Log entry time 11:22:31 on March 04, 2012

Entry number 363512

This entry is a followup to: 363497

Followups:

• 363536 03/04/12 12:00 lerose Q3 setting Right

I just notice that RQ3 regulation is on and as I know, RQ3 has a highest
current limit. I check the halog and found that with regulation on, RQ3
reached 1100 A limit at Momentum=2.274GeV and went upto 1130A at Momentum
= 2.34GeV and sometimes it went up to 1200A. My question is should we
turn off the regulation off and manually adjust the RQ3 current everytime
we change momentum setting.

It is necessary if you only want to use one optics matrix for R-HRS for
all data. We need to know what is the momentum value of RQ3 with 1100A
limit and what is the highest momentum you need for this experiment, and
we get a scale factor for RQ3 each time we change momentum, for example,
if the highest momentum of Dipole is 2.5GeV and RQ3 is about 2.3GeV with
1100A limit, then later on if you change the Dipole to 2.0GeV, then RQ3
should be scaled down to 1.84GeV, although RQ3 can reach 2.0GeV.

During last night's Delta scan, the regulation was on so RQ3 was not
scaled down for each momentum scan point. I believe +-%4 won't have too
much impact on the matrix calibration, but we need to be careful in the
future if we change large value, such as from 2.3G to 1.7G. 

And with RQ3 regulation on, its current might exceed 1100A limit.

Maybe I don't understand the spectrometer stuffs correctly and maybe
there is not problems,  but not matter what we should be careful about
momentum setting with RQ3 current_limit.