Strategies and performance of the CMS silicon tracker alignment during LHC Run 2

The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios

Stent-supported recanalization of chronic iliac artery occlusions

PURPOSE: Iliac artery occlusions that are more than a few centimeters in length are normally treated with surgical bypass grafting. The aim of this study was to evaluate the results of primary stent implantation after Excimer laser-assisted recanalization of iliac artery occlusions. SUBJECTS AND METHODS: We studied 212 consecutive patients with chronic unilateral iliac artery occlusions (mean [+/- SD] length 8.9 +/- 3.9 cm) who were treated with Excimer laser-assisted recanalization and stent implantation. Based on the criteria of the Society of Cardiovascular and Interventional Radiology, lesions were graded as class III occlusions ( or =5 cm) in 166 patients. A total of 527 stents (Palmaz stent, 346; Wallstent, 94; Strecker stent, 38; covered stents, 49) were implanted. RESULTS: Technical success was achieved in 190 (90%) patients. There was a clinical improvement of three grades in 112 (53%) patients and of two grades in 67 (32%) patients. The rate of major complications was 1.4%, which included arterial rupture (1) and embolic events (2). Primary patency rates were 84% at 1 year, 81% at 2 years, 78% at 3 years, and 76% at 4 years. Secondary patency rates were 88% at 1 year, 88% at 2 years, 86% at 3 years, and 85% at 4 years. CONCLUSION: Stent-supported angioplasty is an effective treatment for iliac artery occlusions, with less morbidity and mortality than is associated with surgery. However, reported long-term patency rates after bypass surgery are greater than those we observed with interventional treatment. The value of primary stenting as compared with angioplasty alone should be evaluated in a randomized trial

Improved cerebral protection through replacement of residual intracavital air by carbon dioxide: a porcine model using diffusion-weighted magnetic resonance imaging

AbstractBackgroundMajor risk of central or peripheral organ damage is attributed to air embolism from incompletely de-aired cardiac chambers after cardiac operations. Replacement of air by carbon dioxide insufflation into the thoracic cavity is widely used. Diffusion-weighted magnetic resonance imaging of the brain detects ischemia within minutes after onset. The reversibility of ischemia in cerebral tissue after massive gaseous emboli has not yet been described.MethodsAfter selective catheterization of a common carotid artery in 15 pigs, boli of 1 mL/kg body weight of air (n = 5) or carbon dioxide (n = 5, “low dose”) were applied. Five pigs received 2 mL/kg body weight of carbon dioxide (“high dose”). Diffusion-weighted magnetic resonance imaging of the brain was performed 2, 5, 10, 15, and 25 minutes after embolization.ResultsAll animals of the “air” group showed important circulatory reactions leading to death of 2 animals. In the whole group, diffusion-weighted magnetic resonance imaging revealed irreversible hyperintense signals in both hemispheres. In the low-dose group, no change in signal intensity was observed in 2 pigs, and 3 others showed reversible changes in signal intensity, without important circulatory reactions. In 3 animals of the high-dose group, hyperintense signals were reversible, but 2 others presented with bilateral, irreversible signals in diffusion-weighted magnetic resonance imaging, accompanied by minor circulatory reactions.ConclusionIn contrast to the dramatic effect of air emboli, identical quantities of carbon dioxide injected into cerebral arteries of the pigs were not associated with major clinical symptoms. The early reversibility of ischemic reactions visualized in diffusion-weighted magnetic resonance imaging encourages the use of carbon dioxide insufflation as a protective method in cardiac surgery

Beam test performance of a prototype module with Short Strip ASICs for the CMS HL-LHC tracker upgrade

International audienceThe Short Strip ASIC (SSA) is one of the four front-endchips designed for the upgrade of the CMS Outer Tracker for the HighLuminosity LHC. Together with the Macro-Pixel ASIC (MPA) it willinstrument modules containing a strip and a macro-pixel sensorstacked on top of each other. The SSA provides both full readout ofthe strip hit information when triggered, and, together with theMPA, correlated clusters called stubs from the two sensors for useby the CMS Level-1 (L1) trigger system. Results from the firstprototype module consisting of a sensor and two SSA chips arepresented. The prototype module has been characterized at theFermilab Test Beam Facility using a 120 GeV proton beam

Strategies and performance of the CMS silicon tracker alignment during LHC Run 2

The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios