Participants: Tim Giles.
1. General IssuesAlignment at REX and ISOLDE
-
Pierre Delahaye gave a 20 min. presentation about status and future development of the ECR test stand at ISOLDE. Main topic of the talk was the possible role of the ECR within the HIE-ISOLDE upgrade project. The transparencies can be found attached to these
minutes.
-
Manuela Turrion Nieves has all necessary data from our side and got an account now to construct the REX-ISOLDE database in the CERN oracle database.
-
Peter Butler reminded that the T131900 budget is
blocked at the moment for automatic budget control, because the committed expenditures for the hall
extension are higher than the cash on this account. For urgent things, the physics group account shall
be used. This situation will last for about one month.
-
Peter proposed another REX upgrade meeting on 07. July. Here it shall be decided how and in which order the money allocated by Piet van Duppen can be spent for accelerator cavities and rf-equipment.
-
Thomas Sieber mentioned that it would be helpful to know in advance for which experiments stripper foils
might be required, so they could be ordered in
time with the right thickness.
-Erwin Siesling and Tim Giles were invited to
discuss alignment at REX and at ISOLDE in general.
-The main question was, if ISOLDE should buy the
same type of theodolite, which is used in the alignment group (costs: 40 kCHF).
On the one hand this could be a disadvantage because having an own instrument
might separate us even more from the common CERN alignment scheme and the
responsible group. It is also problematic that these theodolites are
sophisticated systems, which are difficult to handle for non-specialists. On
the other hand it would open the possibility to have support from the alignment
group without asking for their precious equipment.
-Mats proposed to contribute with a certain amount
(for example half the price) to the acquisition of a new theodolite in the
alignment group. Erwin will discuss this possibility with them. The money for
this contribution might be found in the ABP section.
-Thomas pointed out that (in case we have to
continue for some time to do the alignment ourselves) with the currently used
theodolites the alignment of distant objects, like for example of the REX
separator mass-slit, is only possible with an accuracy of 1mm.
-Erwin will clarify with the alignment group 1. How
long in advance we have to ask for support. 2. To what extend the current REX
alignment scheme (alignment on beam axis) will be accepted and kept by them.
-Erwin will also look into the possibility to have
our old instruments recalibrated and to get a fixed installed telescope for the
EBIS.
-The targets for the alignment of the new part of
the REX Linac will beaccording to the common CERN alignment scheme.
2. TRAP
-
-
There have been two air leaks found at the trap setup, one has been repaired by
the vacuum group one is still there. Sophie Meunier will take
care for this.
-
The REXTRAP has been
carefully cleaned and can stand 60 kV.
-
The REXTRAP has been
carefully cleaned and can stand 60 kV.Nicolas David has taken
several trap electrode power supplies for repair.
-The trap will be back in operation in beginning of
February.
-The small emittance meter from Munich will arrive
mid February. Pierre and Romain will continue with measurements for the
rotating wall cooling technique.
3. EBIS
-
The EBIS magnet has been cooled down, but was not yet tested with field.
-
Fredrik found some air leaks on the extractor side,
where new sealings have been installed. EBIS had to be taken apart again.
-
After being pumped down it
was found that the sparking in the extraction region remained. The EBIS was
opened up and again
inspected, polished surfaces, cleaned flange insulators with acid etc. After
remounting and pumping the discharge was gone.
-
Because of the tight schedule, the cathode has been changed already now (in
contradiction to the earlier planning) to avoid another opening of the EBIS
before the startup. ’
-
It was found that some of the electrode (drift tube) insulators were covered with sputtered material (sputtering from the electron beam). During the
change of these insulators another misalignment of one drift tube was detected (if o Old or
caused by the insulator change is unknown).During the insulator change 3 NEG strips (out of 8) caught fire out in the air when placed too closed
to an inspection lamp. New strips were ordered immediately. Urgent delivery time ~1 week.
-
The current time schedule is: assembly of the EBIS
until end of next week. 1 week baking, 1 week startup. The schedule might be again delayed because the required new NEGC strips will arrive at slow ordering and shipping of the
fire classed m aterial)processing of the CERN
purchasing office). Thereafter ion injection from the trap should be
tested.
-
The failure of the problematic turbo pump in the
separator has finallyprobably beeen found. There was a contact problem
on then power supply side.
-
Fredrik was asking for 2000 CHF from the 2005 budget for producing productiondrawings of a kicker bender, which shall be installed between
separator and RFQ to allow for a tape station at this position. Another 6000 CHF has been allocated at the Physics
group account for the production.
-
The electronics (BD rack,
REXTRAP, EBIS ground rack and VMEs) have been cleaned
from dust and should be operational.
-
The air pressure has been
reduced to the beam diagnostics pistons of EBIS.BO10. This is to avoid the Macor insulator to break again due to violent movements.
-
B.
Crepieux from ISOLDE target section has started to take
over the liquid cooling fillings of the REXTRAP and REXEBIS. The technicians
will also assist the low energy part of REX with some mechanical help.
-B. Crepieux from ISOLDE target section has started to take over the liquid cooling
fillings of the REXTRAP and REXEBIS. The technicians will also assist the low energy
part of REX with some mechanical help.The alignment of the magnetic
field of the EBIS solenoid is delayed by more than two weeks because it turned
out to be very difficult. Richard Scrivens supports Fredrik.
-The cooling mantle around the warm bore of the EBIS
is damaged. Leif Lileby from MSL will provide a new tube within the next 3
weeks.
-It was found that the collector holder has a lacking
fixture which makes proper alignment almost impossible. It is necessary to do
some mechanical reinforcement of this holder. Fredrik is working on the issue.
-Romain Savreux was asked to continue with the
installation of a charge readout of the RFQ.BO30 that was started by Fredrik.
-Time schedule for restart of the EBIS: 1.May.
4. Linac
-
BERTRONIX has repaired the
anode capacitor of the 200 MHz amplifier. The geometry of the capacitor has been changed and
additional capton has been inserted to improve the
high voltage stability.
-
There has been a successful test run reaching 100 kW at an anode voltage of 14.5 kV. The operation seemed to be more stable than
before. The former power level of
~110 kW could not be reached. Berdermann will continue to work on the tuning of the amplifier cavity to increase the rf-power. With the current power level of 100 kW on a dummy load we could expect to have 85-90 kW in the cavity for the REX runs.
-
During the test we noticed that the cavity heated up dramatically (already at 1ms, 50 Hz). The reason why this has not been detected during
the tests in
-
100 Hz, 1 ms operation has been
implemented in the system.
-
Some work has been done on
the amplifier PLCs to suppress the interlock for air cooling at the tube
for a few (3) seconds. This is non critical for the tube and we hope to avoid
90% of the “airflow”
switch offs during the runs.
-
Proceeding in the same way
with the interlock for the reflected power turned out to be problematic. Berdermann will propose a solution for this within the next weeks.
-
After some debugging of the program in the
BERTRONIX PLCs (Johann Braun, Jose Marques) it is possible now to read
the status of the amplifiers with the OPC scout, means the communication between the BERTRONIX PLCs and the low-level rf-PLC works correctly now.
-
The
-
The diagnostic box for the
mass scanner has to be realigned because a new slit has been installed.
-
The work on the ventilation
system in the amplifier room has been finished. The new installation has to be
modified because of too much space consumption and mechanical weakness.
-The AB-RF group suspects that the permanent
sparking in the cavity is due to higher order modes, which are not sufficiently
suppressed.
-Nicolas David has replaced the old Danfysik power
supplies for the lenses in the target section by new ones.
5. Control System
-
The question was raised who should be registered as responsible person for the rexdev and rextrap accountstrap computers. I was decided to declare Mr. Potdevin, while putting Sylvester Catin and
Fredrik as administrators.
-
Romain Savreux is changing the
OS of the EBIS workstation to WinXP and rearranging and upgrading trap and EBIS computers in general..
-
Nikolai wants to test his front end computer for PLC communication on the rf-PLC next week.
- For non-Danfysik power supplies the sequence of events should be:
a)
b)
With help of Frank Locci, set up the PLC
software and connect the master PLC to the network. In parallel, Nikolai will develop the front-end
software
c)
We test the full chain (test applications - FEC - PLC) with power supplies in the lab.
-
For point (a) we planned the second half of April,
means: this or next week. There should be something like a month between (a)
and (c)
-For the next running period Thomas wants to have a
control application for the rf-amplifiers, which is similar to the one which
was designed for the FEC control system, but which is now connected to an OPC
server. There will be a meeting about this next week between Nicolai, Ivan
Deloose, Thomas and Jose Marques from AB-RF.
-A test environment for REX separator power
converters has been set up in the control group laboratory by Nicolas David. It
is ready for first tests with the Linux based control system as soon as Nicolai
has finished some elementary control applications.
-Nikolai Trofimov reported from slow extraction out
of EBIS. Implementation into present Windows based system needs three changes:
1. modify console application, 2. changes in the Frontend console, 3. changes
in the C++ library. Some old half ready versions from Joakim Cederkall are
already present, but it's a large amount of code. It would take Nicolai a
couple of months. Nikolai proposes that we wait with the slow extraction
for the arrival of the new AB/CO control system. Could be implemented at next
shut-down.
5. AOB
-The “REX-day” mentioned in earlier meetings is now
preliminary scheduled for 11.03.
-Mats will go to the meeting of the MINIBALL
steering committee on 11.02.
-A new project associate from Russia will start
working in the BDI group, mainly for REX. Enrico Bravin wants us to define his
tasks and to specify detailed work packages for him.
-It was decided that the project associate shall
work more on the integration of existing equipment (in collaboration with
Nicolai) than on daily maintenance.
Minutes
by Thomas