Li run autumn 2005

Target issues:

* Target number #309, surface ioniser Mk8, Ta foils

* The Li current was very sensitive to the line heating. We ran at 330 A on the line.

REX issues

isotopes run: 9Li2+

breeding time: 3.5 ms for 2+, cooling time 20 ms as the linac could not operate above 50 Hz

currents: for 11/12 pulses, 1.6E13 p/p

CA0.FC68 = average 6 pA (jumping from 4 to 11 pA)

BTS.FC20 = average 3 pA with 1/3 of Ne

RFQ.FC20 = 0.3 pA on 9Li2+

efficiency:

* HRS.FC490 to REXTRAP: between 75% and 80% (checked with 7Li beam)

* TRAP 33% for 20 ms,

very short beam gate -> some ten pA out, mainly Li, 10% Ne and a small slow tail

* EBIS eff 10% for 7Li2+ with 3.5 ms breeding time
With radioactive 9Li2+ around 7.5% (large error bars)

* Trap+EBIS eff 4%

* Linac transmission and energy: 75% and 2.76 MeV/u

comments:

* Somewhat time inefficient setting up of the HRS as the separator stood unused for a whole day in total.

* Buffer gas pressure 7 V for Ne.

* Very little (some percent) of 18O4+ in the beam.

* Stripper foils (25 ug/cm2) used to push 9Li2+ into 3+. All beam went to 3+.

* Tried ion-ion cooling by injecting He gas into the EBIS. No improvement seen for 7Li+.

technical problems:

* The air conditioning for the RF amplifier room kept on switching off and as a result the 7-gap cavities stopped due to overheating.

* Difficult to setup the beam transport from HRS to trap as the HRS separator settings were different from normal settings.

* The HRS NMR probes are not working for 9Li when the separator is at 30.2 kV, therefore no feedback. Thus we had to cycle the magnets manually. Fortunately the 9Li could be seen on the scanners and the magnets be calibrated.

lessons learned:

* Checked with Tim Giles that the NMR probes are working for 11Li at 30.2 kV in case that beam will be used next year.