Proton Beam Measurements in the Recycler Duncan Scott On Behalf of the Main Injector Group

Contents Confirm Nova Operations Will Work – Operating the MI8 Injection line at the Recycler energy The MI8 line transfers beam from the booster The RR has a slightly different energy to the MI MI8 has many permanent magnets – Stacking in the Recycler Do we have enough aperture? – What are the expected tune shifts? Due to MI Ramp As Intensity Increases Due to RF Frequency Changes Other Experiment Example – Finding Zero Chromaticity with Schottky and BPMs

Operating MI8 Line at RR Energy The RR has a slightly different energy to the MI – Change Booster Energy and RF Frequency, f RF – Try to Inject into MI Differences between MI and Recycler – Momentum From to GeV/C – Fix the MI Dipole field at RR value and adjust Booster dipole (B:VIMAX) – Calculated change is ~4 A – f RF From to Hz, ∆f=2 400Hz – Change MI f RF and Booster locks to that

Change B:VIMAX Beam in Booster B:VIMAX

MI8 Orbit 1 st attempt beam hits MI8 collimators Calculate changes to horizontal trims and try again 2 nd attempt beam is injected into MI

MI Orbit & Correction Strength Reasonable injection and closed orbit in MI Less current used in horizontal trim magnets Injection Vertical

Longitudinal Stability in MI WCM data shows stable bunches and bunch spacing – Phase is well matched

Slip-Stacking NOVA operations will increase the beam power through the Main Injector by a factor 2 Previously the beam was stacked in the MI then ramped For Nova we will slip-stack beam in the Recycler whilst the MI is ramping – Approximately halves the cycle time

Slip Stacking Stack Beam in Longitudinal Phase Space – Two sets of bunches separated in azimuth and energy in 2 RF systems – They “Slip” relative to each other – Apply large voltage RF to capture 2 bunches in 1 bucket – In the Recycler we plan to do 12 batch slip stacking. Inject 6 Booster batches at one frequency, Reduce that frequency Inject 6 more batches at original frequency Transfer to MI and Recapture +∆f -∆f

Recycler Requirements for 12 Batch Slip Stacking Different schemes can affect the amount of momentum aperture required – We could inject on momentum, decelerate, inject, accelerate Preferred option, centres beam in magnets, better lifetime, etc. – Inject off-momentum, with half required ∆f, then decelerate Requires less momentum aperture 0 -∆f +∆f Inject on momentum Inject off momentum f RF time 52 MeV 40 MeV

Recycler Requirements for 12 Batch Slip Stacking The central frequency separation between the two beams is fixed – ∆f = 1260 Hz or ∆p =24 MeV. Assume Booster beam has momentum spread of ±8 MeV (95%) – The min. momentum aperture required is 40 MeV or ∆p/p = 0.45% 24 MeV 10.2 MeV 95 KV Bucket 8 MeV 40 MeV

Measured RR Momentum Aperture Change RF frequency and measure beam transmission This will need to be remeasured – Currently equipment is being removed, Lambertsons, E-Cool, etc. – This should only increase the aperture > 99% Transmission ∆p/p =0.45 % > 95% Transmission ∆p/p =0.65 % Minimum ∆p/p required H Chrom = +3.0 V Chrom = -4.6

Tune Change with MI Ramp The Ramp of Magnets in MI will affect the RR tune Tune measured from BPM data taken after beam is pinged Time of ping varied over event Kicker firing at different time in cycle

Tune Change vs MI Ramp Tends to follow rate of change of momentum (pdot) Faster ramp may increase ∆Q ? Max ∆Q=0.005

Tune Change with Intensity Measured tune for different intensity beams in MI Line is theory (B. Ng) From Batch 1 to 6 Max ∆Q=0.01

Tune Change with f RF Tune measured with Schottky, for low chromaticity, Hchrom=+3, Vchrom=-4.6 Change at High Chromaticity (-17) measured in MI Max ∆Q=0.04

Zero Chromaticity Measurements with Schottky Width of Schottky signal measures chromaticity – Minimum width is zero chromaticity How does measured 0 Chrom. compare with “Set” 0 Chrom ? Saved Scope images whilst changing Chrom Extract coordinates Fit Gaussian Find min width

Zero Chromaticity Measurements with BPMs Measured Qv vs ∆f RF for different Vchrom settings Plot gradient of each VChrom setting Zero gradient = Zero Chromaticity, at Vchrom=-0.38 (-0.75 from Schottky)

Conclusions Successfully Operated MI8 Line at RR Energy – MI8 line works better with RR energy – Energy matching worked second attempt, phase matching first attempt Verified the RR has the Min. Aperture Required – Slip stacking requires momentum aperture, between 40 and 52 MeV – Measured aperture is at least 40 MeV – Should only increase after Lambertson E-Cool removal, etc. – Re-measure after shutdown Measured Tune Changes that Need Compensating – with MI Ramp – 0.01 with intensity, from batch 1 to 6 – 0.04 for RF changes (at high chromaticity) Other Experiments for Fun and Learning

Thanks Ming-Jen Yang Denton Morris Ioanis Kourbanis & Operations