First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

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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“…A detailed description of the experimental procedure using laser spectroscopy can be found in Refs. [17][18][19].…”

Section: Measurement Of Decay Ratesmentioning

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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“…Laser spectroscopic studies of the primary populations P ͑n,ᐉ͒ ͑t =0͒ [i.e., the number of antiprotons populating a state ͑n , ᐉ͒ at atomic formation, normalized to the total number of antiprotons stopped in the target] and lifetimes of pHe + were started at LEAR [13][14][15][16][17], which delivered antiprotons as either a single high-intensity pulse containing 3 ϫ 10 7 -1ϫ 10 9 antiprotons and lasting ⌬t ϳ 200-300 ns, or as a continuous, low-intensity beam at rates ϳ10 4 p / s. Metastable pHe + atoms were produced by stopping either variety of beam in a helium target. They were irradiated with a resonant laser pulse, which induced antiproton transitions between adjacent pairs of metastable and short-lived pHe + states (Fig.…”

Section: ͑1͒mentioning

confidence: 99%

“…Experimental [12][13][14][15][16][17][18][19] and theoretical studies have shown that five phases can be discerned in the life history of metastable pHe + . (i) Capture: when an antiproton collides with a helium atom at electron-volt energies, it may replace one of the electrons orbiting the helium nucleus, and become captured into a pHe + state.…”

Section: Introductionmentioning

confidence: 99%

Populations and lifetimes in thev=n−ℓ−1=2and 3 metastable cascades ofp¯
Hori
¹
,
Eades
²
,
Widmann
³

et al. 2004
Phys. Rev. A
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The time evolution of the state populations in the v ϵ n − ᐉ −1=2 and 3 metastable cascades of antiprotonic helium (p 4 He + ) atoms were studied using laser spectroscopy. The antiprotonic states ͑n , ᐉ͒ = ͑39, 35͒, (40,36), and (41,37) in the v = 3 cascade were estimated to initially contain, respectively, ͑0.28± 0.04͒%, ͑0.06± 0.02͒%, and ͑0.02± 0.01͒% of the antiprotons stopped in the helium target, while the corresponding values for states ͑37, 34͒, ͑38, 35͒, and ͑39, 36͒ in the v = 2 cascade were ͑0.21± 0.04͒%, ͑0.49± 0.07͒%, and ͑0.19± 0.07͒%. The shortening of the state lifetimes due to collisions between pHe + and helium atoms was studied. As the atomic density of the target was increased from =2ϫ 10 20 to 2 ϫ 10 21 cm −3 , the lifetime of state ͑37, 34͒ decreased by an order of magnitude, whereas the higher states ͑38, 35͒ and ͑39, 35͒ were relatively unaffected. Between densities =6ϫ 10 20 and 2 ϫ 10 22 cm −3 , a short-lived component with a time constant ϳ 0.2 s appeared at early times in the delayed annihilation time spectrum of pHe + , while the total fraction of long-lived antiprotons decreased from 3.0 to 2.5%. These effects were caused by the lifetime-shortening of specific pHe + states such as ͑37, 34͒.

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“…Further precision studies of these atoms by laser spectroscopy [3][4][5] reveal reach possibility to investigate various properties of the antiprotonic helium atoms as well as to infer precise data on antiproton [6,7]. Particularly, it provides a stringent test of CPT invariance in a barion sector.…”

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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First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

Cited by 142 publications

References 13 publications

Systematic study of the decay rates of antiprotonic helium states

Systematic study of the decay rates of antiprotonic helium states

Populations and lifetimes in thev=n−ℓ−1=2and 3 metastable cascades ofp¯
Hori
¹
,
Eades
²
,
Widmann
³

et al. 2004
Phys. Rev. A
Self Cite
35
2
23
0
View full text Add to dashboard Cite

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

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First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

Cited by 142 publications

References 13 publications

Systematic study of the decay rates of antiprotonic helium states

Systematic study of the decay rates of antiprotonic helium states

Populations and lifetimes in thev=n−ℓ−1=2and 3 metastable cascades ofp¯Hori1, Eades2, Widmann3 et al. 2004Phys. Rev. ASelf Cite352230View full textAdd to dashboardCite

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

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Populations and lifetimes in thev=n−ℓ−1=2and 3 metastable cascades ofp¯
Hori
¹
,
Eades
²
,
Widmann
³

et al. 2004
Phys. Rev. A
Self Cite
35
2
23
0
View full text Add to dashboard Cite