Log entry time 15:14:48 on October20,2005

Entry number 157505

Followups:

• 157506 10/20/05 15:16 paschke figure for: postion difference stability

Chao's last PZT monitor scan has revealed that the matching solution he has 
installed in not very stable... in particular, he expects a growth in the 
horizontal position differences since the beginning of the run.  He has no 
information tracking changes on a daily basis, although such frequent 
monitoring will start now.

The position differences observed in the Hall have been somewhat larger than 
observed in the first slug, and this appears to be somewhat independent of 
half-wave plate state. In Figure 1, I show position differences for the 5 slugs 
(NOT sign corrected by waveplate state).  Each slug represents data averaged 
over an alternating waveplate state.  

In principle the source terms could be changing for these plots, either 
changing with halfwave plate state or drifting over time. We don't have good 
information on that, since Hall B beam is on in the 100 keV region. While the 
position differences for single slugs are larger than those measured in the 
first slug, the statistical evidence for (or against) a clear change is weak.  

As one would expect for statistical distributions around zero (or, 
equivalently, for small but drifting distributions around zero), the 
sign-corrected average is very small (after 5 slugs, nothing larger than 7 nm 
+/- 5 nm).