1. Alexandr Drozhdin March 16, 2005 MI-10 Injection

2. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review2 Outline Painting Injection Parameters Injection Scheme Results of Simulation Stripping Efficiency and Beam Loss Conclusions

3. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review3 Painting injection is required to realize uniform density distributions of the beam in the transverse plane for space charge effect reduction. Location MI10 straight section Duration 90 turns (1 msec) or 270 turns (3 msec) Repetition rate 0.67 Hz Accumulated intensity 1.5e14 ppp Injected beam emittance 1.5 mm-mrad Emittance after painting 40 mm-mrad Beam power 143 KW Injection loss (600 µg/cm) 0.005%( nuclear interaction ) +0.004%( foil stripping ) +0.005%( field stripping )=20 W Painting injection parameters

4. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review4 aperture with the required emittance. Vertical kicker magnets located in the injection line provide injected beam angle sweeping during injection time. Painting injection Painting injection is perfor- med by using fast horizontal and vertical magnets. The closed orbit is moved at the beginning of injection by 21 mm to the graphite stripping foil. Gradual reduction of kicker strength permits “painting'' the injected beam across the accelerator

5. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review5 A stripping foil is located upstream of focusing quadrupole Q102. That is necessary for unstrepped component of the beam separation from the proton beam behind the stripping foil. A septum-magnet is used to separate the circulating beam and injected H - at the defocusing quadrupole Q101 by 135 mm. Horizontal septum-magnet located behind the stripping foil is used for removal of unstripped beam to the external beam dump. Painting injection scheme

6. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review6 Horizontal kicker strength and vertical angle of injected beam at the foil (top), horizontal (middle) and vertical (bottom) density distribution of the circulating beam after 90-turn injection. Circulating beam distribution

7. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review7 Average number of hits upon the stripping foil for each particle is equal to 4.4. This effects pretty high level of nuclear interactions and because of this causes 0.0046% (7 W ) of particle loss at injection. Multiple Coulomb scattering in the foil and ionisation loss are negligible small. The increase of painting injection duration to 270 turns increases an average number of hits upon the stripping foil to 16, that increases foil heating and beam loss at injection. Particle hits at the foil

8. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review8 The kicker strength drops fast to ~60% of its maximum during 20 turns, and then slowly decreases to 50% during another 70 turns. Stripping foil is located at the exit of kicker number 2, very close to its edge in the fringe field of the magnet. The kicker magnet field is chosen such a way that during injection the magnetic field provide stripping of Stark states hydrogen atoms with principal quantum number n=5 to protons. Stripping efficiency

9. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review9 This corresponds to kicker maximum field of 0.1T and length of 0.34 m. At these parameters the magnetic field during ~80% of injection cycle is in the range of (0.05-0.06)T. The probability of H - stripping by magnetic field of kicker magnet during the first turn of injection (B=0.1T) is 0.002. It drops to 0.00005 during five turns (B= 0.08T). This gives Stripping efficiency stripping of 5.e-05 of injected beam (7 W ) of power lost in the injection region. An unstripped part of the beam after interaction with the foil - the H 0 states hydrogen atoms - may be stripped to protons by magnetic field of other accelerator elements.

10. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review10 We assumed here that H - atoms pass a distance of (1-2)cm in a fringe field of the kicker magnet number 2. This distance is enough for H 0 atoms with n=5 to be stripped. This part goes to circulating beam without changing emittance of the beam. Some part of atoms with n=4 is left unstripped and goes to the beam dump, and, unfortunately, some fraction of them is stripped along the kicker number 3. These protons contribute to the circulating beam halo and cause losses in the collimation system. Stripping probability of Ho atoms

11. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review11 Experimental Data on H 0 yields [*] [*] Measurement of H(-), H(o), and H(+) yields produced by foil stripping of 800-MeV H(-) ions, M.S.Gulley, P.B.Keating, H.C.Bryant, E.P.MacKerrow, W.A.Miller, D.C.Rislove, S.Cohen, J.B.Donahue, D.H.Fitzgerald, S.C.Frankle, D.J.Funk, R.L.Hutson, R.J.Macek, M.A.Plum, N.G.Stanciu, O.B.van Dyck, C.A.Wilkinson, C.W.Planner, Physical Review A, Volume 53, Number 5, May 1996. n=1, 2 93.3% n=3 3.6% n=4 1.5% n=5 0.7% n=6 0.3% n>6 0.6% total 100% Assuming that fraction of yields of different states n almost does not depend on the foil thickness and energy, one may expect ~97% (n=1, 2 and 3) of the total amount of H(o) to end at the external beam dump, ~1% (n=4) contribute beam halo, and ~2% go to the circulating beam without emittance increase. Foil number 3 is used for a final stripping of atoms (n=1-4) behind the kicker number 3 to reduce field stripping and losses along the extraction magnet and beam line.

12. Fermilab March 15-17, 2005 A. Drozhdin - Proton Driver Director's Review12 No show stoppers have been found at the painting injection system simulations. Calculated stripping efficiency is 99.5%. It is shown that all H 0 atoms with n>4 are stripped to protons and go to circulating beam without changing emittance of the beam. Atoms with n<5 are left unstripped and end at the beam dump. About 70% of atoms with n=4 are stripped to protons along the injection kicker number 3. These protons contribute the circu- lating beam halo and cause losses (~6 W) in the collimation system. Magnetic field stripping in the kicker causes 7 W loss. Nuclear interactions in the foil cause 7 W loss at injection. CONCLUSIONS