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 65 mm (real distance)
* 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

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