Minutes of A0 photoinjector (local) meeting Friday March 12th, 2004 * attendees: Daniel, Jamie, Matt, Gil, Rodion, Kai, Markus, Helen, and Philippe (recorder) * Next meeting: Friday March 19th 4pm in "the Motel" * Plan for next week: -Monday: - 9-cell studies [Philippe] <-- STARTING AROUND LUNCH TIME -Tuesday: - Round beam studies [Kai] -Wednesday: - NORTH CAVE RUNNING CANNOT RUN 9-CELL - calibrate the UV diode in the cave [Jamie et al.] - check current flowing in the solenoid compared to current setting on parameter page [?]. - when above work completed turn on gun and do some gun studies [Philippe] -Thursday: - morning: CTR bunch length measurement [Daniel] - afternoon: Plasma experiment [Matt et al.] -Friday: - Plasma experiment [Matt et al.] Discussions: * Achievements of last week: - Monday: - morning Kai finished taking a full set of data on round beam (spot size + emittance) the data are still being analyzed. It was noted that since a couple of weeks the beam spots along the beamline has less pathology than it used to have: the beam looks less structured, this is believe (but no thoroughly checked) to be due to the laser beam not going through a burn mark in the IR-to-green doubling crystal - evening: the laser was set-up to generate two pulses separated by 20 ps and a series of data on rf-compression, by studying the separation between the two pulses were taken [Rodion + Philippe] - Tuesday: - NORTH CAVE RUNNING -- CANNOT RUN CRYO/9-CELL - cave open, the digital camera was moved to X2, downstream of the gun, [Markus] - afternoon: data on beam spots evolution on X2 versus solenoids settings were measured [Philippe] - Wednesday: - morning: Some test on BPMs software to get data from the "burst module" were done. We have now some capability to measure the beam position of bunches with a macro-pulse. The electronic will be moved to BPM8 (dispersive section), e.g. to be helpful for tuning the 9-cell beam loading compensation scheme [Jason, Manfred and Rudi] - afternoon: 9-cell studies [Philippe]: a full set of difference orbit was taken for different operating phase of the 9-cell, this goal being to finish the 9-cell transfer matrix experiment. - Thursday: - morning: CTR bunch length [Daniel] a series of autocorrelation were recorded for different setting of the 9-cell phase - afternoon: Plasma [Matt et al.]: the laser was tuned to provide 12 nC at the gun exit, but the team managed to transport only ~ 6 nC up to the plasma chamber . More work on the transport is needed, but this might indeed be limited by chromatic effect due to the large energy spread required for compressing the bunch. Even when trying to operate the bunch compressor at a higher current (to increase its R56 and thereby lower the required correlated energy spread). The UV telescope was also slightly tuned in the process of optimizing the charge/UV energy impinging the cathode - Friday - Plasma experiment: The team continued working on transport, the goal being to optimize the beam deceleration through the plasma and then try to look for trapped charge. Other items: CTR bunch length measurement: Daniel gave a report on the status of the analysis of the data he has been taking the past weeks. He has not yet received the trans- mission/response curves from Uwe Happek and this render the reconstruction of the CTR power spectrum difficult if not impossible. Daniel has instead used PARMELA to compute the theoretical spectrum associated to the expected bunch distribution. He then uses this theoretical spectrum and what he has experimentally measured to try to deconvolve a response function for the interferometer. The results are actually close to an experimentally measured response of the pyroelectric detector provided by Henrik Loos (BNL). On another hand, the analysis program now incorporate the Kroenig Kramer dispersion relation, and some example of retrieve versus initial distribution were shown. Of course to apply this dispersion relation on the experimental data means that one first need to complete the spectrum... Markus informed that we will have a digital camera from SONY for testing purpose for 30 days. The camera is schedules to arrive next week. Philippe reported on a meeting at the computing division (Paniagotis Spentzouris, James Admunson, and visitors from BNL Rob Ryne, Ji Qiang), these people are interested in taking beam time to do some benchmark of a couple of space charge codes. Spentzouris/Admunson have developed a very fast tracking program (Synergia) that uses the space charge algorithm of Impact3D (Qiang/Ryne) along with tracking capabilities of mxyzptlk, a Lie Algebra-based toolbox developed by Michelotti at Fermilab. All these codes have been installed on the NIU cluster by Philippe and are still in tests (there is some problem with MPI on the cluster that have not been resolved yet). ----------------------------------------- * Tasks concerning hardware H8/ calibration of upstream directional coupler and insulator (Markus need to speak to Tim and with Kai to schedule this STATUS?) H11/ Some of the toroid need cabling to have signal available out of the cave in the rack area (JAMIE, 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...) H20/ what shall we do with the burnt doubling crystal? Who will specify + order it? CRYSTALS FROM CASIX ORDERED (FEB-04-2004) (NEW DOUBLING CRYSTAL WILL BE SHIPPED ON MAR-15-2004) 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 efficency? H23/ laser spare components list (Jamie, RECEIVED A FIRST VERSION JAN-30-2004) H25/ Software for the digital camera (Jason?)