Linac4 & SPL Status of preparation and Opportunities M. Vretenar (R Linac4 & SPL Status of preparation and Opportunities M. Vretenar (R. Garoby) End of the Trilogy on SPL-Linac4… DAPNIA 9/01/2006

SPL = Superconducting Proton Linac a 4 MW / 3.5 GeV linear accelerator to: increase the performance of the CERN high energy accelerators (PS, SPS & LHC) address the needs of future physics experiments with neutrinos and radio-active ion beams DAPNIA 9/01/2006

SPL (2) Initial design (Conceptual Design Report 1): “optimized” for a neutrino factory assumed the use of LEP cavities & klystrons up to the highest energy Revised design in progress (CDR 2): based on updated physics’ requests using 704 MHz RF and bulk Niobium cavities in collaboration with CEA-Saclay & INFN-Milano to be published in 2005 Up-to-date information is available: on the CERN EDMS on the SPL site: http://project-spl.web.cern.ch/project-spl/ DAPNIA 9/01/2006

Three stages are planned: SPL stages Three stages are planned: Stage 1: 3 MeV test place Þ development and test of linac equipment, beam characterization Stage 2: Linac4 New linac replacing the present injector of the PS Booster (Linac2) Front-end of the future SPL Þ improvement of the beams for physics (higher performance and easier operation for LHC, ISOLDE etc.) Stage 3: SPL New injector for the PS, replacing the PS Booster New physics experiments using a high proton flux Þ improvement of the beams for physics and possibility of new experiments DAPNIA 9/01/2006

Linac4 design DTL CCDTL SCL Drift Tube Linac 352 MHz 13.6 m 3 tanks 3MeV 40MeV 90MeV 160MeV DTL CCDTL SCL Drift Tube Linac 352 MHz 13.6 m 3 tanks 5 klystrons 4 MW Cell-Coupled Drift Tube Linac 352 MHz 25.2 m 24 tanks 8 klystrons 6.4 MW Side Coupled Linac 704 MHz 28 m 20 tanks 4 klystrons 12.5 MW 3MeV line (H- source, IPHI RFQ, chopper line) Duty cycle: 0.1% phase 1 (Linac4) 15% phase 2 (SPL) 4 different structures, (RFQ, DTL, CCDTL, SCL) 2 frequencies Total Linac4: 86.3 m , 18 klystrons Beam current: 40 mA (avg. in pulse), 65 mA (bunch) DAPNIA 9/01/2006

Linac4 Schedule  Linac4 (160 MeV, H-) will double the intensity and brightness of the beam out of the PSB.  Support by the DG for a decision on construction at end 2006. Tentative schedule: 2005-06 Continuation of R&D 2006 (end) Linac4 Design Report (basic design frozen) 2007 Detailed design (=execution drawings!), definition of construction strategy, attribution of contracts 2008-09 Construction 2010 End of installation and commissioning DAPNIA 9/01/2006

IPHI HIPPI ISTC # 2888 & 2889 ISTC # 2875 Linac4 collaborations INDIA: klystron power supplies CHINA: quadrupoles, bendings, buncher IPHI HIPPI ISTC # 2888 & 2889 SCL ISTC # 2875 Network of collaborations for the R&D phase, via EU-FP6, CERN-CEA/IN2P3, ISTC, CERN-India and CERN-China agreements. The same network should support the construction of Linac4. DAPNIA 9/01/2006

Shunt Impedance Effective shunt impedance ZT2 along Linac4 Superfish calculation, not scaled The section between ~90 MeV and ~ 200 MeV is the most difficult for modern linacs: DTL-like structures present a sharp decrease in shunt impedance. Superconducting structures are not yet effective (low real estate gradient). Usual p-mode NC structures (CCL, SCL) at double frequency are considered expensive. DAPNIA 9/01/2006

The nominal Linac4 solution: a Side Coupled Linac Klystron [#] Tanks/Kly. Gradient E0 [MV/m] Power/Kly. [MW] Energy [MeV] N cells/tank 1 5 4 3.00 107.42 11 3.06 125.16 3.15 144.16 2.59 160.2 Tot. Klystr. Tot. tanks Average Grad. Tot. Power Tot. Length. [m] 20 12.46 28.02 RF power source: 4 MW, 704 MHz klystrons similar to SNS – (offer from Thales) DAPNIA 9/01/2006

More on the SCL Chain of cells, coupled via slots and off-axis coupling cells. Invented at Los Alamos in the 60’s. Operates in the p/2 mode (stability). CERN SCL design: Each klystron feeds 5 tanks of 11 accelerating cells each, connected by 3-cell bridge couplers. Quadrupoles are placed between tanks. How it looks like DAPNIA 9/01/2006

Example: the SCL for SNS DAPNIA 9/01/2006

Side Coupled cells Copper units made of one half accelerating cell and one half coupling cell, precisely machined (0.03mm) and brazed. 2 half cells with magnetic field lines 1 half cell with one half bridge coupler DAPNIA 9/01/2006

SNS SCL Construction Cell precision machining on a lathe – RF measurements after machining and before brazing DAPNIA 9/01/2006 Vertical brazing in the oven – final RF tuning, bead-pull measurement of field in the module

Options for CERN SCL construction Present status of Side Coupled Linac studies: * Studied inside HIPPI, jointly by CERN and LPSC Grenoble. Linac design (CERN), thermal analysis (LPSC), RF errors (LPSC, CERN), cell design. * Cold model will be built by LPSC (2006). * Technological model (Cu, brazed) will be built by BINP-Novossibirsk (2006). * INFN-Naples joins now the collaboration (bridge coupler design, stability). The construction of a Side Coupled Linac requires a difficult integration of technologies: Procurement of forged copper - Precision machining on Cu – First RF tuning before brazing – Brazing – Final RF tuning. Note that these technologies are very similar to those used for RFQ’s! Options for construction (2007-2009): Contract with ACCEL (has built the SNS SCL). Construction in Russia (some interest by BINP). Construction in Italy (INFN-Na ready, INFN interest still to be checked) Construction in France…? DAPNIA 9/01/2006

A superconducting alternative to the SCL? SCL can have another meaning: Super Conducting Linac. A SC section could replace the Side-Coupled, providing that we can obtain real-estate gradients ~2.5 MV/m. Needs investment for the cryogenic infrastructure, justified in the optics of an SPL following Linac4. SCL tanks (700 MHz) Spoke cavities (SC) (350 MHz) RF requirements: beam power 2.8 MW  - 20 units 100 kW, 352 MHz - 3 klystrons 1 MW, 352 MHz - 1 klystron 4 MW, 704 MHz DAPNIA 9/01/2006

Spoke, 352 MHz Focusing period in present design 90-160 MeV (FODO): ~ 1.5 m  compatible with Triple-spoke Triple-spoke designed at FZJ for HIPPI (E. Zaplatine): 0.78 m cavity length for b=0.5 E0T = 6.4 MV/m no freq. jump * Low efficiency at 90 MeV. * Do we need a double spoke at lower energy (but b=0.35 probably too low)? * Can we fit it in a cryostat ~ 1.2m long (to keep focusing distance)? * Can we feed 8 of these cavities from a single LEP klystron? DAPNIA 9/01/2006

Elliptical, 704 MHz Elliptical cavities at b=0.5 (CEA, INFN) are giving excellent results. Length ~ 0.9m Designed for 12 MV/m. * Require longer focusing period (~1.5 m). * Low efficiency at 90 MeV. * How many cavities can we feed with one klystron? * We could use the SPL-CDR2 layout, with superconducting quadrupoles and long cryostats, but long R&D time for superconducting quadrupoles. DAPNIA 9/01/2006

Summary for SC options A superconducting option is attractive for the high-energy part of Linac4, but has to compete with the conventional Side Coupled Linac. As a preliminary step in order to compare options we need layouts (mid 2006 ?) for both spoke and elliptical cavities, with a first beam dynamics analysis to be done in the frame of the HIPPI Activity (see ESAC recommendations). To compete with the SCL, average real estate gradient should be > 2.2 MeV/m. The option of cold quadrupoles (as for SPL) can be considered, but time is short to have it fully developed by end 2006. The RF power system can be a cost driver even for a SC linac, if one cannot drive at least 8 cavities/klystron. DAPNIA 9/01/2006

RF tests in SM 18 of prototype structures* for Linac4 Global planning RF tests in SM 18 of prototype structures* for Linac4 * Quotes from R. Aymar (Jan.2005) 3 MeV test place ready SPL approval * “in 2009-2010, to review and redefine the strategy for CERN activities in the next decade 2011-2020 in the light of the first results from LHC and of progress and results from the previous actions. “ Linac4 approval * “… in 2006-2007, to decide on the implementation of the Linac 4 and any increased R&D programme, depending on new funds made available and on a new HR policy” CDR 2 DAPNIA 9/01/2006