Zoran Andjelkovic Johannes Gutenberg – Mainz University GSI Darmstadt Laser Spectroscopy of Highly Charged Ions and Exotic Radioactive Nuclei (Helmholtz Young Investigator Group) SPECTRAP meeting status report

Zoran Anđelković 2 Overview of the HITRAP Facility UNILAC SIS 400 MeV/u ESR U 92+ Pb 81+ Bi 80,82+ 4 MeV/u Electron cooling and deceleration Stripper target Post decelerator Cooler trap Experiments with particles at rest HITRAP SPECTRAP trapping of HCI cooling nearly to rest laser spectroscopy of HFS

Zoran Anđelković 3 A short progress overview Vacuum & magnet business: –high vacuum finally –energizing the magnet –LHe problems Trap stuff: –(re)redisign –detector problems Electronic development: –design and testing with Stefan Stahl New-old beamline: –details from Bettina Sommer

Zoran Anđelković 4 Setup and problem overview ion beam pumps laser fluores- cence bender, beam optics He an N vapour outlets liquid N SC magnet coils liquid He trap 4K electr. 300K electr. vacuum leak complete break missalignment broken electonics sealed (after 4 attempts)! need new anyhow rectified replaced

Zoran Anđelković 5 Vacuum considerations Three different vacuum seals in use: standard copper Helicoflex Delta C-seal thick, high-purity aluminium foil cross section ~ 5 mm sealing surface Found an alternative to the expensive Helicoflex! home made PEEK seal

Zoran Anđelković 6 and finally... we reached high vacuum......which improved further after cooling down

Zoran Anđelković 7 Cooling down and energizing magnet successfully cooled and energized to 30 A, corresponding to ~ 3 T field

Zoran Anđelković 8 LHe problems 1.Although we tried to improve, LHe hold time still in the order of a week 2.Need a new level probe 3.Need a low pressure valve and possibly a gas collection system 4. Transfer line too short, the platform needs to be modified

Zoran Anđelković 9 Trap (re)redesigned trap mount slightly altered to meet the requirements of the cryogenic electronics – details from Stefan Stahl parts machined, awaiting gold plating (cryogen-friendly) cables obtained including a mirror to increase fluorescence intensity

Zoran Anđelković 10 Magnetic fringe field estimate single current loop two single current loops in a Helmholtz arrangement distance from the center / m magnetic field on axis / T

Zoran Anđelković 11 How to detect the ions? plate directly under the trap how to get the laser in? how to move the plate away? MCP in the bottom of the system ion cloud gets blown up again, laser in? channeltron under the trap mount it does not like the environment ion cloud gets blown up

Zoran Anđelković 12 Putting the system together beamline to be attached to HITRAP in the (near?) future "imitating" the output of HITRAP and preparing the setup work done and presented by Bettina Somer

Zoran Anđelković 13 Current status We have: platform with infrastructure working magnet setup incl. trap cryo electronics currently under construction assembled beamline We want: better vacuum (always) longer LHe life time or some recycling system Next steps: prepare the beamline and the control electronics install the trap, electronics and perform tests attach to HITRAP or EBIS to get some HCI

Zoran Anđelković 14 Magnetic field m area single current loop two single current loops in a Helmholtz arrangement magnetic field on axis / T distance from the center / m

Zoran Anđelković 15 Beamline(s) after HITRAP

Zoran Anđelković 16 Beamline & HITRAP platform ion beam line laser light Einzel lens Beam steering Electrostatic bender Retractable Faraday Cup MCP Magnet system Vacuum pumps Collimation plates Trap assembly Deceleration tube Source or HITRAP output