Zn run July 2006
Target issues
* UC2-C #329, W surface, laser ionization
* mass markers Zn and Rb
* separator setup at 30.2 kV
* Yield check
Yield estimation on 80Zn with direct protons on
target: 3.10^4/muC
Some contamination of 80Ga (ca 10%)
At the MB is ~3e3 Zn/s, Zn >60% of beam, rest Ga
* Heating of quartz line broken at start, open circuit.
* Experienced radiation alarm when the beam was shot on the converter. Beam only taken directly on target. Large fraction of Rb for
the first shift, then it disappeared and only Zn and Ga left.
REX issues
Isotopes accelerated: stable
22Ne6+ for MB calibration
radioactive 80Zn21+
breeding time 78 ms, peak charge close to 21+ (?)
Currents: No
currents measured on any FC
Beam
seen on MCP RFQ.BO30 (stable and radioactive)
Beam
seen on MCP
Efficiencies:
TRAP efficiency 50% (inj plate = 13pA, BTS.FC20 =
6.4pA)
EBIS efficiency 18.6% (RFQ.FC20 = 25pA for 21+)
Trap+EBIS+sep eff = 9.1%
This is with 68Zn, no beam gate, 80ms period, and 78ms breeding time.
Higher efficiency (12.4% overall)
with beam gate on TRAP.
LINAC: Transmission for A/q=3.666 82%
Energy
for A/q=3.666 2.79
MeV/u
technical problems:
*
* Low transport efficiency
from
*
* Cavities tripped
occasionally due to interlock faults
* Could not restart
normally the main IH structure (pb with feedback
control / simatic)
* Mechanical problem on
7-gap1 tuner
* A QP in the proton
beam line stopped -> low target yield
* LA2 was vented by
experiment => affected vacuum in source and trap
sections => trap control system vent down and was difficult to restart
* GPIB for Picoamp2 in
the REXTRAP stopped working
comments:
* smooth
run, no major failures except for LA2 venting incident
* the
Ga content is much stronger in the laser on than the laser off spectra. We
therefore believe that at least a component of the Ga contamination at the
Miniball position arises from beta decay of Zn in the trap & ebis