PILLEIR

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PIL/LEIR
Presented by M. CHANEL
April 4th 2002 -PILLEIR
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CONTENTS

• LEAD on LEAD
• Baseline scheme
• Why not other alternatives
• LINAC3
• LEIR
• PS
• Different systems
• Cost
• Planning
• Summary

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Performance needed for LEAD ions

• 7 107 Lead ions/bunch in LHC at 2.7 TeV/n in a
  normalised emittance of 1.5 mm(bg s2/bh,v). (
  quench limit and central detector limit)
• Overall transfer efficiency of 30,
• elt1.2 mm at the exit of SPS,
• elt1 mm at the entrance of SPS after final
  stripping,
• elt0.7 mm at the entrance of PS.
• A total of 0.9 109 ions extracted from LEIR

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GENERAL SCHEME
LHC.LEAD.new.PUB
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Stacking tests of lead ions
requested
Sourceefficiency
Lossescharge state
With the lattice used, it was not possible to
accelerate the beam
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Other solutions
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Measured by GC/MCEmit_Pb_R4.new.xls
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LIS

•  6mA, 5.5ms would suffice. But about 14MF
  investment.
• As the 6mA Laser Ion Source for lead production
  is still an untested prototype and many
  parameters are yet unknown, thus it is not
  recommended to base the LHC ion program on this
  alternative (S. Maury, Reflection on the
  Different Lead Ion Injection Variants for LHC,
  PS/AE Note 2001-019).

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LINAC3

• Improved afterglow pulsed ECR source (450ms
  pulse length but increased current from 100mA to
  120mA-lower stability- to 200mA (RF heating
  from14 to 18GHz) Lead 27 LEIR uses 200 ms).
  If more ions needed than change the
  spectrometer, move the sourceexpensive.
• Accelerate to 4.2 MeV/n, b0.0945
• Add a cavity to ramp the momentum up to 1
• Stripping afterwards and use of Lead 54
  (Slightly less intensity than for Lead53, but
  acceptable lifetime with electrons of the cooler
  )
• Pulsing from 0.8 Hz up to 5 Hz (10 Hz possible).
  (10 pulsed power supplies and thermal switches on
  magnets)

Collaboration Catania, Grenobles, Cern, GSI
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LEIR

• Combined H/V/P multiturn injection inclined
  septum momentum variation of incoming beam such
  the injection orbit (D dp/pbump) remains the
  same during injection. 50 injection efficiency
  reachable(75 on paper). Recuperate magnetic
  septum, bumpers.
• Cool and stack the freshly injected beam by
  electron cooling in 400 ms max.
• 4 injection-cooling-stacking cycles should be
  enough (timelt1.6s).
• Acceleration and ejection (h2) at T72MeV/n
  energy choice is a compromise between the limit
  of incoherent tune shift in PS, the time between
  bunches for the ejection kicker, the min RF
  frequency in PS and the stacking time in SPS/LHC.

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LEIR Injection

• Combined injection gives lower et (better cooling
  time) compared to normal multiturn but increases
  mom. spread (good long. cool.).
• Combined injection implies large D and D/??h
  5m1/2 (D10, bh3).

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X-Y plane105 turns tracked
Cooled beam
E-SEPTUM
New beam from linac D0
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• X-Y plane after 100 turns
• 75 injected

• x and y and momentum projected distributions

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LEIR INJECTION LINE
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Cooling and Stacking

• Electron cooling theory gives

• where q is the relative difference in angle
  between the ions and electrons qi?(?/?)
• the parameter hecool Lcooler/Lmachine
• and Ie is the electron current.
• A and Q atom mass and charge state

• Large b desirable but ion beam size should remain
  smaller then e-beam size and mind the effect of
  the e-beam space charge. optimum around b5m
• With D0, stack and injected beam are in the
  centre of the e-beam, but this not the best value
  for cooling.

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Lattice

• Good for injection and coolingstill 2 periods
• tune(1.8,2.7)
• longitudinal acceptance reduced to dp/p 1
• 5 quad families, more flexibility.

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Electron cooling
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GUN
Dipole
Toroïd
DRIFT
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LEIR cycle for LEAD ions
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LEIR RF

• 2 RF cavities using Finemet built in
  collaboration with KEK

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OTHERS

• With an electron beam of 200mA, the cooling rate
  is sufficient to counteract the IBS growth rate
  and get the emittances wanted.
• The beam will be maintained stable mainly during
  cooling (coasting beam) by a 100MHz bandwidth
  transverse active feedback.

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SPACE CHARGE ALONG THE CHAIN

• Takes into account all the new features
• Note the stripping between LEIR and PS gives
  large De

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LEIR EJECTION TO PS
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A word on vacuum

• During the tests in 1997, the Lear vacuum was
  good (5E-12T without beam) but the lost lead
  ions (e-ion recombination..lead 54 or res. gas
  charge exchange or..) degas the chamber walls.
  One lead ion releases 105 molecules!!!!
• At end of linac3, tests of different vacuum
  chamber treatment are under way.
• Hope outgassing can be reduced by appropriate
  treatment of the vacuum chamber.
• Already known when ions are lost perpendicularly
  to walls, outgassing is decreased.

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LEIR TDR E. Mahner
  Figure 2 Dynamic pressure simulation for a 15
m long part, including a bending magnet, of the
LEIR vacuum system. As input parameters the
measured (at Linac3) desorption yield of ?tot 2
? 104 molec./ion and a typical gas composition
(CO (72), CO2 (18), CH4 (7), H2 (3)) at the
beginning of beam scrubbing has been chosen. Two
scenarios are displayed a) open symbols lumped
pumps (existing from LEAR) resulting in an
average pressure of 3 ? 10-11 Torr, b) closed
symbols lumped pumps plus linear getter (St707
strips) giving an average dynamic pressure of
about 5 ? 10-12 Torr, a number very close to the
design value. The position of the about 6 m long
vacuum chamber inside the bending magnet is
indicated on the x-axis.
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PS

• Inject (change septum-modif. kicker) and
  accelerate on h16 up to ..
• h16?14?12, split 2b. to 4 bunches and finally
  h24 ?21
• h21 is chosen to have 100ns b. separation at
  flatop in LHC and it is compatible at 6.01 GeV/n
  with 200MHz RF system in SPS.
• Acceleration to 6.01 GeV/n(g7.45), cp/Q26.
  GeV/c/charge.
• Stripping in TT2. Change of TT2 line to have a
  low beta at stripper.

Steves talk
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TT2(from PS to SPS, has to be changed)

• At stripper bh,v20m?5m, D-1m
• Blow-up reduced by a factor 4 compared to
  old(normal)optic.needs MD for SPS matching.
  De0.2mm after re-matching in SPS?.
• Need of 4 quads, 6 power supplies
  building.(mostly recuperated)

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Different Systems (not detailed)

• RECUPERATION AS MUCH AS POSSIBLE
• Inj./Ej. Line magnet spec. 8 QTWs, 2 BHN 1.7 and
  0.4 Tm2 cores, 2-4 DVN instrumentation. One
  inclined SEH , one pulsed magnetic septum, and
  pulsed power supplies. All others recup. But some
  power supplies modifications or renewal(kickers,
  bumpers)
• Electron cooling- new by Novosibirsk 2 DHVs and
  Old quad power supplies for solenoids.
• Machine magnets- all recuperated (even 4 reserve
  quad added ) but 6 big powers supplies (BHN5
  quads families) . renewal of controls.
• RF-2 cavities specified-
• Machine instrumentation- specifs known, most of
  the hardware is recuperated.

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Different Systems (suite)

• MechanicsAll elements position known
• Vacuum specified as lifetime of lead30s. The
  final study is nearly to be finished.
• Controls ok but not detailed.

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PLANNING

• x work on machine d design m
  manufacture t test
• l linac3 design/modif. p ps design
• R Runs L LHC runs

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LEIR COST (and only LEIR)
/specifications/cost-recapitule/cost.2008..xls
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Staffing (LEIR only)
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PIL cost
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Total PILLEIR
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Summary

• Lead ion scheme nearly finished (draft DR)
• Electron cooling of heavy ions is defined.
• Space charge limits both in LEIR, PS, SPS are
  harmonised.
• Vacuum degradation due to losses is well
  understood.
• IBS and conservation of high beam density is , as
  for protons, the main challenge.
• Planning established, cost known without
  contingencies, but some points are evolving.
• All technical systems are specified.

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OUTLOOK

• People are ready to start the final design of
  their systems.
• Awaiting for financial resources.

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Why a difference with the original price (1994)
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TUNE SHIFT