Results 11 to 20 of about 442,874 (245)

Vibrational Excitation Cross-Section by Positron Impact: A Wave-Packet Dynamics Study

Atoms, 2021
The vibrational excitation cross-section of a diatomic molecule by positron impact is obtained using wave-packet propagation techniques. The dynamics study was carried on a two-dimensional potential energy surface, which couples a hydrogenlike harmonic ...
Luis A. Poveda, Marcio T. do N. Varella, José R. Mohallem   +2 more
doaj   +1 more source

Production of Highly Polarized Positron Beams via Helicity Transfer from Polarized Electrons in a Strong Laser Field. [PDF]

Physical Review Letters, 2020
The production of a highly polarized positron beam via nonlinear Breit-Wheeler processes during the interaction of an ultraintense circularly polarized laser pulse with a longitudinally spin-polarized ultrarelativistic electron beam is investigated ...
Yan-Fei Li, Yue-Yue Chen, Weimin Wang, Hua-Si Hu   +3 more
semanticscholar   +1 more source

Associations of Plasma Phospho-Tau217 Levels With Tau Positron Emission Tomography in Early Alzheimer Disease

JAMA Neurology, 2020
This cohort study compares plasma levels of phosphorylated tau at threonine 217 with established cerebrospinal fluid and positron emission tomography (PET) tau biomarkers in early Alzheimer disease.
S. Janelidze, D. Berron, Ruben Smith, O. Strandberg, Nicholas K. Proctor, J. Dage, E. Stomrud, S. Palmqvist, N. Mattsson‐Carlgren, O. Hansson   +9 more
semanticscholar   +1 more source

Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions

Atoms, 2022
The variational method is applied to the low-energy positron scattering and annihilation problem. The ultimate aim of the investigation is to find a computationally economical way of accounting for strong electron–positron correlations, including the ...
Sarah Gregg, Gleb Gribakin
doaj   +1 more source

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth [PDF]

Science, 2017
Exotic origin for cosmic positrons Several cosmic-ray detectors have found more positrons arriving at Earth than expected. Some researchers interpret this as a signature of exotic physics, such as the annihilation of dark matter particles.
A. Abeysekara, A. Albert, R. Alfaro, C. Alvarez, J. Álvarez, R. Arceo, J. C. Arteaga-Velázquez, D. Avila Rojas, H. Ayala Solares, A. Barber, N. Bautista-Elivar, A. Becerril, E. Belmont-Moreno, S. Benzvi, D. Berley, A. Bernal, J. Braun, C. Brisbois, K. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, M. Castillo, U. Cotti, J. Cotzomi, S. Coutiño de León, C. de León, E. de la Fuente, B. Dingus, M. DuVernois, J. C. Díaz-Vélez, R. Ellsworth, K. Engel, O. Enŕıquez-Rivera, D. Fiorino, N. Fraija, J. García-González, F. Garfias, M. Gerhardt, A. Gonzalez Muñoz, M. González, J. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernández, A. Hernández-Almada, J. Hinton, B. Hona, C. Hui, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, D. Kieda, A. Lara, R. Lauer, W. Lee, D. Lennarz, H. L. Vargas, J. Linnemann, A. Longinotti, G. Luis Raya, R. Luna-García, R. López-Coto, K. Malone, S. Marinelli, O. Martinez, I. Martinez-Castellanos, J. Martínez-Castro, H. Martínez-Huerta, J. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, L. Nellen, M. Newbold, M. Nisa, R. Noriega-Papaqui, R. Pelayo, J. Pretz, E. Pérez-Pérez, Z. Ren, C. Rho, C. Rivière, D. Rosa-González, M. Rosenberg, E. Ruiz-Velasco, H. Salazar, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, G. Sinnis, A. Smith, R. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, T. Ukwatta, G. Vianello, T. Weisgarber, S. Westerhoff, I. Wisher, J. Wood, T. Yapici, G. Yodh, P. Younk, A. Zepeda, H. Zhou, F. Guo, J. Hahn, H. Li, H. Zhang   +115 more
semanticscholar   +1 more source

What aspects of solar flares can be clarified with mm/submm observations?

Frontiers in Astronomy and Space Sciences, 2022
This paper identifies several unsolved questions about solar flares, which can potentially be answered or at least clarified with mm/submm observations with ALMA.
Gregory D. Fleishman, Juan Carlos Martinez Oliveros, Enrico Landi, Lindsay Glesener   +3 more
doaj   +1 more source

Neutrino and Positron Constraints on Spinning Primordial Black Hole Dark Matter. [PDF]

Physical Review Letters, 2019
Primordial black holes can have substantial spin-a fundamental property that has a strong effect on its evaporation rate. We conduct a comprehensive study of the detectability of primordial black holes with non-negligible spin, via the searches for the ...
B. Dasgupta, Ranjan Laha, A. Ray
semanticscholar   +1 more source

Many-body theory calculations of positron scattering and annihilation in noble-gas atoms via the solution of Bethe–Salpeter equations using the Gaussian-basis code EXCITON+

Frontiers in Physics, 2023
Scattering phase shifts and annihilation rates for low-energy positrons interacting with noble gas atoms are calculated ab initio using many-body theory implemented in the Gaussian-orbital code EXCITON+.
J. Hofierka, C. M. Rawlins, B. Cunningham, D. T. Waide, D. T. Waide, D. G. Green   +5 more
doaj   +1 more source

Evaluation of the performance of a high-resolution time-of-flight PET system dedicated to the head and breast according to NEMA NU 2-2012 standard

EJNMMI Physics, 2022
Background This study evaluated the physical performance of a positron emission tomography (PET) system dedicated to the head and breast according to the National Electrical Manufacturers Association (NEMA) NU2-2012 standard.
Daisuke Morimoto-Ishikawa, Kohei Hanaoka, Shota Watanabe, Takahiro Yamada, Yoshiyuki Yamakawa, Suzuka Minagawa, Shiho Takenouchi, Atsushi Ohtani, Tetsuro Mizuta, Hayato Kaida, Kazunari Ishii   +10 more
doaj   +1 more source

Deep Minimum and a Vortex for Positronium Formation in Low-Energy Positron-Helium Collisions

Atoms, 2021
We find a zero in the positronium formation scattering amplitude and a deep minimum in the logarithm of the corresponding differential cross section for positron–helium collisions for an energy just above the positronium formation threshold ...
Albandari W. Alrowaily, Sandra J. Ward, Peter Van Reeth   +2 more
doaj   +1 more source