78Zn run
22 October - 1 November 2010
Target
issues
* Target number #439 UC2-C, Ta converter, no quartz line
* Beam on target
* Mass
markers: Zn, Rb
* HRS separator
* Extraction electrode
* Uht(HRS,CCV)=30290
V, Uht(HRS, HT_target)=30278.7
V, Uht(trap,CCV)=30200 V,
Elec05=172 V,
Yield measurements:
2.8E6 78Zn /uC
in the focal plane of HRS
Miniball measured around 2-4E5 pps.
Experimental
issues
* Beam to Miniball
* IS491
Tuning
* Slow extraction from EBIS for part of the run, RF=900 us, EBIS
FWHM=200 us.
* REXTRAP timing free-running relative to protons pulses
ISOLDE
For 66Zn, 850 pA on HRS.FC490, 500 pA on HRS.FC748, 500 pA on CA0.FC68, 500pA
on RA0.FC90, 500 pA on trap inj plate
=> 58%
Low energy
Stable beam
66Zn – non-closed shell
Tperiod=61 ms, Tbreed=59 ms
(not fully optimised), no beam gate
Trap inj plate=60 pA, BTS.FC20=30 pA, RFQ.FC20=85 epA =>7.8%
efficiency
Stable beam 66Zn – closed shell
Tperiod=91,8 ms, 50% beam gate, Tbreeding=89 ms (optimized for 20+), Icoll=177
mA
Trap inj. plate=37 pA, RFQ.FC20(10+)=125 pA , trap eff=
50%, Trap+EBIS efficiency=16.7%
Linac transmission and energy:
Between RFQ.FC20 and XL65.FC50 81% for Ar11+ (3.6363), approximately 75-80% for 78Zn20+ (3.9), only 75% transmission through Miniball. E = 2.825 MeV/u +/- 0.8% (checked with A/q=4)
Total
transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac x Miniball
0.58*0.16*0.75*0.75=5.2%
Delivered beams
78Zn20+
Without lasers, 0.8 epA at RFQ.FC20, with lasers 2.3 epA on average => 1.5 pA of Zn,
XL65.FC50~1 pA , Miniball FC~0.75 pA. All for 1.2 uA.
NB! Very rough estimate.
Testof 80Zn20+ on
last two days:
78Zn on inj
plate 1-2 pA in the peak
80Zn protons on target, on inj plate 6-10 pA
(probably 80Rb)
80Zn protons on converter, on inj plate +/-0.5 pA (no change between laser on/off)
In addition, 0.5 epA on RFQ.FC20, most likely 38Ar10+
Setting
summary
For HRS we used:
HRS_SEP_2010-10-19_30300V_85Rb_fred.csv
RFQ_2010-10-19_30300V_85Rb.csv
REX_HRS_2010-10-19_30300V_85Rb.csv
REX low energy settings saved as:
REX-30kV-2010-10-21_HRS_66Zn20_18%.xml
BTS-30kV-2010-10-21_HRS_66Zn20_18%.xml
EBIS_101021_1923_HRS_66Zn20+_18%.csv
REX separator and linac settings saved as:
101022_1646_SEP_78Zn20+_MB_2.82MeVu.csv
101022_1646_78Zn20+_MB_2.82MeVu.csv
Technical problems
Comments / Lessons learned
.