Highly-segmented electron-positron telescope array*

A new array to study electron-positron pair production in nuclear reactions is being constructed at the Cyclotron Institute, Texas A&M University. The array is suitable for a wide range of experiments. One of the first projects planned for the new setup is validation of the recent claim for observation of the hypothetical X17 "dark boson" particle in the decay of the highly excited state of ⁸Be [Ref1]. Investigation of the production of electron-positron pairs in light-ion collisions below the Coulomb barrier [Ref2] and studies of monopole transition probabilities is also envisioned. The design consists of four highly-segmented double-sided silicon strip detectors (DSSDs)  having 128x128 channels, each backed by 9 CsI(Tl) scintillator crystals (36 in total). A Monte Carlo simulation of the setup, combined with the experimental data obtained with the prototype with an electron source, will be presented, and the performance of the detector will be discussed.

[Ref1] A. J. Krasznahorkay et al. Phys. Rev. Lett. 116, 042501 (2016).

[Ref2] T. Settlemyre, H. Zheng and A. Bonasera, Nucl. Phys. A 1015, 122282 (2021).