Activities of FNPL from 12/19 to 01/07
                        Friday Jan 7 th, 2005


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



* Plan for next week:

   - Monday to Wednesday: cave open:
	- modification of plasma chamber
	- modification of the optical beamline from
          laser to streak camera
	- alignement of OTR screen to be able to streak
          OTR light with the streak camera
        - klystron test? [J. Reid]

   - Thursday, Friday: running beam
	- beam to plasma [Matt et al.]
	- do emittance measurement [Philippe + Rodion]    
    
* Last week activity

- one day was dedicated to photo-emission study. Ray reported he 
	could reproduce the same depency observed by Walter Hartung 
	on quantum efficiency + dark current level verus time for 
	flat and round beam solenoids configurations.

- flat beam data were taken, we reproduce emittance ratio of 50 and 
	actually on Thursday reached 80. Yin-e presented a prelinary 
	analysis: the biggest of the flat beam emittance match well 
	the prediction from Astra, the smallest of the emittance is 
	still a factor ~3 bigger than expected. Philippe shown that 
	the requirement on the vertical dispersion is |eta_y|<< 4 cm 
	in the vertical plane to resolve vertical emittance of about 
	0.1 mm-mrad; at the moment because of misalignement and use of 
	steerer the dispersion is about 8 cm -- too large. Last week 
	an attempt was tried to reduce the dispersion and the ratio of 
	80 was measured.

- the work on the test beamline for frequency quadrupling of the IR to UV 
	in the laser room is alsmost completed. Rodion presented the result 
	of measurement of quadrupling efficiency versus incoming beam energy 
	for the IR to green crytal. The curve suggests that the frequency 
	doubling process operates in the saturated regime in our set-up. The 
	curve however shows a maximum efficiency of 30 % (to be compared to 70 %  
	from theory). Rodion has been developing a semi-analytical model to study 
	numerically the conversion process. He shows various dependencies of 
	efficiency versus incoming IR energy, crystall thickness, beam size, and 
	bandwidth of the incoming beam. Rodion is now incorporating the beam 
	divergence (curved wavefront) and crystal tilt.

- Jianliang presented the measured bunch shape at the oscillator exit
	using the CW autocorrelator. The turning table of the autocorrelator
	was changed and a set of retro-reflector were installed to avoid being
	sensitive to table wobble. Now the autocorrelator has the proper
	precision for resolving few ps long laser pulse (e.g. as for the
	foreseen new oscillator) 

- Jamie reported that the home made spectrum analyzer that was not 
	operational for more than a month has now been fixed in collaboration 
	with J. Biggs' group
	
	
ACTION ITEM updated:
Wed Jan 12 07:30:37 CST 2005

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]
H32/ Digital camera from SONY(?): [Philippe/Yin-e]
     to be TESTED with OTR [Sep 27] [FIXED, we have prototype]
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]
H36/ laser room/table vibration studies [Rodion]
H38/ controllable iris [Jamie]
H39/ streak camera new optics for plasma OTR and UV laser 
     streaking. [Jamie, Greg, Rodion, Philippe]

#.39

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[Done]
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