rol johnson 6/22/2005 nufact05 plenary 1 technical challenges of muon colliders rolland p. johnson...

Rol Johnson 6/22/2005Rol Johnson 6/22/2005 NuFact05 PlenaryNuFact05 Plenary 11

Technical Challenges Technical Challenges of Muon Collidersof Muon Colliders

Rolland P. Johnson Rolland P. Johnson

Muon Colliders need small muon flux to reduce proton Muon Colliders need small muon flux to reduce proton driver demands, detector backgrounds, and site boundary driver demands, detector backgrounds, and site boundary radiation levels. Extreme beam cooling is therefore radiation levels. Extreme beam cooling is therefore required to produce high luminosity at the beam-beam required to produce high luminosity at the beam-beam tune shift limit and to allow the use of high frequency RF tune shift limit and to allow the use of high frequency RF for acceleration to very high energy in recirculating Linacs. for acceleration to very high energy in recirculating Linacs.

I will briefly describe 7 new ideas that are driven by these I will briefly describe 7 new ideas that are driven by these requirements, where some of the ideas may be useful for requirements, where some of the ideas may be useful for Neutrino FactoriesNeutrino Factories

Muons, Inc.


Muons, Inc. SBIR/STTR Collaboration:Muons, Inc. SBIR/STTR Collaboration:(Small Business Innovation Research grants)(Small Business Innovation Research grants)

Fermilab; Fermilab; • Victor Yarba, Chuck Ankenbrandt, Emanuela Barzi, Victor Yarba, Chuck Ankenbrandt, Emanuela Barzi,

Licia del FrateLicia del Frate, Ivan Gonin, Timer Khabiboulline, Al , Ivan Gonin, Timer Khabiboulline, Al Moretti, Dave Neuffer*, Milorad Popovic*, Gennady Moretti, Dave Neuffer*, Milorad Popovic*, Gennady Romanov, Daniele TurrioniRomanov, Daniele Turrioni

IIT; IIT; • Dan Kaplan*, Dan Kaplan*, Katsuya YoneharaKatsuya Yonehara

JLab; JLab; • Slava Derbenev, Alex Bogacz*, Slava Derbenev, Alex Bogacz*, Kevin BeardKevin Beard, Yu-Chiu , Yu-Chiu

ChaoChao Muons, Inc.; Muons, Inc.;

• Rolland Johnson*,Rolland Johnson*, Mohammad Alsharo’a Mohammad Alsharo’a, , Pierrick Pierrick HanletHanlet, Bob Hartline, Moyses Kuchnir, , Bob Hartline, Moyses Kuchnir, Kevin Paul*Kevin Paul*, Tom , Tom RobertsRoberts

UnderlinedUnderlined are 6 accelerator physicists in training, supported by SBIR/STTR grants are 6 accelerator physicists in training, supported by SBIR/STTR grants * present at this workshop* present at this workshop


5 TeV

Modified Livingston Plot taken from: W. K. H. Panofsky and M. Breidenbach, Rev. Mod. Phys. 71, s121-s132 (1999)

The Goal: Back to the Livingston Plot

4NuFact05 PlenaryRol Johnson 6/22/2005

2.5 km Linear Collider Segment

2.5 km Linear Collider Segment

postcoolers/preaccelerators

5 TeV Collider 1 km radius, <L>~5E34

10 arcs separated vertically in one tunnel

HCC

300kW proton driver

Tgt

IR IR

5 TeV ~ SSC energy reach

~5 X 2.5 km footprint

Affordable LC length, includes ILC people, ideas

High L from small emittance!

1/10 fewer muons than originally imagined: a) easier p driver, targetry b) less detector background c) less site boundary radiation

Rol Johnson 6/22/2005 NuFact05 Plenary 5

Principle of Ionization Cooling

z

RFp

inp

cool out RFp p p

absp

inp

a

Absorber Plate

Each particle loses momentum by ionizing a low-Z absorber

Only the longitudinal momentum is restored by RF cavities

The angular divergence is reduced until limited by multiple scattering

Successive applications of this principle with clever variations leads to smaller emittances for high Luminosity with fewer muons

Rol Johnson 6/22/2005

NuFact05 Plenary 6

Muon Collider Emittances and Luminosities

• After:

– Precooling

– Basic HCC 6D

– Parametric-resonance IC

– Reverse Emittance Exchange

εN tr εN long.

20,000 µm 10,000 µm

200 µm 100 µm

25 µm 100 µm

2 µm 2 cm

3z mm 4/ 3 10

At 2.5 TeV

35 210*

10 /peak

N nL f cm s

r

42.5 10

0 50f kHz

0.06 * 0.5cm

20 Hz Operation:

10n

111 10N

9 13 19(26 10 )(6.6 10 )(1.6 10 ) 0.3Power MW

34 24.3 10 /L cm s 0.3 / p

50 2500 /ms turns


NuFact05 Plenary 7

Idea #1: RF Cavities with Pressurized H2

•Dense GH2 suppresses high-voltage breakdown –Small MFP inhibits avalanches (Paschen’s Law)

•Gas acts as an energy absorber–Needed for ionization cooling

•Only works for muons–No strong interaction scattering like protons–More massive than electrons so no showers

R. P. Johnson et al. invited talk at LINAC2004, http://www.muonsinc.com/TU203.pdf Pierrick M. Hanlet et al., Studies of RF Breakdown of Metals in Dense Gases, PAC05Kevin Paul et al., Simultaneous bunching and precooling muon beams with gas-filled RF cavities, PAC05 Mohammad Alsharo'a et al., Beryllium RF Windows for Gaseous Cavities for Muon Acceleration, PAC05Also see WG3 talks by D. Cline, S. Kahn, and A. Klier on ring coolers for other use of ideas 1 and 2

http://www.muonsinc.com/TU203.pdf


NuFact05 Plenary 8

Lab G Results, Molybdenum Electrode

H2 vs He RF breakdown at 77K, 800MHz

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600

Pressure (PSIA)

Max

Sta

ble

Gra

die

nt

(MV

/m)

Linear Paschen Gas Linear Paschen Gas Breakdown RegionBreakdown Region

Metallic Surface Metallic Surface Breakdown RegionBreakdown Region

Waveguide BreakdownWaveguide Breakdown

Hydrogen Hydrogen

HeliumHelium

Fast conditioning: 3 h from 70 to 80 Fast conditioning: 3 h from 70 to 80 MV/mMV/m


NuFact05 Plenary 9

Idea #2: Continuous Energy Absorber for Emittance Exchange and 6d Cooling

Ionization Cooling is only transverse. To get 6D cooling, emittance exchange between transverse and longitudinal coordinates is needed. In figure 2, positive dispersion gives higher energy muons larger energy loss due to their longer path length in a low-Z absorber.


NuFact05 Plenary 10

Idea #3: six dimensional Cooling with HCC and continuous absorber

• Helical cooling channel (HCC) – Solenoidal plus transverse helical dipole and

quadrupole fields– Helical dipoles known from Siberian Snakes– z-independent Hamiltonian

Derbenev & Johnson, Theory of HCC, April/05 PRST-AB


NuFact05 Plenary 11

Photograph of a helical coil for the AGS Snake11” diameter helical dipole: we want ~2.5 x larger bore


2 / 1k m

100 /p MeV c.7 , 3.5b T B T

15B br cm

30coilr cm

Due to b

Due to B

Motion due to b + B

Magnet coils

cosb z kz

;

;

h dipole z

solenoid z z

F p B b B

F p B B B

/ 1.zp p

Helical Cooling Channel. Derbenev invention of combination of Solenoidal and helical dipole fields for muon cooling with emittance exchange and large acceptance. Well-suited to continuous absorber.


G4BL 10 m helical cooling channel

RF Cavities displaced RF Cavities displaced transversely transversely

4 Cavities for each 1m-helix period4 Cavities for each 1m-helix period

B_B_solenoid=3.5 T =3.5 T B_helical_dipole=1.01 T =1.01 T B’_helical_quad=0.639 T/mB’_helical_quad=0.639 T/m


G4BL End view of 200MeV HCC

Radially offset RF cavitiesRadially offset RF cavities

Beam particles (blue) oscillating Beam particles (blue) oscillating about the periodic orbit (white)about the periodic orbit (white)


NuFact05 Plenary 15

HCC simulations w/ GEANT4 (red) and ICOOL (blue)

6D Cooling factor ~5000

Katsuya Yonehara, et al., Simulations of a Gas-Filled Helical Cooling Channel, PAC05


NuFact05 Plenary 16

Idea #4: HCC with Z-dependent fields

40 m evacuated helical magnet pion decay channel followed by a 5 m liquid hydrogen HCC (no RF)


NuFact05 Plenary 17

5 m Precooler becomes MANX

New Invention: HCC with fields that decrease with momentum. Here the beam decelerates in liquid hydrogen (white region) while the fields diminish accordingly.


NuFact05 Plenary 18

G4BL Precooler Simulation

Equal decrement case.

~x1.7 in each direction.

Total 6D emittance reduction ~factor of 5.5

Note this requires serious magnets: ~10 T at conductor for 300 to 100 MeV/c deceleration


NuFact05 Plenary 19

Idea #5: MANX 6-d demonstration experimentMuon Collider And Neutrino Factory eXperiment

• To Demonstrate

– Longitudinal cooling

– 6D cooling in cont. absorber

– Prototype precooler

– New technology • HCC

• HTS

Thomas J. Roberts et al., A Muon Cooling Demonstration Experiment, PAC05


NuFact05 Plenary 20

G4BL MANX with MICE spectrometers


NuFact05 Plenary 21

Muon Trajectories in 3-m MANX


NuFact05 Plenary 22

Phase I Fermilab TD Measurements

0

200

400

600

800

1000

1200

1400

1600

0 2 4 6 8 10 12 14 16

Transverse Field (T)

JE, (

A/m

m2 )RRP Nb3Sn round wire

BSCCO-2223 tape

14 K

Fig. 9. Comparison of the engineering critical current density, JE, at 14 K as a function

of magnetic field between BSCCO-2223 tape and RRP Nb3Sn round wire.

Licia Del Frate et al., Novel Muon Cooling Channels Using Hydrogen Refrigeration and HT Superconductor, PAC05


NuFact05 Plenary 23

MANX/Precooler H2 or He Cryostat

Figure XI.2. Latest iteration of 5 m MANX cryostat schematic.


NuFact05 Plenary 24

Idea #6: Parametric-resonance Ionization Cooling (PIC)

• Derbenev: 6D cooling allows new IC technique• PIC Idea:

– Excite parametric resonance (in linac or ring)• Like vertical rigid pendulum or ½-integer extraction• Use xx’=const to reduce x, increase x’

– Use IC to reduce x’

– Detuning issues being addressed

– chromatic aberration example

Yaroslav Derbenev et al., Ionization Cooling Using a Parametric Resonance, PAC05Kevin Beard et al., Simulations of Parametric-resonance IC…, PAC05

x


Transverse PIC schematic

/8

Absorber plates Parametric resonance lenses

Conceptual diagram of a beam cooling channel in which hyperbolic trajectories are generated in transverse phase space by perturbing the beam at the betatron frequency, a parameter of the beam oscillatory behavior. Neither the focusing magnets that generate the betatron oscillations nor the RF cavities that replace the energy lost in the absorbers are shown in the diagram.

The longitudinal scheme is more complex.


NuFact05 Plenary 26

7.20

Fri Apr 08 12:45:48 2005 OptiM - MAIN: - D:\6Dcooling\Sol chann - summ\sol_cav_cell.opt

20

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y

7.20

Fri Apr 08 12:46:30 2005 OptiM - MAIN: - D:\6Dcooling\Sol chann - summ\sol_cav_cell.opt

0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

Beta functions and phases for the solenoid triplet cell. Thin absorbers are placed at the two central focal points. In the simulations for FIG 2 the lost energy is simply replaced at the absorbers. For FIG 3, 400 MHz RF cavities shown as blue bars replace the lost energy and provide synchrotron motion. SEE BOGACZ TALK!


NuFact05 Plenary 27

Openinventor display from the G4Beamline simulation program showing the cell being modeled. The orange cylinders are solenoids as described above and the green cylinder is a solenoid of opposite polarity. The red cylinders represent 400 MHz RF cavities, the cyan disks are the energy absorbers, the large gray disks represent virtual detectors, and the green and red lines at the left end are the horizontal and vertical axes.

The same G4Beamline view as above but with transparent beam line elements so that the muon trajectories can be seen. Detuning compensation schemes are being developed.


NuFact05 Plenary 28

x

x’ Dp/p

s


NuFact05 Plenary 29

Idea #7: Reverse Emittance Exchange

• At 2.5 TeV/c, Δp/p reduced by >1000.• Bunch is then much shorter than needed to

match IP beta function• Use wedge absorber to reduce transverse

beam dimensions (increasing Luminosity) while increasing Δp/p until bunch length matches IP

• Subject of new STTR grant

30NuFact05 PlenaryRol Johnson 6/22/2005

Incident Muon Beam

EvacuatedDipole

Wedge Abs

EvacuatedDipole

Wedge Abs

Incident Muon Beam

Figure 1. Conceptual diagram of the usual mechanism for reducing the energy spread in a muon beam by emittance exchange. An incident beam with small transverse emittance but large momentum spread (indicated by black arrows) enters a dipole magnetic field. The dispersion of the beam generated by the dipole magnet creates a momentum-position correlation at a wedge-shaped absorber. Higher momentum particles pass through the thicker part of the wedge and suffer greater ionization energy loss. Thus the beam becomes more monoenergetic. The transverse emittance has increased while the longitudinal emittance has diminished.

Figure 2. Conceptual diagram of the new mechanism for reducing the transverse emittance of a muon beam by reverse emittance exchange. An incident beam with large transverse emittance but small momentum spread passes through a wedge absorber creating a momentum-position correlation at the entrance to a dipole field. The trajectories of the particles through the field can then be brought to a parallel focus at the exit of the magnet. Thus the transverse emittance has decreased while the longitudinal emittance has increased.

Figure 1. Emittance ExchangeFigure 1. Emittance Exchange Figure 2. Reverse Emittance ExchangeFigure 2. Reverse Emittance Exchange


NuFact05 Plenary 31

Seven New Ideas for Bright Beams for High Luminosity Muon Colliders

supported by SBIR/STTR grants

H2-Pressurized RF Cavities

Continuous Absorber for Emittance Exchange

Helical Cooling Channel

Z-dependent HCC

MANX 6d Cooling Demo

Parametric-resonance Ionization Cooling

Reverse Emittance ExchangeIf we succeed to develop these ideas, an Energy Frontier Muon Collider will become a compelling option for High Energy Physics! (The first five ideas can be used in Neutrino Factory designs.)


NuFact05 Plenary 32

Challenges for Muon Colliders

• Extreme 6D muon cooling essential– Need simulations and demos, more ideas

• Acceleration – Can use ILC technology with recirculation– A good case for collaboration (10xECOM at half the cost?)– Mitigation of decay electrons

• Storage Ring/detectors– Low beta designs, exploit symmetry for multiple IPs– Integrate detectors with IP designs, solve e backgrounds– Understand neutrino-induced site boundary radiation

rol johnson 6/22/2005 nufact05 plenary 1 technical challenges of muon colliders rolland p. johnson...

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