aegis antimatter experiment: gravity, interferometry, spectroscopy c. canali infn sez. genova 11°...
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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