Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence

Intrinsic emittance and coherence of double-gate field emitter arrays

The intrinsic transverse emittance and coherence of double-gate field emitter array cathodes were explored experimentally including the low-energy electron diffraction and compared with theory

O mundo muçulmano em uma era global: a proteção dos direitos das mulheres The muslim world in a global age: protecting women's ights

As mulheres muçulmanas enfrentam, simultaneamente, três desafios. Em primeiro lugar, elas representam uma identidade islâmica que, com freqüência, está em conflito com regimes políticos modernos e com as elites dos Estados. Em segundo lugar, elas devem lutar contra os fundamentalistas islâmicos, cujas idéias, instituições e objetivos são por elas rejeitados com veemência. Por fim, e tão importante quanto os outros desafios, elas enfrentam no dia-a-dia a cultura patriarcal dominante nos lugares onde vivem. As questões relacionadas aos direitos das mulheres são agravadas pelas dificuldades que as mulheres muçulmanas encontram em uma cultura patriarcal na qual a mulher é geralmente caracterizada por estereótipos. Se, por um lado, a "solidariedade sem fronteiras" possibilitou a promoção de direitos das mulheres dentro e através das culturas, por outro, ela também se depara com questões sociais mais amplas e mais complexas. Embora essa solidariedade global sofra resistência em muitas partes do mundo muçulmano, o empowerment das mulheres é visto como o antídoto mais eficaz contra o extremismo no mundo muçulmano. Este trabalho pretende contextualizar a análise de gênero nos âmbitos cultural, econômico e político, de modo a lidar com três questões: (1) por que as mulheres muçulmanas se tornaram agentes de mudança, reforma e democratização no mundo globalizado? (2) qual o impacto da globalização sobre as mulheres muçulmanas e sobre a ascensão do feminismo islâmico? (3) de que maneira as mulheres muçulmanas podem respeitar a integridade de sua cultura, ao mesmo tempo que se mantêm receptivas a valores, idéias e instituições universais?<br>Muslim women encounter three fronts simultaneously. First, they represent an Islamic identity that more often than not is in conflict with modern political regimes and state elites. Secondly, they must fight against Islamic fundamentalists, whose ideas, institutions, and goals they vehemently reject. And finally, and just as importantly, they face a mundane confrontation with a prevailing patriarchal culture within which they live. Questions of women's rights are exacerbated by difficulties Muslim women encounter in a patriarchal culture in which women are often characterized by stereotypes. The "borderless solidarity" has led to the promotion of women's rights across and within cultures, but it stands in a problematic relationship to broader, more complex social issues. Although this global solidarity is resisted in many parts of the Muslim world, women's empowerment is seen as the most effective antidote to extremism in the Muslim world. This paper attempts to contextualize gender analysis in the cultural, economic, and political domains, while addressing three questions: (1) why have Muslim women become the agents of change, reform, and democratization in a globalizing world? (2) what impact has globalization on Muslim women and the rise of Islamic feminism? (3) how could Muslim women maintain the integrity of their culture while at the same time remain receptive to universal values, ideas, and institutions