Difference between revisions of "Beam Recovery"

From PREX Wiki
Jump to navigationJump to search
Line 16: Line 16:
 
*[[Magnets#Set Septum Magnet|Ask MCC to set septum magnet]]
 
*[[Magnets#Set Septum Magnet|Ask MCC to set septum magnet]]
  
−
<span style="color:red">Make sure we have [[Configurations#Tune B | Tune B]].</span>  (If someone has turned off HRS magnets they may not come back in right state.)
+
<span style="color:red">Make sure we have [[Configurations#Tune P | Tune P]].</span>  (If someone has turned off HRS magnets they may not come back in right state.)
  
 
#  Empty target, establish correct beam position [[Beam and Hall checks#Beamline | Check beam position]]
 
#  Empty target, establish correct beam position [[Beam and Hall checks#Beamline | Check beam position]]
−
#* 5 uA empty target
+
#* 1 uA empty target
 
#* BPM4A (X,Y) = ( 0, 0) mm
 
#* BPM4A (X,Y) = ( 0, 0) mm
−
#* BPM4B (X,Y) = ( 0, +1) mm
+
#* BPM4E (X,Y) = ( 0.6, 0.4) mm
 
#* See white board for updates on these.
 
#* See white board for updates on these.
 
#* Tolerances on these :  +/- 0.3 mm  
 
#* Tolerances on these :  +/- 0.3 mm  
 
#  Establish Raster
 
#  Establish Raster
−
#*        It gets turned off for access, sometimes people forget.)
+
#*        It gets turned off for access, (sometimes people forget.)
 
#*        Still at empty target.
 
#*        Still at empty target.
 
#*        All scint HV off (normally they are).
 
#*        All scint HV off (normally they are).
 
#*        Need to use T8 pulser, so use ps8 = 2 on L-HRS.
 
#*        Need to use T8 pulser, so use ps8 = 2 on L-HRS.
−
#*        spot_L check of raster, see 6x4 mm2 on target
+
#*        spot_L check of raster see 4.4 (width) x 7.2 (height) mm2
−
#    Put in BeO target, for visual check of spot (if camera still works)
+
#    Put in Carbon Hole (90 deg) target
−
#*        10 uA rastered beam on BeO.
+
#*        1 uA rastered beam on Carbon Hole target.
−
#*        May need to request MCC for rapid beam-on / beam-off to see spot.
+
#*        Lock the beam position using 1 uA current
−
#*        "Rapid" can be done by turning on/off laser at polarized source.
+
#*        Go to 20 nA current, turned on scintillators HVs and check spot++ on Carbon hole target.  
−
#    Establish 5 nA
+
#    Put in the Lead /1% carbon target
−
#*        Still with BeO target
 
−
#*        Ask MCC for Laser Attenuator = 65 and Slit = 15. (This might need to change)
 
−
#*        These two knobs (atten and slit) can reduce current to nA range.
 
−
#*        Turn on L-HRS upper scintillator paddle HV which makes trigger T5.
 
−
#*        Card 2, chan 10, HV = -1400 V
 
−
#*        Should observe T5 = 2000 Hz +/- 1000.  Adjust atten, slit if necessary.  
 
−
#    Put in the Lead / Diamond target
 
 
#*        See white board for which one we are using
 
#*        See white board for which one we are using
−
#*        As I write this, we're using number 2 (middle).
+
#*        <span style="color:red">IMPORTANT:</span>  Raster always on and 4.4x7.2 when Lead / Diamond target in beam !!
−
#*        <span style="color:red">IMPORTANT:</span>  Raster always on and 6x4 when Lead / Diamond target in beam !!
 
 
#*        Ask for the <span style="color:red">SAME</span> attenuator and slit as above.
 
#*        Ask for the <span style="color:red">SAME</span> attenuator and slit as above.
−
#*        Observe T5 = 13 +/- 3 kHz.  This is fine.  
+
#*        Observe T1/T2 = 13 +/- 3 kHz.  This is fine.  
−
#    Run spot_L again, this time with ps8=65535 and ps5=10
+
#    Run spot_L again, this time with ps8=0 and ps1/2=10
 
#*        Observe the raster current pattern, see if it's flat
 
#*        Observe the raster current pattern, see if it's flat
 
#*        Flat means we're not hitting a frame !
 
#*        Flat means we're not hitting a frame !
−
#*        Gentle slope due in X is presumably form factor (don't worry)
+
#*        Increase raster by 50% and check spot++ again to make sure not hitting the frame
−
#*        For reference, see halog 314132
 
 
#    Turn off all scint HV.
 
#    Turn off all scint HV.
 
#    Ready for high current:  Ramp up to 50 uA at about 10 uA per min.  
 
#    Ready for high current:  Ramp up to 50 uA at about 10 uA per min.  
Line 58: Line 49:
 
less than 2 hours of no beam, and no changes to beam
 
less than 2 hours of no beam, and no changes to beam
  
−
<span style="color:red">IMPORTANT:</span>  Raster always on and 6x4 mm (observed on target) when Lead / Diamond target in beam !!
+
<span style="color:red">IMPORTANT:</span>  Raster always on and 4.4x7.2 mm (observed on target) when Lead / 1% carbon target in beam !!
 
#  <span style="color:blue">      If you are unsure of raster status, check it !!</span>
 
#  <span style="color:blue">      If you are unsure of raster status, check it !!</span>
 
#        Can be sure raster is ok if
 
#        Can be sure raster is ok if
Line 66: Line 57:
 
#        To check raster:
 
#        To check raster:
 
#*            Go to empty target
 
#*            Go to empty target
−
#*            Ask for 5 uA
+
#*            Ask for 1 uA
 
#*            Do a spot_L run with ps8=2 as explained above.  
 
#*            Do a spot_L run with ps8=2 as explained above.  
−
#    Put in Pb/Diamond Target
+
#    Put in Pb/1% Carbon Target
 
#*        See white board for which one.
 
#*        See white board for which one.
−
#*        As I write this, we are using number 2 (middle)
+
#    Ask for 1 uA. Check beam positions.
−
#    Ask for 5 uA. Check beam positions.
 
 
#*        BPM4A (X,Y) = ( 0, 0) mm
 
#*        BPM4A (X,Y) = ( 0, 0) mm
−
#*        BPM4B (X,Y) = ( 0, +1) mm
+
#*        BPM4E (X,Y) = ( 0.4, 0.6) mm
 
#*        See white board for updates on these.
 
#*        See white board for updates on these.
 
#*        Tolerances on these :  +/- 0.3 mm  
 
#*        Tolerances on these :  +/- 0.3 mm  

Revision as of 12:12, 8 July 2019

In the process of editing and updating this page. Please contact Juliette Mammei crowder@jlab.org with questions or suggestions.

PREX Main<< HOW TOs << Expert Tools



PREX I procedure

Procedure for Long Beam Down

Check if the septum on !!

Make sure we have Tune P. (If someone has turned off HRS magnets they may not come back in right state.)

  1. Empty target, establish correct beam position Check beam position
    • 1 uA empty target
    • BPM4A (X,Y) = ( 0, 0) mm
    • BPM4E (X,Y) = ( 0.6, 0.4) mm
    • See white board for updates on these.
    • Tolerances on these : +/- 0.3 mm
  2. Establish Raster
    • It gets turned off for access, (sometimes people forget.)
    • Still at empty target.
    • All scint HV off (normally they are).
    • Need to use T8 pulser, so use ps8 = 2 on L-HRS.
    • spot_L check of raster see 4.4 (width) x 7.2 (height) mm2
  3. Put in Carbon Hole (90 deg) target
    • 1 uA rastered beam on Carbon Hole target.
    • Lock the beam position using 1 uA current
    • Go to 20 nA current, turned on scintillators HVs and check spot++ on Carbon hole target.
  4. Put in the Lead /1% carbon target
    • See white board for which one we are using
    • IMPORTANT: Raster always on and 4.4x7.2 when Lead / Diamond target in beam !!
    • Ask for the SAME attenuator and slit as above.
    • Observe T1/T2 = 13 +/- 3 kHz. This is fine.
  5. Run spot_L again, this time with ps8=0 and ps1/2=10
    • Observe the raster current pattern, see if it's flat
    • Flat means we're not hitting a frame !
    • Increase raster by 50% and check spot++ again to make sure not hitting the frame
  6. Turn off all scint HV.
  7. Ready for high current: Ramp up to 50 uA at about 10 uA per min.

Procedure for Short Beam Down or target movement

less than 2 hours of no beam, and no changes to beam

IMPORTANT: Raster always on and 4.4x7.2 mm (observed on target) when Lead / 1% carbon target in beam !!

  1. If you are unsure of raster status, check it !!
  2. Can be sure raster is ok if
    • You were just running and it was on.
    • Check the scope in middle room (familiar TV pattern of raster)
    • Look at raster EPICS screen.
  3. To check raster:
    • Go to empty target
    • Ask for 1 uA
    • Do a spot_L run with ps8=2 as explained above.
  4. Put in Pb/1% Carbon Target
    • See white board for which one.
  5. Ask for 1 uA. Check beam positions.
    • BPM4A (X,Y) = ( 0, 0) mm
    • BPM4E (X,Y) = ( 0.4, 0.6) mm
    • See white board for updates on these.
    • Tolerances on these : +/- 0.3 mm
  6. If you didn't do spot_L in the first step, do one a quick one now.
    • Want 6x4 mm on target.
  7. Ready for high current: Ramp up to 50 uA at about 10 uA per min.
Retrieved from "https://prex.jlab.org/wiki/index.php?title=Beam_Recovery&oldid=6856"