Log entry time 16:32:11 on November 12, 2010

Entry number 339745

This entry is a followup to: 339738

Followups:

• 339746 11/12/10 16:43 jroche injector spin setting A-ok (ct'd)

I do believe the tool spin calculator Alexandre used for his check is not appropriate for the 
current settings  of the injector. In its current configuration the injector uses the vertical Wien 
angle and the injector soleinoids to manipulate the spin direction before sending the beam in 
CEBAF and I do not see knob in the spin calculator to set those parameters.  So things are a bit 
more complicated but the bottom line is the injector is setup correctly.

I talked with Riad Suleiman this mornig asking him why the injector settings were different 
from the ones of October 31. The nominal injector settings maximize longitudinal beam 
polarization in Hall C and while the beam spin direction is off by 29deg from the longitudinal 
direction. Pre October 31, only the vertical Wien angle was used. The plot below shows that 
beam goes through 3 spin manipulator before being launch in CEBAF (top plot). It also show 
the manipulation pre October 31 and the manipulation for today's settings.

The numbers below show the epic variables we are recording at the beginning of each run for 
two runs (before October 31 and today). Note how the vertical Wien angle and the effective 
soleinoid angle change. 

//////////////////////////////////////////////
October 31 :  run 8170
-----
Wien angle (Vertical) : 0
Wien Vertical BDL (Gcm) : 0
Wien HV Polarity : OFF
Wien electrode Voltage : 0
Wien angle (Solenoids) : 4.4976e-07
Wien BDL (First Solenoid) (Gcm) : -1011.96
Wien BDL (Second Solenoid) (Gcm) : 1011.96
Wien angle (Horizontal) : 29.2003
Wien BDL (Gcm) : 842.25
Wien HV Polarity (Horizontal) : OFF
Wien electrode Voltage (Horizontal) : 0
Laser attenuation Hall A : 60
Laser power Hall A : 100
Half-wave plate (off=out) : IN
rotating waveplate : 4000
Beam Half-wave plate (off=out) : IN

//////////////////////////////////////////////
November 12 : run 8644
-----
Wien angle (Vertical) : 90.0005
Wien Vertical BDL (Gcm) : 2632.9
Wien HV Polarity : POSITIVE
Wien electrode Voltage : 0
Wien angle (Solenoids) : 90
Wien BDL (First Solenoid) (Gcm) : 998.89
Wien BDL (Second Solenoid) (Gcm) : 998.89
Wien angle (Horizontal) : -61.0017
Wien BDL (Gcm) : -1754.8
Wien HV Polarity (Horizontal) : NEGATIVE
Wien electrode Voltage (Horizontal) : 0
Laser attenuation Hall A : 100
Laser power Hall A : 100
Half-wave plate (off=out) : OUT
rotating waveplate : 1850
Beam Half-wave plate (off=out) : OUT

Figure 1