Lost City meteorite: Its recovery and a comparison with other fireballs

Lost City meteoroid trajectory analysis and determination of original mas

Lost City meteorite - It's recovery and a comparison with other fireballs

Photographic and trajectory data for Lost City meteor and establishment of calibration of mass scale of other meteor

Combined observations of meteors by image-orthicon television camera and multi-station radar

Observations from multiple sites of a radar network and by television of 29 individual meteors from February 1969 through June 1970 are reported. Only 12 of the meteors did not appear to fragment over all the observed portion of their trajectories. From these 12, the relation for the radar magnitude to the panchromatic absolute magnitude was found in terms of velocity of the meteor. A very tentative fit to the data on the duration of long enduring echoes versus visual absolute magnitude is made. The exponential decay characteristics of the later parts of several of the light curves are pointed out as possible evidence of mutual coalescence of droplets into which the meteoroid has completely broken

Commissioning of Dedicated Furnace for Nb3Sn Coatings of 2.6 GHz Single Cell Cavities

We present the results of commissioning a dedicated furnace for Nb3Sn coatings of 2.6 GHz single cell cavities. Nb3Sn is a desired coating due to its high critical temperature and smaller surface resistance compared to bulk Nb. Usage of Nb3Sn coated cavities will greatly reduce operating costs due to decreased dependance on cryo cooling. Tin is deposited by use of a tin chloride nucleation agent and tin vapor diffusion. Analysis of the resultant coating was performed using SEM/EDS to verify successful formation of Nb3Sn. Witness samples in line of sight of the source were used in order to understand the coating efficacy.Comment: 21st Intl Conf Radio Frequency Superconductivity (SRF 2023

Thermocurrents and their Role in high Q Cavity Performance

Over the past years it became evident that the quality factor of a superconducting cavity is not only determined by its surface preparation procedure, but is also influenced by the way the cavity is cooled down. Moreover, different data sets exists, some of them indicate that a slow cool-down through the critical temperature is favourable while other data states the exact opposite. Even so there where speculations and some models about the role of thermo-currents and flux-pinning, the difference in behaviour remained a mystery. In this paper we will for the first time present a consistent theoretical model which we confirmed by data that describes the role of thermo-currents, driven by temperature gradients and material transitions. We will clearly show how they impact the quality factor of a cavity, discuss our findings, relate it to findings at other labs and develop mitigation strategies which especially addresses the issue of achieving high quality factors of so-called nitrogen doped cavities in horizontal test

Preservation of the High Quality Factor and Accelerating Gradient of Nb3Sn-coated Cavity During Pair Assembly

Two CEBAF 5-cell accelerator cavities have been coated with Nb3Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb3Sn cavity coating system, and the other in the Fermilab Nb3Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb3Sn cavities into a cavity pair degraded the superconducting properties of Nb3Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.Comment: 21st Intl Conf Radio Frequency Superconductivity (SRF 2023

Routes to credible climate commitment: the UK and Denmark compared

Credible commitment is central to regimes for climate mitigation policy. In the climate policy literature, it is widely argued that the solution to the credible commitment problem is legislation and delegation of goal-setting to a technical body insulated from political incentives, and the UK’s Committee on Climate Change is in part modelled on this approach. However, drawing on the comparative politics literature, this paper argues that the focus on legislation and delegation as the solution to the credible commitment problem is too narrow. Seen within the context of comparative political institutions, it is a response that fits the political logic in countries with majoritarian electoral systems. By contrast, in countries with electoral systems based on proportional representation, while legislation plays a role, an important element in the creation of credible commitment comes in the form of negotiated long-term agreements between political parties. This contrast is explored through a comparison between the Climate Change Act and associated Committee on Climate Change in the UK on the one hand, and a series of Energy and Climate Agreements in Denmark over the 2010s. Both approaches appear to have worked to date. However, while negotiated long-term agreements typically have an internal process for managing conflicts that inevitably arise after the respective mechanisms have been put in place, disputes arising following legislation and delegation must be resolved within the more informal processes of intra-party politics. Mechanisms of accountability also differ between the two approaches