manx at mta andreas jansson fermilab. 2/14/2007lemc workshop, february 12-16, 2007a. jansson 2...

MANX at MTA

Andreas JanssonFermilab

2/14/2007 LEMC Workshop, February 12-16, 2007 A. Jansson 2

Foreseen MCTF Experimental R&D

• Low energy proton beam to MTA– Foreseen since before, but delayed due

to budgetary restrictions. We pushed for it, but not part of MCTF proposal.

• Proton intensity upgrade for MTA– Part of MCTF proposal to Director

• Muon beam to MTA– Initially to test Helical Cooling Channel,

which is also part of MCTF proposal.


6DMANX

[Cummings et al, “A SIX-DIMENSIONAL MUON BEAM COOLING EXPERIMENT”, EPAC06]

Helical Cooling Channel

Default option: stick it in the MICE beamline at RAL… … but, maybe there is another way to do it.


First, a disclaimer

• Investigating a muon beam experiment does not constitute a decision.

• The (HCC) demonstration experiment should be done the way that makes most sense.

• We should agree on what we want to demonstrate, and to whom!

• Need simulations to make informed decision.– Single particle a la MICE by Muons Inc?– Macro-particle (pencil beam) by Fermilab MCTF– Other bright ideas by anyone?– Initial results by PAC07(?)


Why at MTA?

• MTESTvery low intensity, energy of muons on the high end, issues with radiation shielding and compatibility with ongoing ILC tests, to cryo, rate limited by Main Injector availability

• MiniBoonewell matched energy, but no space (need new civil construction), no cryo, unclear availability (existing programme), relies on Booster availability

• MTA restricted space, muon energy on the low end, high beam availability, facility dedicated to muon R&D, cryo will be available

• (Pbar debuncher)not considered (compatibility with proton plan?), but if MECO becomes a reality should reconsider

NB. A lot of the discussion is independent of location.

D. Broemmelsiek


Muon beam at MTA?

• Can we make a muon beam at MTA with suitable momentum and sufficient intensity?


Target, pion capture and decay channel

• Carbon target in 6T solenoid.• Quadrupole decay channel (PAC’01

design)N. Mokhov/V. Balbekov


Preliminary simulation results

• MARS model of target and decay channel (PAC’01 design 42m long).

• Working on simulations with shorter channel.

• Total yield ~1e-6.• Emittance (rms,

unnormalized) of ~500 Pi mm mrad -7.5 -5 -2.5 0 2.5 5 7.5 10

xcm-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

pVeGc

-7.5 -5 -2.5 0 2.5 5 7.5 10xcm

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

pVeGc

N. Mokhov/V. Balbekov


Beam purity (preliminary)

• Main contaminant is π+ (50%), π- (~1%) and µ- (~1%).

• Protons are absorbed in target.

• Need to separate pions from muons

• Use a Tevatron electrostatic separator (Wien filter)?– 2.5m long, 2MV/m,

gives a differential kick of ~10mrad

– Many will be available, soon…

• Alternative: thin target to range out pions.– Would affect muon

momentum…

0 0.1 0.2 0.3 0.4Momentum GeVc0

0.2

0.4

0.6

0.8

1

1.2

dleiY1e701

VeMc

Pi+Mu+


Decay Channel in G4Beamline

• Implementing the Balbekov/Mokhov target and decay channel in G4BeamLine for comparison

• Eventually, should implement entire experimental setup

Work in progress


Muon yield in G4Beamline vs MARS

• 400 MeV (kinetic energy) linac protons on 40cm carbon target in B=6T.

• Detector at 0.5m.• So far, not very good agreement…

G4BeamLine v1.06

MARS

Work in progress


Preliminary MTA Muon Beam Parameters

• 250 MeV/c average muon momentum, 50MeV/c momentum spread

• ~1e6 muons per pulse maximum (peak rate of ~2e11 µ+/second).

• Expect to loose two orders of magnitude in reducing transverse emittance (simulations underway).


Macro-particle experiment

• It is very hard to measure the emittance of a large beam, especially in the presence of non-linear forces.

• Use “pencil beam” as macro particle and scan the aperture!

• Beam position and angle easy to control and measure.

• Can use relatively simple detectors (10000 MIPS vs 1 MIPS).

• Insensitive to muon decays (average position is insensitive to 1 particle out of 10000).

• Can measure transverse non-linearities and acceptance.


4D Raster Scan

x’

x

x’

x

y’

y

y’

y

E

t

E

t

Beam

“Pencil beam”

Macro-particle Macro-particle


5D Raster Scan

x’

x

x’

x

y’

y

y’

y

“Pencil beam”

Macro-particle Macro-particle

E

t

E

t

Macro-particle


Expected MANX cooling

• Note that when matching is included, MANX is currently heating longitudinally!

• Could matching be improved?

coupling

MatchingMANX

Matching

K. Yonehara


G4Beamline simulation

• Cooling term is given by the reduction in volume of 5D voxels bounded by raster points.

• Heating term is given by the beam emittance at the exit of the HCC (assuming zero initial emittance and far from equilibrium).

• Equilibrium emittance can be calculated!

x [m]y [m

]Distribution of initial zero emittance beam after passing thru HCC+matching (no RF)

G4beamline model from K. Yonehara


Pencil beam experiment layout

Transverse collimation Momentum

collimation

Energy distribution measurement

Position and anglemeasurement

Steering dipoles

Electrostaticseparator?

Decay channel

HCC


Schematic

beam in beam out

Spectromete

r Steering

dipoles

Position and angle

measurem

ent

Spectromete

r

Position and angle

measurem

ent

(plus emittance)

Position inside

HC

C


First pass at Optics

• Dispersion free bend with space for momentum selection and momentum spread measurement.

• Matching into HCC with space for steering dipoles and diagnostic.

• Need to refine and add eg electrostatic separator.

• Need to simulate in eg G4BeamLine.


Instrumentation

•Fiber tracker developed by PPD for MTEST•Single MIP sensitivity depending on fiber size and electronics•Can probably be used directly in beam lines•May be modified for use in LHe?

H. Nguyen et al


What About the 6th Dimension?

• Near isochronous HCC is important for adding RF.

• Lowering the muon rate, one could do a dedicated run to measure time-of-flight distribution as well.

• Need to investigate sensitivity and error sources.

Σ

Σ

start

stop

µ+


Possible extensions to the program

• “Simplest” way to add RF to HCC is to interleave HCC sections with RF sections.

• Could be added as a second phase.

• May also test pressurized RF only with muon beam.

HCC with matching sections

HCC with matching sections + RF

Pressurized RF only


To do (not exhaustive list)

• Investigate validity of macro-particle assumption (maximum emittance).

• Re-optimize HCC for 250MeV/c.• Improved design and simulations of

target, decay channel and pion separation.

• Refine the experimental setup, including beamline optics, collimator design and detectors.

• Simulate, simulate, simulate (to understand eg systematics)…


Conclusions

• Fermilab director supportive of Muon Collider work – Hopefully, this moral support will eventually

translate into a fresh infusion of money.• As part of the MCTF work, we are

investigating the possibility of a muon beam at MTA.– Could be used to test the HCC prototype magnet,

but also for other things.– We plan to study the performance of such an

experiment in more detail, and (hopefully) compare to alternatives.

• Could use help, if anyone’s interested…

manx at mta andreas jansson fermilab. 2/14/2007lemc workshop, february 12-16, 2007a. jansson 2...

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