Minutes of the REX integration meeting on ThursdayFriday,13.05.2005, 03.13.085.2005

Participants: Didier Voulot, Johannes Broere, Pierre Delahaye, Thomas Sieber, Mats Lindroos (chair), Fredrik Wenander, Nikolai Trofimov, Nicolas David, Romain Savreux, Pierre Delahaye, Luis Fraile, Mats Lindroos (chair).

1. General Issues

- Didier Voulot has arrived at CERN to work on the operation of the REX Linac after Thomas has left.

- Thomas invited Johannes Broere to the REX meeting. Han will participate in the REX meetings until Didier is more familiar with REX operation and organization.

- For the alignment of the new ISOLDE hall as well as realignment of the “old” REX machine, Mats and Erwin Siesling are still in the discussion with the alignment group.

- Starting on Tuesday 17.05., we will have a daily short REX meeting at 16.00 in the ISOLDE kitchen to discuss the startup and the status of the running Xe experiment.

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2. TRAP

-Pierre

- and Fredrik had the problem of discharges in the trap, means there was more current measured at the exit than injected from the test source. Nicolas David found a broken cable at a transfer element. The bad contact was responsible for the discharges.

-The test ion source ’runs stable now after the regulation has been improved.

-The application for the frequency scan of the trap has to be improved.

23. TrapEBIS

- Pierre will check with Georgi for the assembly of a new scintillator for the tape station to be installed after the separator. In the mean time another scintillator, much simpler, is being assembled in the laboratory of building 155 to replace the old one for the tests at the ECRIS.

- The 2 Summer students of Pierre will be testing the mass resolving power of the trap in the next two weeks during the absence of Romain

- Romain will then continue the improvement of the current control system and the development of a new Labview based GUI for the trap

- The idea to use the same rf-excitation scheme for REXTRAP as used for ISCOOL (Klaus Rudolph) has been discussed with Nicolas David. The main problem is the larger frequency range (up to 15 MHz), which has to be possible in REXTRAP. Nicolas has also another idea to improve the present excitation electronics.

-The bad transmission through the mass separator, which has been observed on Thursday, was partially caused by two switched cables in one of the steerers.

-There was again a problem with the cabling of the Wago module for the high voltage cassettes, which could be repaired by Nicolas.

-The transmission through the separator is at the moment 70- 80%, due to the high residual gas pressure, the current is about a factor 10 higher than usual.

-Stable beam for Linac optimization will be available on Monday.

-The baking after the run will be done now with the old NEG strips.

-One day is needed to optimize beam transport through the BTS.

-Dry injection (without electron beam and magnetic field) into the EBIS is still problematic because of the high noise level on the electrodes.

34. EBISLinac

- The efficiencies for the breeding of 108Sn where in the regular range.

- Increased radiation level during the Sn run in the charge breeder area (>100 uSv on contact).

- The pretrigger scheme for the REX Linac has been changed. The value entered into the GPG ch15 command field (EBIS computer at the platform) has to be always 1 ms smaller than the actual breeding time. This guarantees that only short delay is needed in the Linac pulse generator, which makes the timing much more stable.

- The cathode is behaving well and will NOT be changed before the end of the run.

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- BERTRONIX could not solve the principle problem of the limited power level of the 200 MHz amplifier. Also the unstable operation at 10% duty cycle is still a problem. The amplifier could be tuned to ~100kW output power on a dummy load. It is running quite stable now at 30Hz, 600us. So we can expect closed loop operation on the cavity at about 85 kW.

44. LinacControl System

- The start of the repair of the 200 MHz amplifier is scheduled now for Tuesday morning. By the end of the week or early the following week, it should be clear if we can switch to higher duty cycle operation, or if we have to continue at 0.5%, 60 kW.

5. Control System

- The rf-control application is working very well.

- The control system for the magnet and high voltage power supplies is in principle prepared for operation. The control applications have to be developed as soon as possible.

- Another problem concerning the beam optics controls is, that beam diagnostics is partially (scanners) necessary. The beam diagnostics is still VB applications, running on the XP FEC. It is difficult to implement this in the CERN standard CS.

-The BD FEC is still stopping from time to time, Sylvestre Catin has been informed about this.

-Nikolai found that there are not enough Ethernet connections in the network rack, where he wants to connect his Front end computer.

Last Minutes by Thomas

Goodbye, and best wishes for the future.