Observation of the X17 anomaly in the decay of the Giant Dipole Resonance of $^8$Be
| Autor: | Krasznahorkay, A. J., Krasznahorkay, A., Csatlós, M., Csige, L., Timár, J., Begala, M., Krakó, A., Rajta, I., Vajda, I. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | Angular correlation spectra of $e^+e^-$ pairs produced in the $^{7}$Li($p$,$\gamma$)$^{8}$Be nuclear reaction were studied at a proton beam energy of $E_p$~=~4.0~MeV, which corresponds to the excitation energy of the Giant Dipole Resonance (GDR) in $^8$Be. The spectra measured show a peak like anomaly at 120$^\circ$ and a broader anomaly also above 140$^\circ$. Both anomalies could consistently be described by assuming that the same hypothetical X17 particle was created both in the ground-state transition and in the transition going to the broad ($\Gamma$=1.5~MeV), first excited state in $^8$Be. The invariant mass of the particle, which was derived to be $m_Xc^2 = 16.95 \pm 0.48$(stat.)~MeV, agrees well with our previously published values. Comment: 5 pages, 7 figures. arXiv admin note: text overlap with arXiv:2209.10795 |
| Databáze: | arXiv |
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