Search

The Advanced Light Source (ALS) is a third generation synchrotron light source located at Lawrence Berkeley National Laboratory (LBNL). There was an increasing demand at the ALS for additional high brightness hard x-ray beamlines in the 7 to 40 keV range. Inresponse to that demand, the ALS storage ring was modified inAugust 2001. Three 1.3 Tesla normal conducting bending magnets were removed and replaced with three 5 Tesla superconducting magnets (Superbends). The radiation produced by these Superbends is an order of magnitude higher in photon brightness and flux at 12 keV than that of the 1.3 Tesla bends, making them excellent sources of hard x-rays for protein crystallography and other hard x-ray applications. At the same time the Superbends did not compromise the performance of the facility in the VUV and softx-ray regions of the spectrum. The Superbends will eventually feed 12 new beam lines greatly enhancing the facility's capability and capacity in the hard x-ray region. The Superbend project is the biggest upgrade to the ALS storage ring since it was commissioned in 1993. In this paper we present an overview of the Superbend project, its challenges and the resulting impact on the ALS.

The vertical magnetic structures for the Advanced Light planar wiggler and 20 cm period elliptical hybrid permanent magnet design. The ends of these structures are characterized by diminishing scalar potential distributions the poles which control beam trajectories. They incorporate electromagnetic correction coils to dynamically correct for variations in the first integral of the field as a function of gap. A permanent magnet trim mechanism is incorporated to minimize the transverse integrated error field distribution. The ends were designed using analytic and computer modeling techniques. The design and modeling results are presented.

An elliptical wiggler has been designed for installation in the Advanced Light Source at the Lawrence Berkeley Laboratory. The design has been optimized for the production of circularly polarized light in the 50 eV to 10 KeV energy range. The device will be 3.4 m long consisting of vertical and horizontal periodic structures. The period length for both is 20 cm. The vertical structure is a hybrid permanent magnet design which produces a peak field of 2.0 T. The horizontal magnetic structure is an iron core electromagnetic design shifted longitudinally by one-quarter period relative to the vertical structure; it has a peak field of 0.095 T. The polarity of the horizontal field can be switched at a rate of up to 1 Hz, which results in a modulation of the chirality of the circularly polarized radiation on-axis. This paper discusses the magnetic design and presents the results of radiation spectrum calculations used for determining optimal field parameter settings.

A new scheme helps prepare three binuclear complexes with bridging 1,1-dithiooxalate (i-dto) or trithiooxalate (trto) groups, and X-ray crystallography helps characterize the structures of these complexes. The complexes, ((Ph3P)2M)2(i-dto) (M = Ag, Cu) and ((Ph3P)2Ag)2(trto), have a side-on and a novel side-on/end-on coordination, respectively. The energy levels for the frontier ligand orbitals predicted by ab initio calculations account for the occurrence of various coordination modes.

A study of 17 healthy volunteers between the ages of 21 and 28 to determine the fermentability of diverse samples of resistant starch (RS) compared to lactulose and to one another revealed that completely different H2 responses result from RS from corn flakes, raw potato starch (RPS) and high amylomaize starch because of fermentation or digestion patterns. Gastric emptying is unaffected by RS. Colonic microbial bacteria may ferment the small amount of RPS that is not digested in the small intestine.

Insertion devices for the Advanced Light Source (ALS) incorporate up to 3000 magnet blocks each for pole energization. In order to minimize field errors, these magnets must be measured, sorted and assigned appropriate locations and orientations in the magnetic structures. Sorting must address multiple objectives, including pole excitation and minimization of integrated multipole fields from minor field components in the magnets. This is equivalent to a combinatorial minimization problem with a large configuration space. Multi-stage sorting algorithms use ordering and pairing schemes in conjunction with other combinatorial methods to solve the minimization problem. This paper discusses objective functions, solution algorithms and results of application to magnet block measurement data.

Celiac disease is an intestinal malabsorption syndrome characterized by intestinal bleeding, diarrhea, malnutrition, and disordered calcium metabolism. By the time patients with this condition are diagnosed and treatment is instituted, they have often suffered significant weight loss. Removal of the dietary constituent gluten can usually control the symptoms of celiac disease. However, it is not known whether satisfactory treatment by dietary means completely restores normal body composition and calcium metabolism. To further evaluate the effects of treatment on the restoration of normal body composition and calcium metabolism in patients with celiac disease, a study was undertaken in which 22 patients, aged 20 to 70 years, underwent body composition analysis and determination of bone mineral content (an important endpoint directly affected by altered calcium metabolism). When compared with an age-matched group of healthy control subjects, patients with treated celiac disease showed a 30 percent reduction in body fat, and about a 10 percent decrease in bone mineral content. Decreases were also seen in blood levels of albumin, vitamin D binding protein, and iron. Levels of these indices in treated celiac disease patients were between 6 and 22 percent lower than those of controls. Other aspects of blood chemistry were not different between groups. Individuals who have chronic reductions in bone mineral content suffer from increased susceptibility to bone fractures; this may hold true for patients with celiac disease in spite of treatment that reduces or eliminates outward symptoms of the disease. (Consumer Summary produced by Reliance Medical Information, Inc.)