Minutes of A0 photoinjector group meeting Wednesday Dec 01 st, 2004 minutes at: http://nicadd.niu.edu/fnpl/Operation/Minutes/ * Plan for next week: - Monday, Friday: CTR bunch length - Wednesday, Thursday: OTR setup with digital cameras - Tuesday: laser day * Last week activity - Over last (long) weekend the TESLA cavity was warmed up and various cryogenics components (valves + diagnostics) were cleaned or changed. The cavity has been cooling down since 11/29 afternoon and will be ready for operation from 12/02. - The beginning of these week was dedicated to gun studies, Walter Hartung visited and took part with Ray in measurement of quantum efficiency, dark current and multipacting in the gun for various operating condition * Discussion - Rodion and Jianliang reported on their measurement of table vibration, up to now, the concentrated on vertical vibration, but recently they also found out significant transversal vibration. - They continue working on the 4-f parallel beamline, trying to push the conversion efficiency from IR/UV to 5% (Adrian put the goal to 10 %!). They are trying various incoming beam divergence spot size to study the dependence of the 4-f efficiency. - Philippe presented recent calculations to study the impact of input and HOM couplers in the TESLA cavities (for now he uses DESY-type couplers) -- this work was done with DESY (S. Wipf and M. Dohlus). To date the aim has been to check what are the effects and quantify the associated strength. He showed (up to first order in input position) there are steering effects, and normal and skew quadrupole effects. The strength were computed. At the moment the model uses a standing was 3D pattern in the couplers region, the next step is to mimic the energy flow by superimposing two sets of standing wave (to generate a traveling wave) in the input coupler region. plan for next week: ACTION ITEM updated: Thu Oct 1st 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 [FIXED] H36/ laser room/table vibration studies H37/ imaging system for the laser transport [Jianliang/Rodion/Jamie] #.36 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