Comparative Energy Dependence of Proton and Pion Degradation in Diamond

A comparative theoretical study of the damages produced by protons and pions, in the energy range 50 MeV - 50 GeV, in diamond, is presented. The concentration of primary defects (CPD) induced by hadron irradiation is used to describe material degradation. The CPD has very different behaviours for protons and pions: the proton degradation is important at low energies and is higher than the pion one in the whole energy range investigated, with the exception of the Delta33 resonance region, where a large maximum of the degradation exists for pions. In comparison with silicon, the most investigated and the most studied material for detectors, diamond theoretically proves to be one order of magnitude more resistant, both to proton and pion irradiation.Comment: 7 pages, 5 figure

A Theory of Dual Labor Markets with Application to Industrial Policy, Discrimination and Keynesian Unemployment

This paper develops a model of dual labor markets based on employers' need to motivate workers. In order to elicit effort from their workers, employers may find it optimal to pay more than the going wage. This changes fundamentally the character of labor markets. The modelis applied to a wide range of labormarket phenomena. It provides a coherent framework for understanding the claims of industrial policy advocates. It also can provide the basis for a theory of occupational segregation and discrimination which will not be eroded by market forces. Finally, the model provides the basis for a theory of involuntary unemployment.

The Taxation of Risky Assets

This paper reconsiders the effects of taxation on risky assets, recognizing the importance of variations in asset prices. We show that earlier analyses which assumed that depreciation rates are constant and that the future price of capital goods is known with certainty are very misleading, as guides to the effects of corporate taxes. We then examine the concept of economic depreciation in a risky environment, and show that depreciation allowances, if set ex-ante, should be adjusted to take account of future asset price risk. Some empirical calculations suggest that these adjustments are large, and have important implications for the burdens of, and non-neutralities in, the corporate income tax.

How Does the Market Value Unfunded Pension Liabilities?

We lead off by discussing a number of theoretical reasons for expecting various relationships between a firm's unfunded pension liability and its market value. We then discuss our doubts about the methodology of earlier papers which studied the empirical relation between funding and market value using standard cross sectional techniques. A modified cross sectional approach which alleviates some of these doubts, and a variable effect event study methodology which alleviates most of them are both employed to investigate the issues raised in the first part of the paper. Our conclusion confirms those of earlier studies that unfunded pension liabilities are accurately reflected in lower share prices.

Local Operations and Completely Positive Maps in Algebraic Quantum Field Theory

Einstein introduced the locality principle which states that all physical effect in some finite space-time region does not influence its space-like separated finite region. Recently, in algebraic quantum field theory, R\'{e}dei captured the idea of the locality principle by the notion of operational separability. The operation in operational separability is performed in some finite space-time region, and leaves unchanged the state in its space-like separated finite space-time region. This operation is defined with a completely positive map. In the present paper, we justify using a completely positive map as a local operation in algebraic quantum field theory, and show that this local operation can be approximately written with Kraus operators under the funnel property

The influence of initial impurities and irradiation conditions on defect production and annealing in silicon for particle detectors

Silicon detectors in particle physics experiments at the new accelerators or in space missions for physics goals will be exposed to extreme radiation conditions. The principal obstacles to long-term operation in these environments are the changes in detector parameters, consequence of the modifications in material properties after irradiation. The phenomenological model developed in the present paper is able to explain quantitatively, without free parameters, the production of primary defects in silicon after particle irradiation and their evolution toward equilibrium, for a large range of generation rates of primary defects. Vacancy-interstitial annihilation, interstitial migration to sinks, divacancy and vacancy-impurity complex (VP, VO, V2O, CiOi and CiCs) formation are taken into account. The effects of different initial impurity concentrations of phosphorus, oxygen and carbon, as well as of irradiation conditions are systematically studied. The correlation between the rate of defect production, the temperature and the time evolution of defect concentrations is also investigated.Comment: 14 pages, 8 figures, submitted to Nucl. Instrum. Meth. Phys. Res.