Activities observed in iridium after neutron bombardment. Remarks on a paper by H. H. Hennies and A. Flammersfeld
Recently Hennies and Flanunersfeld (Naturwissenschaften, 47: 11(1960)) reported ths observation of a new 47-sec activity produced by irradiating Ir powder with slowed-down neutrons. The activity was tentatively assigned to Ir/ sup 194//sup m/. Beta activities, previously ascribed to Ir/sup 192//sup m/, were reassigned to Ir/sup 194//sup m/. A repetition of the experiment on the bombardment of Ir/sup 193/ with slow neutrons (Phys. Rev. Lettens, 3: 4S(1959)) confirmed the previous conclusions and ruled out a 47-sec period in Ir/sup 192/ or Ir/sup 19 / 4>s. It was suggested that the Hennies and Flammersfeld results may be partly ascribed to a Rh impurity and partly to the effect of fast neutrons. (J.S.R.)
Gertrude Scharff-Goldhaber, 1911–1998: Nuclear Physicist Against the Odds
The author’s mother, Gertrude Scharff-Goldhaber, was a prominent nuclear physicist who had to overcome steep odds to pursue her work. She lived and worked at a time when it was very uncommon for any woman to be a scientist and even more uncommon for a mother of young children. She also faced Nazi persecution and a series of other challenges in growing up in Germany. Drawing on personal conversations and testimony of her friends, this brief account includes a number of intimate details to illustrate some of the difficulties she faced and the zest for life and for understanding the world that pushed her forward anyway. Details of her work and a bibliography are included.
Ionization by drift and ambipolar electric fields in electronegative capacitive radio frequency plasmas.
Unlike α- and γ-mode operation, electrons accelerated by strong drift and ambipolar electric fields in the plasma bulk and at the sheath edges are found to dominate the ionization in strongly electronegative discharges. These fields are caused by a low bulk conductivity and local maxima of the electron density at the sheath edges, respectively. This drift-ambipolar mode is investigated by kinetic particle simulations, experimental phase-resolved optical emission spectroscopy, and an analytical model in CF(4). Mode transitions induced by voltage and pressure variations are studied.