Motivation

Testing Fundamental Symmetries:

• CPT Invariance is a fundamental property of QFT

• Properties of the hydrogen atom are among the most precisely measuredquantities in physics

• Hydrogen-antihydrogen comparison may provide one of the best tests of CPTinvariance

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ALPHA Program

• 1S-2S Spectroscopy

• Lyman-Alpha Spectroscopy and Cooling

• Microwave Spectroscopy

• Charge neutrality test

• ALPHA-g: Test of gravity with antihydrogen

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ALPHA-2 Apparatus

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Trapping Magnetic Field

05

1015

20

Rad

ial p

ositi

on (m

m)

200

0

- 200

Axial position (mm)

1.0

1.5

2.0M

agne

ticfie

ld (T

)

cb

da

Pro

babi

lity

Frequency

1420.4 MHz

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Experimental ResultsNature, 2017

This represents the first observed spectrum of antiatoms. Hyperfine splitting determined towithin 500 KHz, 200 times more precise than the previous publication.

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Summary

ALPHA has been testing matter-antimatter symmetry in various ways.Our latest microwave spectroscopy publication achieved a factor of 200 precision overour first measurement.

A new measurement addressesseveral key systematics (currentlyunder analysis):– The magnetic field drift within asequence– The drift of the external solenoidbetween runs

We expect a 20-fold improvement in precision.

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Prospects for Microwave Measurements

• Development for a future NMR transition measurement is on-going

• With ever higher trapping rates, better field control, and possible laser coolingapplications we hope to achieve even higher precisions

• Testing CPT invariance to even higher precision, we are pushing the frontiers ofhuman knowledge

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Acknowledgements

ALPHA Canada Collaborators:P. A. Amaudruz, D. Bishop, A. Capra, R. Collister, M. Constable, A. Evans, N. Evetts, W. Faszer, S. Freeman,M. C. Fujiwara, D. R. Gill, M. Grant, W. N. Hardy, M. E. Hayden, R. Henderson, A. Khramov, L. Kurchaninov,P. Lu, L. Martin, N. Massacret, M. Mathers, J. T. K. Mc Kenna, S. Menary, T. Momose, J. J. Munich, K.Olchanski, A. Olin, K. Ong, L. Paulson, B. Shaw, D. Starko, C. So, J. E. Thompson, R. I. Thompson, E. Zaid.

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Supplementary: ALPHA Program

• 1S-2S Spectroscopy

– Nature, 2017; Nature, 2018

• Lyman-Alpha Spectroscopy and Cooling

– Nature, 2018

• Microwave Spectroscopy– Nature, 2012; Nature, 2017

• Charge neutrality test

– Nature, 2016

• ALPHA-g: Test of gravity with antihydrogen

– Please see poster by Phillip Lu

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Supplementary: New Preliminary Results

New measurementaddresses several keysystematics (currentlyunder analysis):– The magnetic field driftwithin a sequence

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Supplementary: New Preliminary Results

New measurementaddresses several keysystematics (currentlyunder analysis):– The magnetic field driftwithin a sequence– The drift of the externalsolenoid between runs

We expect a 20-foldimprovement in precision.

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Supplementary: Further Microwave Measurements

NMR measurement is insensitive to first order to external magnetic field.

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