Minutes from REX meeting 2005-05-04
Present: Pierre Delahaye, Mats Lindroos (chair), Fredrik Wenander, Romain Savreux, Nikolai Trofimov, Thomas Sieber, Giorgi Georgiev, Nicolas David and Peter B
General issues
* Due to the short time available for tests and verifications of the trap, EBIS and Linac before the run, the beam has to be shared in the most efficient way possible during week 9/5. The low energy part can earliest be finished by the end of the week. Thomas is ready to take the beam from the EBIS to setup the Linac from Tuesday evening and onwards.
* For the beam setup in the Linac Thomas could possibly use the PPAC in the Miniball. Then the Coultron MCP presently installed at the Miniball target, can be removed and there will not be a collision with the setup of the experiment.
Controls system etc
* Nicolas D reported on an error in the ISOLDE database system concerning the new Danfysik supplies for beam steering. It has been sorted out.
New CS from beam tuning
* Nikolai reminded us that there will be a test the 25-26/5 of the first part of the new control system (controlling the Danfysik supplies).
* The rest of the new control system is progressing well, with new crates being assembled.
* It was suggested that Romain Savreux could assist with the application programming for the new AB/CO control system when he has finished the REXTRAP CS. Nikolai will explain for him what it involves. Thomas should look into the budget to verify that we can pay him until the end of September.
Old CS for beam tuning and beam diagnostics
* The old ‘passerelle’ for network connections was switched off by AB/CO. This caused several of the REX-ISOLDE control programmes to stop. AB/CO that is in charge of the REX-programmes was notified last 27/4. Some of the problems have been resolved but not all so the startup of the machine will be delayed with almost two weeks.
Status:
* The beam tuning is not working on any console machine, only on the FEC.
* The beam diagnostics is since this morning running on all machines except for the two new XP machines for the trap and the EBIS. Frequent error messages. Sometimes very slow.
To be done (in order of priority):
* Make the beam tuning working on all machines.
* Make the BD run also on the two new XP machines.
* Make the EBIS programs work on the new XP machines.
* Look into error messages and response time for the BD system
* Look into why the Beam Observation windows keep alternating if more than one window active.
* Gerrit Jan-Focker has not had any problems with the ISOLDE scanners. Mats suggested to make use of his dll-files.
* Mats will contact Ivan Deloose to ask him to resolve the control problems (he agrees on coming on Mon evening 9/5).
New Labview control system for REXTRAP
* Some bugs and improvements still remain.
* Romain was asked to convert the old REXTRAP setting files for the new REXTRAP control system.
* The REXTRAP control system will be tested and debugged over the weekend. If it is not performing satisfying on Monday we should go back to the VME based CS.
* The upgraded XP machine should be installed at the EBIS control table.
REXTRAP and REXEBIS
* There is a discharge inside the trap causing a superposition of Ne+ ions on the extracted beam. The Ne current can be several orders of magnitude higher than the injected beam and has to be eliminated before the trap can be used. The cause for it has still not been found.
* The MCP behind the trap did not respond correctly to the commands and did not enter the beam fully. Be increasing the air flow to the actuator the problems was solved and the TOF spectrum regained the correct amplitude.
* The BTS.FC150 showed nonsense values. After quite some testing with the Keithley multiplexer and picoamperemeter, the error was finally localised to the connector of the cable.
* The vacuum inside the EBIS is still poor. A second bakeout can not be performed before the run due to time restrictions. Moreover, a poor vacuum could possibly enhance the production of highly charged Xe ions at the first run due to ion-ion cooling effects.
* A very high electron beam current of >350 mA has been reached under reasonable stable conditions. A high current should be favourable for the Xe run.
LINAC
* The Linac has been cleaned by an external cleaning company.
* The Linac has been pumped and a pressure of 3E-6 (close to the mass separator) to 1E-7 mbar has been reached.
* No stripper foils are installed for the first Xe experiment.
* The ventilation system has been improved and is now satisfying.
* The water flow is at the limit already and can not be reduced more to gain in return pressure for the EBIS circuit.
* Berdermann arrives Mon 9/5 for three days. The 200 MHz amplifier delivers 90 kW to a dummy load (corresponds to ~85 kW in open loop operation) at 50 Hz, which is sufficient for the first Xe experiment.
* Berdermann will also correct the Simatics programme as the last changes done are not compatible with the CERN programmes and the system does not start.
* The water problems in the IH and 9-gap structures are solved, but a long-term solution has to be found, possibly the circuit has to be purged once a year.
* The broken preamplifier for the RFQ has been repaired and a spare one has been found, but a modification of its interface is required.
* The low level modules have now all been tested and they perform well. The phase shifter module for the 200 MHz module still needs modifications.
* The plasma source installed in the mass separator and used for beam tuning of the Linac was removed during the shutdown. This source has never been appropriate for its purpose due to a very divergent beam and high operation pressure. Mats, Richard C and Thomas inspected it and it was concluded that instead of modifying it one should try to find an alternative commercial source (for instance a small multicusp source), if the budget allows. Bernhard W has been contacted for some suggestions and Richard S also promised to have a look.
Minutes taken by Fredrik Wenander