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An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen Bertalan Juhsz Stefan Meyer Institute for Subatomic Physics, Vienna, Austria on behalf of the ASACUSA collaboration IFA (rhus), ISA (rhus), UB (Brescia),

SLIDE 1

An atomic beamline to measure the ground-state hyperfine splitting

f antihydrogen

Bertalan Juhász

Stefan Meyer Institute for Subatomic Physics, Vienna, Austria

n behalf of the ASACUSA collaboration

IFA (Århus), ISA (Århus), UB (Brescia), KFKI RMKI (Budapest), ATOMKI (Debrecen), CERN (Geneva), RIKEN (Saitama), UT (Tokyo), SMI (Vienna) PST05, Tokyo, Japan, November 16, 2005

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.1/19

SLIDE 2

Outline

What is ground-state hyperfine splitting H GS-HFS as CPT symmetry test How we want to measure it Low-velocity H production in Paul trap or cusp trap Sextupole magnets for spin selection and analysis Microwave cavity Monte Carlo simulations Beamline design Expected count rate and precision

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.2/19

SLIDE 3

GS-HFS of (anti)hydrogen

Ground-state hyperfine splitting (GS-HFS): Interaction between (anti)proton and electron (positron) spin magnetic moment Results in triplet (F = 1) and singlet (F = 0) sublevels

1s F = 1 F = 0 M = 1 M = 0 M = 1 M = 0

Between F = 1 and F = 0: νHF ≃ 16 3

mp + me 3 me mp µp µN α2c Ry ≃ 1.42 GHz νHF proportional to (anti)proton magnetic moment µp

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.3/19

SLIDE 4

SME including CPTV and LIV

Kostelecky et al.: Standard Model extension (SME) including Charge-Parity-Time invariance violating (CPTV) Lorentz invariance violating (LIV) terms in Lagrangian ⇒ correction to sublevel energies: ∆EH(mJ, mI) = ae

0 + ap 0 − ce 00me − cp 00mp+

+(−be

3 + de 30me + He 12)mJ/|mJ|

+(−bp

3 + dp 30mp + Hp 12)mI/|mI|

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.4/19

SLIDE 5

SME including CPTV and LIV

Kostelecky et al.: Standard Model extension (SME) including Charge-Parity-Time invariance violating (CPTV) Lorentz invariance violating (LIV) terms in Lagrangian ⇒ correction to sublevel energies: ∆EH(mJ, mI) = ae

0 + ap 0 − ce 00me − cp 00mp+

+(−be

3 + de 30me + He 12)mJ/|mJ|

+(−bp

3 + dp 30mp + Hp 12)mI/|mI|

Parameters a and b have dimension of energy ⇒ not relative but absolute precision matters

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.4/19

SLIDE 6

SME including CPTV and LIV

Kostelecky et al.: Standard Model extension (SME) including Charge-Parity-Time invariance violating (CPTV) Lorentz invariance violating (LIV) terms in Lagrangian ⇒ correction to sublevel energies: ∆EH(mJ, mI) = ae

0 + ap 0 − ce 00me − cp 00mp+

+(−be

3 + de 30me + He 12)mJ/|mJ|

+(−bp

3 + dp 30mp + Hp 12)mI/|mI|

Parameters a and b have dimension of energy ⇒ not relative but absolute precision matters Parameters a, d, and H reverse sign for antihydrogen

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.4/19

SLIDE 7

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 8

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 9

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 10

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field Best candidate: atomic beam with microwave resonance

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 11

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field Best candidate: atomic beam with microwave resonance no H trapping needed – you would need ultra-cold (< 1 K) H for that

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 12

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field Best candidate: atomic beam with microwave resonance no H trapping needed – you would need ultra-cold (< 1 K) H for that AB method can work up to 50-100 K

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 13

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field Best candidate: atomic beam with microwave resonance no H trapping needed – you would need ultra-cold (< 1 K) H for that AB method can work up to 50-100 K inhomogeneous magnetic field needed to guide the neutral H atoms grabbed by their magnetic moment

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 14

Measurement of H GS-HFS

Highest precision for H: ∼10−12 with hydrogen maser But: maser is not possible for H Spectroscopy with trapped H: low precision due to strong confining field Best candidate: atomic beam with microwave resonance no H trapping needed – you would need ultra-cold (< 1 K) H for that AB method can work up to 50-100 K inhomogeneous magnetic field needed to guide the neutral H atoms grabbed by their magnetic moment Measurement at the Antiproton Decelerator (AD) of CERN after ∼2007

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.5/19

SLIDE 15

Ground-state H or H in magnetic field

Energies of hyperfine states change in magnetic field Increase for (F, M) = (1,−1) and (1,0) ⇒ low-field seekers (µ < 0) Decrease for (F, M) = (1,1) and (0,0) ⇒ high-field seekers (µ > 0)

B (T) 0.00 0.02 0.04 0.06 0.08 0.10 (GHz) n

0.0 0.5 1.0 1.5 2.0 (F,M)=(1,1) (F,M)=(1,0) (F,M)=(1,-1) (F,M)=(0,0) 1 p 1 s 2 p H 1 2 3 4 low-field seekers high-field seekers e + p

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.6/19

SLIDE 16

Focusing in sextupole field

potential: V = − µ B force: F = −grad V = grad( µ B) If dθB/dt ≪ ωL and µ constant:

F = µ grad(B)

Sextupole field (cylindrical coord.):

B(r) = (3Cr2 sin 3φ, 3Cr2 cos 3φ, 0)

B(r) = 3Cr2 ⇒ Fr = µ ∂B/∂r = 6Cµr ⇒ harmonic oscillation: ω =

6Cµ/m

⇒ point-to-point focusing for single vz: lf = πvz

m/6Cµ

0.5 1 x

r

N S S

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.7/19

SLIDE 17

Schematic layout

p e sextupole 1 microwave cavity sextupole 2 antihydrogen detector + and trap recombination

low-velocity H atoms from recombination source

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.8/19

SLIDE 18

Schematic layout

p e sextupole 1 microwave cavity sextupole 2 antihydrogen detector + and trap recombination

low-velocity H atoms from recombination source 1st sextuple focuses low-field seekers, defocuses high-field seekers (spin selection)

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.8/19

SLIDE 19

Schematic layout

p e sextupole 1 microwave cavity sextupole 2 antihydrogen detector + and trap recombination

low-velocity H atoms from recombination source 1st sextuple focuses low-field seekers, defocuses high-field seekers (spin selection) microwave cavity flips spin ⇒ conversion from low-field seeker to high-field seeker

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.8/19

SLIDE 20

Schematic layout

p e sextupole 1 microwave cavity sextupole 2 antihydrogen detector + and trap recombination

low-velocity H atoms from recombination source 1st sextuple focuses low-field seekers, defocuses high-field seekers (spin selection) microwave cavity flips spin ⇒ conversion from low-field seeker to high-field seeker 2nd sextupole analyzes spin

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.8/19

SLIDE 21

H source

„Conventional” way: nested Penning trap

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 22

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 23

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 24

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 25

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 26

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap e+ from positron source, p from SC linear Paul trap

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 27

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap e+ from positron source, p from SC linear Paul trap under development at CERN

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 28

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap e+ from positron source, p from SC linear Paul trap under development at CERN Cusp trap i.e. anti-Helmholtz coils

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 29

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap e+ from positron source, p from SC linear Paul trap under development at CERN Cusp trap i.e. anti-Helmholtz coils e+ from positron source, p from (already working) SC Penning trap

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 30

H source

„Conventional” way: nested Penning trap source size too large for atomic beam method limited extraction and optical access small solid angle Superconducting two-frequency Paul trap e+ from positron source, p from SC linear Paul trap under development at CERN Cusp trap i.e. anti-Helmholtz coils e+ from positron source, p from (already working) SC Penning trap under development at RIKEN

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.9/19

SLIDE 31

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 32

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

2 end cap & 1 ring electrodes

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 33

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

2 end cap & 1 ring electrodes RF: 3 GHz for e+, 1 MHz for p

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 34

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

2 end cap & 1 ring electrodes RF: 3 GHz for e+, 1 MHz for p good access, point-like source

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 35

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

2 end cap & 1 ring electrodes RF: 3 GHz for e+, 1 MHz for p good access, point-like source laser-assisted de-excitation

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 36

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

Only 1s or 2s H atoms are emitted 2 end cap & 1 ring electrodes RF: 3 GHz for e+, 1 MHz for p good access, point-like source laser-assisted de-excitation

50 100 150 200 250 5 10 15 20 Principal quantum number n Time until all atoms in 1s or 2s state (µs) 50 K cut-off

100 K cut-off 200 K cut-off RF ionization cut-off

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 37

SC two-frequency Paul trap

Antiproton injection Positron injection Antihydrogen ejection 11000 nm laser 377 nm (886 nm) 11d -> 2s/3d laser

Only 1s or 2s H atoms are emitted Expected production rate: 200 H/sec 2 end cap & 1 ring electrodes RF: 3 GHz for e+, 1 MHz for p good access, point-like source laser-assisted de-excitation

50 100 150 200 250 5 10 15 20 Principal quantum number n Time until all atoms in 1s or 2s state (µs) 50 K cut-off

100 K cut-off 200 K cut-off RF ionization cut-off

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.10/19

SLIDE 38

Cusp trap

p _ e+ H _

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.11/19

SLIDE 39

Cusp trap

p _ e+ H _

Larger source size, but can do some focusing

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.11/19

SLIDE 40

Cusp trap

p _ e+ H _

Larger source size, but can do some focusing Could provide polarized H ⇒ might eliminate the need for 1st sextupole

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.11/19

SLIDE 41

Cusp trap

p _ e+ H _

Larger source size, but can do some focusing Could provide polarized H ⇒ might eliminate the need for 1st sextupole But: H in 1s state?

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.11/19

SLIDE 42

Beamline design considerations

H is abundant ⇔ H is precious

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 43

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 44

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!)

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 45

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!) SC Paul trap is sensitive to magnetic field during cooldown

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 46

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!) SC Paul trap is sensitive to magnetic field during cooldown safe distance from magnet ⇒ large magnet inner diameter (∼10 cm)

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 47

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!) SC Paul trap is sensitive to magnetic field during cooldown safe distance from magnet ⇒ large magnet inner diameter (∼10 cm) proper magnetic shielding

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 48

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!) SC Paul trap is sensitive to magnetic field during cooldown safe distance from magnet ⇒ large magnet inner diameter (∼10 cm) proper magnetic shielding

r simply turn off the magnet (if possible. . . )

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 49

Beamline design considerations

H is abundant ⇔ H is precious high transmission efficiency large opening angle (neutral H goes to 4π!) SC Paul trap is sensitive to magnetic field during cooldown safe distance from magnet ⇒ large magnet inner diameter (∼10 cm) proper magnetic shielding

r simply turn off the magnet (if possible. . . )

Sextupole field has to be very small in the microwave cavity

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.12/19

SLIDE 50

Possible sextupole magnets

Ordinary iron

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 51

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 52

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 53

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 54

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 55

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 56

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off −: 10 cm inner diameter ⇒ expensive. . .

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 57

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off −: 10 cm inner diameter ⇒ expensive. . .

Superconducting

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 58

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off −: 10 cm inner diameter ⇒ expensive. . .

Superconducting

+: strong (∼4 T), variable field; good for UHV

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 59

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off −: 10 cm inner diameter ⇒ expensive. . .

Superconducting

+: strong (∼4 T), variable field; good for UHV −: relatively cumbersome to operate

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 60

Possible sextupole magnets

Ordinary iron

+: variable field, can be turned off −: maximum field just above 1 T

Permanent (e.g. Halbach type REC)

+: easy operation −: constant field, cannot be turned off −: 10 cm inner diameter ⇒ expensive. . .

Superconducting

+: strong (∼4 T), variable field; good for UHV −: relatively cumbersome to operate

Most probable choice: superconducting

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.13/19

SLIDE 61

Microwave cavity

Will be an enlarged version of the 12.9 GHz MW cavity used for microwave spectroscopy of antiprotonic helium atoms

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.14/19

SLIDE 62

Some preliminary Monte Carlo simulations

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.15/19

SLIDE 63

MC – geometry

Assuming 50 K (vm ≃ 900 m/s) point-like H source:

resonance on/off

Opening angle: 20◦, internal diameter: 10 cm, total length: ∼170 cm, pole tip field: 4 T; ǫ ≃ 4 × 10−4

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.16/19

SLIDE 64

MC – geometry

Assuming 50 K (vm ≃ 900 m/s) point-like H source: Opening angle: 20◦, internal diameter: 10 cm, total length: ∼170 cm, pole tip field: 4 T; ǫ ≃ 4 × 10−4 “Single focusing”: total length: ∼150 cm; ǫ ≃ 10 × 10−4 ⇐ larger velocity acceptance

▽An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.16/19

SLIDE 65

MC – geometry

Assuming 50 K (vm ≃ 900 m/s) point-like H source: Opening angle: 20◦, internal diameter: 10 cm, total length: ∼170 cm, pole tip field: 4 T; ǫ ≃ 4 × 10−4 “Single focusing”: total length: ∼150 cm; ǫ ≃ 10 × 10−4 ⇐ larger velocity acceptance

Total efficiency: 5–20 × 10−5 ⇒ expected detection rate: 0.5–2 H/min

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.16/19

SLIDE 66

MC – velocity distribution

velocity (m/s) 200 400 600 800 1000 1200 1400 1600 1800 2000 N 20 40 60 80 100 120 140 160 velocity (m/s) 200 400 600 800 1000 1200 1400 1600 1800 2000 N 20 40 60 80 100 120 140 160

DF SF

Velocity distribution in MW cavity is wider for SF ⇒ MW resonance is broader

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.17/19

SLIDE 67

MC – resonance curve

Per point: 4,000,000 50 K H from point-like source:

MW frequency (GHz) 1420.395 1420.400 1420.405 1420.410 1420.415 normalized counts 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

SF: FWHM: 7.4 kHz δν: 0.25 kHz δν/ν: 1.7 × 10−7 DF: narrower, but worse statistics FWHM: 5.7 kHz δν: 0.74 kHz δν/ν: 5.2 × 10−7

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.18/19

SLIDE 68

Summary

Ground-state hyperfine splitting of antihydrogen is a good candidate to test CPT violation effects Kostelecky et al.: not relative but absolute precision matters Measurement: atomic beam method H source: two-frequency Paul trap or cusp trap 2 sextupoles & 1 microwave resonance cavity Expected count rate: 0.5–2 H/min Expected precision: better than 10−6 Still in the early design phase – comments are welcome

An atomic beamline to measure the ground-state hyperfine splitting of antihydrogen – p.19/19