Slip stacking in Recycler Ioanis Kourbanis 9/14/11

Slip Stacking Requirements Two rf systems with controllable frequency curves. –Available voltage KV –Beam loading compensation Available momentum aperture. –Is a function of the required frequency separation and the beam momentum spread. Tune and chromaticity control –Small negative chromaticity during the injection of the first group of batches. Large negative chromaticity during slipping. –Correct for the chromatic tune shift during deceleration.

RR Momentum Aperture Requirements for 12 Batch Slip Stacking The central frequency separation between the two beams is fixed at 1,260 Hz or Dp of 24 MeV. The bunches from Booster will have a momentum spread of ±8 MeV (95%). The minimum momentum aperture required for slip stacking is 40 MeV or Dp/p of 0.45%(±0.225%). –With the current slip stacking scheme where we always inject at the center of the machine aperture the momentum aperture required is 52 MeV or 0.59% (+0.23%;-0.36%). –If we choose to inject off momentum by half the frequency separation ( 630Hz or 12 MeV) we minimize the momentum aperture required.

Two Different Slip Stacking Schemes Injecting off momentum in order to optimize aperture. Always injecting in the center of aperture. Current SchemeAlternative Scheme

24 MeV Minimum RR Momentum Aperture for slip stacking 10.2 MeV 95 KV Bucket 8 MeV 40 MeV

Recycler Momentum Aperture Measurement Measured with 8E10 pbars, debunched, Dp/p (full) ~.44 % (initial)  ~ 1.3  Qx.413, Qy.419 Setting: Cx -2.0, Cy -1.6 Measurement by: Dan, Dieter, Martin Zero chromaticity Initial distribution Restore nom. Chrom. Z Full aperture nom  – 0.65% zero  +/ % Zero loss nom  % zero  +/- 0.37% For dispersion ~ 2m  x ~ +/- 16 mm motion dp/p ~1.55% 0.3% x.458 y.476 Cx ~6 units 2.4 khz.  p/p.0036  -.02

2/21/06 dejSNuMI Meeting Beams doc 2172 Main Injector Momentum Aperture Measurement (1) dp/p.64% dp/p 1.07 Use K103 to ping beam at injection MI Lambertsons straight sections-> small dispersion (not MOM aperture limit) Strong coupling: hz hz hz

Main Injector Momentum Aperture Measurement (2)

Conclusions We need to measure and understand the RR momentum aperture. –Do we have enough aperture to do slip stacking by injecting always in the center of the machine? It is important to measure and control the tunes during slip stacking in RR. Do we have the chromaticity range in RR required for slip stacking? –Can we do chromaticity jumps?