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Performance of the diamond active target prototype for the PADME experiment at the DA Φ NE BTF

2018; Elsevier BV; Volume: 898; Linguagem: Inglês

10.1016/j.nima.2018.04.062

1872-9576

R. Assiro, Anna Paola Caricato, G. Chiodini, Mauro Corrado, Mary De Feudis, C. Di Giulio, Gaetano Fiore, L. Foggetta, E. Leonardi, M. Martino, Giuseppe Maruccio, Anna Grazia Monteduro, F. Oliva, C. Pinto, S. Spagnolo,

Radiation Detection and Scintillator Technologies

The PADME experiment at the DA$\Phi$NE Beam-Test Facility (BTF) is designed to search for the gauge boson of a new $\rm U(1)$ interaction in the process e$^+$e$^-\rightarrow\gamma$+$\rm A'$, using the intense positron beam hitting a light target. The $\rm A'$, usually referred as dark photon, is assumed to decay into invisible particles of a secluded sector and it can be observed by searching for an anomalous peak in the spectrum of the missing mass measured in events with a single photon in the final state. The measurement requires the determination of the 4-momentum of the recoil photon, performed by a homogeneous, highly segmented BGO crystals calorimeter. A significant improvement of the missing mass resolution is possible using an active target capable to determine the average position of the positron bunch with a resolution of less than 1 mm. This report presents the performance of a real size $\rm (2x2 cm^2)$ PADME active target made of a thin (50 $\mu$m) diamond sensor, with graphitic strips produced via laser irradiation on both sides. The measurements are based on data collected in a beam test at the BTF in November 2015.