Gabrielse High Precision, Low Energy Tests of the Standard Model and Its Symmetries Gerald Gabrielse, Leverett Professor of Physics, Harvard University.

Gabrielse

High Precision, Low Energy Testsof the Standard Model and Its Symmetries

Gerald Gabrielse, Leverett Professor of Physics, Harvard UniversitySpokesperson of the CERN ATRAP Collaboration

Supported by US NSF and AFOSR. Antiprotons from CERN

Testing the Most Precise Prediction of the Standard ModelElectron magnetic moment

Testing Standard Model Extensions (e.g. Supersymmetry) Electron electric dipole moment

Testing the Symmetries of the Standard Model Q/M for the antiproton and proton Antiproton and proton magnetic moments Positron and electron magnetic moments (underway) Antihydrogen and hydrogen structure (still in the future)

Comparing Antimatter and Mater Gravity Gravitational Redshift of the Antiproton and Proton

Gabrielse

Low Energy Particle Physics

70 mK, lowest storage energyfor any charged particles

2p2M c

LEAR and AD

TRAP

1010

4.2 K0.3 meV

AMO Physics, Particle Physics, Plasma Physics

methods and funding goals and facility can’t avoid

Gabrielse

Gabrielse

Electron Magnetic Dipole Moment

• Most precisely measured property of an elementary particle

• Most precise prediction of the standard model

• Most precise confrontation of theory and experiment

• Greatest triumph of the standard model

Gabrielse

The Amazing Electron

/ 2

Sd d

Magnetic dipole moment: What about electric dipole?

/ 2

S

Electron orbits give atoms their size, but the electron itselfmay actually have “no size”

2* 10.3 /m TeV c202 10R m mass of “ingredients” is 20 million times more than the mass 0.5 MeV/c2

Electron has angular momentum (spin) even though it has nosize and nothing is rotating: 2

2~

S m R

IA R

Gabrielse

Standard Model Prediction

essentiallyexact

2 3 4 5

2 4 6 8 101 ...

aB

hadronic weak new physics

C C C C C

a a

1Dirac

QED

Hadronic

Weak weaka smaller

2

e

m

2

0

1 1Fine structure constant:

4 137

e

c

Gabrielse

Probing 10th Order and Hadronic Terms

Dirac

QED

Gabrielse

David Hanneke G.G. Shannon Fogwell

Gabrielse

Need Good Students and Some Time

Elise Novitski Joshua Dorr Shannon Fogwell Hogerheide David Hanneke Brian Odom, Brian D’Urso, Steve Peil, Dafna Enzer, Kamal Abdullah

Ching-hua Tseng Joseph Tan

N$F

20 years8 theses

Gabrielse

Cylindrical Penning Trap

• Electrostatic quadrupole potential good near trap center• Control the radiation field inhibit spontaneous emission by 200x

(Invented for this purpose: G.G. and F. C. MacKintosh; Int. J. Mass Spec. Ion Proc. 57, 1 (1984)

2 2 2~ 2V z x y

Gabrielse

150 GHzcf

Tesla6B

One Electron Quantum Cyclotron

n = 0

n = 1n = 2n = 3

n = 4

0.1 m

2y

0.1 m

2

7.2 kelvinch

Need lowtemperature

cyclotron motionT << 7.2 K

- - - - - - -

- - - - - - -

Trap withcharges

Gabrielse

Quantum Measurement of the Electron Magnetic Moment

Spin flip energy: 2s B B

2c B

eBB

m Cyclotron energy:

s

c B

Bohr magneton2

e

m

Need to resolve the quantum states of the cyclotron motion Relativistic shift is 1 part in 109 per quantum level

/ 2

S

(the magnetometer)

( 1/ 2)s s cE m n

Gabrielse

Quantum Jump Spectroscopy

• one electron in a Penning trap• lowest cyclotron and spin states

“In the dark” excitation turn off all detection and cooling drives during excitation

QND – quantum non-demolition detection

s

c B

Gabrielse

Application of Cavity QED

decay time (s)

0 10 20 30 40 50 60

nu

mb

er

of

n=

1 t

o n

=0 d

ecays

0

10

20

30

time (s)

0 100 200 300

ax

ial fr

eq

ue

nc

y s

hif

t (H

z)

-3

0

3

6

9

12

15

Y A

xis

2

t = 16 s

excite, measure time in excited state

Inhibited Spontaneous Emission

many other new methods

Gabrielse

Electron Magnetic Moment Determined to 3 x 10-13

132.8 10

(improved measurement is underway)

Most precisely measured property of an elementary particle

Gabrielse

from measured fine structure constant

GabrielseFrom Freeman Dyson – One Inventor of QED

Dear Jerry,

... I love your way of doing experiments, and I am happy to congratulate you for this latest triumph.  Thank you for sending the two papers.

Your statement, that QED is tested far more stringently than its inventors could ever have envisioned, is correct.  As one of the inventors, I remember that we thought of QED in 1949 as a temporary and jerry-built structure, with mathematical inconsistencies and renormalized infinities swept under the rug.  We did not expect it to last more than ten years before some more solidly built theory would replace it.  We expected and hoped that some new experiments would reveal discrepancies that would point the way to a better theory. And now, 57 years have gone by and that ramshackle structure still stands. The theorists … have kept pace with your experiments, pushing their calculations to higher accuracy than we ever imagined. And you still did not find the discrepancy that we hoped for.  To me it remains perpetually amazing that Nature dances to the tune that we scribbled so carelessly 57 years ago.  And it is amazing that you can measure her dance to one part per trillion and find her still following our beat.

With congratulations and good wishes for more such beautiful experiments, yours ever, Freeman.

Gabrielse

Test for Physics Beyond the Standard Model

2* 360 /m

m GeV ca

Does the electron have internal structure?

2* 1 /m

m TeV ca

limited by the uncertainty in independent value

if our uncertaintywas the only limit

2* 10.3 /m TeV c LEP contact interaction limitNot bad for an experiment done at 100 mK, but LEP does better

*m total mass of particles bound together to form electron

195 10R m

202 10R m

192 10R m

:1 (2

) SM Hadronic WeaQED NewPh cB

ysi skag

aa

> 20,000,000 electron masses of binding energy

Gabrielse

Gabrielse

Electron Electric Dipole Moment (EDM)

• Most precise test of extensions to the standard model• 12 times more precise than previous measurements

/ 2

Sd d

Magnetic moment: Electric dipole moment:

/ 2

S

Well measured Does this also exist?

Gabrielse

Particle EDM Requires Both P and T Violation

/ 2

Sd d

Magnetic moment: Electric dipole Moment:

/ 2

S

If reality is invariant under parity transformations P d = 0P

T If reality is invariant under time reversal transformations T d = 0

Gabrielse

Standard Model of Particle Physics Predicts a Non-zero Electron EDM

Standard model: d ~ 10-38 e-cm

Too small to measure by orders of magnitude best measurement: d ~ 2 x 10-27 e-cm

CKM matrix relates to d, s, b quarks(Cabibbo-Kabayashi-Maskawa matrix)

Weak interaction couples quark pairs (generations)

almost the unit matrix

four-looplevel inperturbationtheory

GabrielseExtensions to the Standard Model

Much Bigger, Measureable Electron EDM

Low order contribution larger moment

Low order contribution vanishes

From Fortson, Sandars and Barr, Physics Today, 33 (June 2003)

An example

Gabrielse

Improved Electron Electric Dipole Momentand What is Next

Gerald GabrielseLeverett Professor Physics, Harvard University

Science 343, 269 (2014)

Advanced Cold Molecule EDM

NSF, and NIST

Gabrielse

ACME Collaboration

GeraldGabrielse(Harvard)

DavidDeMille(Yale)

John Doyle (Harvard)

Brendon O’Leary Paul Hess Jacob Baron Elizabeth Petrik

Adam West

Ben Spaun Chris Panda Nick Hutzler

Joint effort of 3 research groups

Earlier: Amar Vutha, Yulia Gurevich, Emil Kirilov, Ivan Kozyreyv, Wes Campbell

ACMEPhD

Gabrielse

Before Our ACME Measurement of Electron EDM

ACME aspirationfor first 5 years

BeforeACME

W. Bernreuther, M. Suzuki, Rev. Mod. Phys. 63, 313 (1991)

Gabrielse

How to Measure an Electron EDM

Put the EDM in an Electric Field

H d E

bigger is better

Measure the energy shift for the system

GabrielseCannot Use Electric Field Directly

on an Electron or Proton

Simple E and B can be used for neutron EDM measurement (neutron has magnetic moment but no net charge)

Electric field would accelerate an electron out of the apparatus

Electron EDM are done within atoms and molecules(first molecular ion measurement is now being attempted)

Gabrielse

Schiff Theorem – for Electron in an Atom or Molecule

Schiff (1963) – no atomic or molecular EDM (i.e. linear Stark effect)• from electron edm• nonrelativistic quantum mechanics limit

Sandars (1965) – can get atomic or molecular EDM (i.e. linear Stark effect)

• from electron edm• relativistic quantum mechanics• get significant enhancement (D >> d) for large Z

Commins, Jackson, DeMille (2007) – intuitive explanation Schiff

Lorentz contraction of the electron EDM in lab frame

Schiff, Phys. Rev. Lett. 132, 2194 (1963);

Sandars, Phys. Rev. Lett. 14, 194 (1965); ibid 22, 290 (1966).

Commins, Jackson, DeMille, Am. J. Phys. 75, 532 (2007).

Gabrielse

Why Use a Molecule? To Make Largest Possible Electric Field on Electron

Tl atom (best EDM limit till YbF)123 kV/cm E 72 MV/cmlab effE

ThO molecule100 V/cm E 100 V/cmlab effE G

Molecule can be more easily polarized using nearby energy levels with opposite parity (not generally available in atoms)

Gabrielse

Still, the EDM Gives Tiny Shift of Energy Levels18

27

30

7 10

7 10

7 10

E eV

GeV

TeV

Not so easy to resolve

Example is for an electron edm equal the ACME upper limit.

To detect let a prepared wave function evolve for time T

| (0) |1 | 2 | (T) |1 | 2ie

ET

large as possible

6 31.1 11 10 0.6 10 degreesT ms

2 mHz

Gabrielse

Detect a Small Phase Shift

1 1

2

i om e m ( )11 1

2

i om e m

( B d E)

set by choiceof dark state

set by choice of direction ofthe first of the two orthogonaldetection laser polarizations

timein E, B

Example is for an electron edm equal the ACME upper limit.

6 31.1 11 10 0.6 10 degreesT ms

x

y

xy

Gabrielse

Experiment in Two Labs – 100 Meters Separated

Harvard Jefferson BuildingHarvard LISE Building

Lasers, Iodine Clock, Comb

ThO Sourceand InteractionChamber(2 floors down)100 m optical fibers

Gabrielse

ThO Molecular Beam

MolecularBeamSource

Pulsed YAG

Molecule TrajectoryPrep Lasers

Probe Lasers

Pulse Tube Cooler

“Interaction Region”: E-field plates inside, B-field shields and coils outside

Lasers 100m away

34

Gabrielse

Magnetic Field Coils and Shielding

mu metalendplates

200 mG with uniformity of 10-3 over 26 cm

Cos(theta)coils to providetransverseB field

ThO beam

Interactionchamberinside

5 shields(no shown)

~ 10-5

shielding

Gabrielse

Detect the Tiny Phase Shift Interference

1 1

2

i om e m ( )11 1

2

i om e m

( B d E)

set by choiceof dark state

set by choice of direction ofthe first of the two orthogonaldetection laser polarizations

maximize sensitivity to 6d E 11 10

Gabrielse

coldThO

source

E

electric field plates lightdetector

apparatus control and data acquisition

Detecting an EDM

magnetic field

B

ground state superposition evolve: E + edm

combine emit

Gabrielse

Parity sum (NEB)

Derived quantities

+ + + Bnr g m t + θnr

+ + - B0 g m t

+ - + Bleak g m t

+ - - 0

- + + Bnr Dg m t

- + - B0 Dg m t

- - + de Eeff t

- - - B0 η Enr m t

Total Phase Equation:

block (~1 min)

block (~1 min)

block (~1 min)

phas

e (r

ad)

phas

e (r

ad)

phas

e (r

ad)

3 ± 5 x 10-5 rad

392 ± 5 x 10-5 rad

??? ± 5 x 10-5 rad

single block10 blocks averaged

𝜙 (𝑁 ,𝐸 ,𝐵 )=(𝑔+Δ𝑔|𝑁|) (𝐵0+𝐵𝑛𝑟|�̂�|+𝐵𝑙𝑒𝑎𝑘|�̂�|)𝜇𝐻 𝜏+𝑑𝑒𝐸𝑒𝑓𝑓 |�̂�||�̂�|

Gabrielse

Parity sum (NEB)

Derived quantities

+ + + Bnr g m t + θnr

+ + - B0 g m t

+ - + Bleak g m t

+ - - 0

- + + Bnr Dg m t

- + - B0 Dg m t

- - + de Eeff t

- - - B0 η Enr m tblock (~1 min)

block (~1 min)

phas

e (r

ad)

phas

e (r

ad)

4 ± 5 x 10-5 rad

-1 ± 5 x 10-5 rad

block (~1 min)

phas

e (r

ad)

-1530 ± 5 x 10-5 rad

single block10 blocks averaged

block (~1 min)

phas

e (r

ad)

-2 ± 5 x 10-5 rad

phas

e (r

ad)

-3590 ± 5 x 10-5 rad

Gabrielse

GabrielseConstraining New Physics on the 1 to 3 TeV Scale

prefactor

for weak interactions ~4/137

couples to weak interaction via n=1 or n=2 loop diagrams3 TeV 1 TeV

difficult to suppressnew CP violating phase

mass scale of new particles

Probing same mass scale as the LHC

conservative

Gabrielse

We need molecular theory to get the effective electric field

We actually constrain the EDM and CS

Assuming d=0

Gabrielse

New ACME Electron EDM Measurement

Do NOT quote our hopes

till we realize them!!!

New ACME Result

Gabrielse

How Big is 8 x 10-29 e cm?

earth-sized polarization cloud

around electron(scale classical electron radius)

How sensitive was our princessto the hidden pea?

Shift in earth center by 2 nm

Scale size of the polarization cloudaround the electron earth

Gabrielse

Relationship to LHC Physics

The LHC is exciting and important but EDMs also play a role• should get an improved electron EDM on the LHC time scale

• If the LHC sees new particles, is CP violation involved?• If the LHC sees nothing, EDM game is the only one in town

• Would be great to use LHC results and ours together to see what we have learned together about Standard Model extensions

Gabrielse

https://twiki.cern.ch/twiki/pub/AtlasPublic/CombinedSummaryPlots/AtlasSearchesSUSY_SUSY2013.pdf

Gabrielse

Gabrielse

Testing the Standard Model’s Fundamental Symmetry

and

Comparing Antimatter-Matter Gravity

Gabrielse

Single Particle MeasurementsHave Three Big Advantages

Can be done with antiparticles

Can reach a much higher precision

Direct measurement same measurement and apparatus is used with a particle and antiparticle

Gabrielse

Most Stringent Tests of the Standard Model (and Gravity) with Antiprotons

Q/M of Antiproton and Proton – most stringent test of the Standard Model’s CPT theorem with baryons Comparison of Antiproton and Proton Gravity

680 Times Improved Comparision of the Antiproton and ProtonMagnetic Moments

Gabrielse

Embarrassing, Unsolved Mystery:How did our Matter Universe

Survive Cooling After the Big Bang?

Big bang equal amounts of matter and antimatter created during hot time

As universe cools antimatter and matter annihilate

Big Questions:

• How did any matter survive?

• How is it that we exist?

Our experiments are looking for evidence of any way that antiparticles and particles may differ

Gabrielse

Our “Explanations” are Not so Satisfactory

Baryon-Antibaryon Asymmetry in Universe is Not Understood

Standard “Explanation”• CP violation• Violation of baryon number• Thermodynamic non-equilibrium

Alternate• CPT violation• Violation of baryon number• Thermo. equilib.Bertolami, Colladay, Kostelecky, PottingPhys. Lett. B 395, 178 (1997)

Why did a universe made of matter survive the big bang?Makes sense look for answers to such fundamental questionsin the few places that we can hope to do so very precisely.

Bigger problem: don’t understand dark energy within 120 orders of magnitude

Gabrielse

Why Compare H and H (or P and P)?

Reality is Invariant – symmetry transformationsP parityCP charge conjugation, parityCPT charge conjugation, parity, and time reversal

CPT Symmetry Particles and antiparticles have

• same mass• opposite charge

Atom and anti-atom have same structure

Looking for Surprises• simple systems• extremely high accuracy• comparisons will be convincing

• same magnetic moment• same mean life

• reasonable effort • FUN

_ _

Gabrielse

Comparing the CPT Tests Warning – without CPT violation models it is hard to compare

CPT TestAccuracy

MeasurementAccuracy

FreeGift

K0 K0

Mesons

2 x 10-18 2 x 10-3 1015

e+ e-

Leptons2 x 10-12 2 x 10-9 103

P Pbaryons

9 x 10-11 9 x 10-11 1_

_

improve withantihydrogen

3 fu

ndam

enta

lly

diff

eren

t typ

es o

f pa

rtic

les

Gabrielse

I Came to CERN First in 1986to Compare the Antiproton and the Proton

Started cold antiproton and antihydrogen physics

Now a dedicated storage ring and 6 international collaboration (still amazes me)

Gabrielse

Accumulating Low Energy Antiprotons:Basic Ideas and Demonstrations (1986 – 2000)

• Slow antiprotons in matter• Capture antiprotons in flight• Electron cooling 4.2 K• 5 x 10-17 Torr

TRAP Collaboration at CERN’s LEAR

Now used by 5 collaborations at the CERN AD

ATRAP, ALPHA, ASACUSA,AEGIS, BASE

10-10

energy reduction

magneticfield

+ __

1 cm

21 MeVantiprotons

Gabrielse

Highest Precision Test of Baryon CPT Invariance

/ (antiproton)0.99999999991(9)

/ (proton)

q m

q m

by TRAP at CERN

(most precise result of CERN’s antiproton program)

Goal at the AD: Make CPT test that approach exceed this precision

119 10 90 ppt

Gabrielse

We Improved the Comparison of Antiproton and Proton by ~106

G. Gabrielse, A. Khabbaz, D.S. Hall, C. Heimann, H. Kalinowsky, W. Jhe; Phys. Rev. Lett. 82, 3198 (1999).

100antiprotonsand protons

/ (antiproton)0.99999999991(9)

/ (proton)

q m

q m

119 10 90ppt

56 10

most stringent CPT test with baryons

Gabrielse

Seek to Improve Lepton and Baryon CPT Tests

ATRAP members

2 2[ ] [[H] 1 /[ ] [ ] [

[H]

]

[ ] [ ] [

]

] [1[ /] ]

qm e q e m ep M p

q p Mm e q e m pe

R

R

antiprotonmoment

Gabrielse

Gabrielse

Direct Comparison ofAntimatter and Matter Gravity

antimatter matterg g

acceleration due to gravityfor antimatter

acceleration due to gravityfor matter

Does antimatter and matter accelerate at the same ratein a gravitational field?

Gabrielse

The Most Precise Experimental Answer is “Yes” to at lease a precision of 1 part per million

Experiment: TRAP Collaboration, Phys. Rev. Lett. 82, 3198 (1999).

23( 1)c

c

U

c

for tensor gravity(would be 1 for scalar gravity)

Hughes and Holzscheiter, Phys. Rev. Lett. 66, 854 (1991).

Gravitational red shift for a clock: 2/ /g h c

Antimatter and matter clocks run at different rates if g is different for antimatter and matter

grav. pot. rnergy differencebetween empty flat space timeand inside of hypercluster of galaxies

10 610 1 ( 10 )c

c

Gabrielse

Gravity and Antihydrogen

Gabrielse

May be Hard to Get the Part per Million Precisionof the Redshift Limit

with Antihydrogen and Hydrogen

10 610 1 ( 10 )c

c

Gravitational redshift:

ALPHA trapped antihydrogen released (2013): 110

antimatter matterg g

Worthy goal for AEGIS and GBAR can they get a part per million

(108 times less precise)

Gabrielse

Sometimes It is Said that this Redshift Measurement is not so Valid

Because it “Assumes CPT Invariance”

• Does not assume CPT invariances in the gravity sector of course

• Only assumes that CPT violations in the Standard Model (if they exist) do not cancel the CPT violations in gravity (if they exist)

• Does not seem likely to me that CPT violations in the Standard Model would be just the right size to cancel differences in gravitational redshifts of the antiproton and proton (at our location in space-time).

Gabrielse

Antiproton Magnetic Moment

Gabrielse

Proton and Antiproton Magnetic Momentsare Much Smaller than the Electron Moment

Harder: nuclear magneton rather than Bohr magneton

Gabrielse

Earlier contributions

Phys. Rev. Lett. 180, 153001 (2012)

Later measurement with similar methods

Gabrielse

Gabrielse

Resonance Linesto Determine the “Two” Frequencies

square of extrawidth

Brown-GabrielseInvariance Theorem

Gabrielse

First One-Particle Measurement of the Antiproton Magnetic moment

680timeslowerthan

previous

Gabrielse

680 – Fold Improved Precision

ASACUSA

680

plausibleaspiration

2013

ATRAP, Phys. Rev. Lett. (2013).

Gabrielse

Proton Spin Flip Report

Similar proton result from Mainz group in same issue

Gabrielse

Gabrielse

Antihydrogen Hope for the Future

Note: no scientifically interesting tests of fundamental symmetrieshave yet taken place with antihydrogen – beware the hype

Gabrielse

Proposal to Trap Cold Antihydrogen – 1986

“For me, the most attractive way ... would be to capture the antihydrogen in a neutral particle trap ... The objective would be to then study the properties of a small number of [antihydrogen] atoms confined in the neutral trap for a long time.”

Gerald Gabrielse, 1986 Erice Lecture (shortly after first pbar trapping) In Fundamental Symmetries, (P.Bloch, P. Paulopoulos, and R. Klapisch, Eds.) p. 59, Plenum, New York (1987).

• Produce cold antihydrogen from cold antiprotons

• Trap cold antihydrogen• Use accurate laser spectroscopy to compare

antihydrogen and hydrogen

“When antihydrogen is formed in an ion trap, the neutral atoms will no longer be confined and will thus quickly strike the trap electrodes. Resulting annihilations of the positron and antiproton could be monitored. ..."

Use trapped antihydrogen to measure antimatter gravity

Gabrielse

Most Trapped Antihydrogen in Its Ground State

5 +/- 1 ground state atoms simultaneously trapped

ATRAP, “Trapped Antihydrogen inIts Ground State”, Phys. Rev. Lett.108, 113002 (2012)

Gabrielse

ATRAP Collaboration

Gabrielse

Ultimate Goal: Hydrogen 1s – 2s Spectroscopy

(Haensch, et al., Max Planck Soc., Garching)http://www.mpq.mpg.de/~haensch/hydrogen/h.html

Many fewer antihydrogen atoms will be available

(or similar tests of ground state hyperfine structure)

Gabrielse

Two Methods Produce Slow Antihydrogen

1. In a nested Penning trap, during positron cooling of antiprotons

Device and technique – ATRAP Used to produce slow antihydrogen – ATHENA and ATRAP

Variations: Basic (ATRAP initially, ATHENA-ALPHA) Driven (ATRAP before 2007) Adiabatic well depth change (ATRAP 2007)

2. Laser-controlled resonant charge exchange

ATRAP

GabrielseAnti-H Method 1: Nested Penning Trap 3-Body “Recombination”

Nested Penning Trap 3-Body “Recombination”

Gabrielse

e+

p

Positron Cooling of Antiprotonsin a Nested Penning Trap

TRAP/ATRAP Develops the Nested Penning Trap Proposed nested trap as a way to make antihydrogen "Antihydrogen Production Using Trapped Plasmas" G. Gabrielse, L. Haarsma, S. Rolston and W. Kells Physics Letters A 129, 38 (1988)

"Electron-Cooling of Protons in a Nested Penning Trap" D.S. Hall, G. Gabrielse Phys. Rev. Lett. 77, 1962 (1996)

"First Positron Cooling of Antiprotons" ATRAP Phys. Lett. B 507, 1 (2001)

Gabrielse

Anti-H Method II: Antihydrogen Via Laser-Controlled Resonant Charge Exchange

852 nm

510.6 nm

ATRAP, Phys. Rev. Lett. 93, 263401 (2004)

Gabrielse

1 Collaboration 4 CollaborationsFollowing the 1986 plan:

cold antiprotons

cold antihydrogen

trap antihydrogen

precise laser spectroscopy

ATRAP and ALPHA

Variations

colder antihydrogen

extract from trap

laser spectroscopyASACUSA AEGIS

interferometry

1986 2012

Gabrielse

Gabrielse

First Generation Penning-Ioffe Apparatus

Gabrielse

ATRAP – observed the production of antihydrogen atoms in the fields of a Ioffe trap (PRL 2008) Less than 20 atoms were being trapped per trial

ALPHA – did similar production the following year

ATRAP ALPHA Try to make more atoms Try to detect fewer atoms

two directions

0.7 +/- 0.3 per trial5 +/- 1 per trial

Gabrielse

1.2 K Electrodes and Millions of Antiprotons

1.2 K UsingPumped Helium

Gabrielse

• Lowered electrode temperature to 1.2 K • Started measuring antiproton temperatures• Developed new pbar cooling methods

ATRAP More Antiprotons, Much Colder,More Simultaneously Trapped Atoms

First antiprotons cold enough to centrifugally separate from the electrons that cool them Phys. Rev. Lett. 105, 213002 (2010).

Two new cooling methods for antiprotons -- embedded electron cooling -- adiabatic cooling Phys. Rev. Lett. 106, 073002 (2011).

3 million antiprotons at 3.5 K

Gabrielse

Gabrielse

Particle Physics at Low EnergyGerald Gabrielse

Leverett Professor of Physics, Harvard UniversitySpokesperson of the CERN ATRAP Collaboration

Supported by US NSF and AFOSR

Testing the Most Precise Prediction of the Standard ModelElectron magnetic moment

Testing standard model extensions Electron electric dipole moment

Testing the Symmetries of the Standard Model Q/M for the antiproton and proton Antiproton and proton magnetic moments Positron and electron magnetic moments (underway) Antihydrogen and hydrogen structure (still in far future)

Comparing Antimatter and Mater Gravity Gravitational Redshift of the Antiproton and Proton

Gabrielse

SummaryLow energy particle physics produces the most stringent tests of the standard model, its extensions and its fundamental symmetries - electron magnetic dipole moment - electron electric dipole moment - comparison of antiproton and proton charge-to-mass ratios - comparison of antiproton and proton gravity - comparison of antiproton and proton magnetic moments

Antihydrogen – now have cold trapped antihydrogen atoms in their ground states, but not enough atoms yet – no interesting tests of fundamental symmetries yet, but big hopes for the future