144Xe run Sep 2006
Target issues:
* Experiment
IS411
* Target
#336, UC2, MK7
* Mass
markers: Ar/Xe-gas(95/5%)
* HRS
separator set-up at 30.2kV
* Yield
check:
Ion source efficiency measured and calculated on 132Xe=> 6.3%
Yield of 144Xe, protons on target: ca 1.8e5/muC.
REX issues:
Isotope
run: 144Xe34+
Timing:
198ms breeding time for 34+
Efficiency
and energy:
On the trap inj plate 1965 pA 136Xe => HRS transmission 85-88%
System optimised for 136Xe34+, tperiod=200 ms, tbreed=198 ms, tgate=1 ms, fast extraction => 11.5 pA
in trap inj plate, 6.5 pA
on BTS.FC20 (some Ne) and 34 pA
on RFQ.FC20(34+) => Total efficiency 8.7%.
Similar efficiency for slow
extraction.
Linac
transmission and energy: 70% for
A/q=4.2353 at 2.7MeV/u
Currents: With
7/14 pulses/sc, 3E13 p/p
·
1.7
pA averaged after the trap but the major part is Ne and a large very broad bump around A=144. See
TOF_144Xe_2006_09_12_gated and ungated1,2.csv in
REXTRAP directory.
·
After
REXEBIS 0.3 pA (34+)
·
Beam
can be seen clearly on BEN.BO100, no current seen after the linac
·
REX
low energy part finished with 144Xe setup. After the
trap we've 1.7 pA (averaged) but the major part is Ne and a large very broad bump around A=144.
Technical problems:
·
Ion
source in HRS target repaired twice before the run
·
The
pick up loop on the linac’s main IH structure is
sometime jumping between two values. Need to be sorted
out during the shutdown.
·
BEN.FC40
was out of order (front part and insulator fell off) making linac
tuning very difficult. Design of FC should be improved.
·
Long
proton interruption during night due to a chain of errors (power supplies and
wrong archive values)
·
The
count rate at the Miniball target went down a factor
2-3 during the last 24 h. The reason could be:
drooping target
performance
drooping line performance (broke
later during the weekend)
slow detuning of the HRS
ion source
Lessons learned:
·
One
day is not enough to tune the linac.
·
Have
to use standard settings for HRS separator -> reduce tuning time to REX
·
100%
transmission to tape station is possible with plasma source at 30.2 kV
·
Poor
communication concerning chosen A/q. Fredrik – write clearly, Didier – read
carefully.
·
A
2-days run is very short for REX.