Overview of Ramp Development Giulio Stancari E-835 Collaboration Meeting Torino, May

Ramps  t (new) : to go with the deceleration ramp, so that E-835 phase II runs above transition, consequently avoiding beam losses due to transition crossing. For each beam momentum, it can be obtained manipulating the lattice (mostly quad currents). Bend-bus: since the dipole kicks are fixed, it is a function of momentum only. Instead of calculating it, we will start from the E-835 ramp, which should still work. RF frequency: deceleration is performed with beam on central orbit. Defines momentum. Magnets were scaled accordingly. Time: defines pace of deceleration (about 20 MeV/s). They are tables with two columns: independent variable POFTT (related to beam momentum) and set value for each of about 100 devices. For E-835, 64 entries above transition (14 primary points).

Accumulator Magnets

SKEW QUADS: SQ100 and SQ607 SEXTUPOLES: SEX3, 7, 9, 10 and 12 OCTUPOLES: OCT10 and 12 SKEW SEXTUPOLES: to be installed this summer.

Considerations on  t Ramp It has to start from  t = 6.7 (value at 8 GeV) To facilitate energy calculation for E-835, lattice should be constant in data-taking region. Transition energy should be well below the  0 resonance (for instance,  t = 5.3 corresponds to M - 5  ). In order for the stochastic cooling to work properly, the mixing factor M has to be within a certain range ( approximately 5 < M < 20). A good choice is  t = 4.8 at the low end of the ramp.

Lattice Constraints Tunes must be constant, to avoid crossing resonant lines. Betatron phase advance between transverse cooling pick-ups and kickers close to an odd multiple of 90 degrees. Low dispersion (< 0.1 m) at A-30 and A-50; high dispersion (> 9 m) at A-60 and A-30 (for momentum cooling). Beta function as small as possible; in straight sections,  > 5 m (for transverse cooling pick-ups) and  < 8 m (for aperture). Chromaticity should be small (to keep tunes far from resonant lines) and positive (for longitudinal stability). Six-fold symmetry!

Ramp Development Scheme Measured lattice at 8 GeV (Feb 1999). Calculation of ramps (in progress) using arbitrary starting point: - to demonstrate feasibility of “snowplowing  t down” with given lattice constraints; - to determine procedure for going from one point to the next. During ramp development with beam (this summer): - measure lattice at one ramp point; - compare and correct prediction; - calculate next point; - go there; - repeat at next point.

Commissioning Plan (as of May 3) May Jun 15: 8 GeV Lattice (reverse protons, normal polarity) Jun Jun 22: AP-2, Debuncher, D-to-A line Jun Jul 13: Stochastic Cooling (switch to forward protons, reverse polarity) Jul Aug 3: Proton Stacking Aug 4 -- Aug 10: Shutdown (install skew sextupoles and AP-2 line modifications) Aug Oct 14: Ramp Development Oct Nov 4: Shutdown (Deb. Band I & II) Nov 5 -- Nov 18: Deb. Band I & II Nov ?: E-835 Run