1. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Status of the RT CH-DTL development and beam dynamics layout of the GSI Proton Linac Gianluigi Clemente Institut für Angewandte Physik J.W. Goethe-Universität, Frankfurt am Main, Germany HIPPI YEARLY Meeting Abginton, September 28 th 2005

2. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik TOPIC The FAIR Project: Why a new Proton Injector ? Why a CH-DTL ? Beam Dynamics at 70 mA: Matching with RFQ, Complete Layout; Diagnostics Cavity Design Technical Solution, Fabrication Steps Conclusion People

3. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik The FAIR Project To satisfy the luminosity requirements of the High Energy Storage Ring we must have a particles number in the SIS18 of ~ 6 x10 12 p/cycle that is quite near the space charge limit of this machine at 70 MeV. The existing UNILAC provides 11.4 MeV/u WE NEED A NEW PROTON INJECTOR [2] !!!!!!!!! The Facility for Antiprotons and Ions Research [1] will consist of 2 new synchrotrons (SIS100/300) connected with a system of cooler-storage rings for effective beam cooling at high energies and various experimental halls: the existing GSI will provide the acceleration chain for the injection into the new machine.

4. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik The P-Injector ENERGY Range (MeV)3 - 70 Pulsed Current (mA)70 Bunch Frequency (MHz)352.21 Klystron Power (MW)1.3 Macro Pulse Length (ms)0.1 Repetition Rate (Hz)5 Transv. Emittance 7 mm mrad Longitudinal Emmitance17 KeV ns From the proton injector the beam will be transferred to the SIS18 with a 10 turns injection method: in this way 7 mm mrad are required to fill the space charge limit within half of the Synchrotrons acceptance. To reduce the overall budget the existing 352.21MHz LEP Klystron with a nominal power of 1.3 MW will be employed.

5. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik WHY A CH ? The CH-DTL operates in the H 21(0) mode and, at beam energies between 5 MeV/u and 150 MeV/u, it shows a large potential [3] as well for room temperature as for superconducting designs. At the moment besides IAP also ANL, FNAL [4] and are developing CH Cavities.

6. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik RFQ-INPUT-DISTRIBUTION: Released by Prof. Schempp (IAP) RMS (95 % norm): 0.35 95 % norm: 1.68 RMS (95 % norm): 0.36 95 % norm: 1.74 RMS (95 % ): 1.19 95 % norm: 9.00

7. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Matching Section For high current machines the Matching Section (RFQ-CH) should carefully design to avoid excessive emittance growth [5], particles loss and to host space for diagnostics. To CH KONUS PERIOD To Reduce RF Defocusing Effect and to keep good longitudinal quality the phase of the rebuncher is set at -70°: with 0.18 MV/m Effective Voltage per gap the estimated needed power is ~ 22 KV 95 % RMS nm : 0.376 95 % RMS : 1.193 95 % nm : 1.88 95 % nm : 1.82 95 % nm : 9.01

8. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik 70 MeV Proton Injector Layout @ 70 MeV with 50 cm of free space between Tank V and VI for extended Diagnostics

9. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik 70 MeV Proton Injector Beam ParameterInput Output X-X 95% RMS nm (mm mrad) 0.350.55 X-X 95% nm (mm mrad) 1.683.44 Y-Y 95% RMS nm (mm mrad) 0.360.53 X-X 95% nm (mm mrad) 1.743.00 W- 95% RMS (KeV/ns) 1.191.89 W- 95% (KeV/ns) 9.0013.62 Transmission Rate100 %

10. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Phase Signal Phase Probe Study Lets consider the bunch shape at the input of the 3 rd tanks flange with the second tank switched off: What could we expect? Besides Tank 3 the beam shape is lost….How many phase probes would be needed?

11. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Feeding System Courtesy of W.Vincent At the moment 2 technical solutions are under investigation, both based on IOT/Klystron solution and both promising total reduction of costs!!!!!!!!!!

12. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik CH: Mechanical Development The mechanical development is focused on 3 major problems 1.Flexibility in the tuning of the cavity 2.General mechanical stability and robustness 3.Optimisation of the RF efficiency A cold model consisting of 8 equidistant gaps (β / 2 = 45 mm) is, presently, under construction in order to test the fabrication steps and find out technical solutions for the assembly of the prototype cavity. The main idea is to weld the stainless steel stems into the yoke from outside and to avoid any screws inside the cavity; massive copper half drift tubes will be press-fit into the stems and its expected to achieve excellent RF contacts and mechanical precision with this technique. A complete new ends cell concept has been developed both to host quadruple lens or diagnostics devices and to tune the ends cell of the cavity. Stems, Drift Tubes, End-Flanges were already fabricated and the cavity is ready for final welding.

13. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Drift Tubes Mechanical Simulation performed with the ANSYS CODE has shown how press-fitting will ensure good quality of the contacts: the half tube will be cooled down and then inserted into the stem. The following thermal dilatation will spread the mechanical tension exactly all around the contacts: this technique is expected to ensure both good RF contacts and mechanical stability [6]. First test will be performed next week!!!!

14. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Drift Tubes 2 different shapes will be tested

15. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Stems Channel for the water cooling

16. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik …Some engineering Leak test performed in July has shown the necessity of a higher thickness in the welding region This model is teaching us how to build the Real Prototype!!!!!!!!!

17. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik End Cell Concept To increase the voltage in the ends cell and achieve good flatness of the electric field one possible way is to increase the magnetic inductance at the cavitys extremes: in the IH Cavity, for instance, this can be obtained by large undercuts in the base girder In the proton injector no girder is foreseen and the tuning can be achieved by enlarging the final nose [7] : this drift space can be used to host the quadruple lens or some beam diagnostics device such us phase probes.

18. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik End Cell Concept The result will be a very compact structure with each tank fed by its own generator and directly connected with the following one reducing considerably the overall length of the machine. The linac will be mounted on rails and the intertank flanges could be easily open to perform any kind of maintenance

19. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik End Cells Concept Microwave Studio Simulations of our model have confirmed how this technique can improve the distribution of the electric fields inside the cavity: final adjustments can be obtained by changing the DRIFT/LENGTH period [3]. Expected Effective Shunt Impedance : 90-100 M /m

20. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik End Cell

21. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik IAP-WP2: Status at Sep. 05 The cold model design and fabrication has been completed and its assemblage will be performed as soon as possible in the IAP Workshop This model will be used to gain experience on the realisation of the new CH-DTL Cavity, including the copper plating that will be executed at the GSI: within the end of this year vacuum and RF Measurements will be performed. Beam dynamics: COMPLETED: report will be sent at our coming back in Frankfurt!!!! Concerning the building of the real prototype it seems feasible to complete it within 2006. NTG ® Company was already contacted

22. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik People and Institute J.W.Goethe University, Frankfurt am Main- IAP U.Ratzinger, H.Podlech, R.Tiede, G.Clemente, S.Minaev (ITEP, IAP Guest) GSI, Darmstadt- LINAC TEAM K. Dermati, W.Barth, L.Groening, M.Vincent, P.Fork …And many others……

23. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik …and Finally Grazie! Dankeschön! Merci! Thanks!

24. Name, IAP, Universität Frankfurt LINAC AG Institut für Angewandte Physik Bibliography [1] The Future GSI Facility: beams of ions and antiprotons. H. Henning, Proceed. of the PAC 03, Portland, Oregon [2] The 70 Mev P-Injector for FAIR. U.Ratzinger et Al. Proceed. of the ICFA-HB04, Bensheim, Germany, September 18-22 2004. [3] Habilitazionschrift. U.Ratzinger, Frankfurt University [4] Front End Design of a Multi-GeV H-Minus Linac. P.N. Ostrumov et Al, Proceed. of the PAC 05, Knoxville, Tenesse, May 14-23 2005. [5] KONUS Beam Dynamics Design of a 70 MA, 70 MEV Proton CH-DTL for GSI-SIS12 R.Tiede et Al, Proceed of the LINAC 04 Conference, Lubeck, Germany, August 16-20 2004. [6] Geometrical Optimisation of the 70 mA, 70 MeV CH Cavity for the FAIR Project.G.Clemente et Al. GSI Scientific Report 2004 [7] Development of a normal conductiong CH-DTL G.Clemente et Al. Proceed. Of the PAC 05 Conference, Knoxville, Tenesse.