Minutes from the ISOLDE Physics Group meeting on August 19^th, 2015

Users ask for the diagrams of the HRS exctraction electrode to be added to last week’s minutes.

Technical news

• GPS:
  
  • The target was uncoupled successfully. The end of extraction electrode was indeed just sticking out of the frontend shutter and target valve , but it luckily is still centered.
  • The intervention to replace the extraction electrode mechanism is planned for next Tuesday. No proton on HRS during intervention.
  • The GPS line heating offset (300A) will be tested once a new target is coupled.
• HRS:
  
  • The HRS separator software was updated to increase the field resolution, decreasing field uncertainty and reducing the jumps between small neighboring field values.
  • reminder about slits before the HRS separator.
    • Their values(position of the slits?) can be accessed in the working asets
    • A translation table between voltage and position is needed, which was placed at the control room after the meeting.
• ISCOOL:
  
  • Continuous mode transmission was investigated by Tim:
    • Separator and RFQ set to standard settings
    • Medium masses
    • 90% transmission between Faraday cups just before and after the ISCOOL (FC690 and 748)
  • Bunched beam transmission was investigated with Rb, observing 55% between the cups right in front and after the RFQ.
  • Transmission between FC490 and after the cooler is still ~70%, as observed by users. So either beam is lost between FC490 and FC690 or the beam at FC690 is larger than the entrance size of the Faraday cup, so it is possible to inject efficiently into ISCOOL.
  • Low resolution tune of the separator might be investigated to increase total transmission through the 2^nd HRS magnet and the ISCOOL.
  • The coordinator reminds users to record in the elogs the current in all Faraday Cups leading to users’ setups. This is a necessary input for any discussion about transmission problems or issues with beam diagnostics.
• RILIS:
  
  • One of the lasers pumping the dye lasers in now working again: the parts sent from the company worked in the laser that was left at CERN. The other laser is being repaired at the manufacturer.
  • .
• General technical news:
  
  • The CC0 faraday cup was changed last Tuesday. The RC2 cup will be replaced next week.
  • The RC4 QP20 power supply that showed 300 V oscillation got a temporary fixed.
    • A proper repair requires rebooting the entire rack.
    • IDS users do not oppose running with current situation, it will be repaired after current run.
• The replacement of the RC0 turbo pump is already in the hall. Change scheduled for next week.
• The He leak-detector is back in the ISOLDE hall. It is attached under the stairs, with the key in the control room key  box. Please make sure you know how to use it before taking it.
• New ISOLDE vacuum cleaner should arrive next week. It will be also placed next to the stairs

• REX/HIE-ISOLDE:
  
  • Last Wednesday there was an incident with the HIE-ISOLDE cold box
    • A safety burst disk ruptured releasing a column of He vapour
    • The safety valve did not release because the pressure was set to a value slightly higher than the burst disk
    • The origin of the initial overpressure is not know yet
  • The cryo-module was at the time powered down for beam transmission tests. Possible damage is still to be assessed.

• REX/HIE conditioning activities temporary suspended while investigation takes place:
  • The 7-gap resonator was already fully conditioned for all A/Q values.
  • The 9-gap resonator is connected to a temporary amplifier. Conditionning the final module would take too long so the initial run will be done with the temporary system.

Physics - COLLAPS

• Goal: measure the isotopic shift and charge radii of  ⁵³Ca and ⁵⁴Ca.
• Current beam time used to successfully test the high-sensitivity decay-assisted setup necessary for studying Ca beams of a few ions/s
• Continuous beam of well defined energy is necessary for accuracy in this mode. Because of the GPS problems beamtime was moved to HRS, where beam energy would be affected due to collissions in the ISCOOL. Thus, the final experiment was not possible on HRS.

Physics - Neutron deficient Po at ISOLTRAP 

• Goal: establish the ratio and energy of 3/2- and 13/2+ isomers in odd neutron deficient A=195 and 197 Po isotopes.
• Combination of RILIS, MR-TOF and decay station needed to clean the beam, isolate the different isomers and identify the population ratio with alpha-gamma spectroscopy.

Safety

• The group leader asks users that were in the hall during the rupture of the HIE-ISOLDE burst disk to contact her. Also to please contact CERN medical service in case of auditory problems.
• The coordinator reminds that visitors to the ISOLDE hall must be announced ( in advance) to make sure no intervention with open beamlines are happening at the time of the visit.
• The group leader reminds users to remove radioactive spot signs the moment the level of activity is safe in the area.

AOB

-The next meeting will take place on Wednesday next week (26^th August 2015) followed by  presentations by ISOLDE summer students.

Minutes taken by MMF