AEGIS

Antimatter Experiment: Gravity, Interferometry, Spectroscopy

C. Canali

INFN sez. Genova

11° ICATPP Como, 8 October 2009

The AEGIS CollaborationLAPP, Annecy, FranceD. Sillou

Queen’s U Belfast, UKG. Gribakin, H.R.J.Walters

INFN Firenze, ItalyG. Ferrari, M. Prevedelli, G. Tino

CERN M. Doser, A. Dudarev, D. Perini (+ support from T. Eisel, F. Haug, T. Niinikoski)

INFN Genova, ItalyC. Canali, C. Carraro, V. Lagomarsino, G. Manuzio, G. Testera, S. Zavatarelli

MPI-K HeidelbergA. Fisher,A. Kellerbauer, U. Warring, C.

Kirchhoff Inst. Of Phys.,Heidelberg, GermanyM. Oberthaler

INFN Milano, ItalyI. Boscolo, N. Brambilla,F. Castelli, S. Cialdi, L. Formaro, A. Gervasini, M. Giammarchi, F. Leveraro, A. Vairo

INR Moscow, RussiaA.S. Belov, S. N. Gninenko, V. A. Matveev, A. V. Turbabin

ITEP Moscow, RussiaW. M. Byakov, S. V. Stepanov, D.S. Zvezhinskij

New York Univ. USAH.H. Stroke

Univ. Oslo, NorwayO. Rohne, S. Stapnes

INFN Pavia-Brescia, ItalyG.Bonomi, A. Fontana, A. Rotondi, A. Zenoni

Czech Tech. Univ, Prague, Czech RepublicV. Petracek, D. Krasnicky, M. Spacek

IRNE Sofia, BulgaryN. Djurelov

INFN Padova-Trento, ItalyR.S. Brusa, D. Fabris, M. Lunardon, S. Mariazzi, S. Moretto, G. Nebbia, S. Pesente, G. Viesti

ETH Zurich, SwitzerlandS.D. Hogan, F. Merkt Qatar University

I. Y. Al-Qaradawi

Politecnico Milano, ItalyG. Consolati, A. Dupasquier, R. Ferragut, P. Folegati, F. Quasso

La. Aime’ Cotton, Orsay, FranceL. Cabaret, D. Comparat

INP Minsk, Belarus

G. Drobychev

UCBL Lyon, France P.Nedelec

• Physical Motivations: why antimatter?

• Gravity and antimatter

• AEGIS: measuring g on antihydrogen• Overview• Measuring g on H

• Conclusions

AEGISAntimatter Experiment: Gravity, Interferometry, Spectroscopy

Antimatter system:

• WEP test

• General Relativity test

Gravity:

• Spectroscopy on antihydrogen

CPT:

10-1810-1510-1210-910-6

relative precision

Magnetic moment (g - 2)e- e+

(g - 2)μ- μ+

(q/m)e- e+

Mass differencefK0 K0

Charge/mass (q/m)p p

[P. B. Schwinberg et al., Phys. Lett. A 81 (1981) 119][R. S. Van Dyck, Jr. et al., Phys. Rev. Lett. 59 (1987) 26][G. Gabrielse et al., Phys. Rev. Lett. 82 (1999) 3198][Y. B. Hsiung, Nucl. Phys. B (PS) 86 (2000) 312][G. W. Bennett et al., Phys. Rev. Lett. 92 (2004) 161802]

We need neutral (cold) antimatter:

Charged particles are extremely sensitiveto electric fields: we need a neutral system…

High precision spectroscopy:

The frequency of the 1S-2S transition in hydrogen has been measured with high precision:

f = 2 466 061 413 187 103(46) Hz

Gravity measurement:

Anti-hydrogen!

[M. Niering et al., Phys. Rev. Lett. 84 (2000) 5496]

mVE /106 11

210sma

General relativity is a classical (non quantum) theory!

srvr beaer

mmGV //21 1

• Tensor → “Newton”, always attractive

• Vector → repulsive between like charges

• Scalar → always attractive

The non-Newtonian terms could (almost) cancel out if a ≈ band v ≈ s , but would produce a striking effect on antimatter

Matter-matter:

0 ba

matter-antimatter:

0ba

[T. Goldman, M. Nieto Phys. Lett 112B 437-440 (1982)][ E. Fischbach, C. Talmadge “The search for Non Newtonian Gravity” Springer]

PS210 first

H-bar

Dirac e

quation

ATHENA first

cold H

-bar

ATRAP

Fermila

b

1932

Positro

n discove

ry

1955

Antipro

ton discove

ry

19962002

2008

AEGIS pro

posal

ATRAP2 ALPHA

Wow!… so, let’s start the experiment!

1927

PS210 firs

t H-b

ar

Dirac equatio

n

ATHENA firs

t cold

H-b

ar

ATRAP

Fermila

b

1932

Positron d

iscovery

1955

Antipro

ton d

iscovery

19962002

2008

AEGIS p

roposal

ATRAP2 ALPHA

1999 The AD – Antiproton Decelerator

AD PS

Protons

Antiprotons

protons 26 GeV/cfrom 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 ringStochastic

&electroncooling ASACUSA

ATHENA

ATRAP

1999 The AD – Antiproton Decelerator

AEGIS

(Antimatter Experiment: Gravity, Interferometry, Spectroscopy)

http://aegis.web.cern.ch

2007: proposal submitted

2008: experiment approved by CERN

2009: start building …

asacusa

alpha

atrap

aegis

B= 1 TH prod. region100 mK

PositroniumProductionregion

Moiré’ deflectometer

Positrons trap

AD sidep entrance

Stark accelerator

eHPsp**

Positrons fromaccumulator

Antihydrogen production based on:

Penning traps

• Confinement in vacuum of charged partcles:

B-Field → radial confinementE-Field → axial confinement B=1T

Goal: first direct measurement of Earth’s gravitational acceleration g on antimatter

• p catching and cooling• positrons accumulation• Antihydrogen production• Beam formation• g measurement

0s 100s time

B=1T

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

Ps excitation(Double laser pulsen=1 → n=3 → n=25)

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

• 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 mJ2 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 occurvia charge exchange process:

eHPsp**

Large cross section ~ a0nPs4

σ = 10-9 cm 2

Antihydrogen state relatedto 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:

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 performedwith 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

Binning(grating period)

Vh= 600 m/s

x

counts

Montecarlo results

Vh= 400 m/sVh= 600 m/s

x

counts

Vh= 400 m/sVh= 600 m/s

Vh= 300 m/s

x

counts

Vh= 400 m/sVh= 600 m/s

Vh= 300 m/s

Vh= 250 m/s

x

counts

a

gT

a

dx 2

T: 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

• rate: 103 H / AD cycle

• 105 antihydrogen athoms (2-3 settimane).

Conclusions ( & ambitions):

Gravity on antimatter has never been testedAEGIS could perform the first measure of this kind never performed

An antihydrogen beam open the way to new experimental possibilities

Trapping antihydrogen & spectroscopy, atomic fountain, BEC,High precision g-meas. …

AEGIS will use already well-know techniques togetherwith innovative schemes

Members of AEGIS are already working on this…

Thanks for your attention

http://aegis.web.cern.ch/

The g measurementSend the antihydrogen beam through the deflectometer: tSend the antihydrogen beam through the deflectometer: t00 defined within defined within sec sec

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

Few tens antihydrogen/cycle; flight time ms;Few tens antihydrogen/cycle; flight time ms;

The large beam velocity spread makes pileup negligibleThe large beam velocity spread makes pileup negligible

Reconstruct the flight time T between the 2 gratingsReconstruct the flight time T between the 2 gratings

Group together Hbar having T in a proper interval (TGroup together Hbar having T in a proper interval (T11,T,T22) : make a T) : make a T22 distribution symmetric distribution symmetric

Build the “1 period” arrival position distribution N(x/a) : about 10Build the “1 period” arrival position distribution N(x/a) : about 10 33 detected particles detected particles

Use a phase tracking algorithm to find the shift Use a phase tracking algorithm to find the shift

Find g by fitting the relation Find g by fitting the relation 20

2 2Tg

aT

2T

x/a

10 10 m m resolutionresolution

Infinite resolutionInfinite resolution

N(x)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 microstrips(inner)

CsIcrystals

511-keV γ

511-keV γ

(outer)

π

π

π

Cylindrical Penning trap

Diocotron jump of positrons

P-bar catching region P-bar cooling region

B=5T B=1T