Lattice Design in High-energy Particle Accelerators

This lecture gives an introduction into the design of high-energy storage ring lattices. Applying the formalism that has been established in transverse beam optics, the basic principles of the development of a magnet lattice are explained and the characteristics of the resulting magnet structure are discussed. The periodic assembly of a storage ring cell with its boundary conditions concerning stability and scaling of the beam optics parameters is addressed as well as special lattice insertions such asdrifts, mini beta sections, dispersion suppressors, etc. In addition to the exact calculations that are indispensable for a rigorous treatment of the matter, scaling rules are shown and simple rules of thumb are included that enable the lattice designer to do the first estimates and get the basic numbers 'on the back of an envelope'.Comment: 40 pages, contribution to the CAS - CERN Accelerator School: Advanced Accelerator Physics Course, Trondheim, Norway, 18-29 Aug 2013. arXiv admin note: substantial text overlap with arXiv:1303.651

Workforce Development and the Disadvantaged: New Directions for 2009 and Beyond

Assesses the 1998 Workforce Investment Act's successes and limitations. Outlines the changes needed, such as increasing funding and consolidating programs, for a more effective public workforce training system, especially for the young and hard-to-employ

Introduction to Transverse Beam Dynamics

In this chapter we give an introduction to the transverse dynamics of the particles in a synchrotron or storage ring. The emphasis is more on qualitative understanding rather than on mathematical correctness, and a number of simulations are used to demonstrate the physical behaviour of the particles. Starting from the basic principles of how to design the geometry of the ring, we review the transverse motion of the particles, motivate the equation of motion, and show the solutions for typical storage ring elements. Following the usual treatment in the literature, we present a second way to describe the particle beam, using the concept of the emittance of the particle ensemble and the beta function, which reflects the overall focusing properties of the ring. The adiabatic shrinking due to Liouville's theorem is discussed as well as dispersive effects in the most simple case.Comment: 19 pages, contribution to the CAS-CERN Accelerator School: Ion Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Bailey, CERN-2013-00

Reconnecting Young Black Men: What Policies Would Help?

The term "disconnected youth" refers to young people who have been out of school and out of work for considerable periods of time – like a year or more. They are not temporarily "idle" but are fully disconnected from the mainstream worlds of schooling and work. They may be incarcerated or on parole or probation; they might be aging out of foster care or still attached to their nuclear families. But, overwhelmingly, they come from low-income families and often grow up in poor and relatively segregated neighborhoods. Of all racial and gender groups, young black men are by far the most likely to become "disconnected" from school and work. In the year 2000 – when the labor market was very tight – over 17 percent of all young black men between the ages of 16 and 24 were disconnected, while the comparable percentages for other race/gender groups were much lower. Indeed, this figure implies that one out of every six young black men was disconnected from both school and work at that time

Higher-order Modes and Heating

This chapter gives a basic introduction to the problem of wake fields created in the beam-surrounding environment and the resulting heating effects of machine components. The concepts are introduced and scaling rules derived that are exemplified by several observations from operation of the LHC and other machines.Comment: 14 pages, contribution to the CAS-CERN Accelerator School: Superconductivity for Accelerators, Erice, Italy, 24 April - 4 May 2013, edited by R. Baile

Introduction to Longitudinal Beam Dynamics

This chapter gives an overview of the longitudinal dynamics of the particles in an accelerator and, closely related to that, the issue of synchronization between the particles and the accelerating field. Beginning with the trivial case of electrostatic accelerators, the synchronization condition is explained for a number of driven accelerators like Alvarez linacs, cyclotrons and finally synchrotrons and storage rings, where it plays a crucial role. In the case of the latter, the principle of phase focusing is motivated qualitatively as well as on a mathematically more correct level and the problem of operation below and above the transition energy is discussed. Throughout, the main emphasis is more on physical understanding rather than on a mathematically rigorous treatment.Comment: 15 pages, contribution to the CAS-CERN Accelerator School: Ion Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Bailey, CERN-2013-00

Why do small establishments hire fewer blacks than large ones

This paper shows that small establishments are much less likely to hire and employ blacks than are larger establishments. A number of possible explanations for this result are considered, such as differences across establishments in application rates from blacks, skill needs, locations, and recruiting behavior. Although these factors can account for some of the differences between small and large employers, much remains unexplained. The results suggest that discrimination in hiring may be much more pervasive at smaller establishments than larger ones.

Employer Demand, AFDC Recipients, and Labor Market Policy

This paper discusses the potential labor market prospects of AFDC recipients who will be required to work under the new welfare legislation. Various characteristics of available low-skill jobs are compared with those of long-term AFDC recipients, and more general evidence on the labor market experiences of welfare recipients is reviewed. From these data, the potential availability of employment and wage levels that recipients will face in the labor market is inferred. The data suggest that job availability for long-term recipients will be quite limited, especially in the short run; many will likely be plagued by lengthy durations of nonemployment, as well as high job turnover and low wages and benefits when they do work. The implications of these findings for labor market policy are then discussed.

Wages, Employer Costs, and Employee Performance in the Firm

In this paper I use data from a survey of firms to estimate the effects of a firm's wage level on several measures of its hiring costs and the characteristics and performance of its employees. These measures include the previous experience and current tenure of its employees; subjective productivity scores for these employees; job vacancy rates; perceived ease of hiring qualified workers for the firs; and hours spent hiring and training new workers. In doing so, I distinguish the case of high wages imposed on s firm by unions from that in which the firm might be choosing its wage level in order to maximize its profits. I also provide some rough measures of the extent to which firms offset their high wage costs in each case. The results show generally positive effects of firm wages on employee experience and tenure as well as on subjective productivity scores. The firm's wages generally have negative effects on job vacancy rates and positive effects on the perceived ease of hiring qualified workers. Training time is also reduced. While the magnitude of each individual effect may not always be large or even significant, their combined effects suggest that firms offset a good deal of their higher wage costs through improved productivity and lower hiring and turnover costs among their employees.

On the Rationality of Black Youth Unemployment

In this paper I provide some evidence on the question of whether the behavior of unemployed young blacks, whose reservation wages are relatively high and whose jobless spells are very lengthy, reflect rational maximizing choices. To do this, I use a simple income-maximizing job search model to imply employment probabilities and various elasticities which are compared to those which are actually observed for young blacks.The results show that, for reasonable discount rates, the employment probabilities implied by income-maximization are consistent with those observed for young blacks. The elasticities of reservation wages with respect to nonwage income that are implied by income-maximizing are also consistent with those estimated econometrically for this group. This was true despite the many assumptions embodied in this model whose validity fora sample of low-income youth is highly questionable.The evidence thus suggests that young blacks are making economically rational choices by choosing high reservation wages and lengthy spells without jobs.