Observation of the 1154.9 nm transition of antiprotonic helium

Kobayashi, Takeyuki; Barna, D.; Hayano, R.; Murakami, Yo; Todoroki, K.; Yamada, Hiroyuki; Dax, A.; Venturelli, L.; Zurlo, N.; Horváth, D.; Aghai-Khozani, Hossein; Sótér, Anna; Hori, Masaki

doi:10.1088/0953-4075/46/24/245004

Cited by 13 publications

(24 citation statements)

References 44 publications

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“…This implies that a fractional precision on M π − of < 10 −8 can in principle be achieved, as in the case of pHe + [4,35]. In practice, systematic effects such as the shift and broadening of the resonance line due to atomic collisions [33,[87][88][89] in the experimental target, AC Stark shifts [67], frequency chirp in the laser beam [90], and the statistical uncertainties due to the small number of detected events can prevent the experiment from achieving this precision. The lifetimes of some πHe + states may be shorter than τ π , due to collisional effects (Sects.…”

Section: Discussionmentioning

confidence: 99%

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

Hori

Sótér²,

Korobov

2014

Phys. Rev. A

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Metastable pionic helium (πHe + ) is a three-body atom composed of a helium nucleus, an electron occupying the 1s ground state, and a negatively charged pion π − in a Rydberg state with principaland orbital angular momentum quantum numbers of n ∼ ℓ + 1 ∼ 16. We calculate the spinindependent energies of the π 3 He + and π 4 He + isotopes in the region n = 15-19. These include relativistic and quantum electrodynamics corrections of orders R∞α 2 and R∞α 3 in atomic units, where R∞ and α denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the π − , and the radiative and Auger decay rates of the states are also calculated. Some states (n, ℓ) = (16, 15) and (17, 16) retain nanosecond-scale lifetimes against π − absorption into the helium nucleus. We propose to use laser pulses to induce π − transitions from these metastable states, to states with large (∼ 10 11 s −1 ) Auger rates. The πHe 2+ ion that remains after Auger emission of the 1s electron undergoes Stark mixing with the s, p, and d states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the π − . The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge. A resonance curve is obtained from which the πHe + transition frequency can in principle be determined with a fractional precision of 10 −8 − 10 −6 provided that the systematic uncertainties can be controlled. By comparing the measured πHe + frequencies with the calculated values, the π − mass may be determined with a similar precision. The πHe + will be synthesized by allowing a high-intensity (> 10 8 s −1 ) beam of π − produced by a cyclotron to come to rest in a helium target. The precise time structure of the π − beam is used to ensure a sufficient rate of coincidence between the resonant laser pulses and the πHe + atoms.

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Section: Discussionmentioning

confidence: 99%

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

Hori

Sótér²,

Korobov

2014

Phys. Rev. A

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“…The intensity of the π − absorption spike is plotted as a function of the laser frequency ∆ν detuned from the resonance frequncy ν exp . The width of this profile is predominantly caused by the Auger decay rate of the resonance daughter state (17,14), and the 14-GHz spacing between the fine structure sublines that arise from the interaction between the electron spin and the orbital angular momentum of the π − . Simulations [1] indicate that the centroid of this profile can in principle be determined with a precision of < 1 GHz, which corresponds to a fractional precision of better than ∼ 1 × 10 −6 on the πHe + transition frequency ν exp .…”

Section: Laser Spectroscopy Methodsmentioning

confidence: 99%

“…This corresponds to a π − orbital with the same radius and binding energy as those of the displaced 1s electron. In the case of pHe + , laser spectroscopy experiments [13,14] …”

Section: Pos(tipp2014)342mentioning

confidence: 99%

Attempt at laser spectroscopy of pionic helium atoms at PSI

Hori¹,

Sótér²,

Aghai-Khozani³

et al. 2015

Proceedings of Technology and Instrumentation in Particle Physics 2014 — PoS(TIPP2014)

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Metastable pionic helium is a hypothetical three-body atom composed of a helium nucleus, a π − occupying a Rydberg state, and an electron occupying the ground state. The PiHe collaboration is currently attempting to carry out laser spectroscopy of these atoms using the 590-MeV ring cyclotron of the Paul Scherrer Institute. We briefly describe the method by which we intend to detect the spectroscopic signal. Physics 2014, 2-6 June, 2014 Amsterdam, the Netherlands * Speaker. 1.7 (7) 8 ( Technology and Instrumentation in Particle

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“…Metastable antiprotonic helium (pHe + ≡ p + He 2+ + e − ) is a three-body atom composed of a helium nucleus, an electron in the ground state, and an antiproton occupying a Rydberg state of principal and orbital angular momentum quantum numbers n ∼ − 1 ∼ 38 [1-3]. By measuring its transition frequencies by laser spectroscopy [4][5][6][7], and comparing the values with the results of three-body quantum electrodynamics (QED) calculations, the antiproton-to-electron mass ratio M p /m e can in principle be determined with a relative precision of < 10 −11 . This corresponds to the best determinations of the proton-to-electron mass ratio M p /m e from Penning trap experiments [8][9][10][11][12], or laser spectroscopy of HD + molecular ions [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Single-photon laser spectroscopy of cold antiprotonic helium

Hori

2018

Hyperfine Interact

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Some laser spectroscopy experiments carried out by the Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration to measure the single-photon transition frequencies of antiprotonic helium (pHe + ≡ p +He 2+ +e − ) atoms are reviewed. The pHe + were cooled to temperature T = 1.5-1.7 K by buffer-gas cooling in a cryogenic gas target, thus reducing the thermal Doppler width in the single-photon resonance lines. The antiproton-to-electron mass ratio was determined as M p /m e = 1836.1526734(15) by comparisons with the results of three-body quantum electrodynamics calculations. This agreed with the known proton-to-electron mass ratio. IntroductionMetastable antiprotonic helium (pHe + ≡ p + He 2+ + e − ) is a three-body atom composed of a helium nucleus, an electron in the ground state, and an antiproton occupying a Rydberg state of principal and orbital angular momentum quantum numbers n ∼ − 1 ∼ 38 [1-3]. By measuring its transition frequencies by laser spectroscopy [4][5][6][7], and comparing the values with the results of three-body quantum electrodynamics (QED) calculations, the antiproton-to-electron mass ratio M p /m e can in principle be determined with a relative precision of < 10 −11 . This corresponds to the best determinations of the proton-to-electron mass ratio M p /m e from Penning trap experiments [8][9][10][11][12], or laser spectroscopy of HD + molecular ions [13][14][15]. Spectroscopy of pHe + also provides a consistency test of CPT symmetry, which may be complementary to the experiments on antihydrogen atoms [16][17][18].

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Observation of the 1154.9 nm transition of antiprotonic helium

Cited by 13 publications

References 44 publications

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

Attempt at laser spectroscopy of pionic helium atoms at PSI

Single-photon laser spectroscopy of cold antiprotonic helium

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