AEGIS

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AEGIS Antimatter Experiment Gravity,
Interferometry, Spectroscopy
C. Canali INFN sez. Genova 11 ICATPP Como, 8
October 2009
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The AEGIS Collaboration
LAPP, Annecy, France D. Sillou
Queens U Belfast, UK G. Gribakin, H.R.J.Walters
CERN M. Doser, A. Dudarev, D. Perini ( support
from T. Eisel, F. Haug, T. Niinikoski)
UCBL Lyon, France P.Nedelec
INFN Genova, Italy C. Canali, C. Carraro, V.
Lagomarsino, G. Manuzio, G. Testera, S.
Zavatarelli
MPI-K Heidelberg A. Fisher,A. Kellerbauer, U.
Warring, C.
INFN Firenze, Italy G. Ferrari, M. Prevedelli, G.
Tino
INFN Milano, Italy I. Boscolo, N. Brambilla,F.
Castelli, S. Cialdi, L. Formaro, A. Gervasini, M.
Giammarchi, F. Leveraro, A. Vairo
Kirchhoff Inst. Of Phys., Heidelberg, Germany M.
Oberthaler
INR Moscow, Russia A.S. Belov, S. N. Gninenko, V.
A. Matveev, A. V. Turbabin
ITEP Moscow, Russia W. M. Byakov, S. V. Stepanov,
D.S. Zvezhinskij
Politecnico Milano, Italy G. Consolati, A.
Dupasquier, R. Ferragut, P. Folegati, F. Quasso

New York Univ. USA H.H. Stroke
Univ. Oslo, Norway O. Rohne, S. Stapnes
INFN Pavia-Brescia, Italy G.Bonomi, A. Fontana,
A. Rotondi, A. Zenoni
IRNE Sofia, Bulgary N. Djurelov
Czech Tech. Univ, Prague, Czech Republic V.
Petracek, D. Krasnicky, M. Spacek
INFN Padova-Trento, Italy R.S. Brusa, D. Fabris,
M. Lunardon, S. Mariazzi, S. Moretto, G. Nebbia,
S. Pesente, G. Viesti
INP Minsk, Belarus G. Drobychev
ETH Zurich, Switzerland S.D. Hogan, F. Merkt
La. Aime Cotton, Orsay, France L. Cabaret, D.
Comparat
Qatar University I. Y. Al-Qaradawi
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AEGIS Antimatter Experiment Gravity,
Interferometry, Spectroscopy

• Physical Motivations why antimatter?
• Gravity and antimatter
• AEGIS measuring g on antihydrogen
• Overview
• Measuring g on H
• Conclusions

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Antimatter system
CPT
e
-
e

(
q
/
m
)
e
-
e

Magnetic moment (
g
- 2)
p
p
Charge/mass (
q
/
m
)
0
0
K
K
Mass difference
f
-

µ
µ
(
g
- 2)
-18
-15
-12
-9
-6
10
10
10
10
10
relative precision
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

• Spectroscopy on antihydrogen

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High precision spectroscopy
Gravity measurement
Charged particles are extremely sensitive to
electric fields we need a neutral system
The frequency of the 1S-2S transition in hydrogen
has been measured with high precision f 2
466 061 413 187 103(46) Hz
M. Niering et al., Phys. Rev. Lett. 84 (2000)
5496
We need neutral (cold) antimatter
Anti-hydrogen!
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General relativity is a classical (non quantum)
theory!

• 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

T. Goldman, M. Nieto Phys. Lett 112B 437-440
(1982) E. Fischbach, C. Talmadge The search
for Non Newtonian Gravity Springer
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Wow! so, lets start the experiment!
1927
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1999 The AD Antiproton Decelerator
Protons Antiprotons
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1999 The AD Antiproton Decelerator
protons 26 GeV/c from PS
3.5 ? 0.1 GeV/c
3.5 GeV/c
ATRAP
AD ring Stochastic electron cooling
ASACUSA
ATHENA

• Delivered to experimental areas
• 107 antiprotons delivered every 85 s
• 0.1 GeV/c
• 200 ns bunches

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AEGIS (Antimatter Experiment Gravity,
Interferometry, Spectroscopy) http//aegis.web.ce
rn.ch
aegis
atrap
2007 proposal submitted 2008 experiment
approved by CERN 2009 start building
asacusa
alpha
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Antihydrogen production based on
Penning traps
B 1 T H prod. region 100 mK

• Confinement in vacuum of
• charged partcles
• B-Field ? radial confinement
• E-Field ? axial confinement

B1T
Moiré deflectometer
Stark accelerator
AD side p entrance
Positronium Production region
Positrons from accumulator
Positrons trap
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Goal first direct measurement of Earths
gravitational acceleration g on antimatter

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

0s
100s
time
B1T
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p catching and cooling
Electron plasma
5kV
GOAL gt104 antiprotons _at_ 100 mK

• 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 (?)

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H-bar production (Charge exchange Ps p ? H e)
Stark acceleration
Ps excitation (Double laser pulse n1 ? n3 ?
n25)
Ps production (bound state ee-)
e bounch
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(No Transcript)
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e accumulator positronium production

• Production of positrons from a Surko-type source
  and accumulator
• 22Na radioactive source (40 mC)
• 108 e every 200 s

• 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)

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positronium excitation

• Two laser steps
• nPs 1 ? nPs 3
• nPs 3 ? nPs 20 40 (tunable)

• gt106 Rydberg positronium atoms are expected

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Antihydrogen production occur via charge exchange
process
C. H. Storry et al., Phys. Rev. Lett. 93 (2004)
263401
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• The beam is produced using a stark accelerator
• H is in Rydberg state
• Interactions between electric dipole moment and
• a non-uniform electric field

• ?v 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

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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 _at_
  500m/s
• Poor beam collimation beam size after flight
  several cm

Gravity measurement with ordinary matter have
been performed with a Moirè deflectometer s(g)/g
210-4 M. K. Oberthaler et al., Phys. Rev. A
54 (1996) 3165
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G1
G2
Detector
20 cm
40 cm
40 cm
Ls 30 cm
(distance antihydrogen source-first
grating) Grating distance L 40 cm Grating
size 20 x 20 cm2 Grating period
a80 µm Grating transparency
30 Detector resolution 10 µm
Only classical interactions
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Binning (grating period)
Vh 600 m/s
Montecarlo results
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x
Vh 600 m/s
Vh 400 m/s
counts
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x
Vh 600 m/s
Vh 400 m/s
Vh 300 m/s
counts
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x
Vh 600 m/s
Vh 400 m/s
Vh 300 m/s
Vh 250 m/s
counts
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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).

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Conclusions ( ambitions)
AEGIS will use already well-know techniques
together with innovative schemes Members of
AEGIS are already working on this
Gravity on antimatter has never been
tested AEGIS 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.
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Thanks for your attention
http//aegis.web.cern.ch/
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The g measurement

• Send the antihydrogen beam through the
  deflectometer t0 defined within msec
• 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

N(x)
10 mm resolution
Infinite resolution
x/a
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Capture and cooling of antiprotons

• 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 (?)

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Recombination experiments ATHENA ATRAP
Core idea trapping in the same region and e
Cylindrical Penning trap
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B1T
B5T
Diocotron jump of positrons
P-bar catching region
P-bar cooling region