Muonium Hyperne Structure Measurement in a Zero/High Magnetic Field - - PowerPoint PPT Presentation

Muonium Hyperne Structure Measurement 
 in a Zero/High Magnetic Field 
 at J-PARC

Shoichiro Nishimura / KEK IMSS for the MuSEUM Collaboration

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

MuSEUM Collaboration

2

• M. Abe, Y. Fukao, Y. Ikedo, T.Ito, R. Kadono,
• N. Kawamura, A. Koda, N. Kurosawa, T. Mibe,
• Y. Miyake, K. Nagamine, S. Nishimura,
• T. Ogitsu, N. Saito, K. Sasaki, Y. Sato,
• K. Shimomura, P. Strasser, M. Sugano,
• A. Toyoda, K. Ueno, H. Yamaguchi,
• A. Yamamoto, T. Yamazaki, M. Yoshida
• M. K. Kubo
• K. Ishida, M. Iwasaki, O. Kamigaito,
• S. Kanda, Y. Ueno
• M. Aoki,
• D. Tomono
• H. Iinuma
• E. Torikai
• K. Kawagoe, J. Tojo, T. Yamanaka,
• T. Yoshioka
• S. Fukumura,
• M. Kitaguchi,
• H. Tada
• K. S. Tanaka
• D. Kawall
• S. Choi,
• C. Park
• Y. Matsuda, S. Seo, T. Tanaka,
• H. A. Torii, H. Yamauchi, H. Yasuda
• K. M. Kojima

MuSEUM | Muonium Spectroscopy Experiment Using Microwave

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Muonium HFS

Muonium|Bound state of µ+ and e−

3

• 0.5

Magnetic Field (T) Energy (GHz) (F, MF) (1, 1) (1, 0) (1, −1) (0, 0) Δν (Me, Mμ) (1/2, 1/2) (1/2, −1/2) (−1/2, −1/2) (−1/2, 1/2) Δν12 Δν34

High Field (HF) Zero Field (ZF)

ν12 + ν34 = ∆ν

ν12 − ν34 ∝ µµ µp

Experimental value Δν ZF | 4 463 302.2(14) kHz (310 ppb) HF | 4 463 302.765(51)(17) kHz ( 12 ppb)

• Phys. Lett. B59 (1975) 397-400 ， Phys. Rev. Lett. 82 (1999) 711-714

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Relation between
 Muon g−2 and Mu HFS

Muon g−2

• 3.7σ discrepancy

between theory and experiment

• Precision of Exp. value |

0.54 ppm

• Goal of new Experiment


at J-PARC and FNAL |
 0.1 ppm

• Experimental value is
• btained by using 


Mu HFS result

4

• aµ =

R λ − R

aµ = g − 2 2

g−2 storage ring

Mu HFS measurement

R ≡ ωa ωp

λ ≡ µµ µp

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25 5

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

• Muon Facility MUSE @ MLF

6

H-Line H-Line H1-Area H1-Area

In Operation In Operation Under Construction Under Construction

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

z x y

• MuSEUM Setup

Measurement principal

• Polarized muon beam
• Kr gas target
• Muonium formation
• State transition by

microwave and spin ip

• Measuring the number
• f positron

7 Signal | (Non−Noff)/Noff Non |# of positron when RF ON Noff | “ RF OFF

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Status of MuSEUM

Zero eld

• Measurement with

Kr 1 atm

• Measurement 

• f Mu HFS Kr gas

pressure shift

• New analysis method

(Time Differential Method)

• Kr-He mixture gas
• Achieve the best

precision

8

2020 2019 2018 2020 2019 2018

High Field

• MRI magnet test
• peration
• CW-NMR
• Shimming
• Upstream Detector
• Magnetic probe

production

• High eld

measurement

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

MuSEUM Zero Field Experiment

2017

• Mu HFS resonance was

measured at Kr 1 atm

2018

• Measurement 


at 0.3, 0.4, 0.7 atm

✦ Lower pressure than previous experiment

2019

• Measurement with Kr-He

mixture gas

• Upgrade of silicon strip

detector

9

Silicon Strip Detector Silicon Strip Detector

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Gas Pressure Dependence of Mu HFS Transition Frequency

Gas pressure shift

• Transition

frequency is shift due to collision between Mu and target gas atom

10

0.3 1.0

∆ν(P) = (1 + aP + bP 2)∆ν(P = 0)

: gas pressure, : parameters

a, b P

Various gas pressure measurement Extrapolation 
 to 0 atm Mu HFS in vacuum

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Gas Pressure Dependence of Mu HFS Transition Frequency

Experiment in 2018 June

• Spin ip resonance signal was observed 


for several gas pressure

• Recent analysis achieved 0.9 kHz 


(Assume previous pressure)

11

• Y. Ueno (Riken)

Preliminary

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Development of New Analysis Method (Time Differential Method)

Possible advantage

• f this method
• Each detuning

frequency data tted individually

• Can determine ΔνHFS

with only one frequency data

• Most sensitive

detuning frequency is 〜60 kHz

• Can improve statistical

uncertainty by 3.2 times compared to the conventional method

• Can reduce systematic
• f RF power variation

(free tting parameter)

• Need high statistics

12

Time [µs] Asymmetry

Preliminary

Experiment (2018 June) Experiment (2018 June)

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Kr-He Mixture Gas

Dependence of transition frequency shift is reverse between Kr and He

• Pressure dependence is cancelled 


at Kr/He mixing ratio = 30%

13

Pressure (×105 Pa)

0.2 0.4 0.6 0.8 1 40 − 30 − 20 − 10 − 10

• Freq. - 4 463 302 (kHz)

Pressure dependence of Mu HFS

Kr mixing rate (%)

20 30 40 50 60 70 80 90 100 40 − 30 − 20 − 10 − 10

• Freq. - 4 463 302 (kHz)

Δν (HF)

Mixing ratio dependence (1 atm)

Preliminary

• S. Seo (The Univ. of Tokyo)

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Development for High Field Exp.

Magnetic Field

• CW-NMR probe
• Shimming

✦ r=100mm/z=300mm Spheroid Volume ✦ Field uniformity | 0.45 ppm was achieved

Upstream Detector

• Specication is
• ngoing

14

2.9 T MRI Magnet 2.9 T MRI Magnet

• Field Homogeneity


(After shimming) Field Homogeneity (After shimming)

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Development of CW-NMR

Goal precision｜20 ppb

• Estimation of material effect
• Cross calibration

✦ precision of 15 ppb

15

• H. Yamaguchi (KEK),
• T. Tanaka (The Univ of Tokyo, Poster)

NMR sample 
 (pure water)

Readout board (Amplier)

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

z x y

• Upstream Detector

New detector is under development

• The detector consists
• f Fiber scintillators

and SiPMs

• Obtaining more

statistics

• Improving systematic

uncertainty due to muon beam uctuation (stopping distribution etc.)

16

Upstream Detector Upstream Detector

• S. Fukumura (Nagoya Univ, Poster)

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Summary

MuSEUM | Mu HFS precision measurement Zero Field Experiment

• Gas pressure dependence of Mu HFS transition

frequency was measured

• Kr-He mixture gas
• Development of Time Differential Method

High Field Experiment

• Field uniformity | 0.45 ppm was achieved
• Development of CW-NMR | 15 ppb was achieved
• Development of the upstream detector

17

Back up

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

▶ Pauli exclusion principle -> Increasing transition frequency ▶ van der Waals force -> Decreasing frequency

Transition Frequency Shift 
 due to collision

19

µ+ e−

e−

ー ＋

Attracted

Gas atom

Expand

Mu

Gas
 atom

Repel

Mu

e- e- e- e-

Shrink

Gas
 atom

Shoichiro Nishimura/J-PARC Symposium 2019 2019/09/25

Effect of Fe quantization

20

• M. Abe (KEK)