Interactions of antiprotons with atoms and molecules

Inokuti, Mitio

doi:10.1016/1359-0189(89)90042-3

Cited by 17 publications

(16 citation statements)

References 40 publications

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“…The work to be reported in this paper is expected to add to the present understanding some new insight into the physics of exotic atoms, especially antiprotonic atoms, which have become the subject of more and more intense research recently [18,19], partly because of the developments in the low-energy antiproton ring (LEAR) at CERN and partly because of the thrust to produce antimatter.…”

Section: Introductionmentioning

confidence: 99%

Moleculelike metastable states of antiprotonic and mesic helium

Shimamura

1992

Phys. Rev. A

133

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The exotic helium atom, consisting of a helium nucleus He +, an electron e, and a massive, negatively charged particle X, such as an antiproton (p) or a kaon (K ), is studied theoretically. This exotic atom is more like a polar molecule with two nuclei He + and X, if e is in a lowlying orbital and X is in a highly excited orbital. Such states are generally formed in the capture of X by helium. The Born-Oppenheimer (BO) separation of the e motion and the He +-X motion is a good approximation for these states, and affords a transparent, unified perspective of exotic helium with di6'erent X and different isotopes of He +. A propensity rule that favors small transition energies (except for the smallest one) is found for radiative emission by low vibrational, high rotational levels. This rule resembles the selection rule for infrared emission by the usual diatomic polar molecules, and contradicts the conventional expectation that radiative transitions in exotic atoms favor larger transition energies. The radiative lifetimes~of highly excited states formed immediately after the capture of X are of the order of @sec for He +-p-e and He +-"t . , and those for He +-K -e are about half the values for the antiprotonic helium. The efFect of the electronic charge polarization by X on~is explained quantitatively in a simple picture in terms of the molecular dipole moment. Low vibrational, high rotational states are described as circular or near-circular states in the atomic picture. They are stable against Auger decay, which the nonadiabatic perturbation on the BO states induces. An infinite series of bound E electronic states of exotic helium negative ions (He +-X -e )-c exists for any He +-X distances R beyond 0.819 a.u. in the BO approximation. An infinite II series exists for R & 3.811 a.u. , and an infinite 6 series for R )9. 532 a.u.

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Section: Introductionmentioning

confidence: 99%

Moleculelike metastable states of antiprotonic and mesic helium

Shimamura

1992

Phys. Rev. A

133

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“…A combined charge signal from all of the effects due to annihilation was established [10,24] but it would be rather impossible to implement in any precise way. Existing Monte Carlo codes can provide only a simplified picture of the processes inside the SEM without taking into account many substantial aspects, such as the creation of eV-scale secondaries.…”

Section: Design Considerationsmentioning

confidence: 99%

“…However, stopped antiparticles generate completely different signals than ions. The energy released in annihilation of keV antiprotons is a few orders of magnitude higher than the energy deposited by keV protons [10]. Among various types of secondary particles, high-energy pions and strongly ionizing ions are created and constitute an important contribution to the response of a detector.…”

Section: Introductionmentioning

confidence: 99%

Beam diagnostics for low energy beams

Harasimowicz

Welsch

Coséntino³

et al. 2012

Phys. Rev. ST Accel. Beams

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Low-energetic ion and antimatter beams are very attractive for a number of fundamental studies. The diagnostics of such beams, however, is a challenge due to low currents down to only a few thousands of particles per second and significant fraction of energy loss in matter at keV beam energies. A modular set of particle detectors has been developed to suit the particular beam diagnostic needs of the ultralowenergy storage ring (USR) at the future facility for low-energy antiproton and ion research, accommodating very low beam intensities at energies down to 20 keV. The detectors include beam-profile monitors based on scintillating screens and secondary electron emission, sensitive Faraday cups for absolute intensity measurements, and capacitive pickups for beam position monitoring. In this paper, the design of all detectors is presented in detail and results from beam measurements are shown. The resolution limits of all detectors are described and options for further improvement summarized. Whilst initially developed for the USR, the instrumentation described in this paper is also well suited for use in other low-intensity, low-energy accelerators, storage rings, and beam lines.

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“…Finally, although antiprotons are main focus of research at the AD and at FLAIR, also protons or H -ions will be used for the initial commissioning of the machine. However, stopped antiparticles generate completely different signals than ions with an energy release that is a few orders of magnitude higher than the energy deposited by keV protons [7]. This paper gives a brief overview of beam instrumentation for very low energy antiproton and ion beams.…”

Section: Introductionmentioning

confidence: 99%

“…They will be particularly important for the future Extra Low ENergy Antiproton (ELENA) ring [3] and the Ultra-low energy Storage Ring (USR) [4] and their keV beam lines to the different experiments to provide those with antiproton beams of the required quality and characteristics. It remains a big challenge for beam instrumentation to measure all key parameters of a very low intensity antiproton beam of less than 4·10 7 antiprotons. The boundary conditions for the USR as one example are summarized in table 1.…”

Section: Introductionmentioning

confidence: 99%

Beam Diagnostics for Low Energy Antiprotons

Welsch¹,

Zhang²,

Jeff³

et al. 2017

Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016)

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Advanced beam diagnostics for antiproton beams at keV beam energies are very important for the successful operation and continuous optimization of low energy storage rings and associated beam lines to the experiments. Manifold challenges arise from the low energy and intensity of the beam, its pulse structure and low repetition rate. This paper presents a comprehensive set of beam diagnostics that has been developed to characterize low energy antiproton and ion beams (during initial machine commissioning) and subsequent facility operation. It shows results from simulations and experiments using invasive and non-invasive monitors for absolute beam current measurements; capacitive pickups for position detection; scintillating screens, secondary emission monitors and micro channel plate detectors for transverse profile monitoring, as well as an ultra-cold gas jet for minimally-invasive profile measurements and in-ring experiments. The identified limits are discussed for each technique, and options for further improvements are indicated.

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Interactions of antiprotons with atoms and molecules

Cited by 17 publications

References 40 publications

Moleculelike metastable states of antiprotonic and mesic helium

Moleculelike metastable states of antiprotonic and mesic helium

Beam diagnostics for low energy beams

Beam Diagnostics for Low Energy Antiprotons

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