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Kino, Yasushi; Yamanaka, Nobuhiro; Kamimura, N.; Froelich, Piotr; Kawamura, Hiroshi

doi:10.1023/a:1020827623323

Cited by 25 publications

(17 citation statements)

References 9 publications

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“…5, the frequencies are compared with the results th of theoretical calculations [13][14][15][16][17], which include QED and finite nuclear-size effects. These claim an accuracy of 10 ÿ8 -10 ÿ7 , limited by uncertainties in the three-body wave functions of states with large (ÿ > 10 MHz) Auger widths; by using the complex coordinate rotation method [16,17], the precision has been improved compared to previous values [15] tabulated in Ref. [2].…”

Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 19 Sepmentioning

confidence: 99%

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Direct Measurement of Transition Frequencies in Isolatedp¯He+Atoms, and NewCPT-Viola

et al. 2003

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A radio frequency quadrupole decelerator and achromatic momentum analyzer were used to decelerate antiprotons and produce p 4 He and p 3 He atoms in ultra-low-density targets, where collision-induced shifts of the atomic transition frequencies were negligible. The frequencies at near-vacuo conditions were measured by laser spectroscopy to fractional precisions of 6-19 10 ÿ8 . By comparing these with QED calculations and the antiproton cyclotron frequency, we set a new limit of 1 10 ÿ8 on possible differences between the antiproton and proton charges and masses. DOI: 10.1103/PhysRevLett.91.123401 PACS numbers: 36.10.-k, 14.20.Dh, 32.70.Jz Recently, we measured some transition frequencies in antiprotonic 4 He atoms [1] (p 4 He e ÿ ÿ p ÿ 4 He 2 ) to sub-ppm precision [2] at the Antiproton Decelerator (AD) of CERN. By comparing these with three-body QED calculations and using the measured value of the antiproton cyclotron frequency [3], a 60-ppb limit was obtained for the possible differences p between the antiproton and proton charges and masses. Any such difference, however small, would imply CPT violation, i.e., that physical laws are not perfectly invariant under a combined transformation of charge conjugation, parity, and time reversal [4]. The precision of the experiment [2] was limited by the high density of the cryogenic helium targets (atomic density 10 21 cm ÿ3 , corresponding to pressures p 10-200 bars at room temperature) used to stop the 5.3-MeV antiproton beam and produce these atoms. The p 4 He underwent many collisions with helium atoms, resulting in large shifts [1,2,5] in the transition frequencies. We here report on new laser spectroscopy measurements at ultralow target densities of 10 17 cm ÿ3 , some 10 4 times lower than those previously used. These experiments were made possible by a radio frequency quadrupole decelerator (RFQD, Fig. 1) [6], which decelerated the 5.3-MeV antiprotons used previously [2] to energies E 10-120 keV. The collisional shifts thus became negligible (jj 1 MHz) compared to the natural widths of the transitions, so that the observed frequencies were effectively in vacuo. We also extended our high-precision studies to the isotope p 3 He , and to transitions which could not be observed at high densities, thus increasing the number of measured frequencies with small natural widths (ÿ < 50 MHz) from 4 [2] to 13.In these experiments, laser pulses induced antiproton transitions from metastable pHe states ( Fig. 2) with large principal (n 38) and angular momentum (' n) quantum numbers, to states with short Auger lifetimes [1]. The two-body pHe 2 ions formed after Auger emission suffered collisional Stark effects, which caused the rapid annihilation of the antiproton in the helium nucleus. The resulting spike in the rate of annihilations signaled the transition frequency. In previous experiments made at higher densities, collisions produced large frequency shifts (jj 0:5-5:0 GHz) which were of the order of 10 ÿ6 -10 ÿ5 of the measured transition frequencies . The frequencies 0...

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Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 19 Sepmentioning

confidence: 99%

“…Values for f were estimated [16] by changing the values of the antiproton charge and mass by 1 ppm under the constraint on ! p of 9 10 ÿ11 [3], and noting the change (2.5-6.1 ppm) in the calculated value th .…”

Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 19 Sepmentioning

confidence: 99%

Direct Measurement of Transition Frequencies in Isolatedp¯He+Atoms, and NewCPT-Viola

et al. 2003

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“…Compared with theoretical frequencies of three-body QED calculations [13][14][15][16][17] for some selected transitions inp 3 He + andp 4 He + , these measurement can be used to determine mp/m e [6]. The latest determination of the mass ratio is mp/m e = 1 836.152 673 6(23) [9] which was carried out using the two-photon Doppler reduced laser spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Leading term of the He-p¯He+long-range interaction

2015

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The long range interaction between an antiprotonic helium atompHe + and helium atom in its ground state is studied. We calculate the dispersion coefficients C6 using the Complex Coordinate Rotation (CCR) formalism in order to comply with the resonant nature of metastable states of the antiprotonic helium. We present as well numerical data on static dipole polarizabilities of antiprotonic helium states. The obtained coefficients C6 may be used to estimate the collisional shift and broadening of transition lines in a low density precision spectroscopy of the antiprotonic helium.

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“…Recently stringent CPT-violation limits on the antiproton mass and charge were determined [4] at CERN Antiproton Decelerator using a laser spectroscopic method to measure some transition energies of the pHe + atom to a precision of 50-200 ppb. The measured transition energies were compared with two independent variational three-body calculations with QED corrections by Korobov [5][6][7] and by Kino [8,9].…”

Section: Introductionmentioning

confidence: 99%

Systematic study of the decay rates of antiprotonic helium states

Yamaguchi

Hayano²,

Ishikawa³

et al. 2004

Phys. Rev. A

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A systematic study of the decay rates of antiprotonic helium (p 4 He + and p 3 He + ) at CERN Antiproton Decelerator has been made by a laser spectroscopic method. The decay rates of some of its short-lived states, namely those for which the Auger rates ␥ A are much larger than their radiative decay rates ͑␥ rad ϳ 1 s −1 ͒, were determined from the time distributions of the antiproton annihilation signals induced by laser beams, and the widths of the atomic resonance lines. The magnitude of the decay rates, especially their relation with the transition multipolarity, is discussed and compared with theoretical calculations.

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Cited by 25 publications

References 9 publications

Direct Measurement of Transition Frequencies in Isolatedp¯He+Atoms, and NewCPT-Viola

Direct Measurement of Transition Frequencies in Isolatedp¯He+Atoms, and NewCPT-Viola

Leading term of the He-p¯He+long-range interaction

Systematic study of the decay rates of antiprotonic helium states

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