Log entry time 16:59:48 on December 05, 2011

Entry number 242596

Goal: The goal of this test is to vary the beam angle while keeping the beam centered on the tungsten plug to determine how much the beam angle affects our distribution of main detector asymmetry widths. The size of the angle changes (+/- 0.3 mrad in X and Y) is large enough that it should remove the "dipole" (see https://qweak.jlab.org/elog/Analysis+%26+Simulation/443). At the same time, these angle changes are smaller than the ~ +/- 0.4 mrad changes we did (at 150 uA) in May 2011 (https://hallcweb.jlab.org/hclog/1105_archive/110512142407.html).

Setup: Initially make sure the following is set up:

• Luminosity monitors (upstream and downstream) on at their standard current mode voltages
• Main detectors on at their standard current mode voltages
• Hydrogen target
• Normal parity DAQ (like we use for production running)
• QTOR on at nominal setting
• Current = maximum we are currently using, raster = 4x4 mm^2
• Set up striptools for bellows and W plug temperatures (see here: https://hallcweb.jlab.org/hclog/1105_archive/110512193758.html for the names of the variables to stripchart). We don't expect these to really change at all for these different settings, but it is worth monitoring them in case anything unexpected happens.

1. Note down current setpoints Before changing anything, ask MCC what the current setpoints (for IPM3H07C and IPM3H09B) are for the slow orbit lock system. Also, ask them which screen in Monticello has that information and pop it up so you can monitor it as they make the changes. Put in a snapshot of that and the current BPM gui picture (obtainable from generaltools) into hclog.

2. Procedure for changing settings This plan will involve going to five different settings for the BPMs (IPM3H07C and IPM3H09B) that are used by the Hall C slow orbit lock. Be sure to have a BPM screen up to look at the settings. For each setting, MCC should drop down to tune beam (you can leave the detectors on) and type in the newly desired setting. Then they can turn on the slow orbit lock and check that everything makes sense (and that no ion chambers are tripping, indicating mis-steered beam). This plan is designed so that the computed X,Y values at the tungsten plug should maintain their values (X ~ -.29 mm, Y ~ -.51 mm) that were found during our tungsten plug centering scan.

3. Data to take at each setting: After establishing things with tune beam, MCC can ramp back up to the desired CW current and then you should take a regular parity run for 30 minutes at that setting. Please put a snapshot of the standard BPM GUI (obtainable in general tools) into hclog to show the values of the BPMs corresponding to that setting.

4. Backout: When done, re-establish production running conditions with the BPM setpoints we had been using (from step 1).

Table of values to give to MCC

Spreadsheet used to get these values