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Frascati, 28 Maggio 2003 Accelerator Physics and Design Working Group Summary 2/2 O. Napoly

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Frascati, 28 Maggio 2003 CEBAF Energy Recovery Experiment Michael Tiefenback GeV scale Energy Recovery demonstration. – Testing the potential of ERLs –Demonstration of high final-to-injection energy ratios - 20:1 and 50:1 –Optimized beam transport in large scale recirculating linacs (320 SC cavities) - RF steering and skew field compensation for accelerated/decelerated beams 56MeV injection 56MeV /2 phase delay chicane 1L21 2L21 56MeV 556MeV 1056MeV 556MeV 1056MeV 56MeV 556MeV deceleration acceleration deceleration

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Frascati, 28 Maggio 2003 CEBAF Energy Recovery Experiment Michael Tiefenback rf power measurement - selected cavity at the end of South Linac Standard arc BPMs go dead with ER beam: - BPM signal at RF fundamental - Decelerated beam is λ/2 delayed from primary beam signals destructively interfere in BPM antennae

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Frascati, 28 Maggio 2003 CEBAF Energy Recovery Experiment Michael Tiefenback synchrotron light monitor – accelerated/decelerated beams at 556 MeV Emittance measurements and Halo measurement Beam quality is essentially preserved (80 µA)

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CW Energy Recovery Linac for Next Generation of XFELs General Thoughts based on TESLA XFEL-TDR TJNAF: A. Bogacz INFN: INFN: M. Ferrario, L. Serafini DESY: DESY: D. Proch, J. Sekutowicz, S. Simrock BNL:I. Ben-Zvi LANL:P. Colestock UCLA:J. B. Rosenzweig TESLA_TTF Meeting Frascati, May 26-28, 2003

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Frascati, 28 Maggio 2003 RF-Gun ? BC I : 0.14 GeV BC II : 0.50 GeV BC III : 2.50 GeV En = 10÷20 GeV R~150 m 1.8 km ~3 km Dump (0.5 MW) 3xSASE 2xUndulators Possible layout can be very similar to the present pulsed linac energy recovery 95%

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Frascati, 28 Maggio 2003 Any combination of the bunch charge and the spacing of bunches giving nominal current is OK Example: 1 mA= 1 nC @ spacing 1 µs

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Frascati, 28 Maggio 2003 Conclusion Needed R&D : cw RF gun suppression of microphonics more experience with the energy recovery Total cost without experiments should be < 400 MEuros Total AC power for Cryoplant + RF < 10 MW But we will have : 6 x more bunches /s very flexible time structure of the beam.

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Frascati, 28 Maggio 2003 * TESLA Meeting - Frascati - 27 May 2003 * Towards a Superconducting High Brightness RF Photoinjector M. Ferrario, J. B. Rosenzweig, J. Sekutowicz, L. Serafini INFN, UCLA, DESY

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Frascati, 28 Maggio 2003 Main Questions/Concerns RF Focusing vs Magnetic focusing ? RF Focusing vs Magnetic focusing ? High Peak Field on Cathode ? High Peak Field on Cathode ? Cathode Materials and QE ? Cathode Materials and QE ? Q degradation due to Magnetic Field ? Q degradation due to Magnetic Field ?

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Frascati, 28 Maggio 2003 SCRF GUN Measured Limited by the available voltage Measurements at room T on a dedicated DC system Extrapolation to Higher Field

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Frascati, 28 Maggio 2003 Splitting Acceleration and Focusing 25 cm 10 cm 50 cm The Solenoid can be placed downstream the cavity The Solenoid can be placed downstream the cavity Switching on the solenoid when the cavity is cold prevent any trapped magnetic field Switching on the solenoid when the cavity is cold prevent any trapped magnetic field

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Frascati, 28 Maggio 2003 Q =1 nC R =1.5 mm L =20 ps th = 0.45 mm-mrad E peak = 60 MV/m (Gun) E acc = 13 MV/m (Cryo1) B = 1.9 kG (Solenoid) I = 50 A E = 120 MeV n = 0.6 mm-mrad n [mm-mrad] Z [m] HOMDYN Simulation 6 MeV 3.5 m scaling laws for Q and E peak available

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Progress on Helical Undulator for Polarised Positron Production Duncan Scott ASTeC Daresbury Laboratory

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Frascati, 28 Maggio 2003 SC Magnet Undulator Prototype Prototype Magnet Design for 14mm period: Beam Stay Clear 4mm Helix Diameter 6mm

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Frascati, 28 Maggio 2003 Permanent Magnet Undulator Design 14mm Period, 4mm Bore “Halbach” undulator (Klaus Halbach NIM Vol. 187, No1) Rotate many rings to create Helical Field PPM blocks create Dipole Field

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Frascati, 28 Maggio 2003 Vacuum Problems TESLA requirements of ~10 -8 mbar vacuum CO equivalent For the SC magnet : –this can be achieved, as long as the number of photons above 3eV hitting the vessel wall is not greater than 10 17 s -1 m -1 For the Permanent magnet : –theoretical maximum for a 5 m long 4mm bore vacuum pipe is 10 - 7 mBar –A NEG coated vessel is needed, thought to be feasible although no-one has ever NEG coated a 4mm diameter tube Hope to build two ~20 period prototypes (one of each design) to measure the magnetic field this year Progress on Helical Undulator for Polarised Positron Production

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TESLA Damping Ring: Injection/Extraction Schemes with RF Deflectors D. Alesini, F. Marcellini

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Frascati, 28 Maggio 2003 Injection CTF3-LIKE INJECTION/EXTRACTION SCHEME (simple scheme) 1)If the filling time ( F ) of the deflectors is less than T DR it is possible to inject or extract the bunches without any gap in the DR filling pattern. 2) should be * depending on the ring optics and septum position. Considering a single RF frequency / MAX =1-cos(2 /F) Extraction LINAC TRAIN Rec. factor

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Frascati, 28 Maggio 2003 DEFLECTOR PARAMETERS ( /2) 6 Deflectors (3 inj. + 3 extr.) Defl 1 f RF1 = 433*1/ T L = 1284.87 [MHz] Defl 2 f RF2 = 438*1/ T L = 1299.70 [MHz] Defl 3 f RF3 = 443*1/ T L = 1314.54 [MHz] Total beam deflection = 0.87 [mrad] Deflection defl.1 = 0.29 [mrad] Deflection defl.2 = 0.29 [mrad] Deflection defl.3 = 0.29 [mrad] P = 9 [MW] L = 0.64 [m] F = 48 [nsec] n. Cells/defl = 11 P = 5.00 [MW] L = 0.86 [m] F = 64 [nsec] n. Cells/defl = 15 MAX = 69 % 3 Frequencies maximization of MAX in the range [430*1/ T L 450*1/ T L ] =1.276 1.335 GHz no bunch length 3 distant freq. case 3 close freq. case

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Frascati, 28 Maggio 2003 FINITE BUNCH LENGTH New optimization procedure: - to increase 1 - (if possible) to reduce the RF slope over the bunch length z =6 mm, the same 2 freq. optimized in the previous case give: 1 = 9 % Extracted bunch How to avoid the effect of the RF curvature on the extr. bunches

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Frascati, 28 Maggio 2003 DEFLECTOR PARAMETERS ( /2) 6 Deflectors (3 inj. + 3 extr.) Defl 1 f RF1 = 444*1/ T L = 1317.51 [MHz] Defl 2 f RF2 = 437*1/ T L = 1296.74 [MHz] Defl 3 f RF3 = 435*1/ T L = 1290.80 [MHz] Total beam deflection = 1.05 [mrad] Deflection defl.1 = 0.35 [mrad] Deflection defl.2 = 0.35 [mrad] Deflection defl.3 = 0.35 [mrad] P = 9 [MW] L = 0.78 [m] F = 58 [nsec] n. Cells/defl = 13 P = 5.00 [MW] L = 1.04 [m] F = 77 [nsec] n. Cells/defl = 18 3 Frequencies 1 = 57 % maximization of 1 in the range [430*1/ T L 450*1/ T L ] =1.276 1.335 GHz bunch length z =6 mm 3 distant freq. case 3 close freq. case

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Frascati, 28 Maggio 2003 F=100 L DR 2.85 Km maximization of 1 in the range [430*1/ T L 450*1/ T L ] =1.276 1.335 GHz bunch length z =2 mm P = 9 [MW] L = 1.6 [m] F = 119 [nsec] n. Cells/defl = 28 P = 5.00 [MW] L = 2.15 [m] F = 160 [nsec] n. Cells/defl = 37 DEFLECTOR PARAMETERS ( /2) 6 Deflectors (3 inj. + 3 extr.) Defl 1 f RF1 = 447*1/ T L = 1326.41 [MHz] Defl 2 f RF2 = 440*1/ T L = 1305.64 [MHz] Defl 3 f RF3 = 436*1/ T L = 1293.77 [MHz] Total beam deflection = 2.16 [mrad] Deflection defl.1 = 0.72 [mrad] Deflection defl.2 = 0.72 [mrad] Deflection defl.3 = 0.72 [mrad] 1 = 28 % 3 distant freq.

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Frascati, 28 Maggio 2003 OUR EXPERIENCE WITH RF DEFLECTOR FOR CTF3 1. STUDY AND NUMERICAL SIMULATIONS 2. MECHANICAL DRAWING 3. CONSTRUCTION 4. MEASUREMENTS 1 st turn - 1 st bunch train from linac 2 nd turn 3 rd turn 4 th turn

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Frascati, 28 Maggio 2003 /2 MODE Deflection = 0.5 mrad f RF = 1.3 GHz Disk thickness = 11.53 mm Cell length = 57.65 mm

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Frascati, 28 Maggio 2003 Module III Module II OFF q = 3.5 nC f b = 2.25 MHz Tp = 780 s Agilent E8563E spectrum analyser zero span HOM 2 HOM 1 Att 10 dB GPIB Spectrum analyser Beam used as aparametric bandpass filter: –central frequency –resolution bandwidth signals in time domain ON Beam Position Measurements in TTF Cavities using Dipole Higher Order Modes G. Devanz, O. Napoly, CEA, Gif-sur-Yvette A.Gössel, S. Schreiber, M. Wendt, DESY, Hamburg

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Frascati, 28 Maggio 2003 Dipole mode measurements 2 positions computed using 2 modes with the same beam High gradient in cavities (~ 20 MV/m) orbit is expected to cross ACC1 module axis if entering at an offset

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Scattering Parameter Calculation for the 2x7 Superstructure TESLA Collaboration Meeting INFN Frascati May 26-28, 2003 Karsten Rothemund, Dirk Hecht, Ulla van Rienen

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Frascati, 28 Maggio 2003 2x7-Superstructure 7 Cell TESLA Cavity HOM-Coupler Input-Coupler Images: I.Ibendorf Radius Adapter

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Frascati, 28 Maggio 2003 HOM-Coupler (HOM 2 + HOM 3) HOM 2 HOM 3HOM 1 Input rotate HOM 3 shift planes 27.4 mm

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Frascati, 28 Maggio 2003 7 Cell TESLA Cavity f=1.5-3.0 GHz TE11 TM01 TE21 Plot: MWS, simulation: MAFIA, 2D, time domain f/GHz |S..|/dB f/GHz |S..|/dB

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Frascati, 28 Maggio 2003 CSC-Computation Calculation of overall S-matrix open ports: beam pipe, 3x HOM-, 1x Input-coupler 1500 values computed in 1.5-3 GHz frequency range shown here:2.46-2.58 GHz (3 rd dipole passband) 481 frequency-points + interpolation S-values of 7-cell cavity f/GHz |S..|/dB

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Frascati, 28 Maggio 2003 Results Coupling between HOM1 and HOM2 to beam pipe modes HOM1 HOM2 downstream beam pipe upstream beam pipe f/GHz |S..|/dB f/GHz |S..|/dB

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Frascati, 28 Maggio 2003 Summary S-parameter of 2x7 TESLA-Superstructure have been calculated (an open structure) with CSC 5 modes have been considered in the structure S-parameter of subsections were computed with CST-MicrowaveStudio TM (coupler sections, 3D) MAFIA (TESLA cavity, 2D-rz-geometry) analytically (shifting planes, rotation) some exemplary coupling parameters have been presented computation times for S-parameters of subsections in order of days additional computation times whole structure then in the order of minutes parameter tuning (e.g. rotation angles, distances) possible

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Start-to-End Simulations for the TESLA LC A Status Report Nick Walker DESY TESLA collaboration Meeting, Frascati, 26-28 th May 2003

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Frascati, 28 Maggio 2003 Ballistic Alignment 62

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Frascati, 28 Maggio 2003 New Simulations using PLACET and MERLIN 14 quads per bin (7 cells, = 7 /3) RMS Errors: –quad offsets:300 m –cavity offsets:300 m –cavity tilts:300 rad –BPM offsets:200 m –BPM resolution:10 m –CM offsets:200 m –initial beam jitter:1 y (~10 m) New transverse wakefield included (~30% reduction from TDR) [Zagorodnov and Weiland, PAC2003] wrt CM axis

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Frascati, 28 Maggio 2003 Ballistic Alignment Less sensitive to model errors beam jitter average over 100 seeds

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Frascati, 28 Maggio 2003 Ballistic Alignment average over 100 seeds We can tune out linear y and y’ correlation using bumps or dispersion correction in BDS

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Frascati, 28 Maggio 2003 Beam-Beam Issues optimise beam- beam offset and angle OK for ‘static’ effect D. Schulte. PAC03, RPAB004

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Frascati, 28 Maggio 2003 Simulating the Dynamic Effect Realistic simulated ‘bunches’ at IP –linac (PLACET, D.Schulte) –BDS (MERLIN, N. Walker) –IP (GUINEAPIG, D. Schulte) –FFBK (SIMULINK, G. White) bunch trains simulated with realistic errors, including ground motion and vibration LINACBDSIRBDSIR IP FFBK All ‘bolted’ together within a MATLAB framework by Glen White (QMC)

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Frascati, 28 Maggio 2003 Simulating the Dynamic Effect IP beam angle IP beam offset

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Frascati, 28 Maggio 2003 Simulating the Dynamic Effect 2 10 34 cm 2 s 1 Only 1 seed: need to run many seeds to gain statistics!

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NEW DESIGN OF THE TESLA INTERACTION REGION WITH l * = 5 m O. Napoly, J. Payet CEA/DSM/DAPNIA/SACM Advantages from the detector point-of-view –Larger forward acceptance at low angles –Final doublet moved out of the calorimeter less e.m. showers in the detector –Lighter Tungsten-mask and simpler support

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Frascati, 28 Maggio 2003 NLC-like Optics

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Frascati, 28 Maggio 2003 Simulating the Extraction Line Part of the extraction line included in BRAHMS: Shadow: Distance from IP: 45m 2m long 5mm thick 7mm vertical distance from nominal beam (~156 µrad) Copper Septum Blade: Distance from IP: 47m 16m long 5mm thick ~7mm vertical distance from nominal beam Copper

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Frascati, 28 Maggio 2003 Realistic Beam Shadow: Average deposited power: ~15 kW Septum blade: Average deposited power: ~80 W

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