66Ni run Nov 2009

Target issues
* Target number #418 UC2C W-surface, RILIS
* Beam on target (no converter)
* Mass markers: Ni, Rb
* GPS separator
* Extraction electrode 55 mm
* Uht(GPS,CCV)=30.27 kV, Uht(trap)=30.00kV, Elec05=200 V

66Ni : 3.2e7/muC; 66Ga : 3.0e6/muC (more an order of magnitude than strong estimate)
t1/2 ~ 1.5s for Ga release time characteristics; t1/2 ~ 30 min for Ni release

For A=68: 1 pA total beam on trap inj plate, thus around 5E5 pps 68(Ni+Ga)16+ at Miniball;
About 5E4 pps 68Ni at Miniball => 13% 68Ni

Experimental issues
* Beam to Miniball
* IS469

Tuning
* Slow extraction from EBIS (700us RF pulse)
* REXTRAP timing free-running relative to protons pulses

ISOLDE

Transmission 85Rb: GPS.FC490=755 pA, Trap inj plate=655 pA => 87%

Low energy
Stable beam 87Rb

Tperiod=50 ms, Tbreed=48.5 ms (optimised for 21+), Tbeamgate=10 ms, Icoll~167 mA
Trap inj plate=8 pA, RFQ.FC20=14.5 pA (21+) =>Trap-EBIS efficiency=8.6% efficiency

Radioactive 66Ni

Tperiod=30 ms, Tbreeding=28.5ms, Icoll=170 mA
Trap inj. plate=8 pA, RFQ.FC20(16+)=9 pA => Trap+EBIS efficiency=7%

Linac transmission and energy: 
83% RFQ.FC20=15pA to XL65.FC50=12.5pA for 87Rb21+, E=2.903 MeV/u

80% RFQ.FC20=11 pA to XL65.FC50=9 pA for 66Ni16+

Total estimated transmission (radioactive beam)
GPS.FC490_to_trap x Trap_EBIS x Linac x MBcollimator  
0.87*0.07*0.80*0.9?=4.4%

Delivered beams
* 66Ni16+ and 68Ni16+ / 68Ga16+

Best case 66Ni16+

RFQ.FC20=22.5 pA, XL65.FC50=18 pA, Miniball FC 18 pA

Even up to 20 pA at Miniball FC for 1.75 uA proton beam

Setting summary

ISOLDE settings saved as:

* GPS_SEP_9-11-02-30250V.csv
* GPS_REX_9-11-02-85Rb_30250V.csv

REX settings saved as:

* REX-30kV-2009-11-04_GPS_66Ni.xml
* BTS-30kV-2009-11-04_GPS_66Ni.xml
* EBIS_091104_1800_GPS_66Ni16_6.5%.csv

* 091104_1759_SEP_66Ni16+Aq4.125_2.9MeVu_MB.csv
* 091104_1745_66Ni16+Aq4.125_2.9MeVu_MB.csv
* 091104_1759_66Ni16+Aq4.125_2.9MeVu_L20.csv

Technical problems

* Readback of Icath and Ucath not working. PLC reboot most likely required.

* Difficult to reach a decent efficiency for the low-energy stage. Large electrical bender voltages in the BTS were necessary to transport the beam to the EBIS. Closed shell 87Rb17+ gave only 9% efficiency compared to >15% in July

* REXTRAP CS difficult to restart after the LN2 filling. Did sparking trigger the stop? 1 h stop

* Sparking during HV tests at WITCH experiment caused the control system of REXTRAP to stop. 1 h stop.

* A vacuum PLC at ISOLDE stopped causing the section valves to shut. An electrostatic power supply for the ISOLDE beam was changed during the error search. This had a completely wrong scaling, so the beam was lost until the original power supply was reinstalled. 4 h stop

* A PLC controlling the beam optics elements of the Linac stopped (reason unknowns) -> no beam to Miniball. 4 h stop.

Comments / Lessons learned
* We tested 98A (Sr and Rb) and saw already quite some Sr coming from the target. The Sr-Rb ratio could be increased for longer breeding times using in-trap decay.
* Large Ga contamination on A=68 so no physics. On A=66 clean Ni though.