Evidence for enhanced desorption of hydrogen atoms from a Si 100 surface induced by slow highly charged ions

We report evidence for an enhanced desorption of hydrogen atoms from a Si 100 surface bombarded by 30 keV Xeq q 6?22 ions. The measured desorption yield amounts to 0.76 and 2.2 hydrogen atoms per incident Xe10 and Xe18 ion, respectively. For understanding the behaviour of hydrogen desorption from Si, another experiment was carried out to see the hydrogen signals as a function of time for about 140 min after deliberately introducing hydrogen into the target chamber and then shut off the valve. The results are discussed in the light of potential sputtering which essentially dominates for ions at higher charge states and the interpretation is supported by theoretical estimates

Taking it personally: the effect of ethnic attachment on preferences for regionalism

This article presents three related findings on regional decentralization. We use an original dataset collected in Uganda to establish, for the first time in a developing country context, that individuals have meaningful preferences over the degree of regional decentralization they desire, ranging from centralism to secessionism. Second, multilevel models suggest that a small share of this variation is explained at the district and ethnic group levels. The preference for regional decentralization monotonically increases with an ethnic group or a district’s average ethnic attachment. However, the relationship with an ethnic group or district’s income is U-shaped: both the richest and the poorest groups desire more regionalism, reconciling interest-based and identity-based explanations for regionalism. Finally, we show that higher individual ethnic attachment increases preferences for regionalism using fixed effects and a new matching method

Schalleistungspegel von Planetenradgetriebestufen mit gehaeusefestem Hohlrad

Available from TIB Hannover: RN 7998(1991,2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Multiple ionization of argon by positron impact. Can. J. Phys. 74 (1996) 373-375.

Recent experimental results for the multiple ionization of argon by positron impact have been reanalysed. Absolute cross sections for the double and triple ionization of argon were obtained from measured ratios of double-to-single and triple-to-single ionization, using known cross sections for single ionization and for positronium formation. Distinct differences compared to similar results for electron impact are noted. </jats:p

Multiple and inner shell ionization by positron and electron impact

Recent results for the K- and L-shell ionization of silver and gold, respectively, and the multiple ionization of argon, krypton, and xenon atoms by positron and electron impact will be discussed. The measured cross section ratios for triple relative to single ionization by positron impact decrease more rapidly towards threshold compared to electron impact. This behavior is similar compared to results obtained for the inner shell ionization of silver and gold, and attributed to the acceleration or deceleration which incident electrons or positrons, respectively, undergo in the target nuclear field