Matter‐antimatter asymmetry ‐ aspects at low energy

Willmann, Lorenz; Jungmann, Klaus-Peter

doi:10.1002/andp.201500008

Cited by 9 publications

(9 citation statements)

References 62 publications

(64 reference statements)

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“…Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section. DOI: 10.1103/PhysRevLett.117.253401 While the apparent imbalance between matter and antimatter in the Universe remains a major puzzle in science [1,2], much progress in the understanding of the interactions between the two has been achieved through studies of controlled collisions of positrons ðe þ Þ and positronium (Ps, the short-lived atom made of an electron and a positron) with atoms and molecules [3][4][5][6][7].At low energies, the static and polarization interactions tend to cancel for positrons reducing their scattering probability in comparison with electrons. However, polarization often enhances direct ionization by positrons, so that they can be more penetrating and more ionizing than electrons, a result of potential import in analyses of astrophysical (e.g., [8]) and atmospheric events (e.g., [9]) as well as in positron-track simulations for dosimetry in positron emission tomography (e.g., [10]).…”

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High-Resolution Measurements of e++H2O Total Cross Section

et al. 2016

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Using a purely electrostatic positron beam, the total cross section of positrons scattering from H 2 O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section. DOI: 10.1103/PhysRevLett.117.253401 While the apparent imbalance between matter and antimatter in the Universe remains a major puzzle in science [1,2], much progress in the understanding of the interactions between the two has been achieved through studies of controlled collisions of positrons ðe þ Þ and positronium (Ps, the short-lived atom made of an electron and a positron) with atoms and molecules [3][4][5][6][7].At low energies, the static and polarization interactions tend to cancel for positrons reducing their scattering probability in comparison with electrons. However, polarization often enhances direct ionization by positrons, so that they can be more penetrating and more ionizing than electrons, a result of potential import in analyses of astrophysical (e.g., [8]) and atmospheric events (e.g., [9]) as well as in positron-track simulations for dosimetry in positron emission tomography (e.g., [10]). In turn, these studies contribute to the motivation for investigating the interaction of e þ with water which accounts for about 60% of the human body and which is the most abundant greenhouse gas in the atmosphere.Measurements of positron-water total cross section (σ T ) were first carried out 30 years ago [11,12]. Since then, only a few new results have been added, experimentally [13][14][15] and theoretically [16,17], without a satisfactory agreement emerging among them. The integral (σ el ) and differential (dσ el =dΩ) elastic (el) scattering cross sections for e þ þ H 2 O have also been measured recently [17], complementing theoretical determinations [18,19].Because of the long-range forces involved in the scattering of charged projectiles from a polar molecule such as H 2 O, one of the major difficulties in measuring σ T (even in the case of electrons, e.g., [20][21][22][23]) lies in discriminating against the considerable flux of small forward-angle scattered particles (FSPs) (e.g., [16,19]). The largest error associated with FSPs arises from elastic scattering and rovibrational inelastic processes which cannot be easily distinguished from the incident flux via energy loss discrimination since this is smaller than (or comparable to) typical beam energy resolutions (e.g., the first vibrational excitation from the ground state J ¼ 0 is ≃1595 cm −1 [24]). Detection of FSPs leads to a systematic underestimate of the beam attenuation and, thus, the measured total cross sections. In this respect, beams that employ magnetic fields are more likely to transport FSPs from the...

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High-Resolution Measurements of e++H2O Total Cross Section

et al. 2016

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“…The observation of permanent electric dipole moments (EDMs) in elementary particles, atoms, and molecules could provide hints towards physics beyond the Standard Model of particle physics [1,2]. A considerable number of experiments to search for EDMs are currently underway in several independent experiments, which employ different sample materials.…”

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Electro-optic sensor for static fields

et al. 2019

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A sensor has been developed for low frequency and DC electric fields E. The device is capable of measuring fields with E = 4 (1) V/cm resolution. It is based on a Y-cut Z-propagation lithium niobate electro-optic crystal. For a particular commercially available bare crystal, we achieved an in air time constant c (air) = 6.4(1.8) h for the decay of the electro-optic signal. This enables field monitoring for several hours. As an application, we demonstrated that a constant electric field E ext = 640 V/cm applied via external electrodes to a particular spherical glass container holding an Xe/He gas mixture decays inside this cell with a time constant glass E = 2.5(5) h. This is sufficient for the needs of experiments searching for a permanent electric dipole moment in 129 Xe. An integrated electric field sensor has been constructed which is coupled to a light source and light detectors via optical fibers. The sensor head does not contain any electrically conducting material.

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“…The violation of the combined charge conjugation and parity operation, CP, is of particular importance because of the possible relation to the observed matter-antimatter asymmetry in the universe [1,2]. A. Sakharov [3] has suggested that the asymmetry in matter-antimatter may be explained via CP-violation in the early universe in a state of thermal non-equilibrium together with baryon number violating processes [4]. CP violation has been observed in neutral K and B meson systems, however, the known sources of CP-violation in the SM are insufficient to account for it [1].…”

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Francium: Tool for Fundamental Symmetry Investigations

Dammalapati¹,

Harada²,

Hayamizu³

et al. 2017

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

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Ultra-cold radioactive atomic isotopes produced using laser cooling and trapping methods have been in use for nuclear β-decay studies, atomic parity non conservation and for searches of a permanent electric dipole moment of a fundamental particle in atoms. Among atoms, francium, a radioactive heavy alkali atom has been identified as a promising candidate to search for an electron permanent electric dipole moment. In this context, a laser cooled francium factory is being setup at CYRIC, Tohoku University for the measurement of an electron EDM. We report on the status of the experiment and various stages of the facility such as production of francium isotopes, extraction and transportation of francium ions and conversion to atoms and finally laser cooling and trapping of francium atoms.

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Matter‐antimatter asymmetry ‐ aspects at low energy

Cited by 9 publications

References 62 publications

High-Resolution Measurements of e++H2O Total Cross Section

High-Resolution Measurements of e++H2O Total Cross Section

Electro-optic sensor for static fields

Francium: Tool for Fundamental Symmetry Investigations

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