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
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: