Minutes from REX meeting 2005-06-29

 

Present: Mats Lindroos (chair), Pierre Delahaye, Luis Fraile, Georgi Georgiev, Romain Savreux, Richard Scrivens

 

 

General

 

* Several power cuts happened last week in the ISOLDE Hall most likely because of the stormy weather. Fortunately no equipment was damaged at REX-ISOLDE.

 

* Edgar Mahner was called for helping restarting the vacuum at the LINAC and especially the cryopumps. ISOLDE specialists, David and Sophie were unavailable (vacation).

 

* The LINAC vacuum system is running so-far in manual mode, and the trap, source, section 0 and 1 have to be restarted manually after power stops which makes the vacuum system handling somewhat tricky/ risky.

 

* Nikolaď is currently setting up the CS for the RF amplifiers. A new linux PC has been installed in the control room. He apologized that he couldn’t attend this meeting because of another important appointment with José Marquez for the FEC setup.

 

* The crane has been stopped for tests in the extension from Friday until today without prior notice. This was hindering the safe handling of LN2 and LHe at the EBIS.

 

 

Next beam time preparation

 

* The next beam time is devoted to the coulomb excitation of 68Ni and 70Ni – IS412. RILIS will be used for the resonant ionization of Ni atoms. The target – ion source system is a prototype so no information about contaminants and yield is available yet. Rb will be available as a mass marker to be independent from the RILIS. No particular difficulty is expected from REX for this new beam.

 

* The target will be set-up on Friday afternoon or most likely on Monday morning. Some careful yield measurements and tests will be done with this prototype-target.

 

* A problem with the cooling water for the lasers at RILIS is being addressed. During power cuts the water flow stops, which may cause the destruction the Dye lasers. 3 solutions are in study: a commutation with a safe water circuit, or with a safe electricity circuit, or the permanent surveillance of an operator who stays in the laser barrack. The latter solution is most likely the one which will be adopted for the next beam time. Luis will ask to the MINIBALL team for volunteers.

 

* The transport, trap and EBIS tuning will start on Monday. MINIBALL is asking for residual gas beam on Tuesday.

 

* Georgi will move the ionization chamber from the second to the straight beam line for the next Ni run. It should be reinstalled later on the second beam line for the Be run IS430 for which a stripping foil will be used.

 

 

REXTRAP and REXEBIS

 

* Romain has started efficiency measurement with Asa, Pierre’s summer student. With time of flight spectrum analysis to estimate the relatives Ne+ and K+ contributions in the total intensity, they have found typical efficiencies of about 50% for ion cooling. Different trap voltages, deep or shallow potentials were tested.

 

* With the help of Nicolas David, Romain has corrected the discrepancy between the set and readout values at some quadrupoles in the BTS.

 

* Profile pictures of the beam in the BTS have been taken using the MCPs. However some of the quadrupole voltages have changed from the optimized settings because of the latter modification. A correction factor will be applied and new pictures will be taken.

 

* Romain noticed that a PC from the security group is permanently logged on the REXTRAP control PC. It might be a reason for the screen freezing problem.  Romain will discuss it with the helpdesk.

 

* A new version of TWINCAT is available. It avoids a conflict with the multiprocessor kernel used with recent Pentium processors. Romain is planning to install it in the break of August.

 

* The vacuum at the EBIS has been restarted by Richard during last week. The pressure is currently in the order of 10-10 mbar in the gun region, corresponding to one order of magnitude worse than before the power cut, and 10-9 mbar in the collector region which is almost identical to the pressure before the power cut. Fredrik plans to start a bake out in the middle of August when some time is available for maintenance. No bake out will be done before the next beam time.

 

* The cathode heating has been restarted slowly and the electron beam current is about 140 mA with acceptable losses.

 

 

LINAC

 

* The Linac vacuum system would need some improvements. It would need to be clarified and one should be able to run it in automatic mode.

 

* An engineer from LPSC is another possible candidate for taking in charge the LINAC operation for the next 6 months after the leave of Thomas.

 

 

 

Minutes taken by Pierre Delahaye