Li run August 2006

 

Target issues:

 

* Experiment IS446

* #335 Ta, W surface ionization

* Mass-markers Be and Li

* HRS separator setup at 30.2 kV, run in BH15 mode, use Collaps magnet cycling programme

 

* Yield check

“From Ta308 target benchmark, yield on 8Li is 3.10^7/muC. Yesterday morning, it was 4.10^6 for this target. Taking for granted separator has been optimized yesterday by a x2 factor, we are now at a x4 factor below Ta308.” (ISO-HRS logbook)

 

 

REX issues

 

isotopes run: 8Li3+

 

timing: 18 ms breeding time for 3+, 20 ms cooling time

 

currents:           With 3E13 p/p, 6 p/sc

trap inj plate – negative value with beam on it

BTS.FC20 = 10 pA in the peak

RFQ.FC20 = 8pA of O6+, only 0.6 pA of 8Li3+

efficiency and energy:

* HRS.FC490 to REXTRAP: 85-100%, tested with 8.5 nA K and 90 pA 7Li

* TRAP: 20% for 7Li (~100 pA inj, 20 ms cooling and short gate) <5% Ne in the trap TOF

* EBIS eff 13% for 7Li3+ with 18 ms breeding time

* Linac transmission and energy: 75%-85% for A/q=2.666 and 3.15 MeV/u (50Hz/900us)

 

For 39K form HRS

Trap inj plate=18 pA, BTS.FC20=11.5 pA (some Ne), RFQFC20=18 pa (10+)
Trap eff < 64%; EBIS eff > 15.6%; Total eff = 10%

 

comments:

* A 25ug/cm^2 C foil was used at the linac output to remove 16O

* An extra 4ug/cm^2 foil was installed between the RFQ and buncher. This seems to give good results (factor of 8 improvement in Li/O ratio) but could not be used for data taking due to the low beam intensity.

* Slow extraction was tried. Long beam pulse on SEP.FC80 and at experiment, but not that much more events.

 

technical problems:

 

lessons learned: