Antiproton Acceptance Keith Gollwitzer Dept. of Energy Review March 30, 2005 Antiproton Acceptance Keith Gollwitzer 2 Outline Goal An admittance of AP2 and Debuncher in each plane to be 35 mm-mrad Accepting 320 mm-mrad beam emittance Transfer efficiently to Accumulator via D/A Mitigation Orbit Control Instrumentation Other Work Beam Studies Character of studies has changed from predominately dedicated reverse proton studies to mostly semi-parasitic stacking studies Aperture Finding Antiproton Acceptance Keith Gollwitzer 3 What & Where - Mitigation Open Debuncher Only Filled AP2&Debuncher Shutdown Beam Stop (SD2004) Vertical Band 4 - Widen Array Gap (SD2005) Extraction Kicker (SD2005) Injection Region (SD2004) Move DRF2 (SD2004) and DRF3 (SD2003) Italic & underlined items discussed later Antiproton Acceptance Keith Gollwitzer 4 Mitigation of Limiting Apertures Debuncher Injection Area Debuncher Injection Area Modifications: Injection septum common vacuum Replace D4Q4 SQC quadrupole with two LQB quadrupoles Motorize injection septum and kicker stands Vacuum system modifications oBigger D4Q4 vacuum chamber oMove BPM to downstream of D4Q4 Antiproton Acceptance Keith Gollwitzer 5 Mitigation of Limiting Apertures Debuncher Injection Area Old Layout Septum D4Q4 Beam Antiproton Acceptance Keith Gollwitzer 6 Mitigation of Limiting Apertures Debuncher Injection Area AP2 D4Q5 Septum Circulating Beam Added AP2 BPM just upstream of D4Q5 Antiproton Acceptance Keith Gollwitzer 7 Mitigation of Limiting Apertures Debuncher Injection Area New Layout Septum D4Q4a D4Q4b Antiproton Acceptance Keith Gollwitzer 8 Mitigation of Limiting Apertures Debuncher Injection Area Injection Septum Common Vacuum Antiproton Acceptance Keith Gollwitzer 9 Mitigation of Limiting Apertures Debuncher Injection Area D4Q4 Aperture Old New Note: Injected and circulating beam are vertically separated. 140 mm 205 mm Antiproton Acceptance Keith Gollwitzer 10 Mitigation of Limiting Apertures AP2 Beam Stop AP2 Beam Stop and Vacuum situation prior to 2004 Shutdown. Small vacuum leak at window next to Beam Dump. Installed pair of windows between Q2 and Q3. Eventually, upstream end let up to air (red section). Pair of vacuum windows at large function multiple scattering. Removed Q1 and Q2 to remove Beam Stop and cantilevered beam tube from Steel Shielding. Took opportunity to survey alignment of AP2 wrt to pulsed magnet and map out the shielding passage. Determined that Shielding forced non-optimal alignment of Beam Pipe and Beam Stop {see slide}. Moved Beam Stop downstream (pass Q6) and installed a shorten beam pipe cantilevered from Q1 {see slide}. Reduces multiple scattering with removal of windows and reducing path in air. Extra Antiproton Acceptance Keith Gollwitzer 11 Mitigation of Limiting Apertures AP2 Beam Stop Mis-alignment of AP2 beam stop & beam pipe Beam stop Shielding Edge Beam 35 x 2.25% p/p m mm Antiproton Acceptance Keith Gollwitzer 12 Mitigation of Limiting Apertures AP2 Beam Stop Horizontal aperture after removal of AP2 beam stop m mm Antiproton Acceptance Keith Gollwitzer 13 Mitigation of Limiting Apertures AP2 Beam Stop Secondaries yield to downstream end of AP2 line increased ~10% as a consequence of the removal of the AP2 beam stop. Plans: Plan to install new beam stop downstream of Q704 during the Fall 2005 shutdown. Antiproton Acceptance Keith Gollwitzer 14 Yet to be Corrected Limiting Apertures Widen Vertical band 4 cooling arrays for pickup and kicker Upgrade arrays during 2005 shutdown Likely requires 8 week shutdown Debuncher extraction kicker Ceramic Pipe & module modifications The upgrade will be installed during the 2005 shutdown. Will also motorize extraction kicker stand Upstream End Downstream End Injected Beam Profile Current ceramic pipe Antiproton Acceptance Keith Gollwitzer 15 Limiting Apertures * The numbers in this column were calculated using -functions at p/p = 0 Device Horizontal Vertical * Band 4 H pickup36.8 36.3 48.7 Band 4 V pickup40.5 39.0 29.9 Band 4 H kicker36.0 35.5 48.7 Band 4 V kicker41.2 41.1 30.1 Deb Extr. kicker109.1 21.9 35.8 Central orbit ( p/p = 0) limiting apertures: Current Measurement: Horizontal: 36.0 mm-mrad 29.5 mm-mrad Vertical: 29.9 mm-mrad 24.9 mm-mrad Combined effect of Band 4 Vertical and Extr. Kicker upgrades is ~7.4% (from particle tracking). Not to be changed Antiproton Acceptance Keith Gollwitzer 16 What & Where Orbit Control Open Debuncher Only Filled AP2&Debuncher Shutdown 2 Trim Dipoles (2002) DEX Bump Dipoles (SD2004) Motorized Stands: 5 Quads (SD2000) 10 Quads (SD2003) 20 Quads (SD2004) Italic & underlined items discussed later 2 Trim Dipoles (2003) Shunts (2001) Now capable of bumping locally throughout the Debuncher (all 3-bumps have been verified). Can add additional AP2 trims as needed. Antiproton Acceptance Keith Gollwitzer 17 Orbit Control Debuncher EXtraction Bump During reverse proton studies during 2004, we achieved an admittance of greater than 35 mm-mrad horizontally! This was achieved with a closed orbit bump through the extraction region: horizontal position bump at the Debuncher extraction septum. However, not able to transfer efficiently to the Accumulator via D/A beam line: bumped to far away from septum for extraction kicker. This has led to adding a ramped Debuncher EXtraction (DEX) bump. Antiproton Acceptance Keith Gollwitzer 18 Orbit Control Debuncher EXtraction Bump Large Injected Beam Beam Cooled during cycle Rapidly ramp DEX bump at end of cycle to put beam next to septum New Extraction Channel of Septum Time in cycle Antiproton Acceptance Keith Gollwitzer 19 Orbit Control Debuncher EXtraction Bump Status: Two trim dipoles installed in Debuncher during the Fall 2004 shutdown All cables to the tunnel have been pulled Power supplies built by EE support Commissioning beam studies (March 2005) Ramps built and locality verified Implentation Antiproton Acceptance Keith Gollwitzer 20 What & Where - Instrumentation Open Debuncher Only Filled AP2&Debuncher Shutdown Upgrade BPM system (Spring 2005) Debuncher pbar TBT (2004) Upgraded BPM system Closed Orbit at 2.5MHz (2004) Italic items discussed later D/A Upgrade BPM system (Spring 2005) Upgraded BPM system Closed Orbit at 53MHz (Summer 2005) Accumulator pbar TBT (2005) Toroids (Spring 2005) D/A Toroid (Spring 2005) Debuncher Pbar Intensity Monitor (2005) Antiproton Acceptance Keith Gollwitzer 21 Instrumentation Recent and Ongoing Debuncher pbar Intensity Monitor {see slide} Ongoing modification of Debuncher BPMs for Closed Orbit readout during stacking AP2 and D/A BPMs {see slide} Deb. Extraction kicker noise issues resolved DAQ hardware & software upgrade in progress Debuncher pbar Turn-By-Turn has been made more robust Accumulator pbar Turn-By-Turn has been built and implemented {see slide} Debuncher loss monitor system checked out and calibrated during shutdown Antiproton Acceptance Keith Gollwitzer 22 Instrumentation Debuncher Pbar Intensity Monitor Requires ramping DRF1 in the middle of the stacking cycle and then ramp back down Block diagram of temporary intensity monitor Working on modification to get pbar closed orbit while stacking Pre-amp 1KHz switch Spectrum Analyzer Zero DRF1 Frequency Video Output Oscilloscope Signal External Trigger Front-end Linux Get Trace & Analyze Output ACNET BPM Intensity BPM Signal cable to upstairs Antiproton Acceptance Keith Gollwitzer 23 Instrumentation AP2 BPM Prototype Response AP2 BPM Positions Upstream & Downstream AP2 Intensity Measurements: Ion Chamber & BPM AP1 Trim Dipole Response over an eight hour period 50 mm Timelines have several types of slip-stacking events (normal, switchyard & NUMI) which cause different AP2 orbits. One can see the different timelines and the number of each type of different slip-stacking events. Intensities in the Debuncher change with the different slip-stacking events (not shown). A target tune of an AP1 trim dipole was done and the BPMs track. BPM sum signals follow the established intensity measurement in AP2. Antiproton Acceptance Keith Gollwitzer 24 Instrumentation Accumulator Turn-By-Turn Requires bunched beam at end of Debuncher stacking cycle. There is no attempt to phase/frequency match with ARF1. (ARF1 is the RF system which is used for moving beam from Accumulator injection to stacktail deposition orbit.) Hence, stacking efficiency takes a hit while closing the D2A line into the Accumulator. Shown is a scan of the Debuncher Extraction Septum and the TBT response for several settings (right plot). The oscillations from a single injection is also shown. Scales are arbitrary. Antiproton Acceptance Keith Gollwitzer 25 Other Work Lattice Development Debuncher Lattice measurements have been incorporated into model. Updates and addition of more complete physical aperture dimensions and locations Survey Completion of optical/laser survey of AP1, AP2, Debuncher & D/A line performed during 2004 shutdown Confirmed offset of V730 of AP2 and reset dipole D/A analysis completed and led to septa moves Cross checks of remaining data sets are being done AP2 Chromatic Studies Simulation studies of transport of beam from target to circulating in Debuncher (LBNL) Antiproton Acceptance Keith Gollwitzer 26 Beam Time Most of 2004 reverse protons Commissioning of Debuncher BPMs, motorized quad stands and local bumps, Running Wave for identifying aperture limitations {see slides} Small gains made over several months Large gain Horizontally with bump at extraction septum However, kicker unable to compensate (essentially no gain to stack rate) Has led to ramped Debuncher Extraction (DEX) bump {earlier slides} Some work done with procedures and diagnostic tests for reverse protons up AP2. Since shutdown some reverse protons Commissioning of motorized quad stands and local bumps (including DEX) Recovery of admittance after shutdown Further tests of beam up AP2 Since shutdown mostly semi-parasitic stacking studies Commissioning of instrumentation to see 10^8 pbars & associated procedures Component Centering {see slides} Bumping around the Debuncher {see slides} Antiproton Acceptance Keith Gollwitzer 27 Aperture Finding Reverse Protons Running Wave Two trim dipoles playing sin and cos curves to test for aperture limitations Beam is heated in appropriate plane One period of curve is run to prep beam Inherent diffusion repopulates the beam edge which is then scraped away by limiting aperture(s) in successive periods of Running Wave curve Relies upon monitoring beam current and loss monitors for each step of Running Wave curve Made available fast updating beam current signal Loss monitors received full checkout and calibration during 2004 shutdown Antiproton Acceptance Keith Gollwitzer 28 Beam Size (arb) Phase Advance (arb) Beam Current (arb) Phase Advance (arb) Apertures Phase wrt to Running Wave Aperture Finding Reverse Protons Running Wave Cartoon Antiproton Acceptance Keith Gollwitzer 29 Identification of limiting Apertures Reverse Protons Aperture Finding Running Wave Antiproton Acceptance Keith Gollwitzer 30 Aperture Finding - Stacking Semi-parasitic stacking studies Component Centering about beam Local Bumping Around Debuncher Centering and Bumping require Ability to determine pbar intensity in the Debuncher {earlier slide} Stability of upstream machines and/or offline analysis to disentangle different slip-stacking cycle effects Patience to perform a bump since motorized quad stands controls only allow moving a single stand at a time First component is changed make a 1-bump Second component is changed now have 2-bump Third component is changed closes to make a local 3-bump Can take several minutes to complete the bump Depending upon the number of motorized quad stands in a bump, a scan can take 10 to 30 minutes to perform Antiproton Acceptance Keith Gollwitzer 31 Identification of limiting Apertures Stacking Bumping around the Debuncher Center moveable devices on beam. Built high precision Debuncher intensity monitor (D:BPI10D). Construct 3- bumps that cover the Debuncher (43 horiz vert. bumps) During stacking, move each bump 2 mm while monitoring Debuncher intensity. Measured during Stacking Antiproton Acceptance Keith Gollwitzer 32 Summary Much work has been done in making tools and procedures for Beam Based Alignment Will continue- Rounds of local bumping in Debuncher Component centering about orbit after each round of bumping Completing DEX bump commissioning Commissioning AP2 and D2A BPM system Maximize Debuncher injection aperture via reverse proton studies Measure AP2 lattice Center orbit in AP2 using both reverse protons and stacking secondaries