AEGIS

Antimatter Experiment: Gravity, Interferometry, Spectroscopy

C. Canali

INFN sez. Genova

(AEgIS COLLABORATION)

46° Rencontres de Moriond – 26 March 2011

TCP2010 April 12-16, 2010 Saariselkä C. Canali

LAPP, Annecy,

France

D. Sillou

Queen’s U Belfast,

UK

G. Gribakin,

H. R. J. Walters

U of Qatar, Doha,

Qatar

I. Al-Qaradawi

L. V. Jorgensen

INFN Firenze, Italy

G. Ferrari,

M. Prevedelli

CERN, Geneva,

Switzerland

J. Bremer, G. Burghart,

M. Doser, A. Dudarev,

T. Eisel, F. Haug,

D. Perini

INFN Genova, Italy

C. Canali, C. Carraro,,

. Krasnický,

V. Lagomarsino,

G. Testera,R. Vaccaro

ne, S. Zavatarelli

MPI-K, Heidelberg,

Germany

A. Kellerbauer,

U. Warring

U of Heidelberg,

Germany

P. Bräunig, F. Haupert,

M. K. Oberthaler

U of Lyon, France

P. Nédélec

INFN Milano, Italy

I. Boscolo, F. Castelli,

S. Cialdi,

M. Giammarchi,

M. Sacerdoti,

D. Trezzi, F. Villa

Politecnico di Milano,

Italy

G. Consolati,

R. Ferragut,

A. Dupasquier

INR, Moscow, Russia

A. S. Belov,

S. N. Gninenko,

V. A. Matveev

New York U, USA

H. H. Stroke

Laboratoire Aimé

Cotton, Orsay,

France

L. Cabaret,

D. Comparat

U of Oslo, Norway

J. P. Hansen,

O. Rohne, H. Sadake

INFN

Padova, Trento, Italy

G. Nebbia,

R. S. Brusa, S.

Mariazzi L. Di Noto,

INFN Pavia/Brescia,

Italy

G. Bonomi, L. Dassa,

A. Fontana,

C. Riccardi, A. Rotondi,

A. Zenoni

Czech Technical U,

Prague, Czech

Republic

V. Petráček

INRNE, Sofia,

Bulgaria

N. Djourelov

ETH Zurich,

Switzerland

S. D. Hogan, F. Merkt

AEGISAntimatter Experiment: Gravity, Interferometry, Spectroscopy

• Physical Motivations: why antimatter?

Gravity and antimatter

• The AEgIS experiment

Goals:

Measure g on antihydrogen

Antihydrogen spectroscopy CPT test

Methods:

Produce an Hbar beam

Moirè deflectometer

AEGISAntimatter Experiment: Gravity, Interferometry, Spectroscopy

• Physical Motivations: why antimatter?

Gravity and antimatter

• The AEgIS experiment

Goals:

Measure g on antihydrogen

Antihydrogen spectroscopy CPT test

Methods:

Produce an Hbar beam

Moirè deflectometer

What do we know about gravity and antimatter?

|g|=9.81..m/s2

apple

Earth

|g|=9.81..m/s2

anti

Earth

anti

apple

CPT

|g|= ?? m/s2

CPT is “useless”

Weak equivalence

principle for

antimatter

•General relativity is the fundamental theory of the gravitation

•It is a non quantum theory (classical)

•Many efforts to get a quantum theory

differences between matter and antimatter would of course violate the weak equivalence

principle (WEP), a cornerstone of General Relativity

Weak equivalence principle (for antimatter)

Indirect limits about antimatter:

xHH

g

gg10 x=6,7,8 ….

M. Nieto et al Phys. Rep. 205 (5) 221 (1991)

M. Charlton et al Phys. Rep 241 65 (1994)

R. Hughes Hyp. Int.76 3 (1996)

Xiv:0808.3929v1 [hep-th ] 28 Aug 2008

arXiv:0907.4110v1 [hep-ph] 23 Jul 2009

Equivalence

Principle tests

1,00E-14

1,00E-13

1,00E-12

1,00E-11

1,00E-10

1,00E-09

1,00E-08

1,00E-07

1,00E-06

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

1500 1600 1700 1800 1900 2000 2100

Pre

cis

ion

Year

1585 Stevin

Drop Tower

5 10-2

1686 Newton

Pendulum

1 10-3

1910 Southern

Torsion balance

5 10-6

1976 Shapiro

lunar laser

1 10-12

1999 Baebler

torsion balance

1 10-13

20--

MiniSTEP, MICROSCOPE,

Galileo Galilei 10-17 ??

MATTER-MATTER

EXPERIMENTS

AEGISAntimatter Experiment: Gravity, Interferometry, Spectroscopy

• Physical Motivations: why antimatter?

Gravity and antimatter

• The AEgIS experiment

Goals:

Measure g on antihydrogen

Antihydrogen spectroscopy CPT test

Methods:

Produce an Hbar beam

Moirè deflectometer

TO DO LIST:

• produce antihydrogen

• make an horizonallytravelling H-bar beam

• measure its horizontaldeflection over 1m horizontal path

AD PS

Protons

Antiprotons

Every 200s:

•107 antiprotons delivered

every ~85 s

• 0.1 GeV/c

• 200 ns bunches

The antiproton decelereator (AD) at cern

protons 26 GeV/c

from PS 3.5 GeV/c 3.5 → 0.1 GeV/c

Delivered to experimental areas:

•107 antiprotons delivered every ~85 s

• 0.1 GeV/c

• 200 ns bunches

p

AD ring

Stochastic

&

electron

cooling ASACUSA

ALPHA

ATRAP

1999 The AD – Antiproton Decelerator

AEgIS

10 m

Diluition cryostat

100 mK

Particle

detectors

Plasma

physics

Laser

Rydberg

positronium

Positronium

production

e+ accumulator

Positronium

spectroscopy

Penning traps

Moire deflectometer

Position

Sensitive

detectorMonte carlo

simulation

Antihydrogen

Production/study

1m

1m

Positrons from

Accumulator22Na source

Antiprotons

from AD

5T magnet

Pbar capture

Pbar cooling (4kK

1T magnet

Pbar cooling (100mK)

Deflectometer

(g meas.)

Antihydrogen / anihilations

detectors

Position sensitive

detector1m

B= 1 T

H prod. region

100 mK

Positronium

Production

region

Moiré’ deflectometer

Positrons trap

AD side

p entrance

Stark accelerator

eHPsp**

Positrons from

accumulator

Antihydrogen production based on:

Penning traps

• Confinement in vacuum of

charged partcles,

Penning traps:

B-Field → radial confinement

E-Field → axial confinement

B=1T

e+ bounch Ps production(bound state e+e-)

Ps excitation(Double laser pulse

n=1 → n=3 → n=25)

H-bar production(Charge exchange Ps *+ p → H* + e) Stark acceleration

EnkF

2

3100mK antiprotons

(4K actual “record”)

How to measure g? • Produce an horizontal antihydrogen

beam, velocity few 100 m/s

• Horizontal flight path about 1 m

• Vertical gravity deflection : 20 microns @

500m/s

• Poor beam collimation: beam size after

flight: several cm

H

vh

2

v

L

2 h

gh

L

h

Gravity measurement with ordinary matter have been performed

with a Moirè deflectometer: σ(g)/g = 2×10-4

[M. K. Oberthaler et al., Phys. Rev. A 54 (1996) 3165]

Philippe Bräunig

Group of Prof. Markus Oberthaler

Kirchoff Institute for Physics,

Heidelberg

aegis@matterwave.de

supplementary

gratings for optical

interferometry

active area of 68cm2

Gravity measurement with ordinary matter have been

performed with a Moirè deflectometer: σ(g)/g = 2×10-4

[M. K. Oberthaler et al., Phys. Rev. A 54 (1996) 3165]

40 cm 40 cm

20 c

m

Ls 30 cm (distance antihydrogen source-first grating)

Grating distance L 40 cm

Grating size: 20 x 20 cm2

Grating period: a=80 μm

Grating transparency 30%

Detector resolution <10 μm

G1 G2 Detector

Only classical interactions

Antihydrogen athoms are detected “one by one”

Time of flight is measured (v)

Binning

(grating period)

Vh= 600 m/s

x

counts

Montecarlo results

Vh= 400 m/s

Vh= 600 m/s

x

counts

g=9.81 m/s2

Vh= 400 m/s

Vh= 600 m/s

Vh= 300 m/s

x

counts

g=9.81 m/s2

Vh= 400 m/s

Vh= 600 m/s

Vh= 300 m/s

Vh= 250 m/s

x

counts

g=9.81 m/s2

a

gT

a

dx 2T: time of flight between the two

gratings

a: grating period

Measurement of g to 1%:

• 108 e+ in 200-300 s

• 5x106 Rydberg Ps.

• 105 antiprotons captured and cooled to 100 mK

• 105 antihydrogen athoms (2-3 weeks).

Direct measurement of gravity acceleration

of neutral antimatter system

AEGIS could perform the first measure of this kind never performed

An antihydrogen beam open the way to

new experimental possibilitiesTrapping antihydrogen & spectroscopy, atomic fountain, BEC,

High precision g-meas. …

A journey of a

thousand miles starts

with a single step

老子 Lǎozǐ (c. 4th century B.C.)

Chinese philosopher

The g measurement

Send the antihydrogen beam through the deflectometer: t0 defined within sec

For every antihydrogen measure the vertical position x and the arrival time on the detector

Few tens antihydrogen/cycle; flight time ms;

The large beam velocity spread makes pileup negligible

Reconstruct the flight time T between the 2 gratings

Group together Hbar having T in a proper interval (T1,T2) : make a T2 distribution symmetric

Build the “1 period” arrival position distribution N(x/a) : about 103 detected particles

Use a phase tracking algorithm to find the shift

Find g by fitting the relation 2

0

2 2Tg

aT

2T

x/a

10 m

resolution

Infinite resolution

N(x)

mw

mw

mw

mw

w

radwN

5.174

153

5.125.2

102

01

4.0

det

det

det

det

det

det

Capture and cooling of antiprotons • p catching and cooling

• positrons accumulation

• Antihydrogen production

• Beam formation

• g measurement

From AD:

• 107 antiprotons delivered every ~85 s

• 0.1 GeV/c

• 200 ns bunches

Catching:

• Degrader foil

• Reflecting and trapping in Penning trap (5kV)

• 104 antiprotons in trap [athena]

Cooling:

• previously loaded plasma with 107 electrons

• electrons quickly cool down by cyclotron radiation

• electron cooling of antiprotons

• Resistive cooling

• Sympathetic cooling with negative ions (?)

Recombination experiments: ATHENA & ATRAP

antiprotons

positron plasma

eHep

Hep

2

Core idea: trapping in the same region and e+p

[C. Regenfus, NIM

A 501 (2003) 65]

Silicon micro

strips

(inner)

CsI

crystals

511-keV γ

511-keV γ

(outer)

π

π

π

14

0 m

m

Cylindrical

Penning trap

5kV Electron

plasma

p catching and cooling

From AD:

• 107 antiprotons delivered every ~85 s

• 0.1 GeV/c

• 200 ns bunches

• 104 antiprotons in trap [athena]

• electron cooling of antiprotons

• Resistive cooling

• Sympathetic cooling with negative ions

(?)

GOAL: >104 antiprotons @ 100 mK

• e+ slowing down and Ps formation

• Ps thermalize within target (eV)

• Ground state Ps emitted in vacuum

• High Yield (30-50%)

• Precise timing (few tens ns)

• Production of positrons from a Surko-type source and accumulator

• 22Na radioactive source (40 mC)

• 108 e+ every 200 s

e+ accumulator & positronium production

dye laser

1064 nm, 4 ns

135 mJ

2 205 nm

6 mJ

PPLN 2 cm

PPLN 4 cm

3 mJ1650-1710 nm

Etalon

615 nm

O PA

OPG

Q-switched

Nd: YAG laser

3 mJ

1670 nm

205 nm

n = 1

n = 2

n = 3

n = 35

positronium excitation

• Two laser steps:

• nPs = 1 → nPs = 3

• nPs = 3 → nPs = 20 … 40 (tunable)

• >106 Rydberg positronium atoms are expected

Antihydrogen production occur

via charge exchange process:

eHPsp**

Large cross section ~ a0nPs4

σ = 10-9 cm 2

Antihydrogen state related

to initial Ps* state

Produced antihydrogen has the same temperature of antiprotons (100 mK):

Low energy H!

[C. H. Storry et al., Phys. Rev. Lett. 93 (2004) 263401]

EnkF

2

3• Δv of several 100 m/s within about 1 cm

• Electric fields: few 100 V/cm (limited by

field ionization)

• Already working with Rydberg hydrogen! [E. Vliegen & F. Merkt, J. Phys. B 39 (2006) L241]

The beam is produced using a stark accelerator:

• H is in Rydberg state

• Interactions between electric dipole moment and

a non-uniform electric field: