1. MTE commissioning status S. Gilardoni, BE/ABP With C. Hernalsteens and M. Giovannozzi

2. Brief introduction to PS-SPS transfer Beam for fixed target physics (CNGS) at the SPS are extracted from the PS at 14 GeV/c during five turns repeated on two cycles with large losses in the PS PS cycle SPS cycle PS Beam loss monitors 1 PS circumference 1st PS cycle 1 SPS circumference = 11 PS circumferences {{ 2nd PS cycle

3. Continuous Extraction (CT, 70’s): the principle E → Horizontal tune set to 6.25 phase advance per turn of 90°. A part of the proton beam is pushed by a slow and a fast bumps beyond the blade of an electrostatic septum. The sliced beam that receives the kick of the electrostatic septum is extracted during the current machine turn The rest is extracted with the same mechanism within the next 4 turns. The five beam slices feature the same intensity. ← Five PS turns →

4. New Multi-turn Extraction The beam splitting is not performed using a septum, thus avoiding losses. The main ingredients of the novel extraction MTE extraction The beam is separated in the transverse phase space using: Nonlinear magnetic elements (sextupoles ad octupoles) to create stable islands in which the beam is trapped. Slow (adiabatic) tune-variation to cross an appropriate resonance, 1/4 to have 5 islands. When the 5 beams are separated enough, each islands is ejected in 5 different turns Slow bump to approach extraction septum -> New bump 16 Fast bump to jump the septum blade -> New kickers. This approach has the following beneficial effects: Losses are reduced. The phase space matching is improved with respect to the present situation. The beamlets have the same emittance, optical parameters and nearly the same intensity.

5. MTE: Multi-Turn extraction Core Isl # 1Isl # 2Isl # 3Isl # 4 BWS 54 1.6 10 13 16/12/09

6. Phase space for the extraction septum SEPTUM

7. Beam in the vacuum chamber

8. MTE Slow/Fast bumps Bump 16 Bump 31 Septum 16 New slow bump composed by 6 independent power converter : close the slow bump on 7 ms New fast bump composed by 5 independent kickers: close the fast bump on 5 turns B field ≠ 0 B field = 0 At the septum location KFA9, KFA13, KFA21 ⇒ 5 turn constant kick KFA71/79, KFA4 ⇒ core smaller amplitudes ⇒ extra kick + trajectory correction

9. Step I: probing the phase space with single bunch beam

10. TIME X’ X

11. Protect extraction septum : dummy septum Passive device installed to protect extraction septum from particles lost during MTE kicker rise time. Extraction trajectories to be changed for all beams: - new slow bumps - new fast bumps with use of all extraction kickers

12. New extraction bump trajectories Pick up number X (0.1 mm) Dummy septum Predicted Measured Islands fix points during bump rise Measured

13. Status of setting up New Extraction trajectories on all operational beam LHC-type beam, nTOF, AD - new slow bump - new fast bump with use of all extraction kickers TOF BLMs at extraction with dummy septum No losses change with new extraction Screen MTE beamlet Blade

14. Beam capture resumed Before crossing the resonanceAfter capture before extraction Capture resumed with ~1e12 single bunch beam (nominal for 2014 is 1.5e13 with 16 bunches. Not available yet from PSB)

15. Next steps Compensate feed-down effect of the main magnets closing the islands during the slow bump rise time Extract the MTE islands with bunched beam Check stability of the capture (SPS requires 20% with 3% variation or so) and optimize it Increase the intensity when the h=2 beam will be fully available from the PSB (today at about 2-3e12 ppp and only ring 3) Verify the efficiency of the dummy septum with the MTE debunched beam and optimize dummy angle and position Optimize with higher intensity (1.5e13 ppp) and transfer the beam to the SPS But first we have to recover the KFA21, out of service since few days...

16. Capture evolution By resonance crossing by tune variation and resonance excitation by sextupoles and octupoles, stable islands are created and beam is trapped to form the beamleats.