neutrino factories and muon ionization cooling channels

Neutrino Factories and

Muon Ionization Cooling Channels

D. Errede

HETEP University of Illinois

17 March, 2003

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Why build a Neutrino Factory?(Physics, of course)

What does a Neutrino Factory look like?

In particular, what is an ionization coolingchannel? What has the University of Illinois been doing with respect to a cooling channel?

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The Physics of Neutrinos• Neutrino masses

(pattern of the all fermion masses)

• Neutrino oscillation parameters

(fill in the CKM matrix for leptons)

• CP Violating processes in the Lepton Sector

(origin of baryon-antibaryon asymmetry in

our universe?)

• GUTS: relating properties of quarks and leptons

Is there a grand unified scheme?

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Fermions.ps

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The Physics of Neutrinos

13 12 13 12 13

23 12 13 23 12 23 12 13 23 12 13 23

23 12 13 23 12 23 12 13 23 12 13 23

ic c c s s e

i ic s s s c e c c s s s e c s

i is s s c c e s c s c s e c c

Standard form for Mixing Matrixconnecting weak and mass eigenstates

are the 4 real parameters that describe the mixing… 0 implies CP violation. (phase between 0 and 2

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The Physics of Neutrinos• Connect two weak eigenstates with the

evolution operator – involves Hamiltonian H0

• Use two assumptions: m1 < m2 << m3 and

dM2 = dm2atm = dm2

32 ~ dm231 we get

22 2

13( ) 1 sin (2 )sin ( )4atm

e em L

P v vE

22 2 2

23 13( ) sin (2 )sin (2 )sin ( )4atm

em L

P v vE

22 2 2

23 13( ) cos (2 )sin (2 )sin ( )4atm

em L

P v vE

And something similar but more complicated for

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The Physics of NeutrinosThe sign of m2 : solar neutrinosMatter effects : MSW (Mikheev, Smirnov, Wolfenstein)

e interacts with electrons in matter through the charged current interaction. This adds a term to the evolution operator.

There is a resonance in matter near a = 1 for typical values of sin22 (10-3 - 10-2)

“a” depends on Ne, GF, E, m2 .

= 12 , 13

22

2 2

sin 2sin 2

(cos 2 ) sin 2m

a

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The resonance applies to neutrinos for positive dm2 and antineutrinos for negative m2.

Thus we can get the mass hierarchy.

-----m3 -----------m2 -----------m1

OR-----------m2-----------m1

-----m3


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2 3 3 332

2 5 6 721

223

213

212

2

2

2

3.5 10 3.5 10 3.5 10

5 10 6 10 1 10

sin 2 1 1 1

sin 2 0.04 0.04 0.04

sin 2 0.8 0.006 0.9

0, / 2 0, / 2 0, / 2

sin 0, 1 0, 1 0, 1

sin 2 0.98 0.98 0.98

sin 2 0.04 0.04 0.04

sin 2 0.78 0.78 0

atm

reac

solar

dm

dm

.78

0.02 0.006 0.88J

3 Plausible Sets of Values

1 2 3

J - Jarlskog factor a measure of CP violatioin

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J = c12 c132 c23 s12 s13 s23 sin

Jarlskog J-factor a measure of CP violation

CP Operation: C(eL) = eL

P(eL) = eR

CP Violating Process:

For example: in vacuum

…

( )1

( )e

e

N

N

The Physics of Neutrinos : CP VIOLATION

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The Physics of NeutrinosCP Violating Processes in the Lepton Sector

Why is this interesting/fun/exciting?

A possible explanation for Baryogenesis.(So far CP violating processes in the b quark sector are insufficient to explain baryogenesis)

A SCENARIOHeavy Neutral Leptons: Majorana neutrinos through see-saw mechanism produces a light neutrino pair and a heavy neutrino pair.

N e- H+ or e+ H- (both massless particles because this is occuring before EW symmetry breaking).

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The Physics of NeutrinosN e- H+ or e+ H-

CP Violating processes provides excess of e+,,+

over e-,,- before EW phase transition.

Andrei Sakharov says we also need non-equilibrium conditions so that these processes are not driven to equalize the numbers.

Standard Model nonperturbative processes violate B, L, butconserve B-L. Churns lepton+’s into baryon material.

Thank you Boris Kayser

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The Physics of NeutrinosCP Violation in the Lepton Sector

What would this have to do with CP violating processes in the low mass neutrino sector?

We don’t know, but certainly CP violation in leptons at low mass makes CP violation in leptonic interactions at high mass scales more plausible.

GUTs: one can also imagine unifying quarks and lepton such that their CKM matrices are also related. We won’tunderstand this until all the parameters are measured.

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Neutrino Factory1. High intensity beam on target to produce particles

(’s) for a secondary beam. - Proton Driver + Target

2. Collects ’s, allow them to decay into muons, spread bunch (large E) and then perform phase rotation – Drifts + Induction Linacs

3. Reduce energy (and emittance) between induction linacs – Minicooling

4. Adiabatically change from one lattice to the next lattice – Matching Sections

5. Divide long bunch (~100 m) into short bunches that cooling section can handle - Buncher

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Neutrino Factory

6. Reduce beam emittance – Cooling Channels

7. Accelerate to energy and emittance size that the next recirculating accelerators can handle - Linac

8. Accelerate from 2.8 GeV to 20 GeV – Recirculating Linear Accelerators (RLA’s)

9. Circulate muons and let some decay on production straight – Muon Storage Ring

10. Make measurements on neutrino interactions – Near and Far Detectors

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Neutrino Factory: Proton Driver

• Based on Feasibility Study 2 version of a neutrino factory…hence set at Brookhaven Natl Lab

• AGS proton driver uses existing ring, bypasses existing booster and introduces 3 new superconducting linacs.

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Neutrino Factory: AGS Proton Driver Parameters

Total beam power (MW) 1

Beam Energy (GeV) 24

Average beam current (A) 42

Cycle time (ms) 400

Number of protons per fill 1 x 1014

Average circulating current 6

No. of bunches per fill 6

No. of protons per bunch 1.7 x 1013

Time between extracted bunches (ms) 20

Bunch length at extraction, rms (ns) 3

Peak bunch current (A) 400

Total bunch area (eV-sec) 5

Bunch emittance, rms (eV-sec) 0.3

Momentum spread, rms 0.005

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AGS Proton Driver Layout

To target station

High Intensity Source plus RFQ

116 MeV Drift Tube Linac(first sections of 200 MeV Linac)

Superconducting Linacs

400 MeV

800 MeV

1.2 GeV

Booster

AGS1.2 GeV 24 GeV

0.4 s cycle time (2.5 Hz)6 bunches

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Neutrino Factory: Superconducting Linacs

Period Cryo-Modules

Insertionat room temp

C D

A B

cavity

cavity

A B

Topology of a Period

C D

Configuration of the cavities within the cryo-modules

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Injection turns 360

Repetition rate (Hz) 2.5

Pulse length (ms) 1.08

Chopping rate (%) 65Linac average/peak current (mA) 20/30

Momentum spread +/- 0.0015Norm. 95% emittance (m rad) 12

RF Voltage (kV) 450

Bunch length (ns) 85

Longitudinal emittance (eV-s) 1.2

Momentum spread +/- 0.0048Norm. 95% emittance (m rad) 100

AGS Injection Parameters

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AGS Proton Driver

AGS : Harmonic 2418 bunches

Bunch pattern for using harmonic 24 to create 6 bunches

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Neutrino Factory : TargetEnergy on target 24 GeV, baseline beam power 1 MW,Pion momentum distribution peaks at 250 MeV,

<pT> = 150 MeV large angles coming off target….

Capture with 20 Tesla solenoid (r = 7.5cm, pTmax= 225 MeV).Actually a horn which “tapers” to 1.25 T (r= 30cm,

pTmax= 67.5 MeV)(A horn converts transverse momentum into longitudinal

momentum.)

Target: High Z maximize yield of /p

Goal of 2 1020 muon per year (107 seconds) decaying in detector direction, 50 kT, 1800 km away.

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Neutrino Factory : Target Z

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Neutrino Factory : Target

• Liquid Hg jet target chosen for maximum yield.

• Need to handle 1 – 4 MW beams.

• Want vjet = 30m/s to resupply Hg. Tests achieved 2.5 m/s to date. ( 30m/s only resupplies mercury before next

bunch on average – 6 x 2.5 Hz = 15/sec )

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Target R&D for MW-Scale Proton Beams• Carbon Target tested at AGS (24 GeV, 5E12 ppp, 100ns)

– Probably OK for 1.5 MW beam … limitation: target evaporation

Target ideas for 4 MW: Water cooled Ta Spheres (P. Sievers), rotating band (B. King), conducting target, Front-runner = Hg jet

13 Tesla

CERN/Grenoble Liquid Hg jet tests in 13 T solenoid– Field damps surface tension waves

0 Tesla BNL E951: Hg Jet in AGS beam– Jet (2.5 m/s) quickly re-establishes itself. Will test in 20T solenoid in future.

t = 0 0.75 ms 2 ms 7 ms 18 ms

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Neutrino Factory : Drifts and Induction Linacs

• Beam has large energy spread.

• Drift allows beam to spread out to a long bunch length.

• Induction linacs accerlate late muons (lower energy) and decelerate early muons (higher energy).

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Neutrino Factory : Minicooling in Drifts and Induction Linacs

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Neutrino Factory : Buncher and Cooling Channel

In order to fit muon beam into cooling lattice the Buncher separates the ~100m long trail of muons into rf buckets.

The cooling channel (Pnominal = 200 MeV) then reduces the transverse emittance to a level acceptable for acceleration to 20 GeV.

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Momentum-time distributions through the buncher

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Neutrino Factory : Buncher and Cooling Channel

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Momentum-time distributions through the buncher

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Neutrino Factory : Cooling ChannelLattice Cell

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Neutrino Factory : Cooling Channel

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Absorber : Forced Flow Design

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Approximate Equation Transverse Emittance in a step ds along the particle’s orbit:

2

3

(0.014 )1

2N N T

R

dEd GeV

ds ds E E m L

First term is the Ionization Energy Loss (Cooling) TermSecond term is the Multiple Scattering (Heating) term

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Absorber Aluminum Window Pressure/Burst Testing

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MUCOOL: UIUC Absorber Instrumentation Project

ZachConway

Mike Haney

DebbieErrede

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MUCOOL RF R&D

High Power 805 MHz Test Facility12 MW klystron

Linac-type modulator & controlsX-Ray cavern

5T two-coil SC SolenoidDark-current & X-Ray instrumentation

Need high gradient cavities in multi-Tesla solenoid field

Concept 1 – open cell cavity withhigh surface field

Concept 2 – pillbox cavity - close aperture with thin conducting foil

805 MHz Cavity built & testedSurface fields 53 MV/m achieved Large dark currents observedBreakdown damage at highest gradientsLots of ideas for improvement

805 MHz Cavity built & being tested

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Construction of FODO Quad Cooling Cell

1/2 1/2 abs F rf D rf F rf D abs

COOLING CELL PHYSICAL PARAMETERS:

Quad Length 0.6 mQuad bore 0.6 mPoletip Field ~1 TInterquad space 0.4 - 0.5 mAbsorber length 0.35 m *RF cavity length 0.4 - 0.7 m*Total cooling cell length 4 m

*The absorber and the rf cavity can be made longer if allowed to extend into the ends of the magnets.

Or, more rf can be added by inserting another FODO cell between absorbersIn this design For applications further upstream at larger emittances, this channel can

support a 0.8 m bore, 0.8 m long quadrupole with no intervening drift without matching to the channel described here.

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• MOVIE• Quad cooling movie / Kyoko Makino• GSview - View – fit window – full screen – page

down - escape

Quad Cooling Beam Dynamics GroupUIUC – Debbie Errede, Kyoko Makino, Kevin PaulMSU – Martin BerzFERMILAB – Carol Johnstone, A. Van Ginneken

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Recirculating Linear Accelerators (RLAs)

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Recirculating Linear Accelerators (RLAs) :Preaccelerator

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Recirculating Linear Accelerators (RLAs) :Injection Chicane from Linac to RLA

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Recirculating Linear Accelerators (RLAs) :Arcs

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Recirculating Linear Accelerators (RLAs) :Arcs

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Recirculating Linear Accelerators (RLAs)

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Recirculating Linear

Accelerators (RLAs)

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Muon Storage Ring

• Maximize number of muon on production straight fs = Ls/C• Minimize length of arcs

Real Estate is an important issue here.

• Larger energy decreases angular beam spread (1/) allowing more neutrinos on “target” = detector

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Real Estate is an important issue here! : ARCS

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COSY : Kyoko Makino (UIUC), Martin Berz (MSU)

Tracking performed on a single arc cell.

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COSY : Kyoko Makino (UIUC), Martin Berz (MSU)

Same Lattice with End Fields added

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Conclusions

• Neutrino physics is fascinating, beautiful and accessible.• A Muon Collaboration exists that has done two feasibility studies on neutrino factory designs and R&D on targetry, absorbers, 800 (200) MHz NCRF cavities, solenoid magnets, and constructing a test area off of the Fermilab 400 MeV/c proton linac. Design studies for Ring Coolers, FFAG machines, Emittance Exchange are ongoing.• Alternative technologies pursued at CERN and in Japan.• Future plans include the construction of a cooling channel lattice cell to be tested in a low intensity muon beam at Rutherford Labs near Oxford, England.

neutrino factories and muon ionization cooling channels

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