Photoassociation adiabatic passage of ultracold Rb atoms to form ultracold Rb_2 molecules

We theoretically explore photoassociation by Adiabatic Passage of two colliding cold ^{85}Rb atoms in an atomic trap to form an ultracold Rb_2 molecule. We consider the incoherent thermal nature of the scattering process in a trap and show that coherent manipulations of the atomic ensemble, such as adiabatic passage, are feasible if performed within the coherence time window dictated by the temperature, which is relatively long for cold atoms. We show that a sequence of ~2*10^7 pulses of moderate intensities, each lasting ~750 ns, can photoassociate a large fraction of the atomic ensemble at temperature of 100 microkelvin and density of 10^{11} atoms/cm^3. Use of multiple pulse sequences makes it possible to populate the ground vibrational state. Employing spontaneous decay from a selected excited state, one can accumulate the molecules in a narrow distribution of vibrational states in the ground electronic potential. Alternatively, by removing the created molecules from the beam path between pulse sets, one can create a low-density ensemble of molecules in their ground ro-vibrational state.Comment: RevTex, 23 pages, 9 figure

Judicial Incentives and Indeterminacy in Substantive Review of Administrative Decisions

Uppsatsen tydliggör och beskriver innehållet i elva lokala överenskommelser (LÖK) mellan civilsamhället och offentlig sektor. Studien visar också hur relationen mellan parterna avspeglas i texterna. Uppsatsen visar också på hur olika idéer och synsätt i överenskommelserna kan få praktiska konsekvenser för civilsamhället

Judicial Incentives and Indeterminacy in Substantive Review of Administrative Decisions

In the Chevron and State Farm cases the Supreme Court announced what appeared to be controlling standards for substantive review of administrative decisions. Instead, the Chevron framework has broken down, and State Farm has been all but ignored by agencies and the courts, including the Supreme Court. This article accounts for this breakdown by analyzing the impact of judicial incentives on substantive review in administrative law

The Enlightenment of Administrative Law: Looking Inside the Agency for Legitimacy

This article’s investigation into the “agency for legitimacy” proceeds in five steps: Part I introduces the concept of “administrative constitutionalism,” which encompasses the debate over what should be the role and nature of public administration to ensure its legitimacy. It then lays out the elements of the rational-instrumental and deliberative-constitutive paradigms and explains how they contribute to administrative constitutionalism respectively from the outside-in and inside-out. Part II provides a brief history of administrative constitutionalism, which reveals there have been ongoing tensions between two paradigms—and thus between outside in and inside out accountability—since the 1880s. Part III elaborates on the authors’ argument that the current emphasis on the rational-instrumental model has been administrative constitutionalism unsustainable. Part IV argues that acknowledging and developing the deliberative-constitutive paradigm will strengthen administrative constitutionalism by admitting the existence of agency discretion and by looking for realistic ways to make it accountable. Finally, Part V offers a case study in how the deliberative-constitutive paradigm can contribute to administrative constitutionalism.The Kay Bailey Hutchison Center for Energy, Law, and Busines

Pulsed Adiabatic Photoassociation via Scattering Resonances

We develop the theory for the Adiabatic Raman Photoassociation (ARPA) of ultracold atoms to form ultracold molecules in the presence of scattering resonances. Based on a computational method in which we replace the continuum with a discrete set of "effective modes", we show that the existence of resonances greatly aids in the formation of deeply bound molecular states. We illustrate our general theory by computationally studying the formation of $^{85}$Rb$_2$ molecules from pairs of colliding ultracold $^{85}$Rb atoms. The single-event transfer yield is shown to have a near-unity value for wide resonances, while the ensemble-averaged transfer yield is shown to be higher for narrow resonances. The ARPA yields are compared with that of (the experimentally measured) "Feshbach molecule" magneto-association. Our findings suggest that an experimental investigation of ARPA at sub-$\mu$K temperatures is warranted.Comment: 20 pages, 11 figure

Nonlinearity and pixel shifting effects in HXRG infrared detectors

We study the nonlinearity (NL) in the conversion from charge to voltage in infrared detectors (HXRG) for use in precision astronomy. We present laboratory measurements of the NL function of a H2RG detector and discuss the accuracy to which it would need to be calibrated in future space missions to perform cosmological measurements through the weak gravitational lensing technique. In addition, we present an analysis of archival data from the infrared H1RG detector of the Wide Field Camera 3 in the Hubble Space Telescope that provides evidence consistent with the existence of a sensor effect analogous to the brighter-fatter effect found in Charge-Coupled Devices. We propose a model in which this effect could be understood as shifts in the effective pixel boundaries, and discuss prospects of laboratory measurements to fully characterize this effect.Comment: Accepted for publication in the Journal of Instrumentation (JINST). Part of "Precision Astronomy with Fully Depleted CCDs" (Dec 1-2, 2016), Brookhaven National Laboratory, Upton, NY, US

The place of the Sun among the Sun-like stars

Context. Monitoring of the photometric and chromospheric HK emission data series of stars similar to the Sun in age and average activity level showed that there is an empirical correlation between the average stellar chromospheric activity level and the photometric variability. In general, more active stars show larger photometric variability. Interestingly, the measurements and reconstructions of the solar irradiance show that the Sun is significantly less variable than indicated by the empirical relationship. Aims. We aim to identify possible reasons for the Sun to be currently outside of this relationship. Methods. We employed different scenarios of solar HK emission and irradiance variability and compared them with available time series of Sun-like stars. Results. We show that the position of the Sun on the diagram of photometric variability versus chromospheric activity changes with time. The present solar position is different from its temporal mean position as the satellite era of continuous solar irradiance measurements has accidentally coincided with a period of unusually high and stable solar activity. Our analysis suggests that although present solar variability is significantly smaller than indicated by the stellar data, the temporal mean solar variability might be in agreement with the stellar data. We propose that the continuation of the photometric program and its expansion to a larger stellar sample will ultimately allow us to constrain the historical solar variability.Comment: 10 pages, 5 figures, accepted for publication in Astronomy&Astrophysic