E94-010 Run Coordinator Report

From Friday 9/25/98 Swing Shift to Monday 10/5/98 Owl Shift

Run Coordinator : Sebastien Incerti

For this period, the beam energy was set to E = 1.719 GeV (2 pass).
The spectrometer angles are 15.5 deg for both arms. 


    

  • Commissioning Data 

- Reference cell elastic data on N2 :
   The beam current was I = 3 uA. Momentum P = 1.700 GeV.
   The collimators were in and the pressure was changed from 1 atm to 2 atm
    to study the pressure curve.
   The total number of events collected reaches 1.8 M.

- Reference cell quasielastic data on N2 :
   The beam current was I = 3 uA. Momentum P = 1.600 GeV.
   The collimators were in and the pressure was set to 5 atm.
   The total number of events collected reaches 1.2 M.
 
- Empty reference cell data at I = 3 uA - P = 1.700 GeV :
   a) data with collimators in : 1.8 M
   b) data with collimators out : 1.7 M

- Elastic data on the polarized Helium 3 target at I = 3 uA - P = 1.670 GeV :
   6 M data collected with collimators in.
 

    • 

  • E94010 Run Plan Data - Priority 1 - Rank 1
Momentum
(GeV)
Current
(uA)
Beam Pol.
(%)
Target Pol.
(%)
Parallel Data
(M = 1E6)
Perp. Data
(M)
P1 = 1.607 3 65 25 to 28 97 37
P2 = 1.484 2 to 3 68 28 27 10
P3 = 1.369 3 68 30 26 23
P4 = 1.264 3 68 30 24 16
P5 = 1.167 3 to 5 68 30 21 13
P6 = 1.077 6 68 30 19 10
P7 = 0.994 6 68 30 16 7
P8 = 0.918 6 to 12 68 30 24 8
P9 = 0.847 13 68 30 24 8
P10 = 0.782 10 to 13 68 30 ... /20.8 ... /6.5 
Those rates take into account the difference between the 70 % beam
polarization assumed in the run plan and its actual value, the difference
between the 40 % target polarization assumed in the run plan and its
actual value, the efficiencies of the standard electron cuts and the glass
target window contribution. 

- Reference cell filled with N2 :

   - P = 1.607 GeV - I = 3 uA - Press = 5 atm - Coll. in : 8.4 M data 
   - P = 1.484 GeV - I = 6 uA - Press = 5 atm - Coll. in : 8.1 M data 
   - P = 1.369 GeV - I = 3 to 6 uA - Press = 5 atm - Coll. in : 10.3 M data 
 
- Empty reference cell :

   - P = 1.607 GeV - I = 3 uA - Coll. in. : 3.0 M data 
   - P = 1.607 GeV - I = 3 uA - Coll. out : 6.0 M data 

   - P = 1.484 GeV - I = 8 uA - Coll. in :  2.5 M data 
   - P = 1.484 GeV - I = 4 uA - Coll. out :  5.8 M data 

- Elastic on polarized Helium 3 :

   - P = 1.737 GeV - I = 13 uA - Coll. in. : 10 M data 


  • Polarized Beam
    • 

The polarization of the beam is about 68%. 
The optimal raster size given by newspot is 4 mm in X and 3.5 mm in Y



  • Polarized Target

    • 
The polarization of the target reaches a plateau at ~30 % and
no major polarization loss has been observed when running at high current.



  • Summary of Beam Schedule
    • Date
    BNA
    BIU
    BABNIU
    Major Problems
    9/25/S 8.0 - - -
    9/26/O 6.3 1.7 - -
    9/26/D 7.0 1.0 - -
    9/26/S 1.3 6.7 - -
    9/27/O 2.0 6.0 - -
    9/27/D 2.0 6.0 - -
    9/27/S 0.5 1.5 6.0 H VDC - E Cherenkov
    9/28/O 0.5 - 7.5 DAQ - Moeller
    9/28/D 2.0 4.5 1.5 H VDC - Raster
    9/28/S 1.3 1.7 5.0 He transient in magnets
    9/29/O - 8.0 - -
    9/29/D 1.8 6.2 - -
    9/29/S 1.0 3.7 3.3 H VDC
    9/30/O - 7.0 1.0 Magnets tripped - Coda
    9/30/D 0.7 5.0 2.3 H Q1 JT valve
    9/30/S 1.5 4.9 1.6 H Q1 trips - Coda
    10/1/O - 7.2 0.8 H Q1 trips - Coda
    10/1/D 0.3 3.5 4.2 H Q1 trips
    10/1/S 0.3 6.5 1.2 Moeller - Current asym.
    10/2/O - 4.3 3.7 ERS compressor - E VDC
    10/2/D - 5.4 2.6 Magnets (He)
    10/2/S 2.5 5.5 - -
    10/3/O 0.5 5.9 1.6 E dipole
    10/3/D 0.2 7.6 0.2 -
    10/3/S - 6.3 1.7 -
    10/4/O - 6.5 1.5 -
    10/4/D - 7.1 0.9 -
    10/4/S - 6.5 1.5 -
    10/5/O 4.8 - 3.2 Coda
    TOTAL : 44.5 h 136.2 h 51.3 h -
    Ratio : 19 % 59 % 22 % - 
    
   BNA stands for Beam Not Available
   BIU stands for Beam In Use
   BABNIU stands for Beam Available But Not In Use



  • Hall A Schedule

    • 
- Moeller studies : 20 h ( ~ 9 % of total time)
- Target NMR : 25 h (~ 11 %)
- Target EPR : 2 h (< 1 %)
- Target Field Rotation : 6 h (~ 3 %)
- Target problems : 7 h (~ 3 %)
- DAQ problems : 9 h (~ 4 %)
- Magnets problems : 22 h (~ 9 %)
- Electron Arm problems (Ch, ...) : 3 h (~ 1 %)
- Hadron Arm problems (VDC, Ch, ..) : 13 h (~ 6 %)
- Misc (interlocks) : 5 h (~ 2 %)


  • Problems and remaining tasks

    • 
- Target polarization reaches a plateau at ~30 %. 37 % expected.
- Hadron arm : 
   1) VDC chamber
   2) Data show some unknown problems	
- Small leak in the reference cell (next Maintenance Days).
- Fix downstream BCM cavity (idem)
- Check Moeller system (idem).
- Replace the damaged target heater (idem, but not crucial).
- Install crash button to turn the lasers off from the Counting House A (idem).
- Check target RTD system (idem)

- Improve the beam intensity asymmetry correlated to helicity (.1 % now)
- Display / keep track of the EPICS variable UGL1I00DI24_24M giving the status
   of the half wave plate (in or out) the laser beam (polarized gun) 
- Install the amperemeter to monitor the current in the small Helmholtz coils
- Beam energy measurement wih the e-p device at 2 and 5 pass.


  • Conclusion

 We have not been able to fullfill the Priority 1 - Rank 1 run plan before 
 the maintenance day. The 2 pass running needs to be extended more after 
 the two maintenance days, starting Monday 10/4, 11 PM.
 

    •