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Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
1S-2S Spectroscopy of Positronium
SPS-2017 Geneva, Switzerland
Gunther Wichmann
Precision Physics at Low Energy, Kirch Group
Positron and Positronium Laboratory, Rubbia Group
August 24, 2017
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Exotic Atom Spectroscopy
Von S B from Sydney, Australia - Cockatoos at breakfast, CC BY 2.0,https://commons.wikimedia.org/w/index.php?curid=5445640
muonic hydrogen/deuterium:Pohl R, Antognini A, Nez F, Amaro FD, Biraben F, et al.,Nature 466:213 (2010)
Pohl R, Nez F, Fernandes L M P, Amaro F D, et al.,Science 669-673 (2016)
antihydrogen:M. Ahmadi, B. X. R. Alves, C. J. Baker, W. Bertsche,E. Butler, A. Capra, C. Carruth, C. L. Cesar, M. Charlton,S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts,J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill,A. Gutierrez, J. S. Hangst, W. N. Hardy, M. E. Hayden,C. A. Isaac, A. Ishida, M. A. Johnson et al.,Nature 541, 506510, 2017
muonium (e−µ+, Mu):V. Meyer et al., Phys Rev. Lett. 84, 1136 (2000)
positronium (e+e−, Ps):M.S.Fee, A.P.Mills, Jr., S.Chu, E.D.Shaw, K.Danzmann, R.J.Chichester, and D.M.Zuckerman, Phys. Lett. 70, 1397 (1993)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Motivation
Proton radius puzzle: (due to muonic hydrogen)
Test of bound-state QED without finite nuclear size effects.
1e.g. Krzysztof Pachucki and Savely G. Karshenboim, PRL 80, Nr.10, 1998
2e.g. Adkins, Gregory S. and Kim, Minji and Parsons, Christian and Fell, Richard N., PRL 115, 233401, 2015
3Kostelecky and Vargas, Phys. Rev. D 92, 056002, 2015
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Motivation
Proton radius puzzle: (due to muonic hydrogen)
Test of bound-state QED without finite nuclear size effects.
Precision Test of bound-state QED.
- QED calculations1 completed to the order of mα6
(uncertainty ±0.6MHz, 9 digits).
- Ongoing work2 for mα7.
Lorentz and CPT test3
1e.g. Krzysztof Pachucki and Savely G. Karshenboim, PRL 80, Nr.10, 1998
2e.g. Adkins, Gregory S. and Kim, Minji and Parsons, Christian and Fell, Richard N., PRL 115, 233401, 2015
3Kostelecky and Vargas, Phys. Rev. D 92, 056002, 2015
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2 photon transition:
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2 photon transition:
ν = 1233 607 222.2(0.6)MHz
a: M. S. Fee et al., Phys. Rev. Lett. 70, 1397 (1993)
ν = 1233 607 216.4(3.2)MHz
b: S. Chu, A. P. Mills, Jr. and J. Hall, Phys. Rev. Lett. 52, 1689 (1984)
ν = 1233 607 218.9(10.7)MHz
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2 photon transition:
ν = 1233 607 222.2(0.6)MHz
a: M. S. Fee et al., Phys. Rev. Lett. 70, 1397 (1993)
ν = 1233 607 216.4(3.2)MHz
b: S. Chu, A. P. Mills, Jr. and J. Hall, Phys. Rev. Lett. 52, 1689 (1984)
ν = 1233 607 218.9(10.7)MHz
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium (Ps, e+e−)
Reduced mass mPs = me/2 = 0.26MeV/c2.
Bound system of matter and antimatter.
Lifetime depends on spin configuration ortho-Ps 142 nspara-Ps < 1 ns
Lifetime limited by annihilation(wave function overlap of e+ and e
−)τ2S = 1.1µs
radiative lifetime τ2S = 244ms
negligible annihilation lifetime for 20Pradiative lifetime τ20P ≈ 3 µs
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium (Ps, e+e−)
Reduced mass mPs = me/2 = 0.26MeV/c2.
Bound system of matter and antimatter.
Lifetime depends on spin configuration ortho-Ps 142 nspara-Ps < 1 ns
Lifetime limited by annihilation(wave function overlap of e+ and e
−)τ2S = 1.1µs
radiative lifetime τ2S = 244ms
negligible annihilation lifetime for 20Pradiative lifetime τ20P ≈ 3 µs
In this setup:
The emitted Ps velocity is around 105m/s (≈ 50meV, β = v/c = 3.1 · 10−4).⇒ 10 cm results in an experimental time window ≤ 1µs.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Previous ExperimentPredecessor:
- excitation of 1S-2S withCW laser enhancement cavitydemonstrated.
→ too high noise level (accidentals).
→ frequency reference only bya wavemeter (±10MHz).
D.Cooke et al, Hyperfine Interact. 233 (2015)[arXiv:1503.05755 [physics.atom-ph]]
⇒ e+ in bunches would reduce noise level (shorter time window).
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Current Setup
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Bunched Positron Beam
β+ decay converted to
bunches with
- 1 ns FWHM and σ = 1mm
- 1 to 10Hz repetition rate
- Ekin = 3 to 5 keV
≥ 20′000 e+/s
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Bunched Positron Beam
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
⇒ Noise level reduction is achieved by e+ bunching!
⇒ Time window for hitting the converter generated! (start trigger)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium Generation
thanks toDr. Francesca Nessi-Tedaldi,Dissertori Group ETHZ
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
⇒ Noise level reduction is achieved by e+ bunching!
⇒ Time window for hitting the converter generated! (start trigger)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium Generation
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
⇒ Noise level reduction is achieved by e+ bunching!
⇒ Time window for hitting the converter generated! (start trigger)
100− 0 100 200 300 400 500
0
20
40
60
80
100
120
140
160
180
1 e+ bunch
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium Generation
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
⇒ Noise level reduction is achieved by e+ bunching!
⇒ Time window for hitting the converter generated! (start trigger)
100− 0 100 200 300 400 500
1−
10
1
5400 e+ bunches
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium Generation
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
⇒ Noise level reduction is achieved by e+ bunching!
⇒ Time window for hitting the converter generated! (start trigger)
100− 0 100 200 300 400 500
1−
10
1
5400 e+ bunches
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Positronium Generation
- 1 nsFWHM
- σ = 1mm
- 20’000 e+ per bunch
Next Step:
Generation of excited 2S Ps.
100− 0 100 200 300 400 500
1−
10
1
5400 e+ bunches
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Resonant Multi-photon ionization of ortho-Positronium
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Resonant Multi-photon ionization of ortho-Positroniumusing 3 photons of 486 nm with 17mJ, 7 ns length, waist ≈ 2mm,back reflected by a plane mirror with a misalignment of ≈ 0.5mrad.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Resonant Multi-photon ionization of ortho-Positroniumusing 3 photons of 486 nm with 17mJ, 7 ns length, waist ≈ 2mm,back reflected by a plane mirror with a misalignment of ≈ 0.5mrad.
Large fraction (≈ 10%) of ortho-Ps excited for probing new detection scheme.
Expected broadening of around 150 MHz from 7 ns long pulse andaround 100 MHz from residual first order Doppler broadening.
(low precision, high statistics)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
0 50 100 150 200
1−
10
1
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
200− 0 200 400
0.1
0.2
0.3
0.14−
0.1−
0.06−
200− 0 200 400
0 50 100 150 200
1−
10
1Preliminary
Annihilation signal of ionized Ps
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
200− 0 200 400
0.1
0.2
0.3
0.14−
0.1−
0.06−
200− 0 200 400
Measurement from 10.08.2017
Preliminary Preliminary
Depletion of 1SAnnihilation signal of ionized Ps
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
200− 0 200 400
0.1
0.2
0.3
0.14−
0.1−
0.06−
200− 0 200 400
Measurement from 10.08.2017
Preliminary Preliminary
Depletion of 1SAnnihilation signal of ionized Ps
=⇒ playground inaugurated.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Measurement with Pulsed Laser
200− 0 200 400
0.1
0.2
0.3
0.14−
0.1−
0.06−
200− 0 200 400
Measurement from 10.08.2017
Preliminary Preliminary
Depletion of 1SAnnihilation signal of ionized Ps
=⇒ playground inaugurated.
for example upcoming hyperfine splitting of 2S Ps.(presented by M.Heiss this Friday, CICG Room 5)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Setup with Cavity - 1S-2S CW Spectroscopy
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Excitation Scheme
laser enhancement cavity
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Excitation Scheme
laser enhancement cavity
1. incoming bunched e+ pulses.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Excitation Scheme
laser enhancement cavity
1. incoming bunched e+ pulses.
2. 1S-2S excitation with 486 nm.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Excitation Scheme
laser enhancement cavity
1. incoming bunched e+ pulses.
2. 1S-2S excitation with 486 nm.
3. 2S-20P excitation with 730 nm.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Overview - Excitation Scheme
laser enhancement cavity
1. incoming bunched e+ pulses.
2. 1S-2S excitation with 486 nm.
3. 2S-20P excitation with 730 nm.
4. Detection on MCP.
1S Ps → 3γ
20P Ps → e+,e−
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Laser Cavity
ortho-Ps transits the enhanced laser light
in the cavity:
- No first order Doppler shift.
- Highly collinear counter propagating beams.
- Ultra high finesse cavity.
(enhancement factor > 5000)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Laser excitation
z
x
z
y
- Different interaction times and intensities
for different emission angles.
- Laser intensity limited by the damage threshold of the laser mirrors.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Laser Excitation
detuning [MHz]200 100 0 100
excita
tio
n /
em
itte
d o
rth
o-P
s0.05
0.1
0.15
0.2
3−
10×
Optical Bloch equation with second order Doppler shift and AC Stark shift.
(expected FWHM around 60 MHz)
Natural linewidth 2S: 1.2MHz Laser Power 500W, beam waist 0.3mm
⇒
← 2 · 10−4
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2S Ps Detection
- excitation rate of ≈ 10−4 (> 1 per e+-pulse).
⇒ Need for low background.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2S Ps Detection
- excitation rate of ≈ 10−4 (> 1 per e+-pulse).
⇒ Need for low background.
- Excitation of 2S Ps to
Rydberg states (n=20).
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2S Ps Detection
- excitation rate of ≈ 10−4 (> 1 per e+-pulse).
⇒ Need for low background.
- Excitation of 2S Ps to
Rydberg states (n=20).
- Subsequent ionization and
detection by a micro channel plate (MCP).
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2S Ps Detection
- excitation rate of ≈ 10−4 (> 1 per e+-pulse).
⇒ Need for low background.
- Excitation of 2S Ps to
Rydberg states (n=20).
- Subsequent ionization and
detection by a micro channel plate (MCP).
- Major systematic:
second order Doppler shift and AC Stark shift
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
2S Ps Detection
- excitation rate of ≈ 10−4 (> 1 per e+-pulse).
⇒ Need for low background.
- Excitation of 2S Ps to
Rydberg states (n=20).
- Subsequent ionization and
detection by a micro channel plate (MCP).
- Major systematic:
second order Doppler shift and AC Stark shift
- compared to our previous setup:
→ no DC Stark shift, Zeeman shift or motional Stark shift.SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Ps Velocity and Angular Distribution
t [ns]0 200 400 600 800 1000
pro
ba
bili
ty
0
0.02
0.04
0.06
Expected time spectra for excited Ps on the MCPin 40mm distance to the converter.
⇒ extraction of the mean emission velocity to ≈ 4%
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
- depletion of ortho-Ps (generation of 2S) with pulsed laser working.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
- depletion of ortho-Ps (generation of 2S) with pulsed laser working.
- MCP detector and cavity prepared.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
- depletion of ortho-Ps (generation of 2S) with pulsed laser working.
- MCP detector and cavity prepared.
Next:→ Installation of the MCP detector.→ Ps excitation to Rydberg states and recording of time spectra.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
- depletion of ortho-Ps (generation of 2S) with pulsed laser working.
- MCP detector and cavity prepared.
Next:→ Installation of the MCP detector.→ Ps excitation to Rydberg states and recording of time spectra.
→ change to CW laser with enhancement cavity for spectroscopy.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Status
- pulsed e+ beam working.
- depletion of ortho-Ps (generation of 2S) with pulsed laser working.
- MCP detector and cavity prepared.
Next:→ Installation of the MCP detector.→ Ps excitation to Rydberg states and recording of time spectra.
→ change to CW laser with enhancement cavity for spectroscopy.
⇒ Precision in sub-MHz range, seeking order of mα7.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Acknowledgment
P. Crivelli, D. Cooke, P. Comini, L. Gerchow, M. Heiss, C. Vigo
K. Kirch, A. Antognini, K. Schuhmann, D. Taqqu, M. Rawlik
This work is supported by the ETH Zurich under grant ETH-35 14-1 and theSwiss National Science Foundation under the grant number 200020 159754 and200020 166286.
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides: Converter - Porous Silica
P. Crivelli et al. , Phys. Rev. A81, 052703 (2010)
- para-Ps lifetime: 0.125 ns (11S0, anti-parallel spins, decays into ≥ 2 photons)- ortho-Ps lifetime: 142.05 ns (13S1, parallel spins, decays into ≥ 3 photons)- Mean Ps emission time4 is in the range of a few ns.
⇒ Only ortho-Ps can exit the converter before annihilation.⇒ Monochromatic emission velocity. vPs ≈ 105 m/s ± 2% (particle in a box of 4.1 nm).
4D. B. Cassidy, T. H. Hisakado, V. E. Meligne, H. W. K. Tom, A. P. J. Mills, Delayed emission of cold
positronium from mesoporous materials, Physical Review. A 82, 2010
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides: Second order Doppler shift and AC Stark shift
- Numerically solving Maxwell-Bloch equations.5
- Determination of the Ps velocity.
Assumptions:
Spatial emission Lamberts cosine law6:
ρ(θ) dθ = 12 cos θ dθ
Monochromatic emission velocity:
vPs ≈ 105 m/s ± 2% .
5M. Haas, U. D. Jentschura, C. H. Keitel, N. Kolachevsky, M. Herrmann, P. Fendel, M. Fischer, T. Udem, R.
Holzwarth, T. W. Haensch, et al., Two-photon excitation dynamics in bound two-body coulomb systems includingac stark shift and ionization, Physical Review. A 73 (5). doi:10.1103/PHYSREVA.73.0.
6D. B. Cassidy, P. Crivelli, T. H. Hisakado, L. Liszkay, V. E. Meligne, P. Perez, H. W. K. Tom, and A. P.
Mills, Jr., Phys. Rev. A 81, 012715 Published 29 January 2010; Erratum Phys. Rev. A 81, 039904 (2010)
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides:
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides:
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides:
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
Motivation Experiment Bunched Positron Beam Ionization 1S-2S Spectroscopy Status and Outlook
Backup Slides:
SPS-2017: Positronium 1S-2S Spectroscopy Gunther Wichmann, Kirch Group, IPP, ETH Zurich
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