Development of the New Electron Cloud Detectors in the PS

Transcription

1 Development of the New Electron Cloud Detectors in the PS TE-VSC SEMINAR Christina Yin Vallgren on behalf of LIU-PS project Supervisor: Paolo Chiggiato LIU-PS coordinator: Simone Gilardoni Vacuum, Surfaces and Coatings Group (VSC), TE-department CERN, Geneva, Switzerland June

2 Outline Introduction 1 Introduction Luminosity: quantity to evaluate accelerator performance Electron Cloud (EC): one of main limitations for High Luminosity LHC Electron Cloud Elimination Methods Electron Cloud Detection Methods 2 Existing Electron Cloud monitor in the PS Motivation of this work Development 1: Shielded button-type pick-up 3 Development 1: Shielded button-type pick-up 2 / 52

3 Outline Introduction What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections 1 Introduction Luminosity: quantity to evaluate accelerator performance Electron Cloud (EC): one of main limitations for High Luminosity LHC Electron Cloud Elimination Methods Electron Cloud Detection Methods 2 Existing Electron Cloud monitor in the PS Motivation of this work Development 1: Shielded button-type pick-up 3 Development 1: Shielded button-type pick-up 3 / 52

4 Luminosity: L [cm 2 s 1 ] What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections Definition: a measure of the probability (rate) of particle encounters per unit area in a collision process. The total counting rate of a physics event R is given as: R = L σ phys (1) σ phys : cross-section of studied physics process - very low To increase R, increase luminosity L. 4 / 52

5 Luminosity: L [cm 2 s 1 ] What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections The luminosity for two bunches with identical distribution profiles is defined as: L = fn 1N 2 4πσ x σ z (2) f : the encountering frequency N 1, N 2 : the numbers of particles (the number of bunches the bunch intensity) σ x, σ z : the horizontal and vertical rms bunch widths The luminosity can be increased by: increasing the bunch intensity or the number of bunches, i.e. N 1, N 2. increasing beam focusing at the interaction zones, i.e. σ x, σ z. 5 / 52

6 Electron Cloud Build-Up What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections In high-energy proton, positron or ion particle accelerators, an Electron Cloud can develop: initiated by: residual gas ionization (X + p X + + p + e ). [the PS case] photoemission from synchrotron radiation (X + hν X + + e ). sustained by: subsequent secondary electron emission via a beam-induced multipactoring process if the maximum Secondary Electron Yield (SEY) of the beam pipe surface is larger than a critical value. Secondary Electron Yield (SEY) γ γ γ Primary Electron (PE) SE 2 Secondary Electron (SE) SE 1 Surface of the beam pipe The surface has SEY δ = 2 20 ns 5 ns 20 ns 5 ns 6 / 52

7 Electron Cloud Build-Up What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections The electron cloud leads to: dynamic pressure rise (electron stimulated desorption). beam instabilities. transverse emittance blow-up (bunch expansion). thermal load in cryogenic vacuum systems. fast or slow beam losses. The electron cloud: one of the main limitations for the high luminosity LHC in the future L = f N 1N 2 4πσ x σ z (3) 7 / 52

8 Electron Cloud Build-Up What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections The electron cloud leads to: dynamic pressure rise (electron stimulated desorption). beam instabilities. transverse emittance blow-up (bunch expansion). thermal load in cryogenic vacuum systems. fast or slow beam losses. The electron cloud: one of the main limitations for the high luminosity LHC in the future L = f N 1 N 2 4πσ x σ z (4) 8 / 52

9 Electron Cloud Elimination Methods What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections Elimination of electron cloud in accelerators Mechanical modification in vacuum chambers Modification of material properties in vacuum chambers Clearing electrodes (need of additional electrical feedthroughs) Chambers with grooves and slots (reduction of beam pipe aperture) Chambers with solenoid winding (not applicable in the cases of e.g. dipoles) Thin Film Coatings Surface conditioning (beam scrubbing, graphitization) TiN (works under the effect of conditioning in-situ) TiZrV (NEG) (activation at 180⁰C in-situ) Amorphous carbon thin film δ max ~ 1.0 No need of bakeout Slow ageing Large scale production 9 / 52

10 Electron Cloud Detection Methods What is luminosity? Electron Cloud (EC) build-up EC eliminations EC detections EC detection Local EC measurements Integrated EC over a long section Button-type pickups Strip detectors Microwave transmission Phase shift vs total beam intensity Simple, fast Used in the PS and the SPS straight sections Simple, fast, position Used in the SPS straight sections Implemented in the SPS dipole Measured in the LHC New proposal (photon detection) 10 / 52

11 Outline Introduction Existing EC detectors in the PS Motivation of this work 1 Introduction Luminosity: quantity to evaluate accelerator performance Electron Cloud (EC): one of main limitations for High Luminosity LHC Electron Cloud Elimination Methods Electron Cloud Detection Methods 2 Existing Electron Cloud monitor in the PS Motivation of this work Development 1: Shielded button-type pick-up 3 Development 1: Shielded button-type pick-up 11 / 52

12 Existing EC detectors in the PS Motivation of this work Existing Electron Cloud monitor in the PS First observation of EC in the PS in 2000s. First electron cloud set-up in PS straight section 98, bare st.st. vacuum chamber Second set-up in PS straight section 84, a-c coated st.st. vacuum chamber F. Caspers, T. Kroyer, E. Mahner 12 / 52

13 Existing EC detectors in the PS Motivation of this work Plan for the LIU-PS electron cloud studies So far, no direct electron cloud monitor in any main magnet A dipole in straight section does not represent the real situation in a main magnet: No high magnetic field No ramp of magnetic field Direct Electron Cloud Measurements In straight sections with C-magnet In a dipole magnet? 13 / 52

14 Existing EC detectors in the PS Motivation of this work Plan for the LIU-PS electron cloud studies Measurements of electron cloud in a real magnet, will provide: Prediction of the EC build-up distribution in the PS magnets for higher intensity beams in the frame of the upgrade program. Validation of the EC simulation models and codes. Direct Electron Cloud Measurements In straight sections with C-magnet In a dipole magnet Development of New Electron Cloud Monitors in the PS main magnet 1. Development 1 2. Development 2 14 / 52

15 Existing EC detectors in the PS Motivation of this work Development 1: Shielded button-type pick-up - Design Ideal position for a pick-up: on the top/bottom of vacuum chamber due to magnetic field Not possible due to space limitation in the PS main magnet DN40 flange placed 30 to the bottom part of the vacuum chamber PS magnet vacuum chamber LHC beam e- e- B Use radial steering to move the beam towards the EC pick-up. (30mm possible provided by simulations) shielded pick-up 15 / 52

16 Existing EC detectors in the PS Motivation of this work Development 1: Shielded button-type pick-up - Design Ideal position for a pick-up: on the top/bottom of vacuum chamber due to magnetic field Not possible due to space limitation in the PS main magnet DN40 flange placed 30 to the bottom part of the vacuum chamber Use radial steering to move the beam towards the EC pick-up. (30mm possible provided by simulations) 16 / 52

17 Existing EC detectors in the PS Motivation of this work Development 1: Shielded button-type pick-up - Design Ideal position for a pick-up: on the top/bottom of vacuum chamber due to magnetic field Not possible due to space limitation in the PS main magnet DN40 flange placed 30 to the bottom part of the vacuum chamber Use radial steering to move the beam towards the EC pick-up. (30mm possible provided by simulations) PS magnet vacuum chamber Different types of PS beam Shield Stainless steel plate coated by Ag? 17 / 52

18 Existing EC detectors in the PS Motivation of this work Development 1: Shielded button-type pick-up - Simulations SCALA analysis tool within OPERA-3D to validate current measurement efficiency Beam displacement of 30 mm: 3.3 µa arrives on the pick-up Electron cloud current arrives on the pick-up = na 40 mm width electron cloud flux of 2x10-4 A/mm 2 B (y) = 1.2 T Electron cloud current arrives on the pick-up = 3.3 ma 40 mm width electron cloud flux of 2x10-4 A/mm 2 B (y) = 1.2 T Bias of +60 V on the pick-up Bias of +60 V on the pick-up Assume: The LHC type beams creates a flux of electron cloud: Width of 40 mm and Current density of A/mm 2. Dipole magnetic field: 1.2 T. Pick-up biase: +60 V. 18 / 52

19 Existing EC detectors in the PS Motivation of this work - Theory Phenomenology of electrons impinging on a surface X-rays UV, IR and visible cathodoluminescence e- Secondary electrons Auger electrons Back-scattered electrons Schematic of the principle of metal cathodoluminescence Sample Excited volume 19 / 52

20 Existing EC detectors in the PS Motivation of this work - Theory Phenomenology of electrons impinging on a surface e- Schematic of the principle of metal cathodoluminescence E initial Secondary electrons (escape from the surface) Primary electrons ~300 ev e - Secondary electrons (fall into unoccupied states) X-rays UV, IR and visible cathodoluminescence Secondary electrons Auger electrons Back-scattered electrons E vacuum Unoccupied states hυ E final E LUMO Sample Excited volume E fermi level Occupied states E HOMO LUMO : lowest unoccupied molecular orbital HUMO: highest unoccupied molecular orbital 20 / 52

21 Existing EC detectors in the PS Motivation of this work - Theory => Application Cathodoluminescence of copper and nickel surfaces 405 I ENERGY (ev) i-!- L COPPER Corrected cathodoluminescence Clean Surface 300 ev spectra of clean Cu at Uncorrected electron Spectrum energies 300 ev and 1 kev. B. Papanicolaou and et. al., J. Phys. Chem. Solids, vol. 37, pp , Fig. 2. Cathodoluminescence spectrum of clean Cu. The spectrum is uncorrected for the system response. COPPER Clean Surface Corrected Spectrum EC measurement via electron-photon emission. Electrons in EC has relatively low energies (300 ev). Expected photon wavelength with 300eV electrons: 200nm-700nm (visible). Expected photon energies: from 2 ev to 5eV. I, 1,,I,,,,,,,,,,,,,,, WAVELENGTH (nm) Fig. 3. Corrected cathodoluminescence spectra of clean Cu at electron energies 300 ev and 1 kev. The 230 nm peak appears in every uncorrected lumines- cence spectrum of copper and nickel and it is independent so for any reliable measurement of luminescence from metal the surface must be clean. 21 / 52

22 Existing EC detectors in the PS Motivation of this work - Theory => Application Cathodoluminescence of copper and nickel surfaces 405 I ENERGY (ev) i-!- L COPPER Corrected cathodoluminescence Clean Surface 300 ev spectra of clean Cu at Uncorrected electron Spectrum energies 300 ev and 1 kev. B. Papanicolaou and et. al., J. Phys. Chem. Solids, vol. 37, pp , Fig. 2. Cathodoluminescence spectrum of clean Cu. The spectrum is uncorrected for the system response. COPPER Clean Surface EC measurement via electron-photon emission. Electrons in EC has relatively low energies (300 ev). Expected photon wavelength with 300eV electrons: 200nm-700nm (visible). Expected photon energies: from 2 ev to 5eV. Corrected Spectrum PS magnet vacuum chamber Photomultiplier hν hν hν hν LHC types beam e- e- B I, 1,,I,,,,,,,,,,,,,,, Optical window hν hν hν WAVELENGTH (nm) Fig. 3. Corrected cathodoluminescence spectra of clean Cu at electron energies 300 ev and 1 kev. The 230 nm peak appears in every uncorrected lumines- so for any reliable measurement of luminescence from 22 / 52

23 Existing EC detectors in the PS Motivation of this work - Theory => Application Synchrotron Radiation levels in different accelerators. The UV and visible photons in the PS are out of the SR range. Electron-photon Emission method can be applied the PS. 700nm 200nm by Roberto Kersevan 23 / 52

24 Existing EC detectors in the PS Motivation of this work - Theory => Application Synchrotron Radiation levels in different accelerators. The UV and visible photons in the PS are out of the SR range. Electron-photon Emission method can be applied the PS. 700nm 200nm by Roberto Kersevan 24 / 52

25 Existing EC detectors in the PS Motivation of this work - Experimental set-up in the lab 1 Electron gun: low temperature BaO cathode (1150K) 2 Grid and deflection: prevent the electrons arrive on the sample. 3 Sample: +18 V. 4 Quartz window: nm transmission 100%. 5 Collimating lens: optimized for nm. 6 Optical fiber: transfer the light from the system to the spectrometer. 7 Andor Spectrograph: with CCD camera ( nm). Electron bombard stainless steel surface to validate emitted photons and in which ranges they are. 7. Andor Shamrock Spectrograph 7. Andor idus spectroscopy camera nm Computer 5. Collimating lens 6. Optical fiber 2. Deflection 1. Electron gun with BaO cathode Low light emitter (1150K) 2. Collector 4. Quartz window ee 20 o 2. Grid 3. Sample Bias of +18V 25 / 52

26 Existing EC detectors in the PS Motivation of this work - Experimental set-up in the lab 1 Electron gun: low temperature BaO cathode (1150K) 2 Grid and deflection: prevent the electrons arrive on the sample. 3 Sample: +18 V. 4 Quartz window: nm transmission 100%. 5 Collimating lens: optimized for nm. 6 Optical fiber: transfer the light from the system to the spectrometer. 7 Andor Spectrograph: with CCD camera ( nm). Electron bombard stainless steel surface to validate emitted photons and in which ranges they are. 7. Andor Shamrock Spectrograph 7. Andor idus spectroscopy camera nm Computer 5. Collimating lens 6. Optical fiber 2. Deflection 1. Electron gun with BaO cathode Low light emitter (1150K) 2. Collector 4. Quartz window ee 20 o 2. Grid 3. Sample Bias of +18V 26 / 52

27 Existing EC detectors in the PS Motivation of this work - Experimental set-up in the lab 1 Electron gun: low temperature BaO cathode (1150K) 2 Grid and deflection: prevent the electrons arrive on the sample. 3 Sample: +18 V. 4 Quartz window: nm transmission 100%. 5 Collimating lens: optimized for nm. 6 Optical fiber: transfer the light from the system to the spectrometer. 7 Andor Spectrograph: with CCD camera ( nm). Electron bombard stainless steel surface to validate emitted photons and in which ranges they are. 7. Andor Shamrock Spectrograph 7. Andor idus spectroscopy camera nm Computer 5. Collimating lens 6. Optical fiber 2. Deflection 1. Electron gun with BaO cathode Low light emitter (1150K) 2. Collector 4. Quartz window ee 20 o 2. Grid 3. Sample Bias of +18V 27 / 52

28 Existing EC detectors in the PS Motivation of this work - Experimental results in the lab Cathodoluminescence spectra of an oxidized stainless steel at electron energy of 300 ev. (The spectra are uncorrected for the system response.) Averaging 10 measurements of 60 s integration time with 5 accumulations. The photon counts seems to be proportional to the electron current on the sample. The experimentally estimated yield on st.st. of ph/el for E = 300 ev. Intensity [Counts for 60s with 5 accumelations] Oxidized stainless steel, I(sample)=3µA/2mm 2 Raw data of 10 measurements Smooth data Intensity [Counts for 60s with 5 accumelations] Oxidized stainless steel, I(sample)=9µA/2mm 2 Raw data of 10 measurements Smooth data Wavelength [nm] Wavelength [nm] 28 / 52

29 Outline Introduction 1 Introduction Luminosity: quantity to evaluate accelerator performance Electron Cloud (EC): one of main limitations for High Luminosity LHC Electron Cloud Elimination Methods Electron Cloud Detection Methods 2 Existing Electron Cloud monitor in the PS Motivation of this work Development 1: Shielded button-type pick-up 3 Development 1: Shielded button-type pick-up 29 / 52

30 Which magnet to choose? Possible magnets to choose: LS1 => Good moment to benefit the opportunity Our preferable MU is in Sector 9 Sector 9: Radiation cool MU98: next to the existing EC monitor in SS98 Standard stainless steel vacuum chamber. Never refurbished. Cabling to 355/R-017: <50m. Benefit the existing electronics. Radial steering possible: beam can be moved towards the pick-up by 30 mm. MU55 EC monitor SS98 355/R / 52

31 MU98 vacuum chamber Two flanges are added to the MU98 vacuum chamber: DN35 for installation of shielded pick-up. DN63 for installation of optical window. DN63: optical window DN35: shield pick-up 31 / 52

32 Development 1: Shielded button-type pick-up - 3D design ELECTRON PICK-UP FOR MU98 VACUUM CHAMBER BNC coaxial connector St. Steel arm welded on flange Contacts with vacuum chamber St. Steel sheet th 0.2mm welded on the support DN40 CF Flange with feedtrough from LESKER Holes Ø1mm / space 2mm St. Steel parts Al2O3 ceramic part Silver painted on blue surfaces 32 / 52

33 Development 1: Shielded button-type pick-up - Pick-up Grid ϕ = 1 mm DN40 with feedthrough Ceramic block with silver painting Adjustable arm to ease the insertion 33 / 52

34 Introduction Development 1: Shielded button-type pick-up - Pick-up 34 / 52

35 Development 1: Shielded button-type pick-up - Signal Treatment Similar electronics used for the existing pick-up in the SS98 will be applied. System bandwidth ( MHz) is mainly limited by cable attenuation. EC arrived on the pick up [µa] Output voltage [µv] Input and output signals Signal read-out by oscilloscope Assumed EC arrived on the pick up = 1 µa Time [s] x 10 6 Detected Voltage Time [s] x / 52

36 Development 1: Shielded button-type pick-up - Signal Treatment: Previous results in SS98 25ns 72 bunches nominal LHC beam p/b 50ns 36 bunches nominal LHC beam p/b pick up signal [a.u.] time [s] x 10 6 pick up signal [a.u.] time [s] x 10 6 electron cloud signal [a.u.] time [s] x 10 6 electron cloud signal [a.u.] time [s] x / 52

37 - Input used for estimation of the number of expected photons 1. Experimental electron-photon yield = 5x10-11 ph/el (stainless steel) 2. Reflectivity of stainless steel: 20-50% (assume 40%) => Sticking factor = Electron cloud density = 1 µa/mm 2 4. Electron cloud area = 8.4x10 2 mm 2 37 / 52

38 Introduction - Monte Carlo simulation for estimation of the number of expected photons Photon yield of 1.2% 1575 photons expected Photon yield of 8% with Al/MgF2 coating photons expected High reflectivity coating (85% Mylar foil with Al/MgF2) Electron bombardment area = 8.4x102 mm2 # of electrons generated by beam (ref Giovanni & co) = 8.4x102 mm2 x 1e-6 C/s mm2/1.6e-19c = 5.25x1016 electron/s Experimental radiation yield = 5x10-11 ph/el (stainless steel) # of photons emitted by electrons = 2.625x106 photons # of photon reaches detector = 1.2% x 2.625x106 photons = 3.15x104 photons/s During the last 40-50ms electron cloud development of the PS 1575 photons can be detected! Electron bombardment area = 8.4x102 mm2 # of electrons generated by beam (ref Giovanni & co) = 8.4x102 mm2 x 1e-6 C/s mm2/1.6e-19c = 5.25x1016 electron/s Experimental radiation yield = 5x10-11 ph/el (stainless steel) # of photons emitted by electrons = 2.625x106 photons # of photon reaches detector = 8% x 2.625x106 photons = 2.1x105 photons/s During the last 40-50ms electron cloud development of the PS photons can be detected! 38 / 52

39 - Monte Carlo simulation for estimation of the number of expected photons Photon yield of 8% with Al/MgF 2 coating photons expected # of photons arriving on the DN63 window High reflectivity coating (85% Mylar foil with Al/MgF2) Photons detected on the DN63 quartz window Electron bombardment area = 8.4x10 2 mm 2 # of electrons generated by beam (ref Giovanni & co) = 8.4x10 2 mm 2 x 1e-6 C/s mm2/1.6e-19c = 5.25x10 16 electron/s Experimental radiation yield = 5x10-11 ph/el (stainless steel) # of photons emitted by electrons = 2.625x10 6 photons # of photon reaches detector = 8% x 2.625x10 6 photons = 2.1x10 5 photons/s During the last 40-50ms electron cloud development of the PS photons can be detected! Photon detector yield along horizontal axis along vertical axis / 52

40 - Multi-Channel Plate - Photon Multiplier Tube (MCP-PMT) Multi-channel plate PMT from Photonis is chosen due to high magnetic field (1.2T) BI lab set-up Pulsed Laser f = 1/25ns Filter Lab measurement set-up to validate the MCP-PMT Photonis MCP-PMT UV range Hamamatsu High speed amplifier Ortec Amplifier + timing discriminator (to reduce laser beam Intensity) e-/ph x63 HV power supply -2400V LV power supply +15 V Discriminate 20mV LeCroy oscilloscope 2GHz 40 / 52

41 - PS measurement set-up Magnetic field map in MU98 MCP-PMT: magnetic field direction dependency 41 / 52

42 - PS measurement set-up Magnetic field map in MU98 Magnetic field in MU98 MCP-PMT: magnetic field direction dependency 2 Magnetic field (T) y axis (m) x axis (m) / 52

43 - PS measurement set-up PS measurement set-up Electron cloud 40 mm 70mm Electron cloud 40 mm 160mm Φ = 60mm Lens 1 f1 = 100mm Φ = 50mm 20mm HV -2400V: BNC1 ZNQCVP-63-NM LV +15V: BNC2 300mm 100mm 50mm Black box UV mirror Φ = 50mm Lens 2 f1 = 40mm Φ = 50mm MCP-PMT PS tunnel output: BNC3 AMP x R-017 HV power supply -2400V LV power supply +15 V Trigger at C2460ms in the PS cycle Measure the last 50ms LeCroy oscilloscope 2GHz Discriminator 20 mv 43 / 52

44 - PS measurement set-up Lens 1: f1 = 100mm Lens 2: f2 = 40mm UV mirror Multi-channel plate PMT Black box installed in the PS: Main magnet 98 Amplifier x63 44 / 52

45 A project from the beginning to the end. A collaboration with different people from different groups. Still some work to be done. Improvement is also needed. First nominal beam in the PS planned on 14th of July. More results to come soon / 52

46 A project from the beginning to the end. A collaboration with different people from different groups. Still some work to be done. Improvement is also needed. First nominal beam in the PS planned on 14th of July. More results to come soon / 52

47 A project from the beginning to the end. A collaboration with different people from different groups. Still some work to be done. Improvement is also needed. First nominal beam in the PS planned on 14th of July. More results to come soon / 52

48 Thanks This project has been collaboration with different people from different groups, thanks to Everyone who has been involved in this project. Special thanks to: Holger, Mounir, Wil, Ivo, Luigi, Phillippe and Paul 2 for all the supports for the experimental set-ups, both in the lab and in the PS. Mauro, Jose, Marton, Daniel Schoerling (TE-MSC), Simone Gilardoni/ Guido Sterbini/ Giovanni Rumolo/ Giovanni Iadarola (BE-ABP) for all the inspiring discussions and simulations needed for this work. Enrico Bravin/ Marcus Palm/ Stefano Mazzoni (BE-BI), Thomas Schneider/ Thierry Gys (PH-DT) for the discussion concerning photo-detection in the PS and the lending of their lab instrumentation. The CERN Drawing Office ( Teddy Capelli and Cedric Eymin) and Main Workshop for their collaboration and effort in designing and fabricating all new vacuum equipment during the LS1. Thanks for your attention! and Questions

49 Backup Slide PS beam production Introduction h=42 b.sp.=50 ns (36 b.) h=7 b. sp. 330 ns (4-6 b.) h=21 b. sp. 100 ns (18 b.) h=84 b.sp.=25 ns (72 b.) Triple splitting Double Double Bunch splitting splitting shortening 49 / 52

50 Backup Slide PS beam production Introduction h=42 b.sp.=50 ns (36 b.) h=7 b. sp. 330 ns (4-6 b.) h=21 b. sp. 100 ns (18 b.) h=84 b.sp.=25 ns (72 b.) Before the last bunch splitting e-cloud not expected nor observed Triple splitting Double Double Bunch splitting splitting shortening 50 / 52

51 Backup Slide PS beam production Introduction h=42 b.sp. = 50 ns (36 b.) h=84 b.sp. h=7 = 25 ns (72 b.) b. sp. 330 ns (4-6 b.) h=21 b. sp. 100 ns (18 b.) ns 250 Double splitting 40 MHz RF Voltage [kv] ns Bunch rotation 50 b.l. 14 ns Adiabatic shortening Time [ms] Triple splitting Double Double Bunch splitting splitting shortening 51 / 52

52 Backup Slide PS beam production Introduction h=42 b.sp. = 50 ns (36 b.) h=84 b.sp. h=7 = 25 ns (72 b.) b. sp. 330 ns (4-6 b.) h=21 b. sp. 100 ns (18 b.) ns 250 Double splitting 40 MHz RF Voltage [kv] E-cloud expected and observed 11 ns Bunch rotation 50 b.l. 14 ns Adiabatic shortening Time [ms] Triple splitting Double Double Bunch splitting splitting shortening 52 / 52