1. J.J. García-Garrigós Septiembre 2008 126/09/2008

2. 2 Contents Introduction: Linear Collliders The CLIC and CTF3 The BPS monitor prototype in theTest Beam Line BPS mechanical design BPS sensing mechanism and general description BPS electronic design BPS wire test results and analysis Conclusions and Future work BPS-TBL-CTF3 J.J. García-Garrigós

3. 3 The LHC will probe the new “terascale” energy region : Confirm or refute the existence of the Higgs boson to complete the Standard Model Explore the possibilities for physics beyond the Standard Model, such as supersymmetry, extra dimensions and new gauge bosons 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Present and Future Colliders Particle physics community worldwide have reached a consensus that the results from the LHC will need to be complemented by experiments at an electron-positron collider operating in the tera- electron-volt energy range

4. 4 p-p colliders can reach higher energy than e + e -, but –the energy of the constituents (quarks and gluons) are lower –p-p interaction is too complicated (not easy to analyze collision data) e + e - colliders: –cleaner experimental enviroments –available eγ, γγ and e - e - interactions –available polarized beams p-p and e + e - complementary –particle discovery by p-p colliders –finer study by e + e - colliders  Naturally arise as LHC successors 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Why e + e - Linear Colliders Some physics reasons

5. 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 5 LEP at CERN, CH E cm = 180 GeV P RF = 30 MW Why a Linear Collider, and not just build a bigger Storage Ring 500 GeV LC Livingston Chart

6. 626/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Why a Linear Collider, and not just build a bigger Storage Ring Synchrotron radiation from an e - in a magnetic field: Energy loss per turn of a machine with an average radius  : Energy loss per turn has to be be replaced by the RF system, which is the major cost factor for a collider. average power LEP e + e - storage ring: The biggest superconducting RF system with3640 MV per revolution  just enough to keep the beam in LEP at its nominal energy

7. 7 e+e+ e-e- 5-10 km No Synchrotron Radiation, but new problems arise: we cannot store the beams, LC is one-pass device where the beams must be accelerated to the required energy on each pulse of the machine we cannot take advantage of the stored beam to slowly ramp the energy up, we have to provide several Km of RF Power (25-100 MV/m) to achieve the energy in a single-pass 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Why a Linear Collider, cause no bends, but also needs lots of RF!

8. 8 This study is based on an RF system using superconducting cavities for acceleration, with a nominal accelerating field of 31.5 MV/m and a total length of 31 km for a colliding- beam energy of 500 GeV. The CLIC scheme is based on normal conducting travelling-wave accelerating structures, operating at a frequency of 12 GHz and with very high electric fields of 100 MV/m to keep the total length to about 48 km for a colliding-beam energy of 3 TeV. 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Now, no losses And we can get the RF Power

9. 9 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. 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 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.

10. 10 To demonstrate the Two-beam acceleration scheme. A scaled facility for one branch of the Drive Beam Generation System Layout of the CLIC EXperimental area (CLEX) building with TBL 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós CTF3: The CLIC Test Facility 3

11. 11 16 TBL Cells 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 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.

12. 12 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 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 2 BPS Prototypes developed at IFIC, scaled and redesigned version of IPU used in DBL of CTF3 TBL beam time structure

13. 13 BPS Mechanical Assembly 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 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.  ~10 -10 mbarl/s [High Vacuum] Ferrite cylinder Cooper body PCB plates

14. 14 BPS Basic Sensing Mechanism  Four Outputs with two Calibration inputs: [ V+,V-, H+,H- ] and [Cal+, Cal-], respectively  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−); and, Σ ≡ (V+ + H+ + V− + H- ) 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Primary transformer electrode Longitudinal cross-section view

15. 15 BPS Readout chain 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Amplifier developed at UPC by G. Montoro Digitizer/ADC developed at LAPP(Annecy) Both Designs must be Rad-Hard

16. 16 Typical IPU Frequency Response 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Induced current/signal Pulse deformation ω low = R/L, and ω high = 1/RC S τ droop =1/ ω low, and τ rise =1/ω high τ droop ~ 10 2 t pulse τ rise ~ 10 -2 t pulse To let pass the pulse without deformation Droop time very important for ADC sampling.

17. 17 BPS Electronic design Characteristic Output Signal Levels: 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós with: (Σ /I B ) = 0.55Ω V sec = (R Load R S1 /(R S1 +R S2 +R S1 )N) I elec ≡ (Σ/I B ) I elec 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 elec] for the design values: R Load = 50 Ω, R S1 = 33 Ω, R S2 = 18 Ω and N = 30 turns

18. 18 BPS1 Characterization Tests [The Wire-Test]* Sensitivity and Linearity + Frequency Response 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós 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 (Bldg.37) Testbench used to characterize the BPMs for the Drive Beam Linac (DBL) of the CTF3 *With the help of: CTF3 Collaboration * Accelerator an Beams Department/ Beam Instrumentation Group – Position and Intensity Section

19. 19 Sensitivity and Linearity Test Results Sensitivity 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Electric 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

20. 2026/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Sensitivity and Linearity Test Results Linearity error  Overall Precision/Accuracy σ V = 78 μm σ H = 170 μm ii) Misalignment in the horizontal electrodes i) Low current in the wire (13mA) vs beam 32 A σ TBL < 50μm Typical S-shape BPS above specs

21. 21 Cut-off Frequencies: 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Frequency ResponseTest Results Output electrodesΔV, ΔH and Σ Wire Pos: Center Wire Pos:+8mm V,H f LΣ = 1.76 KHz f LΔ ≡ f LΔH = f LΔV = 282KHz τ droop Σ = 90us τ droop Δ = 564ns Bandwidth specs: [10KHz-100MHz] t pulse =140ns f high > 100 MHz, and τ rise < 1.6 ns Coupling low freq. components don’t feel the beam variation

22. 22 BPS Electric Model  Low cut-off frequencies  Two different cases: I)Centered wire: Balanced wall image curent II)Displaced wire: Unbalanced wall image current (low freq. coupling) 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós  High cut-off frequency  Fixed by secondary Cs for all cases f high = 1/2R e C S Model Cut-off Frequencies:

23. 23 BPS Electric Model I)Centered wire: Balanced wall image curent: Δ ~0  L Δ = 0 because reflects a coupling in the other case Low cut-off fixed by L Σ >>L Δ  f Σ << f Δ 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós

24. 24 BPS Electric Model 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós II)Displaced wire V,H plane: Unbalanced wall image current (low freq. coupling) Δ ≠0  L Δ ≠0 appears on the pair of V or H electrodes Low cut-off fixed by L Δ >> L Σ  f Δ general case and must be compensated by External Amplifier

25. 25 BPS Electric Model II)Displaced wire V,H plane: Unbalanced wall image current (low freq. coupling) Δ ≠0  L Δ ≠0 appears on the pair of V or H electrodes Low cut-off fixed by L Δ >> L Σ  f Δ general case and must be compensated by External Amplifier 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós

26. 2626/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Pulse Response and Calibration problem f LΔ[cal] =180 KHz < f LΔ =282 KHz their difference is about 100 KHz. Represents a problem for the amplifier compensation in the Δ channels, to lower the Δ low cut-off frequency for the wire, 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).  A compromise solution: compensation frequency at the lower one, f LΔ[Cal]  Cal. pulse good flatness and wire-beam pulse flat enough for TBL pulse duration(140ns) τ droop Δ [cal] = 884 ns τ droop Δ = 564 ns τ droop Σ = 90 μs τ droop Σ [Cal] = 90 μs

27. 27 Conclusions and Future Work 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós  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.

28. 28 Conclusions and Future Work 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós  Open issues for improvement in the BPS2 monitor prototype: Correct the possible misalignments of the horizontal plane electrodes suggested in the linearity error analysis. Check if overall-precision below 50μm (under TBL specs), with enough wire current  New wire testbench at IFIC. 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 accurate (anti-vibration + micro-movement system) and automatized measurements.

29. 29 Conclusions and Future Work 26/09/2008BPS-TBL-CTF3 J.J. García-Garrigós Sketch of New IFIC Wire Testbench. Under development right now.

30. 3026/09/2008BPS-TBL-CTF3 J.J. García-Garrigós

31. 3126/09/2008BPS-TBL-CTF3 J.J. García-Garrigós BPS1 Characterization Table BPS1 Sensitivity and Linearity Parameters Vertical Sensitivity, S V 41.09 mm -1 Horizontal Sensitivity, S H 41.43 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) 4.125 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

32. 3226/09/2008BPS-TBL-CTF3 J.J. García-Garrigós BPS Monitors Schedule