摘要
Recent measurements of event-by-event elliptic flow in Au+Au collisions at S_(NN)^(1/2)=200GeV exhibit large relative fluctuations of about 40%—50%.The data are well described by fluctuations in the shape of the initial collision region,as estimated event-by-event with the participant eccentricity using Glauber Monte Carlo.These results,combined with the demonstrated participant eccentricity scaling of the elliptic flow across nuclear species,constitute evidence of transverse granularity in the initial matter production in these collisions.
A new plasma chamber for the Texas A&M 14.5GHz ECR ion source ECR2 has been recently installed and the beam analysis line has been recently upgraded with the replacement of the solenoid with a shorter Glaser lens.The source is now used along with the 6.4GHz ECR1 for injection of beams into the K500 cyclotron.The new plasma chamber incorporates water-carrying copper tubes,each with an inner diameter of 0.7mm and an outer diameter of 1.8mm,interposed between the NbFeB permanent magnets and the aluminum plasma-chamber wall.The design allows for a much higher water flow and thus better cooling than the previous design,which used a thin,water-cooled liner.The source commissioning and operation is described.
