Minutes of A0 photoinjector group meeting
                        Monday August 23rd, 2004


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


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

* Plan for next week:

- Monday:    No RF can be ran, laser work [Jamie/Jiangliang]
- Tuesday:   laser work on autocorrelator [Jianliang et al.]
- Wednesday: bunch length measurement [Daniel]
- Thursday:  Flat beam [Yin-e]
- Friday:    Flat beam [Philippe]


Discussions:

* Achievements of last week:

- Monday/Tuesday: Some work on the laser occured[Jamie/Jianliang]
      
- Wednesday: bunch length measurement using the Golay cell. 
      Compared to last week, the golay cell strange signal 
      was understood (the number of bunch used last week was 
      too much and the Golay was saturated. An autocorrelation 
      measurement was done and the gap in the autocorrelation 
      (typical of the pyro-electric detector) are now gone [Daniel]. 

- Thursday: Plan was to do measure magnetized beam emittance but 
      encountered many problem with Rf phase shift (gun). Steve/Markus 
      reported a jitter of 15 deg p2p for the gun read-back phase. 
      Markus suggest one may want to run the gun to 50/100usec and 
      use the feedback; of course the price we have to pay is 
      dark current... [Markus/Steve]

- Friday: Set-up a flat beam and did a quadrupole scan using  Q2AX06
      with X7 viewer [Yin-e]
     
* Discussion:
     - Philippe mentioned about HOM-beam based alignement performed at 
       DESY by N. Baboi and O. Napoli. The technique consists in 
       measuring HOM-associated powerat the HOM coupler and trying to 
       minimize the power (for a selected mode) by steering the 
       beam upstream from the cavity. We should consider trying the 
       method at A0 to check how well we are  
     - Tim Koeth from Rutgers University joined the team 10 days ago, 
       he will work on 3.9 GHz deflecting mode cavity and its 
       implementation as a bunch length measurement device in the 
       forthcoming A0 upgrade. 
     
* Tasks concerning hardware


ACTION ITEM updated:
Mon Aug 23 14:43:25 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)
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(?): camera sent back waiting for new ones
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