Minutes from REX meeting 2006-05-24

Present: Mats Lindroos (chair), Didier Voulot, Fredrik Wenander, Han Broere, Luis Fraile, Christian Dutriat and Nikolai Trofimov

REX low energy part

* REXTRAP has been used for mass resolution tests/measurements by Sven Sturm. Now used for B. Blank’s experiment until mid next week. They have a good transmission but had to exchange the oven to the local ion source.

* Despite problems with the new cathodes the EBIS electron current has now reached nominal value and the EBIS can be operated almost normally. However the cathode requires excessive heating power and will therefore have a shorter lifetime. A technical stop is foreseen during the running period to replace the cathode (possibly mid August).

* A first injection test in the EBIS failed probably because of a power supply wrongly wired in the BTS line. This has been corrected.

* Some initial slow extraction tests were carried out. However the weak signal due to the extended pulses can not easily be resolved from the background on a scope. A proper test can only be done with Miniball to check the effectiveness of the slow extraction scheme.

* A new version of the control system for REX-trap has been installed and is now running successfully.

REX linac

* The second tuner motor on the IH cavity has been reinstalled. The end positions and forbidden positions have been checked.

* A new timing system will be installed to control timing for all RF chains. This will also enable the tuners to operate at 1Hz regardless of the linac repetition frequency to avoid damaging the motors.

* Concrete blocs have been ordered and will be installed to improve shielding of Miniball from the linac. This work is planned for beginning of week 24.

Move into the extension

* Bruno Favrat TS/MME will start mechanical drawings for Miniball-move Phase 1. Fabrication drawings will be produced for the new vacuum chamber, supports and several connecting pieces. A layout drawing of the extension beamlines will also be produced. All new drawings will follow CERN standards and be included in the database. Fabrication drawings will be ready before end of June.

* Five LHC type alignment target holders have been ordered for hall extension. These will be modified to enable fine adjustment of the target position.

New control system

* The new control applications for REX have been tested and work well. Several improvements have already been implemented by J.L. Sanchez and E. Ovalle following user requirements.

Thanks for the good work!

* Several solutions have been suggested to improve the speed and accuracy of mass scans: synchronization with the FEC and better algorithm. An improvement of at least a factor of two is expected in the scanning speed and better resolution.

* Nicolas David is finishing the design and installation of a new regulation card for the separator magnet power supply to improve the response time of the magnet.

* Following the tests with the mass scanner application long stabilization times and noisy signals were noticed for the separator magnet field. The hall probe is faulty and will have to be replaced for optimum resolution of mass scans.

Beam diagnostics/Compressed air

* A new type of cable was tested to replace the triax cables between FCs and electrometer. The test was not conclusive and the old cables were reconnected. New connectors have also been mounted on these old cables.

* Following the incident on the compressed air circuit, several FC and profiler actuators jammed. One of them was dismounted for inspection and test. The actuators themselves are OK. The problem is caused by powder inside the air switches. These switches need to be replaced. Catheljine Bal is looking into the problem and will order the necessary parts for repair.

Spare actuators will also be ordered.

* Three valves are also damaged in the low energy part by powder in the compressed air circuit. One has already been replaced. Two are still difficult to operate.

Next meeting in one week.

Minutes taken by Didier Voulot