Make New Entry, Make Followup Entry
User name Jin Huang
Log entry time 02:07:46 on April24,2009
Entry number 267721
This entry is a followup to: 267698
Followups:
keyword=Investigating Missing Carbon foilsVince, Bryan and I have tried to investigate why carbon vertex is missing in most recent optics runs (LHRS run # 1297, 1298).
First we notice that there are vertex peaks if cutting very tightly on target phi angles. Further, as shown in plot below, VZ is highly twisted with Target Phi angles (also the upstream/downstream are inversed). Same result come with Transversity optics database. Therefore, to us, it's likely some magnet component is having problems.
Then magnets field reading is checked. See second plot for current hall A tools snapshot. Comparing to old setting, (like halog #211784, CSR, -1.0GeV on LHRS), Q1 "FIELDS" seems inversed (supposed to be negative number). Also during d2n, the Q1 FIELDS reading is also negative (Halog # 261817).
Therefore, we are suspecting LHRS Q1 polarity is inversed, which causing this weired vertex reconstruction, (assuming Q1 gauss meter was not changed during transaction period).
PS: it seems RHRS Q1 FIELDS read back also have different sign than SRC (Halog # 211784).
FIGURE 1
FIGURE 2
