Status of the low emittance upgrade of the advanced light source

The Advanced Light Source is one of the earliest 3rd generation light sources. With an active upgrade program it has remained competitive over the years. The latest in a series of upgrades is a lattice upgrade project that was started in 2009. When it will be completed, the ALS will operate with a horizontal emittance of 2.2 nm and an effective emittance of 2.6 nm. Combined with the high current of 500 mA and the small vertical emittance the ALS already operates at, this upgrade will keep it competitive for years to come. This paper summarizes the status of the upgrade, including beam dynamics studies and lattice optimizations as well as the magnet design

Status of the ALS brightness upgrade

The Advanced Light Source (ALS) at Berkeley Lab while one of the earliest 3rdgeneration light sources remains one of the brightest sources for soft x-rays worldwide. Amultiyear upgrade of the ALS is currently under way, which includes new and replacementx-ray beamlines, a replacement of many of the original insertion devices and many upgradesto the accelerator. The accelerator upgrade that affects the ALS performance most directlyis the ALS brightness upgrade, which will reduce the horizontal emittance from 6.3 to 2.2nm (2.6 nm effective). This will result in a brightness increase by a factor of three forbendmagnet beamlines and at least a factor of two for insertion device beamlines. Magnetsfor this upgrade are currently in production and will be installed starting later thisyear. Copyright © 2012 by IEEE

The Genetic Basis of Heterosis: Multiparental Quantitative Trait Loci Mapping Reveals Contrasted Levels of Apparent Overdominance Among Traits of Agronomical Interest in Maize (Zea mays L.)

Understanding the genetic bases underlying heterosis is a major issue in maize (Zea mays L.). We extended the North Carolina design III (NCIII) by using three populations of recombinant inbred lines derived from three parental lines belonging to different heterotic pools, crossed with each parental line to obtain nine families of hybrids. A total of 1253 hybrids were evaluated for grain moisture, silking date, plant height, and grain yield. Quantitative trait loci (QTL) mapping was carried out on the six families obtained from crosses to parental lines following the “classical” NCIII method and with a multiparental connected model on the global design, adding the three families obtained from crosses to the nonparental line. Results of the QTL detection highlighted that most of the QTL detected for grain yield displayed apparent overdominance effects and limited differences between heterozygous genotypes, whereas for grain moisture predominance of additive effects was observed. For plant height and silking date results were intermediate. Except for grain yield, most of the QTL identified showed significant additive-by-additive epistatic interactions. High correlation observed between heterosis and the heterozygosity of hybrids at markers confirms the complex genetic basis and the role of dominance in heterosis. An important proportion of QTL detected were located close to the centromeres. We hypothesized that the lower recombination in these regions favors the detection of (i) linked QTL in repulsion phase, leading to apparent overdominance for heterotic traits and (ii) linked QTL in coupling phase, reinforcing apparent additive effects of linked QTL for the other traits

Completion of the Brightness upgrade of the ALS

The Advanced Light Source (ALS) at Berkeley Lab remains one of the brightest sources for soft x-rays worldwide. A multiyear upgrade of the ALS is underway, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade [1], which reduces the horizontal emittance from 6.3 to 2.0 nm (2.5 nm effective). Magnets for this upgrade were installed in late 2012 and early 2013 followed by user operation with the reduced emittance

Mechanical design of the superconducting solenoid package for the SARAF-linac project

International audienc

Study and test of an active thermosiphon experimental set-up to validate Super-FRS dipoles cooling system

International audienceIn the framework of the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, CEA is in charge of the design studies for superferric dipole magnets of the Superconducting Fragment Separator (Super-FRS). Each of these dipoles has 2 coils with a trapezoidal shape, each coil being cooled by a horizontal 20 × 10 mm2 liquid helium channel (below or above the coil). The static heat load to extract is 5 W and, to generate a mass flow, the principle of a thermosiphon is implemented with a heater on the return pipe to force the flow direction of the thermosiphon. To validate this cooling system, an experimental set-up was designed and built at CEA Paris-Saclay. This paper presents the experimental set-up and the results of the tests. The effect of the horizontal heat load and the influence of the heater are reported

Gene flow among different teosinte taxa and into the domesticated maize gene pool

International audienceMaize (Zea mays L. ssp. mays) was domesticated from one wild species ancestor, the Balsas teosinte (Zea mays ssp. parviglumis) about 9000 years ago. Higher levels of gene diversity are found in teosinte taxa compared to maize, following domestication and selection bottlenecks. Diversity in maize can be increased via gene flow from teosinte, which has certainly occurred from various taxa, but the rate of flow from different teosinte taxa and the final impact on maize evolution has been difficult to measure. One hundred populations from six Zea taxa, both domesticated (maize) and wild (teosinte), including domesticated landraces from Asia, Africa, and the Americas, were genotyped with 17 SSR markers using 15 individuals per population. Overall levels of diversity were high, and populations could be distinguished based on markers. Relationships between populations followed most published reports, or can now help resolve previously conflicting reports. Gene flow into maize from different teosinte groups, and gene flow between different teosintes, was estimated. Evidence for contributions from the Balsas teosintes and from Chalco teosintes (Z. mays ssp. mexicana) to the maize gene pool was found, as well as from Chalco into ssp. mexicana race "Durango" and Z. mays ssp. huehuetenengensis. These contributions are almost certainly the result of post-domestication (and ongoing) exchanges. This information must give more impetus to in situ conservation of teosinte species, and use of these teosintes to continue to direct the evolution of maize, especially in response to new diseases, insect pests, and other biotic and abiotic stresses

Status of the low emittance upgrade of the advanced light source

The Advanced Light Source is one of the earliest 3rd generation light sources. With an active upgrade program it has remained competitive over the years. The latest in a series of upgrades is a lattice upgrade project that was started in 2009. When it will be completed, the ALS will operate with a horizontal emittance of 2.2 nm and an effective emittance of 2.6 nm. Combined with the high current of 500 mA and the small vertical emittance the ALS already operates at, this upgrade will keep it competitive for years to come. This paper summarizes the status of the upgrade, including beam dynamics studies and lattice optimizations as well as the magnet design

Test Results of the MQYYM: A 90 Mm NbTi Quadrupole Magnet Option for HL-LHC

International audienceFor the HL-LHC project, a 90 mm NbTi cos(2θ) double aperture quadrupole magnet with an operating gradient of 120 T/m at 1.9 K has been designed as an option to replace the 70 mm aperture LHC quadrupole MQY. CEA in collaboration with CERN designed and manufactured a single aperture short model magnet with a magnetic length of 1.215 m at 1.9 K called MQYYM. The MQYYM cold test occurred at CEA at 4.2 K in a vertical cryogenic station. During the power test, the operating gradient at 1.9 K has been reached after two training quenches. All along the test, magnetic and mechanical measurements were done using respectively a rotating probe and strain gauges. This paper describes the performance of the MQYYM at 4.2 K and gives an analysis of the data acquired during the test, including training behavior, quench detection, protection and field quality measurements