications.
Randi Weingarten, the American Federation of Teachers, and the Challenges of Policy Leadership in a Hostile Environment
Randi Weingarten is the president of the most vocal and influential teachers’ union, the American Federation of Teachers. Since rising through the ranks to AFT president in just two years, Weingarten is now a major, if not the most prominent, nongovernmental player in national education policy. She has earned deep respect from many educational policy actors. Likewise, Weingarten elicits withering criticism from others. This fascinating profile explains why, in such a brief period, she has proved to be a fierce, fearless, and effective leader under extraordinarily difficult circumstances. Her experience offers invaluable lessons applicable for others working in similarly intense policy arenas.