Minutes of A0 photoinjector group meeting
                        Monday May 24th, 2004

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

* Next meeting: Monday May 3rd in WH10

* Plan for next week: 

- Monday:    NO BEAM: work on laser [Rodion/Nick]
- Tuesday:   Flat beam experiments [Steve from LBL]
- Wednesday: Flat beam experiments [Yin-e]
- Thursday:  Flat beam experiments [Philippe]
- Friday:    CTR interferometry [Daniel/with some help from Rodion]


Discussions:

* Achievements of last week:

- Monday:
        -  no beam; work on the interlock. The interlock is not yet 
           activated. It will require training of all "certified" 
           operator this week. [Worel/Lautenschlager]
           
- Tuesday/Wednesday:
        -  Two pulses experiment. A last set of full data was taken:
           measurement of chicane R56, and compression rates in the 
           gun and TESLA-cavity versus phase of the gun and TESLA-
           cavity respectively [Rodion]
           
- Thursday: 
        -  took a set of difference orbit to try to 
           calibrate the quadrupoles with beam. The difference 
           orbit were taken for various excitation of the 1st 
           (normal) quadrupole and all the skew quadrupoles [Jason/
           Yin-e/Philippe]
           
- Friday: 
        - flat beam experiment: took again a set of data of spot sizes 
          and slits angle versus B field on the cathode. Also attempted 
          to do a quadrupole scan but failed, we need to use several 
          quads during a quad scan to insure the beam get confined 
          within the viewer field of view [Philippe/Yin-e]
           
* Discussion:

          
        - Nick and Rodion did some work on the laser over this week-end: 
          a spatial filter was installed between the multi-pass and two-
          pass amplifiers. More work on tuning up the laser is needed 
          today. 
          
        - There were also some brief discussion on the laser; the oscil-
          lator has been very unstable the past days (it costed half 
          day of downtime Thursday and Friday): the bandwidth was oscil-
          lating between 13 and 19 A in a 30 sec period. There were 
          some mentions of possible new oscillator -- Philippe will set
          up a video conference with Adrian Melissinos (and all other 
          interested people) so that Nick can present his forseen 
          plan for upgrading the photo-cathode drive laser.
         
        - Philippe reported on data analysis on flat beam (work with 
          Yin-e). Angular momentum dominated beam for various B field 
          on cathode was propagated downstream of the 9-cell and the 
          spot sizes + angular momentum were computed. The agreement 
          with simulation based on Poisson map of the b-field is decent, 
          as far as the beam sizes vs B evolution is concerned. There 
          are some discrepancies on the angle. The evolution of angular 
          momentum versus B is also in better agreement than previous 
          data reported. We still need to do a full simulation of the 
          measurement to check for some systematic effects.
          
        - Philippe showed some data on CTR signal when the laser is 
          set-up to generate to pulse separated by 15 and 30 ps. The 
          CTR power versus 9-cell phase was recorded. When the two pulses 
          are separated by 30 ps (like it was done in one experiment 
          to test the resolution of the CTR-autocorrelator), there is 
          no overlap in the CTR signal from one pulse with the other, 
          and therefore because of the sensitivity of the detectors, one 
          should not at all expect to resolve the two pulses structure. 
          However with 15 ps separation, the CTR signal from the two pulses 
          overlap -- this is the delay we should use in the next round 
          of experiment (this Friday) to try to resolve the two pulses 
          structure on the time distribution. 
          
        - Matt briefly reported on the on-going work at UCLA in analyzing 
          the data taken the past week on the plasma transition trapping 
          experiment. There is, as expected, some emittance blow-up downstream 
          of the aluminum foil. It is however believe that the large 
          emittance come from upstream of the foil (compressor, etc...). 
          There is some work to do in understanding the beam dynamics of 
          highly charge/compressed bunch in the A0 set-up. UCLA is setting 
          up some simulations. 
                    
        
* Tasks concerning hardware 

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]                            
H25/ Software for the digital camera (Jason -- DONE); Now need 
     to choose which camera we are going to use [Jason/Markus]
H26/ trigger problem on a couple of CCD camera 
     (->Kai will look into it 03/2004)
H27/ The temperature sensors on the laser components need to be 
     wired and archived on ACNET (Jamie 03/26/04)
H28/ Problem with emittance measurement at X7 (Philippe 04/16/04)
H29/ Need daily monitoring of the laser parameters (Jamie/Rodion 04/23/04)
H30/ Need monitoring of laser oscillator spectrum from HP spectrum 
     analyzer (Jamie 05/21/04)