72,74,76Zn run 17-21 November 2011

 

Target issues
* Target number #466 UC2C Re surface, RILIS
* no converter
* Mass markers:
 Rb, Cs
* GPS separator
* Extraction electrode 75 mm (or 60 mm?), real distance
* Uht(GPS, CCV)=30.2 kV ??, Uht(trap, CCV)=30.00 kV, Elec05=180 V

 

Yield measurements

Beam visible on FC – see below

 

Experimental issues
*
Beam to Miniball, g-factor measurement
* IS483


Tuning
* Slow extraction from EBIS 
* REXTRAP timing free-running relative to protons pulses

 

ISOLDE
 For 87Rb YGPS.FC490=110 pA (overestimated?), YGPS.FC558=61 pA, YCA0.FC68=62 pA,
RA0.FC90 =59 pA

 

Stable beam

87Rb19+
XTRAP.FC10=8.8 pA, XBTS.FC20=6.2 pA          trap eff 70%
RFQ.FC20=20.5 pA                                              trap+EBIS 12.3%


Linac transmission and energy: 
   No stripper foils. WITCH magnets 0.1 and 3T.

   Transmission from RFQ.FC20 to XL65.FC50 at 2.60 MeV/u

   - 85%                                   for A/q = 3.7         74Zn20+

Delivered beam at 2.94 MeV/u

 

Total transmission (radioactive beam)
GPS.FC490_to_trap x Trap_EBIS x Linac 
0.9*0.11*0.85=8.5%


Delivered beams

74Zn20+
For around 1.8-2 uA proton beam

GPS.FC490       35 pA average (100 peak)
TRAP.FC10       18 pA average (45 peak)
RFQ.FC20(20+)   40 pA average (100 peak)
-> 11% low energy efficiency
Tbreed=88 ms, Tperiod=91 ms, Icoll=193 mA, Tinj=100 us

2E7 pps to Miniball, still a small jitter on the RF reading when the RILIS off (see REX elogbook 16/11-2011, 21:02)

Reduced proton intensity 1 uA => 6 epA at XL65.FC50

 

76Zn20+
XTRAP.FC10=3.5 pA average
RFQ.FC20=7.5 pA, 15 epA in the peaks    => 10.7%
0.92 uA proton beam, 2E13 ppp

 

72Zn20+

Reduced proton intensity 0.4 uA

XL65.FC50=22 pA


Setting summary
For GPS we used:

GPS_REX_2011-11-15_30.2kV_#466_87Rb.csv
111115_1308_GPS_87Rb_63%.csv


REX low energy settings saved as:

111116_2108_TRAP_GPS_74Zn.csv
111116_2107_BTS_GPS_74Zn.csv
EBIS_111116_2127_GPS_74Zn20+half_slowextraction.csv

 

REX separator and linac settings saved as:
111116_2113_SEP_74Zn20+_2.94MeVu_85%_MB
111116_2113_74Zn20+_2.94MeVu_85%_MB

 

Technical problems

* 7Gap1 phase shifter found not working. Phase set to 318 degrees manually.

* RF PLC connection problem; loose cable.

* The vacuum in BTS stopped, beam off for 4 h.

 

Comments / Lessons learned

* Radiation alarm B (>6 uSv/h) in PAX08 for 2 uA proton beam with 74Zn. With 0.52 uA proton beam we had 2.6 uSv/h