A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z  

Dahl, L.A.

Paper Title Page
MOP019 The HITRAP Decelerator Project at GSI - Status and Commissioning Report 100
 
  • L.A. Dahl, W. Barth, P. Gerhard, F. Herfurth, M. Kaiser, O.K. Kester, H.J. Kluge, S. Koszudowski, C. Kozhuharov, G. Maero, W. Quint, A. Sokolov, T. Stöhlker, W. Vinzenz, G. Vorobjev, D.F.A. Winters
    GSI, Darmstadt
  • B. Hofmann, J. Pfister, U. Ratzinger, A.C. Sauer, A. Schempp
    IAP, Frankfurt am Main
 
 

For injection into the ion trap facility HITRAP, the GSI accelerator complex has the unique possibility to provide beams of highly stripped ions and even bare nuclei up to Uranium at an energy of 4 MeV/u. The HITRAP facility consists of linear 108 MHz-structures of IH- and RFQ-type to decelerate the beams further down to 6 keV/u for capturing in a large penning trap for cooling purpose. The installation is completed except of the RFQ-tank. During commissioning periods in 2007 64Ni28+ and 20Ne10+ beam was used to investigate the beam optics from the experimental storage ring extraction to the HITRAP double-drift-buncher system. In 2008 the IH-structure decelerator and the downstream matching section was examined with 197Au79+ beam. Comprehensive beam diagnostics were installed: Faraday cups, tubular and short capacitive pick ups, SEM grids, YAG scintillation screens, a single shot pepperpot emittance meter, and a diamond detector for bunch shape measurements. Results of the extensive measurements are presented.

 
MOP032 Upgrade of the Unilac High Current Injector RFQ 136
 
  • A. Kolomiets, S. Minaev
    ITEP, Moscow
  • W. Barth, L.A. Dahl, H. Vormann, S. Yaramyshev
    GSI, Darmstadt
 
 

Funding: Work supported by the European Community INTAS Project Ref. no. 06-1000012-8782.
For the operation of the GSI-accelerator chain as an injector for the future FAIR facility a considerable increase of the heavy ion beam intensity by a factor 3-5 at the end of the UNILAC is required. The bottleneck of the whole UNILAC, is the front-end system of the High Current Injector. It is shown that the transverse RFQ-acceptance can be significantly increased while the emittance growth can be reduced. Both goals are achieved with only a moderate change of the RFQ electrode geometry; the intervane voltage raised from 125 kV to 155 kV keeping the design limit of the maximum field at the electrode surface. The changed resonant frequency can be compensated with a relatively small correction of the carrying rings. The beam parameters in the final focusing elements of the LEBT were improved together with the input radial matcher design; the length of the gentle buncher section was considerably increased to provide slow and smooth bunching resulting in a reduce influence of space charge forces. DYNAMION-simulation with the modified electrode design resulted in an increase of U4+-beam current of up to 20 emA. It is planned to start the upgrade measure in spring 2009.

 
MOP046 Commissioning of the New GSI-Charge State Separator System for High Current Heavy Ion Beams 175
 
  • W. Barth, L.A. Dahl, P. Gerhard, L. Groening, M. Kaiser, S. Mickat
    GSI, Darmstadt
 
 

A dedicated charge separator system is now installed in the transfer line to the GSI-synchrotron SIS18. In former times charge separation was performed with a single 11 degree dipole magnet after a 25 m beam transport section. This was not adequate to meet the requirements during high current operation for FAIR: it only allows for charge state separation of low intensity and low emittance beams. With the new compact charge separator system emittance blow up and unwanted beam losses for high intensity beam operation will be avoided. Additionally a new beam diagnostics test bench is integrated. With this the beam parameters (ion current, beam profile, beam position, transversal emittance, bunch structure and beam energy) for the injection into the SIS18 can be measured in parallel to the routine operation in the transfer line. Results of the commissioning with high intensity argon beams as well as with an uranium beam will be reported.

 
MOP075 Benchmarking of Measurement and Simulation of Transverse RMS-Emittance Growth Along an Alvarez DTL 251
 
  • L. Groening, W. Barth, W.B. Bayer, G. Clemente, L.A. Dahl, P. Forck, P. Gerhard, I. Hofmann, G.A. Riehl, S. Yaramyshev
    GSI, Darmstadt
  • D. Jeon
    ORNL, Oak Ridge, Tennessee
  • D. Uriot
    CEA, Gif-sur-Yvette
 
 

Funding: CARE, contract number RII3-CT-2003-506395) European Community INTAS Project Ref. no. 06-1000012-8782
Transverse emittance growth along the Alvarez DTL section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth appropriate tools to simulate the beam dynamics are indispensable. This paper is on benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittance growth for different machine settings. Experimental set-ups, data reduction, the preparation of the simulations, and the evaluation of the simulations will be described. It was found that the mean value of final horizontal and vertical rms-emittances can be reproduced well by the codes.

 
TUP074 Commissioning of the HITRAP Decelerator Using a Single-Shot Pepper Pot Emittance Meter 564
 
  • J. Pfister, R. Nörenberg, U. Ratzinger
    IAP, Frankfurt am Main
  • W. Barth, L.A. Dahl, P. Forck, F. Herfurth, O.K. Kester, T. Stöhlker
    GSI, Darmstadt
 
 

Funding: Work supported by BMBF under contract 06FY160I.
The Heavy highly charged Ion TRAP (HITRAP) project at GSI is in the commissioning phase. Highly charged ions up to U92+ provided by the GSI accelerator facility will be decelerated and subsequently injected into a large Penning trap for cooling to the MeV/u energy level. A combination of an IH- and an RFQ-structure decelerates the ions from 4 MeV/u down to 6 keV/u. In front of the decelerator a double drift-buncher-system is provided for phase focusing and a final de-buncher integrated in the RFQ-tank reduces the energy spread in order to improve the efficiency for beam capture in the cooler trap*. This contribution concentrates on the beam dynamics simulations and corresponding measurements in the commissioning beam times up to the position of the entrance to the RFQ. Single-shot emittance measurements at higher energies using the GSI pepper pot device and construction of a new device using Micro-Channel Plate technology for low energies as well as profile measurements are presented.


*HITRAP webpage of AP division at GSI, http://www.gsi.de/forschung/ap/projects/hitrap/index_e.html