Eric Hjort sent two messages describing part of the 1998 test data; edited versions appear below.
Sector 6: Crossing angles in the 15-30 degree range, similar to data from LBL 1997.
Sector 10: Again crossing angles 15-30 degree range, I believe.
Sector 1: At this point we switched to a configuration where we would cover all 45 rows (to look at the IFC, too) with the maximum crossing angle possible, about 15 degrees.
Sector 23: Again 45 rows w/crossing angle ~ 15 degrees.
Future plans: Sector 24 and sector 18 with similar plans to those used for sectors 1 and 23.
This data is interesting because RDO 1 was on sector 19 while RDO's 2-6 were on sector 18. Tracks go through about 7 rows of inner sector 19 (crossing angle ~45 degrees) and about 7 rows of inner sector 18 (crossing angle ~15 degrees) and all the rows of outer sector 18. By running in this fashion we are sensitive to distortions produced when the IFC and/or OFC voltages are mismatched w/respect to the gated grid voltage. The data file above has the voltages matched to minimize distortions. It's also interesting in that it's the first time we've taken data where tracks cross a sector boundary.
Technical note/bug report: Dipswitches on the RDO's for this data were set for sectors 17 and 18 - not 19 and 18, because somewhere in the analysis chain the sector numbering convention for the east end of the TPC [was] reversed!
Roy Bossingham, LBNL