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