Ultra slow muon; its production and application to material and particle … · 2013-06-10 · 2013. 06. 05 at Hongo Sohtaro Kanda / Saito Laboratory Ultra slow muon; its production

2013. 06. 05 at Hongo

Sohtaro Kanda / Saito Laboratory

Ultra slow muon; its production and application to material and particle physics

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[email protected]

mailto:[email protected]


2013. 06. 05 at Hongo. Prof. Leggett’s Intensive Course

Before we start... self introduction■ Sohtaro Kanda

‣ D1 student of Saito Naohito Laboratory

‣ Major is experimental particle physics

■ Scientific background

‣ Spintronics : Magnetization of superlattice

‣ Particle physics : Muon dipole moment

■ Research activities (in KEK, J-PARC, and RIKEN)

■ muon g-2/EDM measurement in J-PARC

■ muonium hyperfine splitting measurement in J-PARC

■ Phenix experiment in Brookhaven National Laboratory

2


Overview■ Introduction

‣ Muon as a spin probe

‣ Muon spin rotation method

■ Ultra slow muon

‣ Production scheme

■ Applications

‣ Material physics

‣ Particle physics

■ Our study for ultra slow muon beam

3


Introductionmuon and muSR

4


Muon’s property■ What is muon?

- Charged lepton of 2nd generation

- spin = 1/2

- charge = e (elementary charge)

- mass = 200 ×electron mass

- life = 2197 nsec

‣ decays into an electron and neutrinos

๏ Parity conservation is violated in muon decay via the weak interaction

5

list of standard model particles

muon decay


Usage of muon■ Particle physics

■ Trigger for collider experiment

■ Probe for new physics

■ Material physics

■ Probe for local magnetization

‣ muon spin rotation method

■ Geography

■ Muon tomography for volcano imaging

6

Phenix Collaboration, “PHENIX detector overview”, NIM A., 499, 2-3(2003)469-479

Geophys. J. Int. (2012) 190, 1008–1019

mµ

me� 200( )


Muon production from pion decay■ How to produce muon?

■ Proton beam -> Pion production -> Pion decay

7

Proton beamGraphite

Positive Pion

Negative Pion

pion decay (lifetime : 26 nsec)

muon decay (lifetime : 2197 nsec)

p + p� p + n + �+

�+ � µ+ + �µ

µ+ � e+ + �e + �µ

reaction between proton beam and nuclear


Parity violation in muon decay■ The relation between the angular distribution of positron

from muon decay (V-A interaction)

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arXiv:1007.3814 [quant-ph]

muonless backward positrons

all energy maximum energy

more forward positronsspin

momentum

decay

http://arxiv.org/abs/1007.3814

http://arxiv.org/abs/1007.3814


Muon spin rotation 9

forward counterNf hits of positron

backward counterNb hits of positron

H

muon

momentumspin

target

electronsspin

muon spin’s Larmor precession

magnetic field in the targetdecay asymmetry

muonpositron

A =Nf �Nb

Nf + Nb

(a) (b)

(c) (d)

muon stops inside of the

target


Muon spin rotation (muSR) 10

Photo http://www.kek.jp/ja/NewsRoom/Highlights/20130124170000/

Spectrometer for muSR experiment in J-PARC

Positron counter Sample

no field

uniform

distributed

Asym

met

ryAs

ymm

etry

Asym

met

ry

Time

Time

Time

Typical timing resolution : 1 nsB-field sensitivity : 0.04 mTSample size : ο(10) mm2Sample thickness : more than 100 um

http://www.kek.jp/ja/NewsRoom/Highlights/20130124170000/

http://www.kek.jp/ja/NewsRoom/Highlights/20130124170000/


Difficulty of muSR 11

muon

target(a)

muon

target(b)muon

momentumspin

target(c)

How to inject “tunable” low energy muon?

The solution is “Ultra slow muon”

Incident muon’s kinetic energy is fixed

It is difficult to investigate the “surface” or “interface”

spin momentum

spin momentum


Ultra slow muon;its production and application

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2013. 03.27 at JPS Annual Meeting, Sohtaro Kanda/The Univ. of Tokyo

Ultra cold muon beam 13

■ High intensity is challenging‣ Our study : development of muonium production target

Surface muon(4 MeV)

Target Ionization lasersMuonium

Ultra slow muon(0.2 eV)

LINAC(320 MeV)

Initial accel.(5.6 keV)

RFQ(0.3 MeV)

■ Muon beam with extreme small transverse dispersion

Muonium is a bound state of muon and electron


Laser ionization of muonium■ 355 nm wavelength laser for muonium excitation

■ 122.09 nm Lyman-α laser for muonium ionization

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Spectrochimica Acta Part B 58 (2003) 1019–1030Hyperfine Interactions, 04-1997, Volume 106, Issue 1-4, pp 237-244

4 waves mixing in Kr gas cell

high laser intensity is required for high efficiency for ionization

http://link.springer.com/journal/10751

http://link.springer.com/journal/10751

http://link.springer.com/journal/10751/106/1/page/1

http://link.springer.com/journal/10751/106/1/page/1


Ultra slow muon production■ Experimental apparatus of muonium production and ionization

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Phys. Rev. Lett. 74, 4811–4814 (1995)

# of ionized particle v.s. laser wavelength

Principle had been proofed. However, we need ×4 muonium yield for our experiment

(will be talked in later)


Application : Material physics■ Electron state investigation on the surface or interface

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Ultra slow muon’s injection depth resolution ~ 1 nm

Injection energy is tunable

It is able to investigate the electron states from the

surface to the bulk region

＋

bulk region100 nm~ 20 keV~

surface0.2 nm~1.0 nm~50 eV

intermediate region1.0 nm~100 nm1 keV~20 keV

Ultra slow muon


Topological Insulator■ Exotic physics on a topological insulator

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REVIEWS OF MODERN PHYSICS, 83, OCTOBER–DECEMBER 2011

Can be detected by ultra slow muon?

magnetic monopole axion (phase transition of axion field)

arXiv:1112.1414v2 [cond-mat.mes-hall]

B=0 Eex<Ecrit

B Eex>Ecrit

TI

TI

Ein

Ein


■ Precision measurement of muon’s dipole moment in J-PARC

‣ MDM(g-2) : There is 3.3 σ discrepancy between theory and experiment

‣ EDM : Violates CP asymmetry and it is expected for matter universe.

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Storage ring+Positron tracker

Surface muon28 MeV/c

Surface muon production

Laser ionization

Muonium

Ultra cold muon beam

Re-accelerationUltra cold muon beam

Ultra slow muon0.2 eV

Application : Particle physics


Ultra cold muon beam 19

■ What is the benefit of ultra cold muon beam?

■ Comparison of our method and conventional method

EoM of spin precession


Our experiment andDevelopment of ultra slow muon source

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J-PARC■ Japan Proton Accelerator Research Complex

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cited from http://j-parc.jp/

Experimental facility with muon beam and neutron beam

Particle production in J-PARC

http://j-parc.jp

http://j-parc.jp


MLF MUSE■ Material Life science Facility, MUon Science Establishment

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cited from http://j-parc.jp/researcher/MatLife/en/instrumentation/ms.htmlhttp://j-parc.jp/researcher/MatLife/en/instrumentation/ns.html

for neutron sciencefor muon science

g-2/EDM

Ultra slow muonmuSR

http://j-parc.jp/researcher/MatLife/en/instrumentation/ms.html

http://j-parc.jp/researcher/MatLife/en/instrumentation/ms.html

http://j-parc.jp/researcher/MatLife/en/instrumentation/ns.html

http://j-parc.jp/researcher/MatLife/en/instrumentation/ns.html


Super Omega Beamline■ New beamline for ultra slow muon

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Y Miyake et al 2011 J. Phys.: Conf. Ser. 302 012038

Experimental area

2 bending magnets for momentum selection

Quadrupole magnets for beam focusing

DC separator for positron removal

Ultra slow muon production


Our study subject

■ Realization of high intensity ultra slow muon beam

‣ We need higher yield of muonium!

■ High performance production target is required

■ Development of a muonium production target

‣ Also we need muonium counting detector

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simulation study of muonium production

development of muonium detector

muonium production experiment＋ ->


Muonium production simulation 25

X (cm)-10 -8 -6 -4 -2 0 2 4 6 8 10

Y (c

m)

-10

-8

-6

-4

-2

0

2

4

6

8

10Entries 1369359Mean x 2.372Mean y 0.01766RMS x 3.099RMS y 1.965Integral 1.364e+06 0 0 0 0 1363516 5843 0 0 0

0

200

400

600

800

1000

1200

Entries 1369359Mean x 2.372Mean y 0.01766RMS x 3.099RMS y 1.965Integral 1.364e+06 0 0 0 0 1363516 5843 0 0 0

y0+Py0*42/1000:x0+Px0*42/1000+4

Muon beam Profile Muon Stopping distribution

μ+μ+

e-μ+

MuSurface muon Target

Lasers Target surface


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Muonium in vacuum

μ+μ+

e-μ+

Mu

Muon diffusion

Surface muon Target

Target surface Lasers

Muonium production simulation

2013. 02.22 at PCPV2013

Simulation v.s. Experiment 27

Time (µsec)

# of

muo

nium

Muonium distribution in

vacuum

■There is good consistency between MC and Experiment

■It is important to evaluate muonium emission in higher accuracy

S. Kanda, PCPV2013

A. P. Mills, Jr. et al., Phys. Rev. Lett. 56, (1986) 1463

2013. 02.22 at PCPV2013

Design of muonium production target

■ More surfaces, more yield -> micro-fabrication on surface

‣ ×4 muonium yield is expected

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Designed target（Fabrication is possible by femto second pulse laser）

○ : Large surface area→More muoniums escape○ : Short distance to laser→Less decay loss

S. Kanda, Nucl. Phys. B, Proc., TAU2012(to be published)

2013. 02.22 at PCPV2013

Muonium production experiment 29

S. Kanda et al., KEK-MSL Progress Report 2012 (to be published)

2013. 02.22 at PCPV2013

Muonium production experiment 30


We need high performance positron detector for muonium counting

2013. 02.22 at PCPV2013

Detector Prototypes ■ Motivation1：Data acquisition for decision of detector components

■ Motivation2：Track back demonstration

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TB proto. Eff. proto.

6ch(front)+30ch(back)for e+ tracking

2 triggers + detector under testEff. ≡ Triple coin./Trigger coin.

Scintillator Width : 2 mmScintillator Thickness : 0.5 mm, 1.0 mm, 2.0 mm

2013. 02.22 at PCPV2013

Experimental setup 32


2013. 02.22 at PCPV2013

Results of the detector development study 33


Demonstration of the detector performance Simulated muonium detection

S. Kanda, PCPV2013

We can measure space-time distribution of muonium by using our new detector!

Muonium background


■ Muon is a good probe for ...

- Local magnetization in a material

- Beyond Standard Model Physics

■ Ultra slow muon is...

- The solution for muSR’s depth resolution problem

- The key component of muon dipole moment measurement

■ We are...

- Developing a muonium production target

- Developing a muonium counting detectors

■ Muonium production experiment in J-PARC is ongoing!

Summary 34


Thank you for listening! Sohtaro Kanda/Saito [email protected]

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Ultra slow muon; its production and application to material and particle … · 2013-06-10 · 2013. 06. 05 at Hongo Sohtaro Kanda / Saito Laboratory Ultra slow muon; its production