Participants: Pierre Delahaye, .
1. General Issues
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The
current 70Se run will continue until at least Monday evening.
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On
Friday 10.06., there will be a meeting with
Paul Van den Bergh and several members of the BDI group to discuss
the work on the REX beam diagnostics.
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Also
on Friday there
will be a meeting between Mats,
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There
are still problems with the PC for the trap controls. Romain will take care for installation of a new PC.
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A
callout list for REX operation has been fixed. It looks as follows:
Thomas Sieber 164239
Fredrik Wenander 162991
Pierre Delahaye 163644
Romain Savreux 100450207519
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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. Current REX Experiment. TRAP
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The
trap works well, showing an efficiency for the stable SeC of about 50%.
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We
use the 70Se19+ (A/q=3.684). EBIS efficiency is at 5%.
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The
Linac has been scaled from A/q=4 to the Se. Transmission and spot were checked with the nearby 22Ne6+. Even at the slightly
wrong A/q (0.5%
off) we reach 75%
transmission at a good spot at the target.
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With
a reported SeCO yield of 3E5 per uC
this translates to max. 7000 pps at the MINBALL.
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First
results from the experiment look promising. There are about 30 counts per hour
in the Coulex peak.
-Pierre
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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.
3. TrapEBIS
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The
emittance measurements done by Romain
and Ivan have been finished. The results can only partially be compared to
earlier results (Friedhelm Ames). Furthermore at 60 keV
there seems to be a limitation given by the voltage limit in the emittance scanner. Romain and
Ivan will write a report about their measurements.
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The
emittance scanner will be dismounted in the beginning
of next week for being shipped back to LMU.
-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.
4. EBISLinac
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There
are problems with the motor generator on the EBIS platform. It makes irregular noise during the startup. Nicolas
will have a look at this after the run.
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The
MCP in the mass scanner box seems to be not working properly. We will look into this
next week and replace the system by a new
one if necessary.
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Fredrik
noticed that some of his Faraday cups in the low energy section are working unstable. The
reason seems to be on the control system side because the cups show reasonable
values on an independent Keithley.
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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.
54. LinacControl
System
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The
problem of switch offs due to reverse power at the 200 MHz amplifier could be solved by
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The
FC in sect. 5 is not working, we will check if there is a relation to the FC
problems in the low energy part.
6. Control System
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After
looking into the application Nikolai has
developed for the REX rf-system, Thomas and Jose Marques from AB-RF agree that this application
is more than suitable to be used for REX operation and diagnostics. There are some details to be added for data
saving and A/q scaling. Nikolai estimated he would
need two weeks to complete it. In June his priority is on the tests with the magnet power
supplies, so it might be beginning of July until we can use the application during the runs.
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An additional Unix PC will be placed now
among the REX terminals. It shall be used for Nikolais tests and also for the new rf-controls.
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Notes from a meeting on 24.05. and
some correspondences concerning the discussions between the REX
team and CO about the future development of the
REX control system can be found attached to these minutes.
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Mats is currently trying to find somebody who shall participate in the work on
the EBIS control system after 01. July. The main goal is to make the programs on the FEC
compatible to the new passarelle. In a second line, modifications (slow extraction) are discussed.
-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.
Minutes by Thomas