1 / 28

DEVELOPMENT OF A BEAM LOSS DETECTION SYSTEM FOR THE CLIC TEST FACILITY 3

DEVELOPMENT OF A BEAM LOSS DETECTION SYSTEM FOR THE CLIC TEST FACILITY 3. T. Lefevre, M. Velasco , M. Wood, Northwestern University H. Braun, R. Corsini, M. Gasior, F. Tecker, CERN. Beam loss monitors for the CLIC Test Facility 3 Preliminary study done in 2003 Geant3 simulations

cruz
Download Presentation

DEVELOPMENT OF A BEAM LOSS DETECTION SYSTEM FOR THE CLIC TEST FACILITY 3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DEVELOPMENT OF A BEAM LOSS DETECTION SYSTEM FOR THE CLIC TEST FACILITY 3 T. Lefevre, M. Velasco , M. Wood, Northwestern University H. Braun, R. Corsini, M. Gasior, F. Tecker, CERN • Beam loss monitors for the CLIC Test Facility 3 • Preliminary study done in 2003 • Geant3 simulations • First experimental data • Conclusions & Perspectives T. Lefevre BIW 2004, 5 May 2004

  2. CLIC Test Facility 3 • The CLIC Test Facility 3 is built to demonstrate the Compact LInear Collider feasibility • - Drive Beam Generation : • Efficient way of producing a high current (35A) high frequency (15GHz) 150MeV and 1.6ms electron beam • Done using a fully loaded linear accelerator (94% RF to beam efficiency) and two rings • - Drive Beam Deceleration stability (two beam acceleration section) • The beam is strongly decelerated in order to provide the 30GHz RF source • Study the Beam halo & Beam loss mechanisms • Provide a 30GHz power source to continue the R&D program on high gradient accelerating structures (150MV/m) • Housed in the LEP injector complex and scheduled for completion before 2010. • The construction of the linac will be finished by the end of the year T. Lefevre BIW 2004, 5 May 2004

  3. BLM for CTF3 Linac • Northwestern University joined the CTF3 collaboration in 2003 and we are designing and building the beam loss detection system for the CTF3 linac. • Dangerous beam losses : > 10% of the total beam charge (6mC) • The protection system will rely on wall current monitor • The BLM system will be a tool for the optimization of the Linac operation • The operation of a fully loaded linear accelerator • Heavy beam loading in accelerating structures  Transient effects where the energy gain per cavity for the beam head can be twice higher than its nominal steady state value • Beam transient compensation scheme by adjusting the delay between the beam and the RF signal in the cavities • We designed our system to observe the beam transient loss T. Lefevre BIW 2004, 5 May 2004

  4. BLM for CTF3 Linac Y • Beam loss detectors • Fast time response (ns-10ns) for beam transient study • Segmented X-Y beam loss positioning for tuning z x Design beam optics Goal : To install the BLM at a position where the beam transient would be lost Accelerating structure Typical Linac section Quadrupoles Beam position monitor High probability that beam loss occurs in the quadrupole region e- T. Lefevre BIW 2004, 5 May 2004

  5. Geant3 Simulations 100MeV • The total flux of electrons in the shower is proportional to the electron energy • With higher beam energies, the shower asymmetry is more pronounced Beam pipe simulations : Transverse distribution of the e-/e+ shower Simulations based on a beam loss corresponding to the ‰ of the nominal beam current Beam loss at + Y Position of observation : 1m dowstream e- T. Lefevre BIW 2004, 5 May 2004

  6. Geant3 Simulations Z=25cm Z=75cm Z=120cm Z=155cm Positions of observation Beam loss Beam loss in the Central quadrupole e- Screening effect of the 3rd quadrupole which reverses the transverse distribution of the e-/e+Shower T. Lefevre BIW 2004, 5 May 2004

  7. Geant3 Simulations + Y +/- X - Y • The shower transverse distribution is affected by the presence of Quadrupoles • For losses on the beam pipe the asymmetry corresponds to 50% • Beam loss position  more than 2 orders of magnitude difference in the shower efficiency • For losses > 1‰ of beam current  Detector must be able to measure currents > 100nA done by Matthew Wood e- shower efficiency : Number of particles detected / Number of particles lost Positions of the beam loss e- BLM’s (size and position) Simulations • 35MeV, 0mm beam size, 3mrad beam angle • Beam loss at + Y • Ø40mm detector installed at 15cm from the beam axis T. Lefevre BIW 2004, 5 May 2004

  8. Test on CTF3 in 2003 Beam loss monitors Two Aluminum Cathode Electron Multipliers Ø40mm, Sensitivity range [100nA-100mA] Beam line layout Collimator Dipoles Quadrupoles BPM 402 BPM 502 BPM 690 Steerers Accelerating structures e - Cleaning chicane First Linac Section Injector Using the collimator in the cleaning chicane to study the beam transient T. Lefevre BIW 2004, 5 May 2004

  9. Observation of the beam transient loss Case 2 : Slit Closed 20MeV < 35MeV • The slit is closed so that the beam transient is stopped in the collimator. • The rest of the beam enters the next accelerating structure and is accelerated to 35MeV Case 1 : Slit opened Chicane & Collimator < 80MeV 35MeV • The slit is opened so that the full beam enters the next accelerating structure. • The beam transient is then re-accelerated up to 80MeV and is lost somewhere because the beam optics are not adapted to its energy T. Lefevre BIW 2004, 5 May 2004

  10. Slit closed : Horizontal and Vertical scans BLM Left BLM Right e- Localizing the beam loss transversely ? Beam goes Up Beam goes to the Right Beam goes to the Left • In vertical scans the beam loss is equally distributed on the two detectors and their output signals are equivalent (<5% difference) • In horizontal scans the BLM output signals are different in a ratio of 2 (40-60%) Beam goes Down T. Lefevre BIW 2004, 5 May 2004

  11. Geant3 expectations e- shower efficiency for different beam loss positions and energies 35MeV, 3mrad, 0mm beam size 80MeV, 3mrad, 0mm beam size T. Lefevre BIW 2004, 5 May 2004

  12. Vertical scan with the slit opened • Using BPM data’s to estimate the beam current lost in a linac section • Using the BLM measurement to estimate the Z position of the beam loss Close to the detector E = 35MeV 35 < E < 80MeV Detector  3rd Quad 3rd Quad 3rd  2nd Quad T. Lefevre BIW 2004, 5 May 2004

  13. Conclusions • Beam loss transverse positioning works in agreement with the Geant3 predictions • During this test, the beam losses were relatively high (beam transient ~ 1A) and they were located near the quad’s region (which was consistent with the design lattice) • Using the BPM’s data & the energy measurements, the BLM system can be used to localize the losses along the accelerator accurately (< 50cm) • Without the BPM data, one system per section is not enough to monitor beam loss intensity & position (more complicated for beam losses distributed along the linac) • How can we be quantitative : I & Z ? • Adding detectors every 50cm to get the Z beam loss position: • Longitudinal positioning using a Cherenkov fiber and a time of flight measurement (already developed at SLAC and TTF) T. Lefevre BIW 2004, 5 May 2004

  14. Perspectives • The system to be installed in the next months : • The detectors are developed at Northwestern University (M. Velasco and A. Dabrowski) in conjunction with Fermilab (G. Tassotto) • 12 sets of 4 detectors (SEM/SIC) located near the quadrupoles region • Special set-up to study the losses one a single linac section using 12 detectors • The signals are then amplified and acquired using 100MHz ADC’s • 1mm gap chamber • Can be operated with gas • (ionization) or vacuum (SEM) • Radiation hard T. Lefevre BIW 2004, 5 May 2004

  15. CTF3 little shop of horrors Damage on a Vacuum valve Spectrometer line T. Lefevre BIW 2004, 5 May 2004

  16. Suggestion ! Respect the steering limitation T. Lefevre BIW 2004, 5 May 2004

  17. The CLIC Test Facility 3 • CLEX : CLic EXperimental area: • Provide a 30GHz power source for the development of high gradient (150MV/m) accelerating structures • Test the Drive beam stability in the Drive Beam Decelerator (beam loss rate) • Drive Beam generation : Efficient way of producing a 35A beam bunched at 15GHz • Acceleration of a high current beam in a 3GHz fully loaded Linac (95% RF to beam efficiency) • Production of a high frequency (15GHz) bunched beam using a delay loop and a combiner ring • Housed in the LEP • Pre-injector complex • Scheduled for completion • before 2010 T. Lefevre BIW 2004, 5 May 2004

  18. 3TeV Compact LInear Collider • Damping rings • 4ps, >10mm • e-/e+ Source • 42ns, 2,424GeV • 157 bunches (400pC) • 4ps, >50mm Combiner Ring 2 • 25 Drive Beams Decelerators per linac • 1.79GeV, 144A over 56ns • 1ps, >50mm Combiner Ring 1 Delay loop Source • Drive Beam Generator • 4.5A over 92ms with an final energy of 1.79GeV: 43000 bunches (9.6nC each) • 10ps, >50mm • Main Linac • 9  1500GeV • 100fs, >1mm e- Main Linac e+ Main Linac BDS 30 GHz Power Source and distribution line T. Lefevre BIW 2004, 5 May 2004

  19. What have been achieved up to now LEP injector EPA ring CTF3 – Preliminary phase - 2002 Low-charge demonstration of electron pulse combination and bunch frequency multiplication by up to a factor 5 Streak camera image of the beam time structure evolution

  20. Heavy beam loading in the accelerating structure Beam head sees a much higher accelerating field Strong transient effects so that in the first 50ns of the pulse the beam energy can be twice higher than the energy of the rest of the beam Beam transient compensation by adjusting the delaying the RF pulse in the accelerating structure to suppress the transient effect Operation of a fully loaded linac Drive beam acceleration in 2003 Beam current – BPM 402 Beam current 4 A Beam pulse length 1.5 ms Power input/structure 35 MW Ohmic losses (beam on) 1.6 MW RF power to load (beam on) 0.4 MW RF-to-beam efficiency ~ 94% Phase variation along pulse ±4º 1.5 ms 4 A RF signals / output coupler of an accelerating cavity RF power Power to load (beam off) ±4º phase 1.5 ms RF phase Power to load (beam on) T. Lefevre BIW 2004, 5 May 2004

  21. BLM detectors - A 4mm thick plastic scintillator (Ø40mm) coupled to XP2020 photomultiplier tube Scintillator Photocathode 25% QE e- current amplification <106-107 • e- / e+ : • [1, 20]MeV  500 - 1000 photo-e- • g & x rays : • [10keV,20MeV]  4 - 100 photo-e- e-/e+ Visible Photons 1.75% e- HV Signal 50mV/50Ω mA-pA - An Aluminum Cathode Electron Multiplier (ACEM) (Ø38mm) Aluminum cathode 100nm thick e- current amplification <105-106 • e- / e+ : • [1, 20]MeV  1 - 5% SEM e- • g & x rays : • [10keV,20MeV]  4.10-6- 2.10-9 SEM e- e-/e+ e- HV x & g rays x & g rays Signal 50mV/50Ω 100mA-100nA Two different types of detectors (ns time response) have been tested in parallel T. Lefevre BIW 2004, 5 May 2004

  22. BLM detectors : Calibration Scintillator + PMT ACEM Calibration is done at ESRF using a 20keV X-ray beam Calibration using a very intense Cesium source ( - emitter: 53pA) For 1.5kV High voltage 20keV energy deposition  0.32±0.03mV 1mV  6.2±0.6MeV (≈ the calibration using radioactive sources) T. Lefevre BIW 2004, 5 May 2004

  23. Lattice design in a linac section Quadrupoles Beam loss detectors BPM 890 BPM 790 Steerer Example in the central Quad: • b≈ 10m • e ≈ 100 p.mm.mrad • ≈ 80 (40MeV) s ≈ 6mm Beam size Relativistic factor Beam emittance T. Lefevre BIW 2004, 5 May 2004

  24. Beam optics reconstructed from experimental data BLM’s • High probability to have beam losses in the quadrupoles region T. Lefevre BIW 2004, 5 May 2004

  25. Geant3 Simulations Positions of the beam loss done by Matthew Wood Shower asymmetry as a function of the beam loss position 80MeV, 0mm beam size 35MeV, 0mm beam size • Beam loss position  more than 2 orders of magnitude difference in the shower efficiency • Can the longitudinal beam loss position be determined by the ‘angular shower shape’ ? T. Lefevre BIW 2004, 5 May 2004

  26. Geant3 Simulations Positions of the beam loss done by Matthew Wood Shower versus beam angle 35MeV • During this test we were using very small steering forces (I<1.5A) so that 5mrad can be considered as a maximum deviation angle • Beam loss angle effects are small compared to the effect due to the beam loss position T. Lefevre BIW 2004, 5 May 2004

  27. Geant3 Simulations ~ e-/ e+ shower of 0.3nA, not seen by the ACEM with a 400volts bias done by Matthew Wood Shower generated by the beam losses in the collimator T. Lefevre BIW 2004, 5 May 2004

  28. Example 1 : Observation of the beam transient loss ‘BLM signals depend on beam energy, position and current’ Low - - - - - - - - -  high energy • Time – Energy correlation in the beam transient (Each slit aperture selected a given beam energy range between 35-70MeV) • You normalize the BLM signals to the beam current loss seen by the BPM502 (≈ BPM690) • Possibility to estimate where the beam transient is lost • The different energies are not lost at the same position • Beam loss distributed between the detector and the 3rd quadrupole T. Lefevre BIW 2004, 5 May 2004

More Related