Everyone involved in or using tpc-determined vertices, please read this! While working on the dNdEta anatysis, I have discovered that an algorithm I use to reduce the CPU-usage of BrTPMClusterVertexModule biases the y-determination quite heavily towards y=0. In clear words, do _not_ trust the y-determination from BrTPMClusterVertexModule for the time being. The problem comes from the beam not being close enough to 0, and the clusters not looking like the digitized clusters that I used for testing the module when creating it. I'll get around to fixing this problem pretty soon - in fact it may turn out to be a good thing since this error will have reduced our precision in z also (due to cutting away statistics). In the meantime, just use the avereage y for a run from track projections (the beam doesn't drift much in y in the course of a single run anyway...) Ping :-) ------------------------------------------------ Bjorn H. Samset Master-student in Heavy Ion physics Mob: +47 92 05 19 98 Office: +47 22 85 77 62 Adr: Kri 2A709 Sognsveien 218 0864 Oslo
This archive was generated by hypermail 2b29 : Tue Jan 30 2001 - 11:21:22 EST