72Znrun 20-24 October 2011

Target issues
* Target number #462 UC2C Ta vertical, quartz line,

* RILIS
* W-converter (tried for a while, but bulk beam time with protons on target)
* Mass markers: Zn
* HRS separator
* Extraction electrode 65 mm, real distance
* Uht(HRS, CCV)=30.25 kV, Uht(RFQ)=30.20 kV, Uht(trap, CCV)=30.00 kV, Elec05=180 V

Yield measurements

Beam visible on FC – see below

30 times lower yield when shooting on the converter compared to shooting on the target

Experimental issues
* Beam to Miniball, T-REX
* IS510

Tuning
* Slow extraction from EBIS 
* REXTRAP timing free-running relative to protons pulses

ISOLDE
For 87Rb YHRS.FC490=7.3 pA, YCA0.FC68=5.9 pA, XTRAP.FC10=5.9 pA

REX low energy

Stable beam 70Zn
HRS.FC490=9 pA, XTRAP.FC10=6 pA, BTS.FC20=3 pA
Charge          Tbreed (ms)     Tperiod Efficiency
17+             40              51      8%
19+             60              81      9.6%
20+             60              81      12.7%
20+             70              81      16%
20+             78              81      17.8%   

Radioactive 72Zn20+

Tperiod=71 ms, Tbreed=68 ms
Cycle freq=634.5 kHz, Icoll=210 mA
Using the peaks to calculate the efficiency => trap+EBIS=13%

Linac transmission and energy: 
No stripper foils. WITCH magnets 0.1 and 3T.

Transmission from RFQ.FC20 to XL65.FC50 at 2.70 MeV/u

- 86% for A/q = 3.666 22Ne6+

Delivered beam at 2.7 MeV/u

Total transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac
0.73*0.13*0.86=8.2%

Delivered beams

72Zn20+
Protons on target. This is for 2.9E13 ppp, 10/39 pulses/sc
XTRAP.FC10 70-80 pA in the peaks ; RFQ.FC20(20+) 130 pA in the peaks; XL65.FC50 70-80 pA in the peaks  

Decide to try Tperiod=71 ms, Tbreed=68 ms, 72Zn20+

7*10^6 pps at Miniball before the collimator

From Miniball: We can’t identify any contaminations larger than 1%. However, it might be difficult to see a week 72Ga contamination, so we are not absolutely sure if there is 72Ga coming with the beam, but it does not seem to be much.

Setting summary
For HRS we used:

HRS_SEP_2011-10-19_30200V_87Rb.csv
RFQ_2011-10-19_30200V_87Rb.csv
111020_1217_REX_RFQ_72Zn_30200.csv

REX low energy settings saved as:

111020_1217_HRS_BTS_72Zn20+.csv
111020_1217_HRS_TRAP_72Zn20+_16%.csv
EBIS_111020_1210_HRS_72Zn20+_slowextraction_15%.csv

REX separator and linac settings saved as:
111019_1837_SEP_Aq4_2.7MeVu_90%_L65
111019_1837_Aq4_2.7MeVu_90%_L65

Technical problems

* Found that 7-gap1 phase shifter was not working during the setup.

* RFQ.MQ120, X7GP.MQ10,20 and X9GP.MQ10

* RFQ cooler HT went down

* Had to reboot cfv-170-arextrap reboot a few times.

Comments / Lessons learned

* We see that we stop about 10-15 % of the beam in our active collimator (10 mm hole), placed about 40 cm in front of the MINIBALL target. From the diamond detector we estimate a beamspot size of about 3mm on the MINIBALL target.