200Po run September 2009

Target issues
* Target number #410 UC2C W-surface, RILIS
* Beam on target (no converter)
* Mass markers: 133Cs
* HRS separator
* RFQ cooler operated in cw mode
* Extraction electrode 50 mm
* Uht(HRS,CCV)=30.34 kV, Uht(HRS, HT_target)=30.3371 kV, Uht(RFQ cooler)=30.20 kV, RFQ extraction=0 V, Uht(trap)=30.00kV, Elec05=170 V

No yield measurements carried out. Miniball reported 2E6 200Po per second for 1 uA proton beam. Assuming a total ISOLDE-REX transmission of 1.8% => 1E8 200Po/s*uC

Experimental issues
* Beam to Miniball
* IS479

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

ISOLDE

Transmission 238U: HRS.FC490=1.65 nA, Trap inj plate 1.15 nA => 70%

Low energy
Stable beam 238U

Tperiod=255 ms, Tbreed=245 ms (optimised? for 48+), Icoll~200 mA
Trap inj plate=11 pA, RFQ.FC20=25 pA (48+) =>Trap-EBIS efficiency=4.7% efficiency

Radioactive 200Po

Tperiod=255ms, Tbreeding=250ms, Icoll=201 mA
Trap inj. plate=10 pA, RFQ.FC20(48+)=20pA => Trap+EBIS efficiency=4-5%

Linac transmission and energy: 
85% RFQ.FC20 to XL65.FC50 for A/q 4, 2.85 MeV/u

77% RFQ.FC20 to XL65.FC50 for 133Cs32+, 2.85 MeV/u
~70% RFQ.FC20 to XL65.FC50 for 200Po48+, 2.85 MeV/u

With 200Po48+: RFQ.FC20=17 pA, XL65.FC50=9 epA, MB FC=7 epA (all large variations)

Total estimated transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac x MBcollimator
0.70*0.04*0.70*0.84?=1.6%

Delivered beams
* 200Po48+

* Miniball reports around 2E6 200Po per second at their target for 1 uA proton beam.

Setting summary

ISOLDE settings saved as:

* HRS-SEP-9-09-02-30340.csv

* RFQ-9-09-01-30340.csv

* RFQ-REX-9-09-01-30340.csv

REX settings saved as:

* REX-30kV-2009-09-07-HRS_200Po.xml

* BTS-30kV-2009-09-07-HRS_200Po.xml

* EBIS_2009-09-07_HRS_200Po_slowextraction.csv

* 090909_200Po48+_MB,csv (Linac)

Technical problems

* Problems with the PSB extraction and changes in the proton steering on the HRS target during the setup called for repeated protons scans and delays.

Comments / Lessons learned
* Highly charge beams have a limited transmission through the linac section. An A/q=4 beam is transmitted with >85% efficiency while highly charged 238U57+ with only 57%. Is charge exchange also occurring at higher velocities?