Minutes from the ISOLDE Physics Group meeting on November 20th, 2014
No comments to the minutes from the meetings on November 13th.
Technical news
GPS
- Lanthanum carbide target to measure production of neutron deficient Ba isotopes at tape station and IDS (IS545).
- Small issues: heating of line and target, high voltage went down once. Reason not understood. To be investigated.
- PS booster could not deliver the maximum current per pulse during part of the experiment (2.6 1013 instead of 3.3 1013). Booster operators think the problem is solved but ask users to cross check in the next GPS run.
- RILIS observed only 5% Ba enhancement online, compared to 50% offline, but it can be due to better surface ionization with Re cavity.
- In order to enter the HV room protons have to be interrupted for 30 min before and after. This feature is unwanted and will be investigated during the winter shutdown.
- The HV software got inverted by itself. The GPS console accessed the HRS platform and vice versa. Solved.
- Titanium target installed on Thursday morning.
- Solid state physics with 27Mg beam. Physics require low Al contamination (observed below pA).
- Small issues clamping the target. Solved.
HRS
- Target and HV voltage dropped off on Monday. Under investigation.
- ISCOOL tests:
- Test of molecule breakup inside the RFQ. No molecular beams from mass marker observed after the ion source, no test possible.
- Laser pumping of Sr in the trapping region of the RFQ in order to populate atomic metastable states. Fast diagnostic: Sr+ metastable state neutralizes more effectively in Na vapor (COLLAPS line). Result: when RILIS pump lasers were turned on 75 to 100% of Sr+ was in the metastable state, depending on the assumed beam purity.
- Faraday cup FC490 still reads incorrect values. Under investigation.
- Users ask about the status of the magnet cycling software.
- Magnet cycling is reliable now.
- The current cycling time is dictated by the hardware used.
- Users ask about the long period of “software cycling”. During this process the power supplies are ramped up and down to cross check they react to commands.
Safety
- The radiation alarm above the RILIS cabin, 603, was setting off.
- The alarm is located next to the HRS target water station. The station is only partially shielded with lead.
- The alarm starts are correlated with protons on the neutron converter.
- Temporarily, RP agreed to increase the alarm threshold slightly in order to be able to put full power on the target.
- A permanent solution will be implemented during winter shutdown.
- The worksite passage is now blocked by scaffolding.
- LN2 dewars can be moved along the miniball beam line and then around the IDS (under the staircase).
- The scaffolding will be removed next Tuesday.
115-120Ba @ IDS
- Experiment goals:
- Measure proton and alpha-unbound high energy states populated in beta decay.
- Cesium beams were successful. Barium beams are still under development.
- Test of BaF+ molecules release on Tuesday.
- Very preliminary yields: Y(116Cs)=50 pps; Y(115Cs)~1 pps(?); Y(114BaF)=18 p/min; Y(117BaF)=0.3 pps; Y(120BaF)=3 pps.
COLLAPS
- Measure ground state spins, radii, and e-m moments of Zn isotopes around the N=50 shell closure.
- Observed all even Zn up to 78Zn and most of the odds. From short test observed promising yield of 80Zn.
- Yields can be improved fixing small issues, e.g. ISCOOL radio-frequency was not optimized.
Building 508
- Fire alarms will be installed in January.
- The building cannot be used for the total work hours before the fire alarms are installed
- But equipment can be moved in before January.
- Emergency exits will be places at the hallways, not through the SSP labs.
- Equipment and furniture should have as little as possible flammable materials, plastics and wood.
- Users are responsible of furnishing the experiment laboratories.
AOB
The next meeting will take place at 14:00 Thursday next week (27th November 2014) followed by a seminar by Morten Lund (http://indico.cern.ch/event/354404/).
Minutes taken by MMF