Booster Beam Notching PMG Meeting Salah Chaurize August 21, 2013

Notching History Notching is controlled removal of selected proton bunches to facilitate a gap in the beam. This gap allows the Booster extraction kickers magnetic fields to reach full value to allow extraction of the remaining bunches. Without the gap or “notch” in the beam, the extraction kickers would displace these bunches in a non- controlled fashion causing losses in the extraction region In the past “notching” was less critical due to lower beam intensities and lower beam duty cycles. Losses were tolerable.

Longitudinal distribution of 3 removing (red), circulating (green) and survival at notching (blue) bunches, and long (1.08m) and short (0.54m) notchers waveform at Long-13, and 1.08-m notcher waveform for Long-05 straight section. December, 2011 A.Drozhdin

The Notch/Gap 3 Bucket Notch Width non-cogged Cycle 400MeV Cogged Cycle ~700MeV Extraction Loss Gap

Booster Kicker Notching Plans Phase I – Create a Horizontal Notch scheme to deposit beam at L13 using existing Notching magnet systems. – Reduce losses to sensitive locations such as gradient magnets and RF cavities. – Phase I is complete. Phase II – Improve notch kicker rise time to allow cleaner gap clearing and emmittance growth of bunches adjacent to the cleared bunches. – Build new short kickers and fast pulser to drive faster notch producing system. – Magnets building in progress. Kicker power system building underway. – Phase II is in progress.

Notching Pre-Shutdown 2012 – A 3 bucket gap is created using two kickers located at Long 5 and Long 12 Notcher – A High Voltage(55kV) Kicker at Long 5 Noker - Lower Voltage Kicker (20-40 kV) at Long 12 – Used to clean out remnant notched beam in buckets At ~700 MeV due to Cogging operations. – Beam is kicked vertically into Gradient Magnet dipoles at L5 and L12. Some notched beam reaches the collimator region at Long 6 and beam pipe mask at Long 13. This is not optimal – Non-cogged notched cycles occurs at ~400 MeV. – Cogged notch cycles occurs at ~700 MeV.

Notching Magnets at Long 5 and Long 12 Pre-Shutdown 2012 Notcher Hor. Pinger De-commissioned Horz. Pinger Ver. Pinger Noker MKS04 Beam direction L12 Pre-2012 Shutdown L5 Pre-2012 Shutdown Beam direction

December, 2011 I.Tropin Residual dose profiles, vertical cross section (30 days irradiation/1day cooling, mSv/hr). Vertical notcher Notching at Long 5 Pre-shutdown

Booster Kicker Notching Plans Phase I – Create a dedicated region to deposited 3 bunches of beam to produce a extraction kicker rise time gap. – Use current CX1168 thyratrons and PS systems to drive 3 kickers that kick Horizontally rather than vertically. – We implemented a three kicker system to go into Long 12 and Long 13 as the absorber regions. – This first phase is completed. Notched beam has been achieved with this new horizontal configuration. – Further orbit tuning and timing adjustments will continue as we commission MI beam.

Horizontal position of 3-σ circulating beam and removed beam at notching for magnetic field of two horizontal notchers of B=67Gauss at 400 MeV (top) and two notchers of B=72.5Gauss plus one notcher of B=35.2Gauss at 700 MeV (bottom). Three horizontal notchers at Booster Long-12 with beam dump at Long-13 straight section. August, 2011 A.Drozhdin

Three notchers with field of B=62 Gauss. The aperture of Short- 12 straight section should be increased to R>86mm to eliminate losses. This can be done by displacement of R66.5mm aperture (without BPM) by dX=20 mm. [ ]mm Y Short-12 dX=70mm 400MeV Circulating beam 3σ (ε=18π) Dump-13 X Red – 30π, green - 18 π August, 2011 A.Drozhdin

Long-13: Loss Simulations December, 2011 I.Tropin Side view Top view

Reason to redesign S12 Spool piece Need to kick beam horizontally at L12 to create a notch in the beam. Horizontal aperture is current 4.5 in at S12 Maximum aperture through Booster Short Corrector is about 5 in. Current aperture restriction at S12 is BPM plates and upstream and down stream bellows which are all 4.5in.

Reason to redesign S12 Spool piece New Extra Wide aperture BPM will give us 5 in aperture with new spool. New spool would use original spool design without the standard BPM components inside and larger aperture spool bellows

Extra Wide Aperture BPM

Short 12 Corrector Spool Upgrade New 5” Aperture Spool Standard aperture 4.5 Inch New Extra wide BPM Standard BPM inside

Notching Post Shutdown Phase I – A 3 bucket gap is created using three Long kickers located at Long 12 3 Notcher – High Voltage(46-54kV) Kickers at Long 12 Notcher PS converted to NOKA PS Noker PS converted to NOKB PS Built/Commissioned new NOKC PS mostly with parts on hand. – Beam is kicked Horizontally into new absorber at Long 13 – Extra Wide Aperture BPM and Short Corrector Spool needed to allow kicked beam horizontal displacement before reaching absorber. – Non-cogged notched cycles occurs at ~400 MeV.(unchanged) – Cogged notch cycles occurs at ~700 MeV.(Unchanged)

L12 Post Shutdown NOKC MKS04 NOKB NOKA

12-13 sections of Booster tunnel. Long-13 Long-12 Kick at L12 to Aisle.

Long 13 Notched beam absorber Beam direction Before After

Long 13 Beam direction

Long 13 Actual new absorber

Current Configuration In East Gallery NOKA NOKB NOKC

Current Configuration In East Gallery NIM Gate Modules Altera Based CAMAC Controls and Ramp Cards LeCroy Delay modules & CAMAC Trigger

Notching turned On and Off Extraction loss monitor Notching off Notching on Beam Charge

400 MeV Notched beam Absorber in operational position

400 MeV Notched beam Absorber Retracted

700 MeV Notched beam Currently

Preliminary Results and Commissioning

Phase II Current BKED (Long) design kicker have a rise time of about 35ns Short BKEF kicker modules are about half as long. They will produce a rise time of about 25ns. The voltage propagation time through the short kicker is cut from 20ns to 10ns due to half length. Two short kickers will rise faster with appropriate pulser to reach a desired flatop value. We will use a ANU style pulser using a CX2610 hydrogen thyratron rather than the existing CX1168 tube. This new pulser we gain us about 8-15ns of rise time. One Pulser can drive 4 magnets, possibly 6.

Phase II C. Jensen and J. Biggs along with EE support group is currently working on acquiring and building an ANU style pulser. Pulser components will be built through out We hope to have one pulser operating in a test configuration by the end of We will try to convert one long kicker to a pair of 2 short kickers as soon as feasible(2013/14)

C. Jensen

New Short kicker PS Rack Front/Back view EE Support currently building System

New Pulser for Short BKEE/BKEF Kicker Example(ANU Pulser Test Unit)

1Long Kicker BKED Series 2 Short Kicker BKEE Series

Conclusion Horizontal Beam notching is working. Estimated notched beam power max is about 250watts which is half the budgeted power loss for Booster. The New L13 notched beam Absorber gives us 50% more head room on lost beam power. This helps towards future 15Hz. Operations Phase II should give us further improvements towards 15Hz. Operations.

Thanks to: - L13 Notched Beam Absorber Assembly- PPD Experiment Fabrication- L13 Absorber Build and Assembly D.Erickson, J. Judd, W. Blaszynski, W. Gatfield V. Sidorov - L13 Absorber Mechanical Design APC Energy Deposition Simulations by- N.Mokhov, I. Tropin, S.Drozhdin M. Coburn L13 Absorber Motion Controls -L12, S12, L13 Upgrade Support- Mechanical Support/ Instrumentation Groups – L13/S12 BPM and Corrector R. Reily, B. Ogert, J. Kubinski, J. Briney,D. Wallace, J. Fitzgerald Controls Group CAMAC modules Booster Techs - Power supply and load reconfiguration New timing module build and support electronics R. Mraz, T. Boes, D. Dick Operations - Database work, O. Marshall, R. Jones AMG-L12, S12,L13 alignment Radiation Safety – Joel Fulgham Consultation – J. Lackey, B. Pellico Machine Shop, Welding Shop Many More I missed

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Reserve Slides

Looking upstream towards L13 Before After

Short Kicker/ Power Supply Effort Purpose of short kicker is to reduce kicker magnet rise/fill time. We can improve rise time of magnet field from current ~32nsec to about 25nsec. This will improve beam bunch removal with reduced disturbance of bunches intended for extraction.

New Short Kicker Pulser Control and PS racks location. East Booster Gallery

BKEE02(Short Module) Voltage ~40kV

BKED012(Long Module) Voltage ~40kV

BKEE001 Short 42KV Noker BKED012 Long 42KV Noker Channel 1 V in Channel 2 Vout Channel 3 Load I

Preliminary finding is a 8-15 ns difference between ANU pulser and Operational Booster pulser(Slower) Testing by Jensen, Chaurize