453 research outputs found
Significance of the high charge state of projectile ions inside the target and its role in electron capture leading to target-ionization phenomena
Get PDFThe K x-ray spectra of different targets (Cu, Zn, and Ge) induced by 3-5 MeV/u Si projectile ions have been measured to determine the K-shell ionization cross section. A significant difference is observed between the measurements and theoretical estimates, with the latter being about 50% below the experimental results. This underestimation is attributed to the charge exchange from the target K shell to projectile K and L shells. Such an observation can only be possible if the projectile ions attain up to H- and He-like charge states. Corresponding projectile charge state fractions have been evaluated from the Lorentzian charge state distribution, where the mean charge state is taken from the Fermi gas model [W. Brandt, Phys. Rev. Lett. 30, 358 (1973)PRLTAO0031-900710.1103/PhysRevLett.30.358] and the width from the Novikov and Teplova approach [Phys. Lett. A 378, 1286 (2014)10.1016/j.physleta.2014.03.004]. The sum of the direct ionization cross section and K-K+K-L capture cross sections gives a good agreement with the measured cross sections. Furthermore, we have validated this methodology with available data for a Si ion on Ti target. Such results may be useful in many solid target-based applications.Fil: Chatterjee, Soumya. University Of Kalyani; IndiaFil: Sharma, Prashant. Weizmann Institute Of Science Israel; IsraelFil: Singh, Shashank. Panjab University; IndiaFil: Oswal, Mumtaz. No especifíca;Fil: Kumar, Sunil. No especifíca;Fil: Montanari, Claudia Carmen. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mitra, D.. University Of Kalyani; IndiaFil: Nandi, T.. No especifíca
Understanding the mechanisms of L-shell x-ray emission from Os atoms bombarded by 4-6 MeV/u fluorine ion
No full textThe L-subshell ionization mechanism is studied in an ultra-thin Os target bombarded by 4-6 MeV/u fluorine ions. Multiple ionization effects are considered through the change of fluorescence and Coster-Kronig yields while determining L-subshell ionization cross sections from L x-ray production cross sections. The present experimental values are compared with various theoretical approximations: (i) the relativistic semi-classical approximation (RSCA), (ii) the shellwise local plasma approximation (SLPA), and (iii) the ECUSAR theory. We also take into account the vacancy sharing among the subshells by the coupled-states model (CSM) and the electron capture (EC) by a standard formalism. We find that the ECUSAR-CSM-EC describes the measured excitation function curves the best. However, the theoretical calculations are still about a factor of two smaller than the measured values even though the recent fluorescence and Coster-Kronig yields are considered. Hence, a re-evaluation of these parameters is a challenge for the theoretical works. Whatsoever, this work leads to demonstrate that in the present energy range the heavy-ion induced inner-shell ionization of the heavy atoms can be understood by combining the direct Coulomb ionization, the electron capture, and the vacancy sharing among subshells, together with optimizing the atomic parameters. Optimization of the atomic parameters shows that our experimental results agree with theoretical vacancy production theories if the L1 fluorescence yield is nearly doubled. Such a optimization is validated by the proton induced L-shell ionization data of uranium atoms.Fil: Chatterjee, Soumya. University Of Kalyani; IndiaFil: Kumar, Sunil. No especifíca;Fil: Kumar, Sarvesh. Universidade Nova de Lisboa; PortugalFil: Oswal, M.. No especifíca;Fil: Mohanty, Biraja. Panjab University; IndiaFil: Mehta, D.. Panjab University; IndiaFil: Mitra, D.. University Of Kalyani; IndiaFil: Mendez, Marta Patricia Alejandra. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mitnik, Dario Marcelo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Montanari, Claudia Carmen. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Sarkadi, L.. Institute for Nuclear Research of the Hungarian Academy of Sciences; HungríaFil: Nandi, T.. Inter-University Accelerator Centre; Indi
Why does caste still influence access to agricultural credit?
Get PDFIn India, caste shapes access to a variety of resources and outcomes mainly through its influence on inter-generational prosperity, but also the linked phenomenon of discrimination. This paper examines whether caste-based differences in access to formal agricultural loans reflect discrimination in banks' lending. We find, first, that there are significant caste-based differences in loan application rates. Having controlled for the decision to seek credit and various borrower characteristics, we also find that loan approval rates across castes are largely equal across three of four caste-groups, but that Scheduled Tribe (ST) borrowers are less likely to have loans approved. Through a simulation-based approach, we show that these lower approval rates for STs are most likely not explained by unobserved credit histories, suggesting that banks do discriminate against STs. We discuss the policy implications that arise from these finding
RCTs for better policy? The case of public systems in developing countries
Get PDFThis paper considers the application of randomised controlled trials (RCTs) to improve public systems in developing countries. Arguing that existing critiques of RCTs as to problems with extrapolation and narrowness of scope are especially relevant in this context, I consider the claim that these shortcomings can be ameliorated through better causal explanations. I analyse how theoretical mathematical models are used to construct causal explanations, and argue that it is still difficult to extrapolate or address the subjectivity inherent in the choice of interventions. I illustrate these arguments using two prominent RCTs that have trialled interventions to improve government schools in India
Comparing private and government schools in India: the devil is in the maths
Get PDFRecent research shows that the gap in learning achievement between private and government schools in India can be explained away by self-selection. Analysing four rounds of panel data and distinguishing between ‘knowing’ and ‘applying’ dimensions of maths learning, I find that there is no private school advantage in the applying domain but that there is an advantage in the knowing domain
Economic Structures and Dynamics: A Morphogenetic View
Get PDFEconomic systems are characterised by constant change and evolution, and explanations concerning the properties of economic structures have received sustained interest. The structure of a system and its dynamics can influence each other through feedback effects. In this paper we offer a brief survey of how structure plays a role in dynamic economic theory – in particular, growth and business cycles. We propose a morphogenetic framework, inspired from the creation of forms in developmental biology, as a potential unifying approach for studying economic structures and their dynamics. We synthesise insights from three different strands of research, focusing on the role of coupling, diffusion and symmetry-breaking. We highlight their existing and prospective links with economics
The implications of foreign aid fungibility for development assistance
Get PDFA foreign aid or foreign lending policy that focuses exclusively on project financing may have unintended consequences, report the authors. New research shows that aid intended for crucial social and economic sectors often merely substitutes for spending that recipient governments would have undertaken anyway and the funds that are thereby freed up are spent for other purposes. If the aid funds something that would have been done anyway, traditional ways of evaluating the aid's effectiveness are not really accurate. Ifaid funds are fungible and the recipient's public spending program is unsatisfactory, project lending may not be cost-effective. If the recipient's public spending program is satisfactory, perhaps the donor should finance a portion of it instead of financing individual projects. One solution to the problem of fungibility, then, is that donors could tie assistance to an overall public spending program (in the recipient country) that provides adequate resources to crucial sectors. To make this kind of reform operational, the authors propose a new lending instrument: a public expenditure reform loan (PERL). A PERL would tie an institution's lending strategy to the recipient country's achievement of mutually agreed-upon development goals. Everyone agrees that better donor coordination is needed, but it has been difficult to achieve because some donors tend to prefer projects (usually with the national flag flying over them). By agreeing on a public expenditure program and financing a portion of it, the World Bank credibly ask other donors to do the same.Payment Systems&Infrastructure,Development Economics&Aid Effectiveness,Gender and Development,Decentralization,Economic Adjustment and Lending,Development Economics&Aid Effectiveness,Poverty Assessment,National Governance,Economic Adjustment and Lending,Public Sector Economics&Finance
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