LINAC 2006 - List of Authors (Dahl, L. A.)

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Dahl, L. A.

Paper	Title	Page
MOP058	Heavy-Ion-Beam Emittance Measurements at the GSI UNILAC	177
	W. B. Bayer, W. Barth, L. A. Dahl, L. Groening, S. Yaramyshev GSI, Darmstadt
	The GSI UNILAC, a linac for high current heavy ion beams, serves as an injector for the synchrotron SIS 18 and hence being a part of the future FAIR (Facility for Antiproton and Ion Research) project. The UNILAC post stripper section consists of an Alvarez accelerator with a final energy of 11.4 MeV/u. In order to meet the requirements of the FAIR project (15emA U²⁸⁺, transversal normalised emittances of ex = 0.8 and ey = 2.5 mm mrad) a part of the UNILAC upgrade program is the increase of the beam brilliance. A detailed understanding of the correlation between space charge forces and focusing during acceleration of high intensity ion beams is necessary. A suited quantity to study is the beam brilliance dependency on the phase advances in the Alvarez section. Measurements are planned in 2006 and coincide with the beam dynamics work package of the European network for High Intensity Pulsed Proton Injector (HIPPI). Results of the measurements are presented as well as corresponding beam dynamics simulations.
MOP059	Long-Term Perspective for the UNILAC as a High-Current, Heavy-Ion Injector for the FAIR-Accelerator Complex	180
	W. Barth, L. A. Dahl, L. Groening, S. Yaramyshev GSI, Darmstadt U. Ratzinger IAP, Frankfurt-am-Main
	The present GSI-accelerator complex, consisting of the linear accelerator UNILAC and the heavy ion synchrotron SIS 18, is foreseen to serve as an U²⁸⁺-injector for up to 10⁺¹² particles/s for FAIR. In 2003 and 2004 different hardware measures and careful fine tuning in all sections of the UNILAC resulted in an increase of the beam intensity to 9.5·10⁺¹⁰ U²⁷⁺ ions per 100 mks (max. pulse beam power of 0.5 MW). In addition a dedicated upgrade program for the UNILAC will be performed until 2009. It is intended to fill the SIS 18 up to the space charge limit of 2.7·10⁺¹¹ U²⁸⁺ ions per cycle. After completion of the FAIR complex in 2015 the running time for the accelerator facility at least will be 20 years, while the UNILAC will then be in operation for more than 60 years as a high duty factor heavy ion linac. Different proposals for a new advanced short pulse, heavy ion, high intensity, high energy linac, substituting the UNILAC as a synchrotron injector, will be discussed. This new "High Energy-UNILAC" has to meet the advanced FAIR requirements, will allow for complete multi-ion-operation and should provide for reliable beam operation in the future.
MOP060	A New LEBT and RFQ Radial Matcher for the UNILAC Front End	183
	L. A. Dahl, W. Barth, S. Yaramyshev GSI, Darmstadt S. A. Visotski, I. Vorobyov ITEP, Moscow
	The UNILAC heavy ion accelerator will serve as a high current injector for the future FAIR accelerator complex of GSI. This requires to inject 2.7x10¹¹ ions/0.1x10^-6s of U²⁸⁺ into the existing synchrotron (SIS). Additionally, the UNILAC serves in multi beam operation experiments with high duty factor beams of different species. To meet all future demands a dedicated upgrade programme of the UNILAC is in work. This paper focuses on front end improvements. A new beam transport system will provide achromatic deflection and high mass resolution for the heavy ion beams from both existing ion source terminals. A new terminal for high current ion sources with a straight line solenoid based beam channel will be added. E.g. U³⁺ and U⁴⁺ ions with and a total beam current of 55mA will be injected into the RFQ for a maximum intensity yield of U⁴⁺-beam at the exit. To optimize the total front end beam transmission a redesigned radial input matcher of the RFQ is already implemented. It enables a smoother RFQ input matching of the high current beam resulting in smaller beam diameter and in lower particle losses. Beam measurements comparing old and new input radial matchers are presented.
MOP061	The 70-MeV Proton Linac for the Facility for Antiproton and Ion Research FAIR	186
	L. Groening, W. Barth, L. A. Dahl, W. Vinzenz, S. Yaramyshev GSI, Darmstadt G. Clemente, U. Ratzinger, A. Schempp, R. Tiede IAP, Frankfurt-am-Main
	A significant part of the experimental program at FAIR is dedicated to antiproton (pbar) physics requiring up to 7·10¹⁰ cooled pbars per hour. Taking into account the pbar production and cooling rate, this is equivalent to a primary proton beam of 2·10¹⁶ protons per hour to be provided by a 70 MeV proton linac preceding two synchrotrons. It has to deliver a pulsed proton beam of 70 mA of 36 μs duration at a repetition rate of 4 Hz. The normalized transverse emittances must not exceed 2.8 mm mrad and the total relative momentum spread must be less than 0.1%. The normal conducting DTL comprises 12 Crossed-bar H-cavities (CH) fed by six rf-power sources in total. The basic layout of the linac as well as the overall cost estimate has been completed including several reviews by external committees. A technical report has been completed in May 2006. This paper gives a general overview on the status of the project.
MOP063	Deceleration of Highly Charged Ions for the HITRAP Project at GSI	189
	O. K. Kester, W. Barth, L. A. Dahl, F. Herfurth, M. Kaiser, H. J. Kluge, C. Kozhuharov, W. Quint GSI, Darmstadt B. Hofmann, U. Ratzinger, A. C. Sauer, A. Schempp IAP, Frankfurt-am-Main
	The highly charged heavy ion trap (HITRAP) project at GSI is a funded mid term project and is planned to be operational end of 2007. Highly charged ions up to U⁹²⁺ provided by the GSI accelerator facility will be decelerated from 4 MeV/u down to 6 keV/u and subsequently be injected into a large Penning trap for further deceleration and phase space cooling. The deceleration is done in a combination of the GSI experimental storage ring (ESR) and a linac based on an IH-structure and a RFQ. In front of the decelerator linac a double drift-buncher-system provides 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. The paper reports the beam dynamics design along the entire decelerator down to the trap injection point, as well as and the status of the cavities. Finally the time schedule and ESR and linac commissioning are discussed.
TU3001	High-Current Proton Beam Investigations at the SILHI-LEBT at CEA/Saclay	232
	R. Hollinger, W. Barth, L. A. Dahl, M. Galonska, L. Groening, P. S. Spaedtke GSI, Darmstadt R. Gobin, P.-A. Leroy CEA, Gif-sur-Yvette O. Meusel IAP, Frankfurt-am-Main
	For the injection of a high current proton beam into the future proton LINAC at GSI for FAIR the ion source and the low energy beam transport system have to deliver a 100 mA proton beam with an energy of 95 keV within an acceptance of 0.3 mm mrad (normalized, rms) at the entrance of the RFQ. Besides the ion source a 2-solenoid focusing system is foreseen as an injection scheme for the subsequent RFQ. The beam parameters of the SILHI ion source and the 2-solenoid LEBT setup generally meet these requirements. Therefore joint emittance measurements on various beam parameters have been performed at the end of the LEBT system. In the frame work of the design study for the future proton LINAC it was a unique possibility to investigate the injection of a high current proton beam into a low energy beam transport system under the influence of space charge. The measurements reveal that a proton current of 100 mA can be achieved at the end of the LEBT while the emittance (95 %, rms, normalized) is as high as 0.3 to 0.5 mm mrad.
TUP078	Status of the End-to-End Beam Dynamics Simulations for the GSI UNILAC	438
	W. Barth, W. B. Bayer, L. A. Dahl, L. Groening, S. Yaramyshev GSI, Darmstadt
	The heavy ion high current GSI linac UNILAC serves as an injector for the synchrotron SIS18. The UNILAC mainly consists of a High Current Injector (HSI), the stripper section at 1.4 MeV/u, and the Alvarez postaccelerator (11.4 MeV/u). During the last years the systematic experimental and numerical studies resulted in an increase of the U⁷³⁺ beam intensity of up to a factor of seven. The needs of the FAIR project (Facility for Antiproton and Ion Research at Darmstadt) require further improvement of the beam brilliance coming from UNILAC up to a factor of five. End-to-end beam dynamics simulations with the DYNAMION code have already been started. The general goal is to establish a simulation tool which can calculate the impact of the planned upgrade measures on the performance of the whole UNILAC. The results of the HSI calculations including influence of the beam intensity on the beam parameters (current, emittance, Twiss-parameters) at the stripper section are presented. Recent calculations and measurements of the beam matching to the Alvarez section under space charge conditions are discussed in the paper.