1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

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1 Ionization Cooling – neutrinos, Ionization Cooling – neutrinos, colliders and beta-beams colliders and beta-beams David Neuffer July 2009
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Transcript of 1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

Page 1: 1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

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Ionization Cooling – neutrinos, Ionization Cooling – neutrinos, colliders and beta-beamscolliders and beta-beams

David Neuffer

July 2009

Page 2: 1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

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OutlineOutline

Front End and Cooling – IDS neutrino factory Study 2A – ISS baseline example

•Target-capture, Buncher, Rotator. Cooler Shorter bunch train example(s)

•nB= 10, Better for Collider; as good for ν-Factory

Variation – 88 MHz

Rf cavities in solenoids – major constraint? up to 15MV/m, ~2T Alternatives

•Use lower fields (B, V’), use “magnetic insulation” ASOL lattice, use gas-filled rf cavities

Large Emittance Muon Collider option Low-Energy Cooling discussion

ERIT results Ion cooling for Beta-beams

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Official IDS layoutOfficial IDS layout

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Neutrino Factory-IDS

For IDS need baseline for engineering

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ISS Study 2B baselineISS Study 2B baseline

Base lattice has B=1.75T throughout buncher and rotator rf cavities are pillbox grouped in same-frequency

clusters• 7 to 10 MV/m Buncher; 12.5 Rotator

with 200μ to 395μ Be “windows”,• 750μ windows in “Rotator”

Cooling Lattice is alternating-solenoid with 0.75 half-period 0.5m pillbox rf cavity 1cm LiH absorbers 15.25MV/m cavities

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IDS - Shorter VersionIDS - Shorter Version

Reduce drift, buncher, rotator to get shorter bunch train:

217m ⇒ 125m 57m drift, 31m buncher, 36m rotator Rf voltages up to 15MV/m (×2/3)

Obtains ~0.26 μ/p24 in ref. acceptance Similar or better than Study 2B

baseline Better for Muon Collider

80+ m bunchtrain reduced to < 50m Δn: 18 -> 10

-30 40m

500MeV/c

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Shorter Buncher-Rotator settings Shorter Buncher-Rotator settings

Buncher and Rotator have rf within ~2T fields rf cavity/drift spacing same

throughout (0.5m, 0.25) rf gradient goes from 0 to 15

MV/m in buncher cavities Cooling same as baseline

ASOL lattice 1 cm LiH slabs (3.6MeV/cell) ~15MV/m cavities also considered H2 cooling

Simulated in G4Beamline optimized to reduce # of

frequencies Has 20% higher gradient

ASOL lattice

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Rf in magnetic fields?Rf in magnetic fields?

Baseline has up to 12 MV/m in B=1.75T (in 0.75m cells)

short version has up to 15MV/m in B=2.0T

Experiments have shown reduced gradient with magnetic field

Results show close to needed ? 14MV/m at 0.75T on cavity wall half-full or half-empty ?

Future experiments will explore these limits will not have 200 MHz in constant

magnetic field until summer 2010 Open cell cavities in solenoids?

did not show V’ /B limitation

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Solutions to possible rf cavity Solutions to possible rf cavity limitationslimitations

For IDS, we need an rf cavity + lattice that can work

Potential strategies: Use lower fields (V’, B) Use Open-cell cavities?

Use non-B = constant lattices• alternating solenoid

Magnetically insulated cavities• Is it really better ???

• Alternating solenoid is similar to magnetically insulated lattice

Shielded rf lattices• low B-field throughout rf -

Rogers Use gas-filled rf cavities

• but electron effects?

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Lower-field (?) VariantLower-field (?) Variant

Use B=const for drift + buncher Low-gradient rf ( < 6 MV/m) B= 1.5 to 2.0 T ?

Use ASOL for rotator + Cooler (and/or H2 cavities) 12 MV/m rf Rotator 15 MV/m cooler 0.75 half-cells

Simulation: fairly good acceptance Lose some low energy mu’s

• bunch train shortened

~0.25 μ/24p after 60m H2 cooling

~0.19 μ/24p after 60m LiH cooling

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Change cavity material-PalmerChange cavity material-Palmer

Be windows do not show damage at MTA no breakdown?

Model: Energy deposition by electrons crossing the rf cavity causes reemission on the other side

less energy deposition in Be higher rf gradient threshold

~2× gradient possible with Be cavities ?? calculated in model extrapolation to 200MHz ?

B

electrons

2R

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Variant: “88” MHz Front end Variant: “88” MHz Front end

Drift ~90m Buncher ~60m

166→100 MHz, 0→6MV/m

Rotator ~58.5m 100→86 MHz, 10.5 MV/m

Cooler ~100m 85.8MHz, 10 MV/m 1.4cm LiH/cell ASOL

10 m ~80 m

FE

Targ et

Solenoid Drift Buncher Rotator Cooler

~60m 60m ~100 m

p

π→μ

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88 MHz example88 MHz example

Performance seems very good ~0.2 μ/p24

smaller number of bunches > ~80% in best 10 bunches

Gradients used are not huge, but probably a bit larger than practical up to ~10 MV/m ~2T magnetic fields

With 10 MV/m (0.75m cells) probably not free of breakdown problems

redo with realistic gradients 6MV/m ?

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Plan for IDSPlan for IDS

Need one design likely to work for Vrf/B-field rf studies are likely to be inconclusive

Hold review to endorse a potential design for IDS – likely to be acceptable (Vrf/B-field)

April 2010 ?

Use reviewed design as basis for IDS engineering study

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Cooling for first muon colliderCooling for first muon collider

Important physics may be obtained at “small” initial luminosity μ+μ- Collider

μ+ + μ- -> Z* , HS L > 1030 cm-2s-1

Start with muons fron neutrino factory front end:

3 × 1013 protons/bunch 1.5× 1011

μ/bunch• ~12 bunches – both

signs! εt,rms, normalized ≈ 0.003m

εL,rms, normalized≈ 0.034m Accelerate and store for

collisions Upgrade to high

luminosity

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Proton Source: X -> Proton Source: X -> νν-Factory/-Factory/μμ-Collider-Collider

Project X based proton driver

8 GeV SRF linac , 15 Hz 1.2×1014/cycle

H- inject full linac pulse into new “Accumulator” “small” dp/p Large εN6π =120π mm-mrad

Bunch in harmonic 4 adiabatic OK !! (2kV)

Transfer into new “Buncher” 100kV h=4 1250 turns (2ms) short ~1 m bunches !! 3×1013/bunch

• BF = 0.005

• δν = 0.4

8GeV LinacAccumulator

Buncher

p tot

2F N

3r N

2 B

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Large Emittance Muon ColliderLarge Emittance Muon Collider

Parameter Symbol Value

Proton Beam Power Pp 2.4 MW

Bunch frequency Fp 60 Hz

Protons per bunch Np 3×1013

Proton beam energy Ep 8 GeV

Number of bunches nB 12

+/-/ bunch N 1011

Transverse emittance t,N 0.003m

Collision * * 0.05m

Collision max * 10000m

Beam size at collision x,y 0.013cm

Beam size (arcs) x,y 0.55cm

Beam size IR quad max 5.4cm

Collision Beam Energy E+,E_ 1 TeV (2TeV total)

Storage turns Nt 1000

Luminosity L0 4×1030

Proton Linac 8 GeV

Accumulator,Buncher

Hg target

Linac

RLAs

Collider Ring

Drift, Bunch, Cool200m

Detector

Use only initial “front-end” coolingAccelerate front-end bunch train; collide in ring

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Must be upgradeable to “high-Must be upgradeable to “high-luminosity”luminosity”

MEMC Upgrades reduce εt to 0.001m

• initial part of HCC 1300MHz rf combine 12 ->

1bunch L -> 3 1032

High luminosity Cool to 0.000025

Parameter Symbol HEMC MEMC LEMC Value

Proton Beam Power Pp 2.4 MW 4MW 4MW

Bunch frequency Fp 60 Hz 60Hz 15Hz

Protons per bunch Np 3×1013 5×1013 4×1013

Proton beam energy Ep 8 GeV 8 GeV 50 GeV

Number of bunches nB 12 1 1

+/-/ bunch N 1011 1.5×1012 2×1012

Transverse emittance t,N 0.003m 0.001m 0.000025

Collision * * 0.06m 0.04 0.01

Beam size at collision x,y 0.013cm 0.0063cm 0.0005cm

Beam size (arcs) x,y 0.55cm 0.32cm 0.05cm

Beam size IR quad max 5.4cm 3.2cm 0.87cm

Collision Energy E+,E_ 1 TeV (2TeV total)

1 TeV 1 TeV

Luminosity turns nt 1000 1000 1000

Luminosity cm-2s-1 L0 4×1030 2.7×1032 1.5×1034

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Other cooling uses- not just high-energy Other cooling uses- not just high-energy muons!muons!

. Stopping beam (for 2e, etc.) C. Ankenbrandt, C. Yoshikawa

et al., Muons, Inc.

For BCNT neutron source Y. Mori - KURRI

For beta-beam source C. Rubbia et al

g

P (MeV/c)

gL

0

-1

(dE/ds)/E= gL(dp/ds)/p

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Virtual detector

r = 3 m

end of NF/MC drift regionμ± & π± from 100k POT MERIT-like targetry

Revisit Use of NF/MC Front End to Stop Muons with Momentum-dependent HCC

HCC

matching (not done)100k Mu-’s w/ Bent Sol Spread at start of HCC.

Mu-’s midway to end of HCC (20,836/100,000)

Mu-’s at end of HCC. Displayed is 5398/100k, but stopping rate is 3519/100k.

170

25

P(MeV/c)

μ−’s stopped

Potential to enhance yield via P vs. y correlation in bent solenoid.

C Yoshikawa

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FFAG-ERIT neutron source FFAG-ERIT neutron source (Mori, (Mori, KURRI)KURRI)

Ionization cooling of protons/ ions is unattractive because nuclear reaction rate energy-loss cooling rate

But can work if the goal is beam storage to obtain nuclear reactions Absorber is beam target, add rf

ERIT-P-storage ring to obtain neutron beam (Mori-Okabe, FFAG05)

10 MeV protons (β = v/c =0.145) 10Be target for neutrons 5µ Be absorber, wedge (possible) δEp=~36 keV/turn

Ionization cooling effects increase beam lifetime to ~ 1000 turns not actually cooling

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Observations of “Cooling”-PAC09Observations of “Cooling”-PAC09

ERIT ring has been operated

Beam lifetime longer than without energy-recover rf agrees with ICOOL simulation

Beam blowup is in agreement with simulation multiple scattering heating in

agreement with ICOOL

Page 23: 1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

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ββ-beam Scenario -beam Scenario (Rubbia et al.)(Rubbia et al.)

β-beam – another e source Produce accelerate, and store unstable

nuclei for -decay Example: 8B8Be + e++ν or 8Li8Be + e-

+ ν*

Source production can use ionization cooling Produce Li and inject at 25 MeV nuclear interaction at gas jet target

produces 8Li or 8B• 7Li + 2H 8Li + n

• 6Li + 3He 8B + p Multiturn storage with ionization

“cooling” maximizes ion production 8Li or 8B is ion source for β-beam

accelerator• C. Rubbia, A. Ferrari, Y. Kadi, V.

Vlachoudis, Nucl. Inst. and Meth. A 568, 475 (2006).

• D. Neuffer, NIM A 583, p.109 (2008)

e

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ββ-beams example: -beams example: 66LiLi + + 33HeHe 88BB + + n n

Beam: 25MeV 6Li+++ PLi =529.9 MeV/c Bρ = 0.59 T-m; v/c=0.094 Jz,0=-1.6

Absorber:3He -gas jet ? dE/ds = 110.6 MeV/cm ,

If gx,y,z = 0.13 (Σg = 0.4), β┴ =0.3m at absorber

Must mix both x and y with z εN,eq= ~ 0.000046 m-rad,

σx,rms= ~2 cm at β┴ =1m

σE,eq is ~ 0.4 MeV

Could use 3He as beam 6Li target ( foil or liquid)

,

2 2

, 22

z a

sN eq dE

x p R ds

z E

J am c L

22 2 4 3

e p β2E,eq 2

L

(m c )(am c )β γσ = 1-

2J ln[]

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ββ-beams alternate: -beams alternate: 66LiLi++33HeHe 88BB + n + n

Beam: 12.5MeV 3He++ PLi =264 MeV/c Bρ = 0.44 T-m; v/c=0.094

Absorber: 6Li - foil or liquid jet dE/ds = 170 MeV/cm, LR=155cm

•at (ρLi-6= 0.46 gm/cm3)

Space charge 2 smaller If gx = 0.123 (Σg

= 0.37), β┴ =0.3m at absorber εN,eq= ~ 0.000133m-rad

σx,rms= 2.0 cm at β┴ =0.3m,

σx,rms= 5.3 cm at β┴ =2.0m

σE,eq is ~ 0.3 MeV ln[ ]=5.34

,

2 2

, 22

z a

sN eq dE

x p R ds

z E

g am c L

22 2 4 3

e p β2E,eq 2

L

(m c )(am c )β γσ = 1-

2g ln[]

Page 26: 1 Ionization Cooling – neutrinos, colliders and beta-beams David Neuffer July 2009.

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Cooling Ring for Beta-BeamsCooling Ring for Beta-Beams

Assume He-3 beam Bρ=0.44T-m, β=0.094

Cooling ring parameters C =12m (?)

Absorber 0.01 cm Li wedge βt = ~0.3m, η= ~0.3m

rf needed 2 MV rf

Injection charge strip He+ to He++

(?) Extraction

kicker after wedge NuFACT09

miniworkshop: July27-29

Solenoid1.38T-m

Cooling wedgeβ=0.3m, η=0.3m

rf

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SummarySummary

Rf in magnetic field problem must be addressed Need rf configuration that can work with high

confidence

Need to establish scenario Use as basis for engineering study

Further meetings/studies NuFACT 2009 miniworkshop at Fermilab (July 27-28) front end and beta-beam cooling

•9-11am WH3NE

•1:30-4PM Front End Review

•April 2010?

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Future Funding … ??Future Funding … ??