Xe run autumn 2005

Target issues:

* Target number #311. UCx, Mk7

* Ran with 500E10 p/p for 138Xe and 140Xe and with 2000E10 p/p for 142Xe

REX issues

isotopes run: 138,140,142Xe34+

breeding time: 198 ms for 34+ (NB! Not at the maximum of the charge state distribution)

currents:

* For 1.7E13 p/p, 12/12 pulses with 138Xe:

Trap inj plate = 230-270 pA, BTS.FC20=70 pA; RFQ.FC20=38 pA

(NB! At HRS.FC690 only 15-54 pA)

* For 500E10 p/p 12/12, 140Xe:
HRS.FC690=5-10pA ; Trap inj plate=11pA ; BTS.FC20=8pA ; RFQ.FC20=17pA

* For 2E13 p/p 12/12, 142Xe:
HRS.FC490 negative value; HRS.FC690 10-30 pA; Trap inj plate 10-17 pA; BTS.FC20=35 pA (maybe 30% Ne); RFQ.FC20=15 pA

* Check of 144Xe with 2E13 p/p, 11/12:

HRS.FC690 maybe 1-2 pA in the pulse but could also be noise.

efficiency:

* HRS.FC490 to REXTRAP: 100% (checked with 133Cs beam)

During the actual run the efficiency was 50-55% (checked with stable 136Xe and 133Cs)

* Trap: 54% efficiency for stable 133Cs (49 Hz, 10 ms beam gate);

* EBIS : 1.6% for 138Xe ; 6.2% for 140Xe ; 1.8% for 142Xe (all for 198 ms breeding time, not peak CSD, underestimation as total efficiency trap+EBIS is higher)

* Total Trap+EBIS efficiency: 0.5% for 138Xe (maybe 2.2% if HRS.FC690 value used);

6% for 140Xe;

2.9% for 142Xe

* Linac transmission: 70% for 138Xe

71-73% for 140Xe

70% for 142Xe

Linac energy:

* 2.83 - 2.85 MeV/u

comments:

* Even after the 138Xe beam was stopped BTS.FC20 showed a positive reading up to 10 pA for a few hours, slowly decaying.

* for 142Xe the fraction of Ne was substantial; could be decreased by lowering Electrode 40 to -5700 V

* the experiment could not go to the desired 144Xe due to a long half life of a daughter nuclei

* radiation for 500E10 p/p 140Xe:

70uSv/h on contact pump inlet

220uSv/h on contact bellows before FC RFQ.FC20

* 9-gap tuning proved quite difficult and did not match with previously saved settings. Tuning should be redone with a stable beam (A/q 3.5) to check amplitude and phase are right. Also verify input energy.

technical problems:

* the transmission from HRS to the REXTRAP dropped from 100% to 50% without any explanation; could not be regained

* one of the HRS magnets lost the Tesla meter reading

* the 9-gap resonator broke at the end of the run

lessons learned:

* HRS is not ideal to use together with REX