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LEAR PROJECT M. Chanel

19 juin 2000: PS MBM. LEAR PROJECT M. Chanel. THE BASIC NUCLEUS. J. BOSSER(BD) C. CARLI(AE) M. CHANEL(AE, L.P.L.) N. MADSEN(fellow AE) S. MAURY(AE) D. MOHL(P.I.L.) G. TRANQUILLE(BD) C. TOEPFER(Associate from Erlangen University. THE GOALS.

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LEAR PROJECT M. Chanel

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  1. 19 juin 2000: PS MBM LEAR PROJECTM. Chanel

  2. THE BASIC NUCLEUS • J. BOSSER(BD) • C. CARLI(AE) • M. CHANEL(AE, L.P.L.) • N. MADSEN(fellow AE) • S. MAURY(AE) • D. MOHL(P.I.L.) • G. TRANQUILLE(BD) • C. TOEPFER(Associate from Erlangen University

  3. THE GOALS • Provide the amount of ions per bunch necessary for LHC taking in account the overall transfer efficiency. • As much as possible 4 bunches /transfer in an emittance<1mm • Injection,cooling, acceleration, extraction in less than 3.6s!

  4. PLANNING as it could be • PROJECT CONCEPTUAL DESIGN end 2000 • BUT SPS Physicists ask ions for 2002-2003 then linac3 move in 2001 or 2004…. . • But resources not available before 2002…… • and we have to order ecool pieces in 2001 , make drawings, do test on vacuum systems, do some measurements on cooling…need money • Some modifs. delayed beg. 2004

  5. Tentative planning

  6. THE MAIN POINTS (in LEAR) • Charge state • Space charge • Injection • Cooling • Vacuum

  7. Charge State • The charge state has to be chosen such that there is no dielectronic recombination with electrons (ex:not Pb53+ but Pb54+) but only radiative recombination and charge exchange with residual gases. Consequence: lifetime and additional losses which degrades vacuum.

  8. A. Wolf (heidelberg) Ecool99,p187

  9. SPACE CHARGE • As the requirements of LHC are very demanding especially for light ions(ex: Oxygen ~1011 ions in LEAR for e*=1mm) space charge is very important(>2 at b=0.1) we need to choose the charge state (DQinc~Z2/A/b), the energy where the cooling is done(b=0.354). • The choice of the charge state implies to move Linac3 in the south Hall to avoid the E0 Loop limited to Z/A>0.25

  10. INJECTION • Linac source improved( mainly for Lead) • All Planes Injection: Horizontal vertical oscillations with inclined septum + change of beam momentum(up to 1%): • prior to injection by change of phase of the debuncher cavity • or in LEAR with a betatron • Bumpers and electrostatic septa • Avoid stripping in LEAR(vacuum) • full emittances(60h and 40v)

  11. Cooling

  12. ELECTRON COOLING • Electron cooling theory gives • q is the relative angle between ions and electrons(e/b)0.5 • h is the ecool relative length • Ie the electron current

  13. ELECTRON COOLING • Emittance limit is the equilibrium between IBS and cooling • IBS~(Z2/A)2 • Cooling ~Z2/A • Decreasing the charge state gives lower emittances but longer cooling time.

  14. Vacuum • Ions lost mainly by: • recombination with electrons • charge exchange with residual gas. • Lost ions hit the vacuum chamber and with their high charge and energy they produce a lot of outgassing….mean vacuum increased by >5 in 97. One ion of lead54 hiting the V.C. releases 5000 adsorbed molecules(105 in AGS) • Reduce the outgassing by special treatment of the vacuum chamber(experiment in Linac3 underway: Niels, LHC/Vac…)

  15. ELECTRON COOLING • Ie=Perv. V3/2 • V fixed by energy the increase Perv. • Normally 0.5mP but try to obtain 2 or more. • Thesis Dimopoulou, works also with russians at Fermilab…which collaboration?

  16. Canon à cathode sphérique convexe de semi-angle  = 450Simulation faite avec le code SSAM/CERN par C. Dimopoulou. La géométrie du canon a été fournie par A.Shemyakin/FNAL. Ua = 3kV , I = 0.92A , P = 5.6 microperv B = 2000 Gauss a= 0.5 cm 450

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