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 pA. On RFQ.FC20 average 1.5 pA for 97Rb23+; in the peaks 4 epA

                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 l’intensité 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.