M. Bai, GSI GSI Helmholtzzentrum fr Schwerionenforschung GmbH - - PowerPoint PPT Presentation

GSI Helmholtzzentrum für Schwerionenforschung GmbH GSI Helmholtzzentrum für Schwerionenforschung GmbH

Current Technical Capabilities

• M. Bai, GSI

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Achieved nominal beam intensity

https://www.gsi.de/work/beschleunigerbetrieb/beschleuniger.htm?no_cache=1

GSI Helmholtzzentrum für Schwerionenforschung GmbH

GSI Facilities uniqueness

• versatileness and flexibilities
• unique hadron facility for multi users
• both dedicated operation as well as parallel operation mode
• variety of operation modes
• relative short transition in between

courtesy of

• S. Reimann
• D. Severin

courtesy of R. Steinhagen

Histogram of experiment durations

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Core competence

• Variety of ion sources available for operation to fulfill

the needs of ion species with the desired charge state

• Penning Ionization Gauge (PIG) ion source
• Multi Cusp Ion Source (MUSIC)
• highly charged gas ions
• Cold or Hot Reflex Discharge Ion Source
• Metal Vapor Vacuum Arc Ion Source (MEVVA)
• low charge state high current source
• Electron Cyclotron Resonance Ion Source (ECRIS)
• high charge state ion source

High Charge state Injector

• Excellent ion preparation
• always well-prepared and flexible
• desired 107Ag2+ separated, and high intensity of 5 emA in UH1

reached.1mA 208Pb4+ was obtained from nature materials

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Core competence: Deceleration

ESR CRYRING HITRAP

SIS

Stripper 400 MeV/u UNILAC FRS

ESR

4 MeV/u

HITRAP

4 K 10 MeV/u

CRYRING

4 MeV/u … 100 keV/u 400 MeV/u

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Current known technical limitation

• Ion source on-going R&D
• High current uranium source FAIR mode
• ECR for fulfilling users. Most demanding/challenging are from the cw

users w.r.t. the ion species and intensity

• UNILAC
• HSI no heavy ions A/Q > 43, i.e. no Pb and no Uranium
• mitigation: replace HSI-RFQ electrodes during summer shutdown
• Operation modes that require LEBTQQ to be ramped at average

repetition rate above 1Hz

• mitigation options:

1. new beam pipe with less eddy current effects 2. avoiding cycling LEBTQQ at high repetition rate by regulating the ion beam intensity with pulse gas striper

• no fine energy adjustment for UNILAC users
• mitigation: repair ER1

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Current HSI RFQ limitation on heavy ion intensity

• The calculation assumes
• # of loss free turns for the multi-turn injection: 12
• SIS18 injection+ ramping time: 1 sec
• SIS18extraction time: 2 sec
• For unranium5+, since the HSI RFQ can only reach up to 80% required voltage, additional 50% reduction of nominal

transmission through UNILAC is assumed on top of the available current directly out of the ion source

• For Pb208, it was planned to provide the Pb4+ from the high current source. Nevertheless, this source for Pb5+ can

experience stability issues. Hence, the Pb5+ for operation 2018 will be provided from PIG

• For Bi, it is mono isotope and will be provided from the high current ion source

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Current known technical limitation

• SIS18
• Long extraction pulse vs. high ramp rate of 10T/s not simultaneously
• Slow extraction beam quality
• electrostatic septum is too weak for 100% extracting highest momentum beam
• feedback for macro-spill structure not yet operational
• ideas for smoothing micro-spill structure investigated, not yet available for

routine operation, especially at high energies

• air-core quad feedback
• spill cavity
• its user operation is not-yet compatible with ESR operation
• expect to be addressed by Engineering run in 2019

GSI Helmholtzzentrum für Schwerionenforschung GmbH

Current known technical limitation

• Limited function and scope of LSA/FESA based FAIR controls
• not-yet reliable parallel operation mode
• Storage ring re-commissioning
• At the moment, only the synchrotron mode of operating ESR is

available from the FAIR controls.

• The storage ring mode operation that is required for restoring all ESR

capability, i.e. beam accumulation, fine control/tuning for deceleration etc, is scheduled to be commissioned in the engineering run of 2019

• complete commissioning of CYRING with beam from ESR is

scheduled in the engineering run of 2019

• Vacuum level in the CRYRING is not yet ideal for long storage of highly

charged heavy ions.

GSI Helmholtzzentrum für Schwerionenforschung GmbH

The Art of Deceleration

• Deceleration requires many careful machine tuning and

beam manipulation

• Be able to have controls to allow stand-alone tuning of the

machine settings is highly critical

• M. Steck, et al, Proceedings of EPAC 2000, Vienna, Austria

Cycle for deceleration of U92+ from 300 MeV/u to 15 MeV/u with intermediate cooling at 30 MeV/u. beam from SIS18 intermediate cooling final acceleration preparation for deceleration

GSI Helmholtzzentrum für Schwerionenforschung GmbH

• FAIR Phase 0 requirements
• forseen 2 order of magnitude higher intensity w.r.t advertised in 2017
• 1st priority is to reproduce the performance back in the good old days!
• FAIR requirements
• Ion source: 2.7Hz Uranium
• pLINAC 35mA. Design for current 70mA
• SIS18: 1.5x1011 Uranium28+ per cycle, 2 bunches per cycle
• Machine Development reached 4e10 uranium28+ 1Hz in 8 hours (2007)

UNILAC 4.5mA at SIS18 injection (LG)

• need to reproduce asap
• UNILAC eached 2 times higher of 4.5mA U28+ at 1.4MeV/u (WB)
• SIS100: 5x1011 Uranium28+ per cycle
• Action item for all MKs
• provide the achieved performance, ion species and corresponding

parameters (intensity, brightness etc): routine operation as well as best performance

Discussion