sa cla y - GBAR Home r f u sa cla y Efficiencies 08/04/2010 P. Debu - CS P2I 22 Rate could be improved a lot with:-Higher energy Linac (close to 10 MeV)-ELENA upgrade of AD at CERN

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27/04/2011 Pascal Debu - CEA/DSM/IRFU 1

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Motivation

2

A direct test of the Equivalence Principle with antimatter

The acceleration imparted to a body by a gravitational

field is independent of the nature of the body :

Inertial mass = gravitational mass

27/04/2011 Pascal Debu - CEA/DSM/IRFU

13

Be/Ti

13

Earth/Moon

Weak Equivalence Principle (torsion pendulum)

S.Schlamminger et al, Phys Rev Lett 100 (2008) 041101

Strong Equivalence Principle (Lunar Laser Ranging)

a / a 0.3 1.8 x10

a / a 1.0 1.4 x10

J.G.Williams et al, Phys Rev Lett 93 (2004) 261101

Tested to a very high precision with many materials

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Theory and Experiments:

J. Scherk, Phys. Lett. B (1979) 265

Discussion and experimental constraints : M. Nieto and T. Goldman, Phys. Rep. 205 (1991) 221

Motivation for antigravity in General Relativity: G. Chardin, Hyperfine Interactions 109 (1997) 83

.

Supergravity : one componentof repulsive gravity

Newton

Indirect Tests Antimattercontent of matter K0 - K0 system ν from SN1987a Cyclotron frequency

p/p

Direct Tests Charged

antimatter

e+

p

Pb : e.m. shielding

F. Witteborn and W.

Fairbank, Phys Rev Lett 19

(1967) 1049

PS200 Los Alamos Report

LA-UR 86-260

Neutral

antimatter

n hard to slow down T. Brando et al, NucI.

Instrum. Methods 180

(1981) 461

Ps short lifetime

polarisability…

A.P. Mills, M. Leventhal,

NucI. Instrum. Meth. .

B192 (2002) 102

No direct measurement available yet


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Next simplest system: H

-L = 1 m & vh = 1000 m/s → h = 5 µm (T(H) ~ 4 K ~ 0.3 meV)AGE : LOI FNAL suspended

-L = 1 m & vh = 500 m/s → h = 20 µm (T(H) ~ 100 mK ~ 7 μeV) AEGIS : approved CERN experiment

- L = 0.1 m & vh = 0.5 m/s → h = 20 cm (T(H) ~ 20 μK ~ 1 neV)

GBAR : cooled H+ → slow H

P. Pérez et al, LOI CERN –SPSCI-038 (2007) Irfu, Riken, Tokyo U.

L

HPrinciple :

parabolic flightInterferometer

deflectometer

free fall

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Gbar : g experiment using H+ to get H atoms

• Produce ion H+

• Capture ion H+

• Sympathetic cooling 20 µK

• Photodetachment of e+

• Time of flight

Error dominated by

temperature of H+

Relative Precision on g:

H+in ion trap g/g

5 105 0.001

104 0.006

103 0.02

h = 10 cm ∆t = 143 ms

J.Walz & T. Hänsch,

General Relativity and Gravitation, 36 (2004) 561.

h = 1/2 g (t1-t0)2

H+

gravity

detector (t1)

detector

Laser (t0)

cooling 20 µK


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Gra

vity m

easure

ment

e+ Production

& Accumulation fast H & H + slow H + slow H

1- 6 KeV

Photo

detach

12

137

8

Ps dense6

Ps → Ps*Target2

LINAC1

Moderator/

Collector

e+ ~ MeV→eV

3

Penning Trap

e+ ~meV

4

5

p

Penning Trap ELENA

H+ Trap

Paul Trap

Be+

laser cooling

9

10

11

ε=10-4

ε=10-2-10-4

ε=0.5

ε=10 ?

ε=0.35

Synoptic Scheme

27/04/2011 6Pascal Debu - CEA/DSM/IRFU

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High intensity slow positrons source


LINAC

e-

5.5 MeV

targ

et

e+

0-3 MeV

e- and γ0-5 MeV

Moderator

e+ “slow” : 3 eV

Tungsten target

εe+/e- prod = 2 10-4

200 Hz / 4 μs

0.1-0.2 mA

Tungsten near primary target

εmoderation = 10-4

Solid neon after e+/e- selector

εmoderation = 3 10-3

e+/e-

selection

~ 3 1011 fast e+/s

107 –108 slow e+/s

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Installation at Saclay


Concrete

shielding X

rays

Demonstrator e- Linac

Ec ≈ 4.5 MeV

Imeasured = 0.14 mA

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Fast e+ detection35 Faraday cups


expected positron yield from 1 mm W target at 5.5 MeV

~ 1 x10-4 per electron

Linac peak current ~ .14 mA during 4 μs

charge seen on pads 11-12 ~ 4 pC per burst as expected

from Linac effective energy

First positrons measured end of 2009

e+ e-

E = (5.5 - 8.7 x 10-4 x I)

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Slow e+ Beam line in construction


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RIKEN Multi Ring Trap


• Cooling by e- plasma, 106 e+ stored, trapping efficiency εtrapping~ 1%

• Trap now at Saclay: start test accumulation with pulsed e+ beam end 2011

εtrapping ≈ 50% expected, few 1010 e+ needed

N. Oshima et al., Phys. Rev. Lett. 93 19 (2004)

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Trapping pulsed e+ beam

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Gra

vity m

easure

ment

e+ Production


1- 6 KeV

Photo

detach

12

137

8

Ps dense6

Ps → Ps*Target2

LINAC1

Moderator/

Collector

e+ ~ MeV→eV

3

Penning Trap

e+ ~meV

4

5

p

Penning Trap ELENA

H+ Trap

Paul Trap

Be+

laser cooling

9

10

11

ε=10-4

ε=10-2-10-4

ε=0.5

ε=10 ?

ε=0.35

Synoptic Scheme


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Production of 1012 Ps/cm2

14

Positronium target is produced with a porous SiO2 converter:

dump few 1010 e++in less than ~ 140 ns onto converter

e+ converter → Ps

Experiments at CERN: Irfu/ETHZ (e+ beam)

and at UCR Cassidy et al. (trap)

• Ps in fundamental state

• Ec ~40 meV

• Efficiency of Ps production in vacuum > 30%


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Energy of o-Ps : comparison CERN/UCR

EΤ

E//

P. Crivelli et al., Phys. Rev. A 81, 052703 (2010)

D. B.. Cassidy et al., Phys. Rev. A 81, 012715

(2010).

Measurement

at CERN

Measurement

at UCR


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Yield of o-Ps : comparison CERN/UCR

16

Measurement

at CERN

Measurement

at UCR~ 5.6 x 1016 e+ cm-2s-1

~ 3.5 x 105 e+ cm-2s-1

No loss in conversion efficiency in spite of the 1011 intensity factor

e+ flux

x

~1011

0 1 2 3 4 5 60

10

20

30

40

Inte

nsity o

f th

e 1

42 n

s

com

ponent (%

)

Positron energy (keV)

Cb 44

CTACl-0.22 Saclay

1000 rpm


L.Liszkay et al., Appl. Phys. Lett. 92 (2008) 063114

D. B. Cassidy et al.,Phys. Rev. A 81 012715 (2011)

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H+ production


p + Ps → H + e –

H + Ps* → H+ + e –

SiO2

coating

fast extraction from trap

tube geometry to keep density

(SiO2 reflects Ps)

Dump 1011 e+ in

Ps converter

in < τPs=142 ns

e+ trap

accumulate few 1010 e+

during p filling ~ 20’

Linac

108 slow e+/s

RIKEN test :

1.3 1010 e- / 75 ns

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Cross-sections on PS

Pascal Debu - CEA/DSM/IRFU

18

p + Ps H + e+

σ ~10-15 cm2

J. P. Merrison et al., Phys. Rev. Lett. 78, 2728

(1997)

2 5 10 20 50 100

Ep [keV]

H + Ps H- + e+

EH = 6 keV in Ps frame

σ ~10-16 cm2

H.R.J. Walters and C. Starett, Phys. Stat. Sol. C, 1-8

(2007)

EPs [eV]

if fraction of Ps

excited to n=3

expect × ~ 10

107 p

1012 Ps/cm2}

8 104 H

8 H+2.5 x1010 e+

from trap

AD FacilityCERN

27/04/2011

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Gra

vity m

easure

ment

e+ Production


1- 6 KeV

Photo

detach

12

137

8

Ps dense6

Ps → Ps*Target2

LINAC1

Moderator/

Collector

e+ ~ MeV→eV

3

Penning Trap

e+ ~meV

4

5

p

Penning Trap ELENA

H+ Trap

Paul Trap

Be+

laser cooling

9

10

11

ε=10-4

ε=10-2-10-4

ε=0.5

ε=10 ?

ε=0.35

Synoptic Scheme


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H+ cooling


• Segmented RF Paul Trap, well depth ~1 eV

• Sympathetic cooling using Be+ ions

Laser cooled Be+ ions

Coulomb interaction of H+ and Be+

H+ capture

trapBe+ trap

Cooling laser

• Be+ Doppler cooling

Temperature ~ 1 mK

• Be+ sub-Doppler cooling

Temperature 4.5 or 9 μK

NIST group

M. D. Barrett, …, D. Wineland, PRA 68, 042302 (2003)

Sympathetic cooling of 9Be+ and 24Mg+ for quantum logic

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Photo detachment

H+ binding energy 0.76 eV => pγ ~ 0.76 eV/c

Recoil due to absorption: vrecoil = pγ / mH = 0.2 m/s =>

4 cm for 0.2 s fall

Recoil due to e+ emission: γ very close to threshold

Ec = Eγ – 0.76 => ~ 1 m/s for Ec = 10 μeV

vrecoil 2meE c

mH


H free fall detection

-ejected e+ direction => sign(vz)

-arrival position x,y (mm) => vx, vy

-TOF (140 ms)

=> cross-check of initial temperature

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Efficiencies

2208/04/2010 P. Debu - CS P2I

Rate could be improved a lot with:

-Higher energy Linac (close to 10 MeV)

-ELENA upgrade of AD at CERN

Electrons

Linac frequency (Hz) Ie- (mA) Ie- /pulse (mA) pulse length (s) Ne- / pulse Ne

-(s

-1)

200 1.40E-01 1.75E+02 4.00E-06 4.38E+12 8.75E+14

Positrons

ε (e- e+) ε (transport) ε (moderation) Ne+fast / pulse Ne+ fast (s-1

) Ne+ slow / pulse Ne+ slow (s-1

)

1.50E-04 0.8 1.00E-03 5.25E+08 1.05E+11 5.25E+05 1.05E+08

Positron Storage

ε (trapping) accum. time (s) Ne+ stored

0.2 1200 2.52E+10

Positronium

ε (e+ Ps) volume tube (cm3) Ps density (cm

-2) ε (excitation)

0.35 0.01 8.82E+11 10

H

Np / pulse σ(p+Ps H) σ(H+Ps H+) NH NH

+

1.00E+07 1.00E-15 1.00E-16 8.82E+04 7.78E+00

every ~ 20 minutes

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Perspective:

towards a higher precision on g ?

23

Gravitational quantum states of Antihydrogen

A. Yu. Voronin, P. Froelich, and V. V. Nesvizhevsky,

Phys. Rev. A 83, 032903 (2011)

• H Source:

• very low temperature

• high phase-space density

• compact system

• Improve the precision on g with the spectroscopy of

gravitational levels of H : similar method as for UCN

neutrons (GRANIT spectrometer)

only few events needed to reach ~10-3 precision !


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GBAR Schedule


• 2007: P. Pérez et al, LOI CERN –SPSCI-038, CEA/IRFU, RIKEN, Tokyo U.

• 2011: CERN Proposal

• 2014: Installation at CERN

• 2016: First measurements

Documents

sa cla y - GBAR Home r f u sa cla y Efficiencies 08/04/2010 P. Debu - CS P2I 22 Rate could be improved a lot with:-Higher energy Linac (close to 10 MeV)-ELENA upgrade of AD at CERN