A Natural Application for High Temperature Superconductors: a Bearing for the Azimuth Mount of a Lunar Telescope

A bearing for telescope mounts on the moon has to function in a cold dusty vacuum environment that impairs the operation of almost all traditional bearings, but it is a natural environment for bearings constructed out of magnets and high temperature superconductors. The challenge lies not so much in the weight of the telescope that has to be supported, but in the smoothness of forces required for precision positioning control over a long stretch of time without human intervention. In this paper, we present a design of hybrid superconductor magnet bearings intended for use on the azimuth mount of an altitude-azimuth telescope mount system. In addition to the general features of hybrid super conducting magnet bearings, we will address particular issues connected with the application of these bearings on a telescope mount

The HL-LHC Low-β\beta Quadrupole Magnet MQXF: from Short Models to Long Prototypes

In order to reduce the beam size by a factor two in the inter-action points, and to increase the rate of collisions by a factorof five, the HL-LHC Project [1] is planning to install in the LHC Interaction Regions (IR) new inner triplet (or low-β) quadru-pole magnets, called MQXF [2]-[6]. With respect to the current triplet quadrupole magnets, MQXF will feature a larger aper-ture, from 70 to 150 mm, a higher peak field, from 8.6 to 11.4 T, and a new superconducting material, Nb3Sn instead of Nb-Ti. Out of the 30 triplets magnets (including spares) that will be installed in the HL-LHC, 20 magnets, called MQXFA and 4.2 m long, will be fabricated by the US Accelerator Research Program (AUP), a continuation of the LARP Program [7].Among the components to be upgraded in LHC inter- action regions for the HiLumi-LHC projects are the inner triplet (or low-β) quadrupole magnets, denoted as Q1, Q2a, Q2b, and Q3. The new quadrupole magnets, called MQXF, are based on Nb3 Sn superconducting magnet technology and operate at a gradient of 132.6 T/m, with a conductor peak field of 11.4 T. Q1 and Q3 are composed of magnets (called MQXFA) fabricated by the U.S. Ac- celerator Upgrade Project (AUP), with a magnetic length of 4.2 m. Q2a and Q2b consist of magnets (called MQXFB) fabricated by CERN, with a magnetic length of 7.15 m. After a series of short models, constructed in close collaboration by the US and CERN, the development program is now entering in the prototyping phase, with CERN on one side and BNL, FNAL, and LBNL on the other side assembling and testing their first long magnets We provide in this paper a description of the status of the MQXF program, with a summary of the short model test results, including quench performance, and mechanics, and an update on the fabrication, assembly, and test of the long prototypes

Lessons learned from the prototypes of the MQXFA Low Beta Quadrupoles for HL-LHC and status of production in the US

With the successful test of the first two pre-series magnets the US HL-LHC Accelerator Upgrade Project has started production of the MQXFA magnets to be used in Q1/Q3 inner triplet elements of the HL-LHC. This good start comes after the test of two prototypes with limited performance, and it demonstrates the importance of learning from past issues. Therefore, in this paper we want to share the most important lessons learned so far, focusing on those which may be more interesting for similar projects. We will also present the status of MQXFA fabrication in the US

Emerging sex allocation research in mammals: marsupials and the pouch advantage

1. Adaptive adjustments in offspring sex ratios in mammals have long been reported, but the conditions and mechanisms that prompt shifts in the proportion of sons and daughters born are still unclear.\ud \ud 2. Empirical evidence indicates that offspring sex in mammals can be related to a diversity of environmental and maternal traits. However, the underlying assumptions regarding offspring and maternal fitness are rarely tested.\ud \ud 3. Physiological mechanisms of maternal selection of offspring sex may occur at many stages during the prolonged maternal investment stage, and a pluralistic approach to studying mechanisms might prove fruitful.\ud \ud 4. This review highlights the apparent frequency, in marsupial mammals, of sex ratio bias, which has largely been recorded as conforming to one of a few hypotheses.\ud \ud 5. Marsupials are ideally suited to experiments involving cross-fostering of offspring, which can allow rigorous tests of the fitness consequences of rearing one sex vs. the other. The reproductive biology of marsupials lends the group to detailed studies of the timing and physiological correlates of offspring sex biases.\ud \ud 6. Many components of metatherian biology may prove advantageous in experimental studies of sex allocation in mammals, and together may provide a prosperous avenue for examining adaptive and mechanistic hypotheses in mammalian sex allocation