Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility's initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type RF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a Helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. In addition, the potential for radiation-induced degradation of the graphite is discussed.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012) 20-25 May 2012. New Orleans, Louisian

Revisiting the 'Cotton Problem': A Comparative Analysis of Cotton Reforms in Sub-Saharan Africa

The cotton sector has been amongst the most regulated in Africa, and still is to a large extent in West and Central Africa (WCA), despite repeated refirm recommendations by international donors. On the other hand, orthodox refirms in East and Southern Africa (ESA) have not always yielded the expected results. This paper uses a stylised contracting model to investigate the link between market structure and equity and efficiency in sub-Saharan cotton sectors; explain the outcomes of refirms in ESA; and analyze the potential consequences of orthodox refirms in WCA. We argue that the level of the world price and of government intervention, the nature of pre-refirm institutional organisation, as well as the degree of parastatal inefficiency, all contribute to making refirms less attractive to firmers and governments in WCA today, as compared to ESA in the 1990s.We illustrate our arguments with empirical observations on the perfirmance of cotton sectors across sub-Saharan Africa

Examining the Determinants of Food Prices in Developing Asia

How the price of food is determined has become a critical issue, given the drastic surges in prices in recent years and the prevailing expectation of further increases. Along this line, this paper examines the sources of food price fluctuations in 11 developing Asian countries. The working model is a block vector autoregression (VAR), and 10 variables are classified into three blocks - world, region, and country - depending on their origin and nature. Empirical evidence shows that the regional shock plays a pivotal role in explaining the variations of domestic food prices, particularly at medium- to long-term horizons. Contrary to conventional belief, the world food price shock contributes little to the dynamics of domestic food prices in developing Asia. The findings suggest Asian food markets are more integrated regionally than with the world market. The short-run movements of domestic food prices are accounted for largely by the country's own shock. Taken together, our findings suggest that promoting food price stability would require efforts at the regional level as well as at the domestic level, reflecting the influence of region-specific factors. Extensions to the developing countries in other regions produce similar findings on the determination of food prices

Capital Flows and Real Exchange Rates in Emerging Asian Countries

This paper examines the nexus between capital flows and real exchange rate (RER) in emerging Asian countries using a dynamic panel-data model for 2000–2009. In contrast to previous studies, capital flows here are separated into foreign direct investment (FDI), portfolio investment, and other investment (bank loans) flows. Inflows and outflows are also treated separately in the model. The estimation results show that compositions of capital flows matter in determining impacts of the flows on the RER. Portfolio investment and other investment (including bank loans) bring in a faster RER appreciation than FDI. However, the magnitudes of appreciation among capital flows are close to each other. The increasing importance of merger and acquisition activities in FDI makes the flows behave closer to other forms of capital flows, especially portfolio investment. The estimation results also show that capital outflows bring about a greater degree of exchange rate adjustment than capital inflows. All in all, the results imply that the swift rebound of capital flows in the region could result in excessive appreciation of the (real) currencies, especially when capital flows are in a form of portfolio investment and bank loans