Activities of FNPL from 01/23 - 01/28 Friday Jan 28 th, 2005 minutes at: http://nicadd.niu.edu/fnpl/Operation/Minutes/ * Plan for next week: - Monday: - laser study [Jianliang, Rodion] - measure the UV pulse length - Tuesday, Wednesday, Thursday, and Friday: running beam - flat beam: - work on improving emittance ration - do a clean measurement of e+/-=e0+/-L - flat beam emittance vs B and sigma_c - round beam: - emittance measurements, test mask - bunch length measurements * Last week activities: -Due to Friday (01/21) drop in laser intensity while realigning the multi-pass, the beginning of the week was spent realigning all the IR beam line from the fiber stretcher exit to multipass. The multipass Q-switch was realigned and Wednesday night beam in IR was back to nominal power (200 \muJ) In parallel (Monday) a dying pump (for gun water cooling) was changed. Since then the gun temperature could not reach its nominal setpoint (39.4 C) but stalled at ~ 37 C. The problem was not solved by today (Friday 01/28). Tim Koeth suggested that this might be due to a flow regulation; while Jamie was proposing to install a new heater on the water pipe. -Jianliang mentioned last week activities on the laser, he also shown a measurement of the IR transverse spot along the 2 pass. The beam has some cocentring ring-type distorsion downstream of the 2 pass; this is not understood and will be further investigate -Gregory reported on his work for the OTR used in the plasma chamber. The e- beam, after passing through the plasma lens will be focused. Close to the focus location an OTR (screen) is located and the forward OTR is reflected at 45 deg by a second mirror, collimated by a 150 mm lens and extracted from vacuum via an optical port. One of the concern is that the 45 deg mirror also intercept the beam and emits OTR - this in turn "pollute" the OTR signal coming from the OTR screen and results in some background on the CCD camera (note: this will not be a problem when we streak the OTR because the OTR screen and the mirror are separated b ~ 4cm). Gregory did a mock-up experiment on the optical table and find out that the light coming from the mirror contribute to the image of the screen at a level ~ 1/4 in total intensity. -Rodion presented is latest analysis of the laser room vibration (this is done in context to the upcoming laser oscillator upgrade). His findings and recommendation will be written up as a beam-docs report soon. Rodion's main conclusions are: . the air compressor installed next to the laser room should be moved away (this air compressor turn on periodically to maintain proper pressure in the air system used for the screen air-cylinder insertion in the beamline). When on the compressor drive a strong vibration at 40 Hz. . floating the optical table shift all the frequency to lower frequency but is then very sensitive to people working in the laser room; so its seems there is no strong advantage. -Yine-e discussed her later analysis of the flat beam data taken early January. After more carefull computation of the rms values the emittance ratio is about 70. She discussed the way she computed rms value from the picture. A new algorithm based on looking at the rms value convergence versus window size of the region-of-interest selected on the picture was presented. The algorithm seems robust and give a true rms of 90-95 % of the distribution. Early analysis of flat beam were produced based on Gaussian fit of distribution which are not a fortiori legitimate. The plan is to come up with a small toolbox that we could install in the control room for everybody to be able to analyse distribution on line. -Tim presented the plan for the time-of-flight detector, the phase detector consisting of a ring-type pickup was donated by DESY in 2003 and commissionned a couple of weeks ago. Now the plans are: build a simple electronic (based on the path length measurement developed for the CEBAF machine). Develop procedure to calbrate the detector and then measure the compression (R55) and momentum compaction (R56) of different beamline part (gun, cavity, and bunch compressor when back in). -Jamie presented the present plan for upgrading the water system for the laser. The were still questions and he will present this to the laser meeting Tuesday ACTION ITEM updated: Sat Jan 29 07:15:54 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] H39/ streak camera new optics for plasma OTR and UV laser streaking. [Jamie, Greg, Rodion, Philippe] H40/ installation of UIUC experiment, beamline design [Philippe] H41/ OTRI experiment [Greg] H42/ revisit EO sampling experiment [Jianliang] H43/ laser cooling system upgrade [Jamie-> discuss with Adrian, Jianliang,Rodion] H44/ do we need to get our rf system out of the TeV LCW and Why [Jamie/Philippe] #.43 from Adrian Melissinos: NEEDED LASER STUDIES: 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 4. _harware_: replacing all coolers with new system IV + use existing system III as back-up (see H43) 5. pulse stacker studies, new pulse stacker R&D (see H13)