Minutes of A0 photoinjector group meeting
                        Monday September 20 th, 2004


     
      minutes at: http://nicadd.niu.edu/fnpl/Operation/Minutes/


* Next meeting: Monday September 27th 10:30 CDT, in WH10


* Plan for next week:

Since there is uncertainty on when the LCW will be back (TeV-related 
shutdown), We will decide about the schedule as soon as the LCW is 
back: the plan are then:
    - resume operation 
    - run beam 1 nC for HOM-based beam alignment
    - test CCD digital camera optics on an OTR screen
    - when e- beam cannot be run, laser work/study are 
      scheduled.
    


Discussions:

* Achievements of last week:

- we did not run most of the week due to the TeV LCW 
    shutdown. The LCW was re-establish Wednesday and 
    the water had propoer resistivity only on Friday. 
    Tim and Markus run beam through the TESLA cavity, 
    and a first attempt to measure the HOM signal of 
    one of the dipole mode in the first band (f=1.636 GHz) 
    was performed. Tim showed results that clearly show 
    the dependence of the signal on incoming beam orbit 
    steering by using H/VTBX01 and H/VTB9-C. Tim pointed out 
    the HOM and e pickup label on the couplers are reversed.
   

- more work on the laser:
      - Jianliang and Rodion have been working on the 
        CW autocorrelator, Jianliang showed he could align 
	the beam going into the CW autocorrelator better than 
	last week. This allowed to couble the time accepetance 
	given by the rotating harm of the autocorrelator by 
	a factor 2 to 24 ps. Though this is by far not enough 
	to measure the length of the incoming pulse (200 ps), 
	it should be already enough to measure the pulse 
	length of the new oscillator (8 ps) so the CW autocor-
	relator will be helpfull in the commissioning of the 
	new oscillator. 
	
* Other discussion:

      - Yin-e presented a numerical study of the two solutions for the 
        round-to-flat beam transformations. 
	 
      - Rodion presented the an update of proposal for the laser 
        oscillator upgrade being planned at FNPL, the proposal is available 
	on the www at:
	 http://beamdocs.fnal.gov/cgi-bin/public/DocDB/ShowDocument?docid=1342&version=2
        he refined the jitter Table, and summarized how one would commission 
	the oscillator
	
      - Philippe presented the resolution measurement of the 
        new digital camera system a details on the set-up and measurement is 
	available at:
	
	http://beamdocs.fnal.gov/cgi-bin/public/DocDB/ShowDocument?docid=1346&version=1
	
	In summary the expected resolution is about 1.3 times the pixel size 
	in the obect plane = 1.3*23 ~ 30 microns


ACTION ITEM updated:
Thu Sep 23 16:07:11 CDT 2004

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)
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]
H28/ Problem with emittance measurement at X7 (Philippe 04/16/04)
H32/ Digital camera from SONY(?): [Philippe/Yin-e]
     to be TESTED with OTR [Sep 27]
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]
H35/ A0 cryosystem contamination

#.35

from Adrian Melissinos:

NEEDED LASER STUDIES:

1. Study of oscillator bandwidth versus length of
   compressed pulse. Measure IR length using stepping
   autocorrelator [Done week of AUG 23rfd 2004]
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