R&D for Future Accelerators at IFIC Scientific Staff: A. Faus-Golfe, C. Alabau, J.J. García, S. Verdu, J. Alabau Technical Staff: J.V. Civera, C. Blanch GDE Meeting Madrid1January 20-21

Capabilities - CALCULATION BEAM DYNAMICS EXPERTISE:  Electromagnetic analysis Electric circuits & electronics  Mechanical analysis  Optics design  Non-linear dynamics studies  New instrumentation techniques  Commissioning 3-D modelling ot BPM Optics study for LHC non-linear collimation sysytem - PROTOTYPING  Design: tooling, drawings  Fabrication follow-up  Assembly  Testing GDE Meeting Madrid 2 BEAM INSTRUMENTATION :

Main ongoing projects  ATF-ATF2: Beam dynamic studies and commissioning of the EXT line (LAL,KEK,SLAC)  CLIC-CTF3: BPM’s for TBL (UPC, CERN) Pieces of BPM-TBL for CTF3 GDE Meeting Madrid 3

ATF and ATF2 ATF was built in KEK (Japan) to create small emittance beams. The Damping Ring of ATF has a world record of the normalized emittance of 3x10 -8 m rad at 1.3 GeV. ATF2 is being built to study the feasibility of focusing the beam into a nanometer spot (40 nm) in a future linear collider. Extraction line drives the beam from ATF to ATF2 4 GDE Meeting Madrid

The Extraction Line (EXT) drives the beam from the ATF DR to the ATF2 Final Focus beam line ATF and ATF2: the Extraction Line Beam extraction process - Shared magnets with the DR - The beam passes off-axis Extraction Line extraction diagnostic section 5GDE Meeting Madrid

Hypothesis Since several years, the vertical emittane measured in the diagnostic section of the EXT line is significantly larger than the emittance measured in the DR and present a strong dependence with the beam intensity. The beam experiences some non-linear magnetic fields while passing off-axis through the shared magnets. 6GDE Meeting Madrid ATF and ATF2: Emittance growth in the EXT line

ATF and ATF2: Non-linear magnetic fields in the shared magnets of the EXT line Non-linearity of the magnetic field of the shared magnets: QM6, QM7, BS1X, BS2X, BS3X In order to quantify the effect of the non-linearity of the magnetic field on the extracted beam, the computation of the magnetic field on a finite mesh has been done with the code PRIAM. Polynomial fit with the code MINUIT in order to get a continuous representation of the magnetic field: Multipole MAD coefficients: 7GDE Meeting Madrid

ATF and ATF2: Non-linear magnetic fields in the shared magnets of the EXT line Non-linearity of the magnetic field of the QM6 quadrupole Dipole component 0.008% Quadrupole component -0.03% Zone of interest for tracking x=0.0065m y =0m nKn (m -n ) MAD notation E-3K0L E-1K1L E-1K2L E+2K3L E+6K4L E+3K5L E2K6L 70.0K7L 80.0K8L 8GDE Meeting Madrid

Non-linearity of the magnetic field of the QM7 quadrupole Dipole component -2% Quadrupole component -24% Zone of interest for tracking x=0.022 m y=0m KN (m -n ) MAD notation E-3K0L E-1K1L E+1K2L E+6K3L E+6K4L E+06K5L E+5K6L E+4K7L E+4K8L 90.0K9L 9 GDE Meeting Madrid ATF and ATF2: Non-linear magnetic fields in the shared magnets of the EXT line

Non-linearity of the magnetic field of the BS1X septum magnet Dipole component -1.5% Quadrupole component small Sextupolar component small Zone of interest for tracking x=0.0855m, y=0m NKN (m -1 ) MAD notation E-2K0L E-3K1L E+0K2L E+3K3L E+5K4L E+9K5L E+12K6L E+15K7L E+18K8L E+21K9L E+23K10L BS2X (x=0.0153m, y=0m) and BS3X (x=0.016m, y=0m) more linear part 10 GDE Meeting Madrid ATF and ATF2: Non-linear magnetic fields in the shared magnets of the EXT line

: ATF and ATF2 : Tracking simulations including non-linear fields in different magnets of EXT line Tracking performed with MAD and PLACET without horizontal bumps 11GDE Meeting Madrid

12 GDE Meeting Madrid : ATF and ATF2: Tracking simulations for different x/y bump amplitudes

open the bump in DR and EXT offset in QM7 close the bump in the DR Beam size after the shared magnets is correlated with the emittance: - OTR monitor recently installed images the beam angular spread out of QM7 - Creating bumps in QM7 to probe effects on the vertical emittance - Measure beam sizes at the DR (XSR monitor) and the EXT line (OTR monitor) as a function of the bump amplitude OTR monitor 13 : ATF and ATF2 : Experimental Proposal

ATF and ATF2: Experimental Work (Dec’07-May’08) Vertical beam size vs vertical bump amplitude at QM7 Extraction Line (OTR monitor) Damping Ring (XSR monitor) OTR/XSR (Measurements 19 th Dec’07) 14

Measurements 19 th Dec 2007 Simulations: - including non-linear fields in different magnets - for different horizontal bump amplitudes in QM7 (nominal extraction 22.5 mm) - with the input emittances the corresponding to the measured during the shift Measurements 28 th May 2008  y =36 pm ~ 3*  y,nom  x =2.4 nm ~ 2*  x,nom  y =24.0 pm ~ 2*  y,nom  x =2.28 nm ~ 1.9*  x,nom ATF and ATF2: Experimental Work (Dec’07-May’08) σ y increase at the OTR as a function of the y bump amplitude 15

ATF and ATF2: Conclusions The non-linear content of: QM6, QM7and BS1X has been calculated with PRIAM. Tracking simulations including non-linear field errors in: QM6, QM7 and BS1X shared by both the ATF EXT line and its DR, and orbit displacements from the reference orbit in the extraction region predict a vertical emittance growth of the extracted beam. Simulations show that the non-linear fields are very sensitive to the extraction position. The more important source on non-linearity is QM7. Recently, measurements using closed orbit bumps in the DR to probe the relation between the extraction trajectory and the emittance growth in the EXT line have been carried out. The results shows an emittance growth with a strong dependence with the extraction position. Both horizontal and vertical positions of the beam in the extraction region have to be controlled to avoid this emittance growth. Based in this work QM7 will be replaced from the EXT line by a magnet with large bore to avoid the non-linear field impact. 16GDE Meeting Madrid

The peak RF power required to reach the electric fields of 100 MV/m amounts to about 275 MW per active meter of accelerating structure. Not possible with klystrons. GDE Meeting Madrid CLIC: The Compact Linear Collider Each sub-system pushes the state-of-the art in accelerator design Hence a novel power source, an innovative two-beam acceleration system, in which another beam, the drive beam, supplies energy to the main accelerating beam. 17

To demonstrate the two-beam acceleration scheme A scaled facility for one branch of the Drive Beam Generation System of CLIC Layout of the CLIC EXperimental area (CLEX) building with TBL CTF3: The CLIC Test Facility 3 GDE Meeting Madrid18

16 TBL Cells TBL: The Test Beam Line The main aims of the TBL: Study and demonstrate the technical feasibility and the operability a drive beam decelerator (including beam losses), with the extraction of as much beam energy as possible. Producing the technology of power generation needed for the two-beam acceleration scheme. Demonstrate the stability of the decelerated beam and the produced RF power by the PETS. Benchmark the simulation tools in order to validate the corresponding systems in the CLIC nominal scheme. GDE Meeting Madrid19

TBL + BPM Specifications Main features of the Inductive Pick-Up (IPU) type of BPM: less perturbed by the high losses experienced in linacs; the total length can be short; it generates high output voltages for typical beam currents in the range of amperes; calibration wire inputs allow testing with current once installed broadband, but better for bunched beams with short bunch duration or pulse IPU type of BPM suitable for TBL 2 BPS prototypes design and constructed at IFIC (scaled version of IPU DBL of CTF3) TBL beam time structure GDE Meeting Madrid20

BPS Mechanical Assembly Vacuum assembly: ceramic tube with Kovar collars at both ends, one collar TIG welded to the downstream flange, and the other one electron welded to a bellow and a rotatable flange (~ mbar l/s High Vacuum) Ferrite cylinder Cooper body PCB plates GDE Meeting Madrid 21

BPS Basic Sensing Mechanism Four Outputs (V+,V-, H+,H-) with two Calibration inputs (Cal+, Cal-) Difference signals ( Δ ) normalized to sum signal ( Σ ) (proportional to beam position coordinate) x V α ΔV /Σ Vertical plane x H α ΔH /Σ Horizontal plane where: ΔV ≡ (V+ − V-); ΔH ≡ (H+ − H−); Σ ≡ (V+ + H+ + V− + H- ) Primary transformer electrode Longitudinal cross-section view GDE Meeting Madrid22

BPS Frequency Response Induced current/signal Pulse deformation ω low = R/L or f low = R/ 2L ω high = 1/RC S or f high = 1/2RC S τ droop =1/ ω low and τ rise =1/ω high τ droop ~ 10 2 t pulse τ rise ~ t pulse to let pass the pulse without deformation (droop time very important for ADC sampling) GDE Meeting Madrid23

BPS Electric Model High cut-off frequency: Fixed by secondary C s for all cases Low cut-off frequencies: I)Centered wire: Balanced wall image curent II)Displaced wire: Unbalanced wall image current (low frequency coupling) f high = 1/2R e C S Cut-off Frequencies: GDE Meeting Madrid f L  = (R P +R C )/2L  f L  = (R P +R C )/2L  24

BPS Electronic Design GDE Meeting Madrid25

BPS Electronic Design Characteristic Output Signal Levels: V sec = (Σ/I B ) I elec with: (Σ /I B ) = (R Load R S1 /(R S1 +R S2 +R S1 )N) = 0.55Ω for design values: R Load = 50 Ω, R S1 = 33 (13) Ω, R S2 = 18 (0) Ω (Ver. 2) N = 30 turns PCBs Schematics and Output relation For a beam current of: I B = 30A Σ = 16.5 V outputs sum V sec = Σ /4 = 4.125V centered beam ||ΔV|| max = ||ΔH|| max = Σ /2 = 8.25V beam at electrodes GDE Meeting Madrid26

BPS Readout Chain Amplifier developed at UPC Digitizer/ADC developed at LAPP(Annecy) Both designs must be rad-hard GDE Meeting Madrid27

BPS Characterization Tests (Wire-Test) Sensitivity, Linearity and Frequency response carried out during several short stays at CERN, in the AB/BI-PI [1], where the wire testbench is placed, and it has been previously used for testing and calibrating BPMs for the Drive Beam Linac (DBL) of the CTF3. [1] Tests carried out during several short stays at CERN, in the AB/BI-PI* Labs. Testbench used to characterize the BPMs for the Drive Beam Linac (DBL) of the CTF3 Accelerator an Beams Department/ Beam Instrumentation Group – Position and Intensity Section GDE Meeting Madrid28

BPS: Sensitivity test (Ver. 1) SensitivityElectric Offset Sensitivity for V,H planes Electric Offset for V,H planes Linear fit equations S V = (41.09±0.08)10 −3 mm −1 S H = (41.53±0.17)10 −3 mm −1 EOS H = (0.15±0.02) mm EOS V = (0.03±0.01) mm GDE Meeting Madrid29

BPS: Linearity test (Ver.1) Linearity error  Overall Precision/Accuracy σ V = 78 μm σ H = 170 μm i)Low current in the wire (13 mA) vs beam 32 A ii) Misalignment in the horizontal electrodes σ TBL < 50μm Typical S-shape BPS above specs: GDE Meeting Madrid 30

Cut-off frequencies: BPS: Frequency Response test (Ver.1) Output electrodesΔV, ΔH and Σ Wire Pos: Center Wire Pos:+8mm V,H f high > 100 MHz τ rise < 1.6 ns f LΣ = 1.76 KHz τ droop Σ = 90  s f LΔ ≡ f LΔH = f LΔV = 282KHz τ droop Δ = 564ns Bandwidth specs : 10KHz-100MH t pulse =140ns Coupling at low frequency (no beam variation) GDE Meeting Madrid 31

BPS: Pulse Response and Calibration (Ver.1) f LΔ[cal] =180 KHz < f LΔ =282 KHz (difference is about 100 KHz) Represents a problem for the amplifier compensation in the Δ channels (lower f LΔ ), because the same compensation designed for the f LΔ will be applied when exciting the calibration inputs to f LΔ[Cal ] (bad pulse for calibration,overcompensation) Compensation frequency at the lower one f LΔ[Cal] gives a calibration pulse good flatness and wire-beam pulse flat enough for TBL pulse duration τ droop Δ [cal] = 884 ns τ droop Δ = 564 ns τ droop Σ = 90 μs τ droop Σ [Cal] = 90 μs GDE Meeting Madrid32

BPS: Characterization Table (Ver.1) GDE Meeting Madrid BPS1 Sensitivity and Linearity Parameters Vertical Sensitivity, S V mm -1 Horizontal Sensitivity, S H mm -1 Vertical Electric Offset, EOS V 0.03 mm Horizontal Electric Offset, EOS H 0.15 mm Vertical overall precision (accuracy), σ V 78 μm Horizontal overall precision (accuracy), σ H 170 μm BPS1 Characteristic Output Levels Sum signal level, Σ16.5 V Difference signals max. levels, ||ΔV|| max, ||ΔH|| max 8.25 V Centered beam level, V sec (x V = 0, x H = 0) V BPS1 Frequency Response (Bandwidth) Parameters Σ low cut-off frequency, f LΣ 1.76 KHz Δ low cut-off frequency, f LΔ 282 KHz Σ low cut-off frequency calibration, f LΣ [Cal] 1.76 Hz Δ low cut-off frequency calibration, f LΔ [Cal] 180 KHz High cut-off frequency, f high > 100 MHz High cut-off frequency calibration, f high [Cal] > 100 MHz BPS1 Pulse-Time Response Parameters Σ droop time constant, τ droopΣ 90 μs Δ droop time constant, τ droopΔ 564 ns Σ droop time constant calibration, τ droopΣ [Cal] 90 μs Δ droop time constant calibration, τ droopΔ [Cal] 884 μs Rise time constant calibration, τ rise < 1.6 ns Rise time constant calibration, τ rise [Cal] < 1.6 ns 33

BPS: Conclusions A set of two BPS prototypes with the associated electronics were designed and constructed. The performed tests yield: Good linearity results and reasonably low electrical offsets from the mechanical center. Good overall-precision/accuracy in the vertical plane considering the low test current; and, a misalignement in the horizontal plane was detected by accuracy offset and sensitivity shift. Low frequency cut-off for Σ/electrodes signals, f LΣ, and high cut-off frequency, f high, under specifications. Low frequency cut-off for Δ signals, f LΔ, determined to perform the compensation of droop time constant, τ droopΔ, with the external amplifier. GDE Meeting Madrid34

BPS: Future Work Open issues for improvement in the BPS2 monitor prototype: o correct the possible misalignments of the horizontal plane electrodes suggested in the linearity error analysis o check if overall-precision below 50μm (under TBL specs), with enough wire current  New wire testbench at IFIC o study the different low cut-off frequencies in the calibration, f LΔ[Cal], and wire excitation cases, f LΔ Test Beam of the BPS1 in the TBL  Resolution at maximum current. BPS series production and characterization (15 more units). The new wire testbench will allow higher currents, accurate (anti-vibration and micro- movement system) and automatized measurements. GDE Meeting Madrid35

GDE Meeting Madrid BPS: Future Work 36 Sketch of new IFIC Wire Testbench (under construction) x/y range 50x50 mm Resolution 0.1  m Precision 0.7  m

Main Future projects  ATF-ATF2: Beam Instrumentation design and construction: BPM’s supports with micromovers for FONT4 (KEK, JAI) multi OTR (KEK, SLAC)  ILC: BDS instrumentation studies  LHC: non-linear collimation options for sLHC (SPS experiments) (EUCARD)  IFIMED: Imaging and Accelerators applied to Medicicine Monitoring of secondary beams (beam position and size) (CERN; LLR, CNAO) Cyclinacs applications (TERA, CTF3) CABOTO: Carbon Boster for Therapy in Oncology 37 GDE Meeting Madrid

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