93, 95,
97, 99Rb run
18-23 August and 1-3 September 2010
Target
issues
* Target number #433 UC2C surface W
* Beam on target (no converter).
* Mass markers: Na, Rb and Pb
* HRS separator
* Extraction electrode N/A mm (real distance)
* Uht(HRS,
HT_target)=30.310 kV, Uht(RFQ,CCV)=30.210
kV, Uht(trap)=30.00kV, Elec05=180 V,
No yield measurements
Experimental
issues
* Beam to Miniball
* IS493
Tuning
* REXTRAP timing free-running relative to protons pulses
* Used EBIS slow extraction for part of the beam. RF pulse 700 us.
Changed connections of the 4 TREK supplies:
Normal This run
Tube1 Trap1 Trap1
Tube2 Trap2+3 Trap2
Tube3 Outer barrier Trap3
Tube4 Outer drift tube Outer barrier
Outer drift tube grounded.
ISOLDE
For 87Rb, 78% transmission from HRS.FC490 to the trap inj. plate for 450 pA
Low
energy
Stable beam 87Rb
Tperiod=60 ms, beam gate=10 ms, Tbreeding =55 ms (optimized 21+), Icoll=204 mA
Trap inj. plate = 22 pA, RFQ.FC20(21+)
= 40 pA
Trap+EBIS efficiency = 8.7%
Tperiod=80 ms, beam gate=2 ms, Tbreeding=79 ms (optimized 23+), Icoll=209 mA
Trap inj. plate = 16.5 pA, RFQ.FC20(23+)
= 23 pA
Trap+EBIS efficiency = 8%
95Rb23+ Tperiod=82 ms, Tbreeding=79 ms, slow extraction
93Rb22+ Tperiod=71 ms, Tbreed=68 ms, slow extraction, Icoll 209 mA, HRS.WG470 slits in
99Rb23+ Tperiod=70 ms, Tbeamgate=2 ms, Tbreed=69 ms. Opted for shorter period time to reduce half-time losses. Trap+EBIS efficiency = 6% (for 87Rb23+). Normal extraction.
97Rb23+ Tperiod=82 ms, Tbreeding=79 ms, slow extraction?
Linac transmission
and energy:
Transmission from RFQ.FC20 to XL65.FC50 at 2.84 MeV/u
- 80-85% for 87Rb21+
- 70% for 95Rb23+
(large error bars)
Total
transmission (radioactive beam)
HRS.FC490_to_trap x Trap_EBIS x Linac
0.78*0.08*0.80=5%
Delivered beams
93Rb22+
Running with 14 pulses out of 38 pulses with 2.5E12 ppp, 0.12 uA
trap inj plate 9 pA average, with peaks up to 25 pA
RFQ.FC20 6 pA average, 14 pA peak, 22+
XL65.FC50 9 pA average, peaks up to 10
pA
MB FC 5 pA average current
95Rb23+
Running with 12 pulses out of 38 pulses with 1E13 ppp, 0.46 uA
RFQ.FC20=14 epA in
the peaks
XL65.FC50=12-13 pA in the peaks
MB FC around 12-13 pA in the peaks
97Rb23+
With
1.5 uA proton on the target we see about 1.5 pA
average current on trap inj plate;
in the peaks 10-12
XL65.FC50=2 epA in the peaks
99Rb23+
Not visible
Setting
summary
For HRS we used:
* HRS_SEP_2010-08-09_30310V.csv
* RFQ-2010-08-09_30310V_87Rb.csv
* REX_RFQ_2010-08-12.csv
REX low energy settings saved as:
BTS-30kV-2010-08-12_HRS_238U_2.7%.xml
REX-30kV-2010-08-18_HRS_87Rb_8.7%.xml (cyclotron frequency to 481000 Hz for 95Rb)
EBIS_100818_1642_HRS_95Rb23+slow_extraction.csv
EBIS_100820_2022_HRS_99Rb23.csv
REX separator and linac settings saved as:
100818_1652_SEP_95Rb23+_2.83MeVu_85%_mb.csv
100818_1652_95Rb23+_2.83MeVu_85%_mb.csv
100820_2021_SEP_99Rb23+_2.83MeVu_mb.csv
100820_2021_99Rb23+_2.83MeVu_mb.csv
100901_1516_97Rb23+_2.83MeVu_mb.csv
Technical problems
* Radiation alarm. Had to lower proton intensity to 2.5E12 ppp. With this proton current we have 2.5 uSv/h on PAXY08 next to the REX separator.
19/08/10, A. Dorsival
Alarme PAXY08 niveau B (>6 µSv/h) avec le faisceau de Rb-93 (22+) avec
une intensité de 0.48 µA, réduction de lintensité à 0.12 µA (PAXY08 stable à
2.5 µSv/h).
* IHS tripped off 06:18 on Wed and could not be restarted by users, but could be restarted normally a couple of hours later by RF specialist (reason unclear).
* The tuner for 7gap2 was stuck. Repaired within 3 hours.
Comments / Lessons learned
* During this running period (Pb,Rb,Na,Ra) the machine was scaled more than 10 times between different isotopes, stable and radioactive, light and heavy, without any problems.