### Abstract

A monoenergetic positron (e^{+}) beam (ΔT/T-4) from the Stuttgart pelletron accelerator and a 4.6 mg/cm^{2} Be target has been employed to investigate e^{+}e^{-}scattering in the MeV region in a large solid angle with high statistics by means of a novel positionsensitive detector system. Superimposed on the Bhabha scattering, a structure has been found at an e^{+} kinetic energy of 2263 keV (810 keV excitation energy in the e^{+}e^{-}rest frame). From the energy-integrated resonance cross-section of {Mathematical expression} ≅30 b·eV (c.m.) and the standard resonance cross-section we estimate partial resonance widths {Mathematical expression} ≅72 meV or 24 meV for total angular momenta J=0 or J=1, respectively. The structure, which has not been predicted within the framework of quantum electrodynamics, coincides with one of the sum energies of the correlated e^{+}e^{-}lines observed in heavy-ion collisions.

Original language | English |
---|---|

Pages (from-to) | 173-181 |

Number of pages | 9 |

Journal | Zeitschrift für Physik A Atomic Nuclei |

Volume | 330 |

Issue number | 2 |

DOIs | |

Publication status | Published - Jun 1988 |

### Fingerprint

### Keywords

- 12.20.Fv
- 13.10.+q
- 14.80.Pb

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Zeitschrift für Physik A Atomic Nuclei*,

*330*(2), 173-181. https://doi.org/10.1007/BF01293393

**Evidence for a resonance in positron-electron scattering at 810 keV centre-of-mass Energy.** / Maier, K.; Widmann, E.; Bauer, W.; Bosch, F.; Briggmann, J.; Carstanjen, H. D.; Decker, W.; Diehl, J.; Feldmann, R.; Keyerleber, B.; Maden, D.; Major, J.; Schaefer, H. E.; Seeger, A.; Stoll, H.

Research output: Contribution to journal › Article

*Zeitschrift für Physik A Atomic Nuclei*, vol. 330, no. 2, pp. 173-181. https://doi.org/10.1007/BF01293393

}

TY - JOUR

T1 - Evidence for a resonance in positron-electron scattering at 810 keV centre-of-mass Energy

AU - Maier, K.

AU - Widmann, E.

AU - Bauer, W.

AU - Bosch, F.

AU - Briggmann, J.

AU - Carstanjen, H. D.

AU - Decker, W.

AU - Diehl, J.

AU - Feldmann, R.

AU - Keyerleber, B.

AU - Maden, D.

AU - Major, J.

AU - Schaefer, H. E.

AU - Seeger, A.

AU - Stoll, H.

PY - 1988/6

Y1 - 1988/6

N2 - A monoenergetic positron (e+) beam (ΔT/T-4) from the Stuttgart pelletron accelerator and a 4.6 mg/cm2 Be target has been employed to investigate e+e-scattering in the MeV region in a large solid angle with high statistics by means of a novel positionsensitive detector system. Superimposed on the Bhabha scattering, a structure has been found at an e+ kinetic energy of 2263 keV (810 keV excitation energy in the e+e-rest frame). From the energy-integrated resonance cross-section of {Mathematical expression} ≅30 b·eV (c.m.) and the standard resonance cross-section we estimate partial resonance widths {Mathematical expression} ≅72 meV or 24 meV for total angular momenta J=0 or J=1, respectively. The structure, which has not been predicted within the framework of quantum electrodynamics, coincides with one of the sum energies of the correlated e+e-lines observed in heavy-ion collisions.

AB - A monoenergetic positron (e+) beam (ΔT/T-4) from the Stuttgart pelletron accelerator and a 4.6 mg/cm2 Be target has been employed to investigate e+e-scattering in the MeV region in a large solid angle with high statistics by means of a novel positionsensitive detector system. Superimposed on the Bhabha scattering, a structure has been found at an e+ kinetic energy of 2263 keV (810 keV excitation energy in the e+e-rest frame). From the energy-integrated resonance cross-section of {Mathematical expression} ≅30 b·eV (c.m.) and the standard resonance cross-section we estimate partial resonance widths {Mathematical expression} ≅72 meV or 24 meV for total angular momenta J=0 or J=1, respectively. The structure, which has not been predicted within the framework of quantum electrodynamics, coincides with one of the sum energies of the correlated e+e-lines observed in heavy-ion collisions.

KW - 12.20.Fv

KW - 13.10.+q

KW - 14.80.Pb

UR - http://www.scopus.com/inward/record.url?scp=33747031480&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33747031480&partnerID=8YFLogxK

U2 - 10.1007/BF01293393

DO - 10.1007/BF01293393

M3 - Article

AN - SCOPUS:33747031480

VL - 330

SP - 173

EP - 181

JO - Zeitschrift fur Physik A Hadrons and Nuclei

JF - Zeitschrift fur Physik A Hadrons and Nuclei

SN - 0939-7922

IS - 2

ER -