128Cd run 29 July - 4 August 2011
Target
issues
* Target number #454 UC-Ta surf with quartz line (to avoid Cs
contamination)
* W-converter (not used during the run)
* Mass markers: 133Cs, Cd
* HRS separator
* Extraction electrode 70 mm (real distance)
* Uht(HRS,
CCV)=30.24 kV, Uht(RFQ,CCV)=30.20 kV, Uht(trap, CCV)=30.00 kV, Elec05=175 V
Yield measurements (from HRS logbook
28/7-2011):
Preliminary yields are:
Protons on target:
Y_(128Cd) = 3e5 1/uC
Y_(128Cs) = 5e4 1/uC
No 128In detectable, detection limit 100 1/uC
Neutron converter:
No
128In and no 128Cs detectable. Detection limits are 150 1/uC (128In) and 500 1/uC
(128Cs)
Y_(128Cd) = 9e4 1/uC
/AG, CS, TM
Experimental
issues
* Beam to Miniball
* IS477
Tuning
* Normal extraction from EBIS
* REXTRAP timing free-running relative to protons pulses
ISOLDE
For 90 pA of 133Cs transmission from
HRS.FC490 to CA0.FC68: 80%.
Low
energy
Stable beam
114Cd
Tperiod120 ms, Tbeamgate=10
ms, Tbreeding=118 ms, Icoll=183
mA
Trap inj. plate=6.0 pA, BTS.FC20 2.8 pA, RFQ.FC20(30+)=6.0 pA => Trap+EBIS efficiency=3.3%
Linac transmission
and energy:
No stripper foils. WITCH magnets
0.1 and 3T.
Transmission from RFQ.FC20 to XL65.FC50 at 2.82 MeV/u
- 85.4% for A/q = 4
- 75% for A/q = 4.2666 128Cd30+
Total
transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac
0.80*0.033*0.75=2%
Delivered beams
128Cd30+
Tperiod=120 ms, Tbreeding=118 ms, Icoll=183 mA, Ugun=3900 V, Igun=104 uA, running with high EBIS cathode heating (3.02 A, 3.11 V)
NORMHRS=>ISOHRS
Prot.current: 1.64uA 3149ppp
Total cycles: 15/41
RFQ.FC20 2 pA peak
L65.FC50 1.5 pA peak
Miniball 1.5 pA peak, assuming
0.5 pA average -> 1E5 pps
Miniball saw ~1e3 pps. From yield checks
and transmission should be ~1e4 pps. -> mostly impurities?
126Cd30+
NORMHRS=>ISOHRS
Prot.current: 1.68uA 3086ppp
Total cycles: 15/38
RFQ.FC20 1.7 pA in the peaks
XL65.FC50 1.2 pA in the peaks, assuming 0.5 pA average -> 8E4 pps
Cannot be all Cd -> impurities?
Setting
summary
For HRS we used:
HRS_SEP_133Cs_30.3kV_2011_07_25.csv
RFQ_133Cs_30.3kV_2011_07_25.csv
REX_RFQ_2011_07_25_133Cs_30Kv.csv
REX low energy settings saved as:
110729_1409_TRAP_HRS_114Cd30+_3.3%.csv
110729_1409_BTS_HRS_114Cd30+_3.3%.csv
EBIS_110729_1412_HRS_114Cd30+_3.3%.csv
REX
separator and linac settings saved as:
not saved
Technical problems
* Failure of HRS HT (switched HT1 and HT2)
* Poor vacuum in the target (most likely a leak), had to change vacuum interlock threshold and force section valve open to keep running
* Target heating stopped on water interlock, must adjust flow to sufficiently high value (> 200 l/h) to keep enough margin
* RFQ stopped several times on over-temperature, the problem disappeared on its own, no clear explanation (either sensor problem or faulty grid 1 supply i.e. tube not pulsing)
* Several interruptions of 9-gap amplifier
Comments / Lessons learned