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NLC 2001 Beam Delivery Layout

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'Big Bend' (designed for 1.5 TeV) limits upper range of energy for HE IR ... 110m of tunnel per 10mrad of bend for 5% dilution if Emax=500 GeV ... – PowerPoint PPT presentation

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Title: NLC 2001 Beam Delivery Layout


1
NLC 2001Beam Delivery Layout
  • Tom Markiewicz
  • Fermilab Meeting of Detector WG Leaders
  • 05 January 2001

2
Summer 2000 Configuration
3
Summer 2000 Configuration
  • Linacs point at each other
  • One lt 1 TeV Collimation section common to two
    IRs
  • Energy collimation with tune-up dumps
  • Relaxed Betatron collimation with consumable
    spoilers
  • 10 and 10 mrad Big Bends to get to each of two
    symmetric IRs
  • 20 mrad crossing angle at each IP
  • Working assumption is Large and Small
    detector
  • Non-simultaneous delivery of beam to either
    detector
  • 280m IP Stretch provides separation and vibration
    isolation of IR halls
  • New FF with L4.3m and magnet apertures designed
    for 1 TeV
  • Most magnets could be re-used up to 1.5 TeV
  • Length of FF tunnels compatible with 5 TeV
  • Either
  • same FF lattice to each IR or
  • leave tunnel to IR2 empty (Lehman cost estimate)

4
Conceptual Problems with Symmetric Two IR Layout
  • Experimenters seem to want full luminosity at 90
    GeV 1 TeV, be able to quickly change energy
    and continually question the maximum energy reach
    of NLC X-band technology
  • Big Bend (designed for 1.5 TeV) limits upper
    range of energy for HE IR
  • Emittance growth due to SR 5 by limiting
    strength of bends
  • Magnet apertures set by lowest energy
  • Magnet design set by aperture and highest energy
  • Ambiguous physics justification for two detectors
    given symmetric layout and fact that only one
    detector gets data at a time
  • As FF gets shorter, two FF tunnels merge into one
  • lateral displacement of IRs shrinks (44m in ZDR,
    16m in CD4)
  • No design provision for gg, which needs larger
    crossing angle

5
Base Element of 2001 Layout
Emin, Enom, Emax 250 GeV(?), 500 GeV, 1000
GeV No Big Bend New FF w/ L 4.3 m Collimation
lattice with dog-leg energy collimation 20 mrad
crossing angle One IR Hall with One Large Detector
6
The 2nd IR Hall in the 2001 Layout
  • Assume a 2nd IR is part of the baseline package
  • Questions In order of importance
  • Emin, Enom, and Emax for high luminosity
    running
  • Sequential or simultaneous beam delivery
  • Crossing angle, hall size, and facilities
    infrastructure
  • Detector staging spacing of halls for vibration
    isolation

Optimal tunnel layout for cost, flexibility,
performance?
IR2
??m
IR1
Linac and bypass
One collimation system or two?
7
First Working Answers to IR2 Questions
  • Transverse and longitudinal spacing of halls for
    vibration isolation
  • Dx100m Dz 0m
  • Emin, Enom, and Emax for high luminosity beam
    delivery
  • 90, 250, 500 GeV, respectively
  • Need to know Emax to before bend tunnels are dug
  • Sequential or simultaneous beam delivery
  • Sequential BUT supporting simultaneous operation
    if issues resolved
  • Polarized beam to each IR
  • 2nd INDEPENDENT collimation system allows
    possibility of simultaneous operation at
    different energies
  • Crossing angle, hall size, and facilities
    infrastructure
  • 30 mrad (20-40 possible keep E(LBsq)5/2 lt
    current value)
  • 10mrad gg stay-free requires bigger angle
  • 2nd detector? Precision?

8
Site Layout Dx100m Dz 0m
9
BDIR Detail Dx100m Dz 0m
FF2
27mrad
Coll2Bends
52mrad
Coll1
FF1
10
An Alternative Layout
  • Length of tunnels to IR2 is just that required
    for bends that maintain good emittance beam at
    500 GeV c.o.m.
  • 110m of tunnel per 10mrad of bend for 5 dilution
    if Emax500 GeV
  • Can we reduce IR separation and either reduce
    cost or increase program flexibility?
  • Reduce Dx to 25m
  • Vibration, simultaneous occupation of halls,
    etc??
  • Use ONE collimation system for BOTH IRs
  • Need some empty IP-Stretch tunnel to make
    geometry work
  • Second collimation system in same tunnel also
    allows possibility of simultaneous operation at
    different energies
  • 25 mrad big bend and NO reverse bend
  • Are there advantages to ONE big IR Hall?

11
Site Layout Dx25m Dz 0mOne Collimation Tunnel
per Side
FF2
Coll
0 mrad
Bend
25mrad
Stretch
FF1
12
Reversed Linac Angle, IR Separation 25mand
Separate Collimation Lattices and IR lead to Big
Bend Reverse Bend Angles 21.8mrad
13
Another Possibility Dx25m Dz 440mOne
Collimation Tunnel per Side
FF2
Coll
0 mrad
Bend
25mrad
Stretch
FF1
14
Site layout with Dx25m Dz 440m
15
VERY, VERY Rough Cost EstimateLength Scaling
Only, NOT Parts counting
16
Summary
  • Its really a Users choice You get what you
    pay for
  • Model 0 One IR
  • Cheapest option 251M
  • Model 1 Dx100m Dz 0m
  • Most flexible?
  • Most bending, perhaps lowest maximum energy reach
  • Most expensive 499M
  • Model 2 Dx25m Dz 0m
  • Allows for flexibility in detector/IR staging. Is
    this interesting?
  • 407M plus 60M for second collimation system
    (simultaneous running)
  • Model 3 Dx25m Dz 440m
  • Seems best suited to a low start up cost
  • Begin with one collimation system sequential
    data taking
  • Better vibration isolation same cost as Model 2
  • Is there another variation we are missing?
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