Minutes of A0 photoinjector group meeting
                        Monday July 19th, 2004

           http://home.fnal.gov/~piot/FridayMeeting/Minutes/
           

* Next meeting: Monday July 26th, 2004

* Plan for next week:
 
Monday:
	North cave (3.9 GHz) [L. Bellantoni et al.]
Tuesday:
	morning: North cave: Phase shifter test [D. Wildman et al.]
	afternoon: South cave: Bunch compression studies [Rodion
		and Daniel]
Wednesday:
	Beam studies [Yin-e et al.]
Thursday:
	Beam studies [Steve(LBL) et al.]
Friday:
	Beam studies [Philippe et al.]

Discussions:

* Achievements of last week:

  - Monday work on the photocathode laser
  
  - Tuesday [Jason et al.] power supplies of skew quadrupoles 
   were measured, The measurement indicate that the zero of 
   the power supply (on 3 out of 4 power supplies) do not put 
   at 0 Amps as measured on the load. One can use a potentiometer 
   to tune the zero of the power supply but this potentiometer 
   is located on the power supply board (not easy to access) and 
   power supply zero seems to vary when the power supply board is 
   pulled out of the rack... [probably due to interference 
   between the various power supply on the rack]. So in short it 
   is very hard without modifying the power supply (moving the 
   zeroing potentiometer on the front panel of the power supply).
   On another hand we have not diagnostics of the current put out 
   by the power supply on the load. The diagnostics on the front 
   panel ("LOAD CURRENT") does not corresponds to the real 
   current measured at the load (for reason not understood at the 
   moment). The power supply need more studies this week [Jason 
   and Jamie] 
       
  -Wednesday/Thursday/Friday [Yin-e/Philippe], investigated the 
   x-y coupling and beam asymmetry, the conclusion are the 
   skew coupling comes from the skew quadrupole that even when 
   set to zero are not indeed at zero B-field. The skew quadrupole 
   where first unskewed and the beam did not have any skew coupling 
   but was asymmetric (under round beam settings for the solenoids) 
   and still has some coupling when the solenoids were set for 
   typical flat beam settings. The skew quads were then removed from 
   the beamline and the beam spot then appeared round. 
   
     Friday an experiment to see the effect of the chicane IN (and 
   set to zero after degaussing) and out of the beamline was carried 
   on with help of Wade/Mike/Rocky. The conclusion is that the chicane 
   when off and degauss seems to still have some field high enough to 
   steer the beam by few millimeters on  X8 (compare to the case 
   chicane out of the beamline). However the impact of the chicane 
   on the beam spot shape is, as far as we could see, insignificant.     


* Other discussed items:

  - The laser oscillator bandwidth data logs are now available on 
    the web address [Jamie]:
        http://131.225.136.161:8000/~laser/Osc_BW_logs 
  - Uwe Happek will _not_ be here this week 
  - Jason announced he received the camera primary test show few 
    problems that need to be addressed to the camera distributor:
    two of the 6 cameras do no work (no power); and  the camera 
    have different version of firmware, since Jason left this 
    Monday, Markus will look into this problem and interact with 
    the camera distributor.
    
* Tasks concerning hardware 

Wed Jul 21 10:16:53 CDT 2004
ACTION ITEM updated:

H8/ calibration of upstream directional coupler and 
    insulator (Markus need to speak to Tim and with Kai to  
    schedule this STATUS?)
H13/ Pulse stacker, what do we do? (Rodion)
H14/ air coil steerers, Kai will gather all the paper he has 
     and we will decide whether we can give this project to one of 
     the NIU engineering student
     (Kai, STATUS: nobody at NIU picked up this project...)
H21/ the laser uniformity problem can this be due to the new (since 
     late summer) tight focusing in the doubling crystal area to 
     improve conversion efficiency? On going work [Rodion]                            
H26/ trigger problem on a couple of CCD camera 
     (->Kai will look into it 03/2004)
H28/ Problem with emittance measurement at X7 (Philippe 04/16/04)
H29/ Need daily monitoring of the laser parameters (Jamie/Rodion 04/23/04)
     [OSCILLATOR BW AT 131.225.136.161:8000/~laser]
H32/ Digital camera from SONY(?) need to be ordered
     (Jason) [CAMERA HERE + PROBLEM WITH THEM], Markus will 
     take over the camera business 
H33/ laser fluctuation since June 1st week [FIXED?]
H34/ Need more work on power supply + devise a way to measure 
     the current being put out to the magnet [Jamie]

from Adrian Melissinos:

NEEDED LASER STUDIES:

1. Study of oscillator bandwidth versus length of 
   compressed pulse. Measure IR length using stepping 
   autocorrelator
2. beam profile (wavefront) studies both in IR and UV
   in laser room and on virtual cathode. Use spatial filters
3. study of doubling and quadrupling efficencies with old 
   and new crystal, take a tuning curve

POSSIBLE LASER UPGRADE PROJECTS

1. Measure IR pulse length before compression (use diode?) 
   implement cw autocorrelation
2. Install new beamline between multipass and 2-pass -- 
   install spatial filter, rebalance 2-pass amplifiers
3. Relay imaging UV from laser room to cave 
4. _harware_: replacing all coolers with new system IV + 
   use existing system III as back-up
5. pulse stacker studies, new pulse stacker R&D