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In this work we report on the systematic characterization of a rare-gas moderated magnetically-transported continuous positron beam based on a 22Na radioactive source. The characterization was performed with three different rare-gas solid moderators: Ne, Ar, and Kr. Each moderator was deposited and then thermal annealed at temperature ∼ 35 % and ∼ 30 % lower than the melting point, respectively. Tests of moderation/magnetic transport efficiency of the apparatus have shown a maximum efficiency of 1.8 10-3, 2.0 10-3 and 0.6 10-3 for Ne, Ar, and Kr, respectively. The average longitudinal kinetic energy of positrons was found to be ∼ 0.95 eV, ∼1.25 eV, and ∼ 0.45 eV for Ne, Ar, and Kr moderator, respectively. The spin polarization measurement of moderated positrons was performed by using the Doppler broadening of the annihilation γ-rays from positronium formed in oxidized nanochanneled silicon positron/positronium converters. Polarization values of 0.30 ± 0.01, 0.29 ± 0.01 and 0.29 ± 0.01 were found for Ne, Ar, and Kr moderator, respectively. [ABSTRACT FROM AUTHOR]

Studies based on imaging the annihilation of the electron (e −) and its antiparticle positron (e +) open up several interesting applications in nuclear medicine and fundamental research. The annihilation process involves both the direct conversion of e + e − into photons and the formation of their atomically bound state, the positronium atom (Ps), which can be used as a probe for fundamental studies. With the ability to produce large quantities of Ps, manipulate them in a long-lived Ps states, and image their annihilations after a free fall or after passing through atomic interferometers, this purely leptonic antimatter system can be used to perform inertial sensing studies in view of a direct test of Einstein's equivalence principle. It is envisioned that modular multi-strip detectors can be exploited as potential detection units for this kind of studies. In this work, we report the results of the first feasibility study performed on a e + beamline using two detection modules to evaluate their reconstruction performance and spatial resolution for imaging e + e − annihilations and thus their applicability for gravitational studies of Ps. [ABSTRACT FROM AUTHOR]

A novel method for the measurement of the number of positrons contained in intense positron bunches is presented. The technique is based on the Poisson distribution of the number of gamma rays emitted by many simultaneous positron–electron annihilations in a small solid angle. The results have been found in good agreement with those achieved with a calibrated CsI(Tl) detector coupled to a photodiode. The small dimension of the required equipment and the reduced constraints of the technique open the possibility of monitoring, in complex positrons systems, the number of positrons at different positions that are too difficult to reach with other devices. [ABSTRACT FROM AUTHOR]

A large area low-cost detector for detailed studies of ortho-Positronium formation and decay is being designed. The detector will be made of four modules each consisting of a thin slab of YAP(Ce) scintillator read out by a multi-anode flat panel photomultiplier tube. The proposed configuration will provide a position sensitive detector capable of recording, on an event-by-event basis, both the 2 γ and the 3 γ decay channels, for immediate information on the 2 γ /3 γ ratio. It will as well provide a 3D density distribution of the decay vertexes, thus enabling angular and velocity distribution measurements. In this paper we present the results of measurements performed on one module of the detector using conventional electronics, as well as Monte Carlo simulations on the performances of the system. Using a series of laboratory gamma sources we deduced values of energy and spatial resolution. • Low-cost detector for detailed studies of ortho-Positronium formation. • YAP:Ce slap coupled to a multi-anode photomultiplier as position sensitive detector. • Center-of-mass based method to reconstruct the position of the photon interaction. • Spatial and energy resolution studies of a position sensitive detector. • Distribution of photon interaction points by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]