A liquid helium target system for a measurement of parity violation in neutron spin rotation

A liquid helium target system was designed and built to perform a precision measurement of the parity-violating neutron spin rotation in helium due to the nucleon-nucleon weak interaction. The measurement employed a beam of low energy neutrons that passed through a crossed neutron polarizer--analyzer pair with the liquid helium target system located between them. Changes between the target states generated differences in the beam transmission through the polarizer--analyzer pair. The amount of parity-violating spin rotation was determined from the measured beam transmission asymmetries. The expected parity-violating spin rotation of order $10^{-6}$ rad placed severe constraints on the target design. In particular, isolation of the parity-odd component of the spin rotation from a much larger background rotation caused by magnetic fields required that a nonmagnetic cryostat and target system be supported inside the magnetic shielding, while allowing nonmagnetic motion of liquid helium between separated target chambers. This paper provides a detailed description of the design, function, and performance of the liquid helium target system.Comment: V2: 29 pages, 14 figues, submitted to Nucl. Instrum. Meth. B. Revised to address reviewer comment

Eureka and beyond: mining's impact on African urbanisation

This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-states’ urbanisation trends have shown considerable variation over the past half century. The current surge in ‘new’ mining countries and the slow-down in ‘old’ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)

Constructing Exactly Solvable Pseudo-hermitian Many-particle Quantum Systems by Isospectral Deformation

A class of non-Dirac-hermitian many-particle quantum systems admitting entirely real spectra and unitary time-evolution is presented. These quantum models are isospectral with Dirac-hermitian systems and are exactly solvable. The general method involves a realization of the basic canonical commutation relations defining the quantum system in terms of operators those are hermitian with respect to a pre-determined positive definite metric in the Hilbert space. Appropriate combinations of these operators result in a large number of pseudo-hermitian quantum systems admitting entirely real spectra and unitary time evolution. Examples of a pseudo-hermitian rational Calogero model and XXZ spin-chain are considered.Comment: To appear in the Special Issue PHHQP 2010, International Journal of Theoretical Physics; 16 pages, LateX, no figur

Plasticity in Diurnal Activity and Temporal Phenotype During Parental Care in European Starlings, Sturnus Vulgaris

We used an automated radiotelemetry system to determine diurnal patterns of activity and temporal phenotype (onset and cessation of activity) in female European starlings during breeding. Parental care is thought to be the most ‘costly’ part of reproduction, with high rates of intense activity due to foraging and provisioning for chicks, so we predicted that variation in timing of activity should be closely related to breeding success. Diurnal variation in activity varied systematically with breeding stage in a way consistent with specific demands of each phase of parental care: incubating females were more active late in the day (1600–1800 hours), while chick-rearing females were more active early in the morning (0700–1100 hours). There was marked individual variation in timing of onset, and to a lesser extent cessation, of activity, e.g. chick-rearing females first became active 7–127 min after morning civil twilight, with low to moderate repeatability within and among breeding stages (individual explained 2–62% of total variation). On average, females were active later, and ceased being active earlier, during chick rearing compared with incubation. Chick-rearing birds had a longer active day, but only by 2.3% (36% of the seasonal increase in total available daylength). Thus, chick-rearing females were relatively less active (‘lazier’), which is consistent with the idea that parents work more efficiently rather than simply working harder. We found little evidence that chick-rearing activity was associated with variation in measures of current reproduction (provisioning rate, number and quality of chicks), future fecundity (initiating a second brood, cumulative 2-year productivity) or survival (local return rate). Our study demonstrates that time-keeping mechanisms show plasticity in response to reproductive state and can be modulated by ‘biotic’ (e.g. prey availability) or ‘social’ time (demands of parental care)

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

CSR Business as Usual? The Case of the Tobacco Industry

Tobacco companies have started to position themselves as good corporate citizens. The effort towards CSR engagement in the tobacco industry is not only heavily criticized by anti-tobacco NGOs. Some opponents such as the the World Health Organization have even categorically questioned the possibility of social responsibility in the tobacco industry. The paper will demonstrate that the deep distrust towards tobacco companies is linked to the lethal character of their products and the dubious behavior of their representatives in recent decades. As a result, tobacco companies are not in the CSR business in the strict sense. Key aspects of mainstream CSR theory and practice such as corporate philanthropy, stakeholder collaboration, CSR reporting and self-regulation, are demonstrated to be ineffective or even counterproductive in the tobacco industry. Building upon the terminology used in the leadership literature, the paper proposes to differentiate between transactional and transformational CSR arguing that tobacco companies can only operate on a transactional level. As a consequence, corporate responsibility in the tobacco industry is based upon a much thinner approach to CSR and has to be conceptualized with a focus on transactional integrity across the tobacco supply chain

Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values