The possibility to detect fast neutrons as a distinct signal from that one of γ-rays background is surely of great importance for several topics, spanning from homeland security to radiation ...monitoring in nuclear physics research plants. Nowadays, Helium-3 based detectors are extremely expensive, while the use of large volume liquid scintillators presents serious concerns related to spillage risks and waste disposal. A very attractive alternative is the use of commercially available solid scintillators, which exploits an aromatic polymer matrix entrapping very high loadings of primary dye, thereby enabling the use of pulse shape analysis (PSA) to discriminate between fast neutrons and γ-rays. In this work, we analyse in detail the optical features of a solid scintillator composed by polymethylphenylsiloxane (PMPS) as base polymer loaded with moderate amounts of 2,5-diphenyloxazole (PPO). Furthermore, fluorescence decay kinetics have been correlated to the observed pulse shape discrimination capabilities of this radiation and thermally resistant scintillator, whose performances have been discussed in terms of conformational features and excimers formation revealed by the optical analyses.
In this paper the technological aspects of the FAZIA array will be explored. After a productive commissioning phase, FAZIA blocks started to measure and give very useful data to explore the physics ...of Fermi energy heavy-ion reactions. This was possible thanks to many technical measures and innovations developed in the commissioning phase and tuned during the first experimental campaigns. This paper gives a detailed description of the present status of the FAZIA setup from the electronic and mechanical point of view, trying also to trace a path for new improvements and refinements of the apparatus.
The energy loss profiles of different ion beams (6Li, 27Al and 50Ti) impinging on CF4, isobutane and P10 have been measured with the active target ACTAR TPC demonstrator. The pressure of the gas, ...monitored during the experiment, has been chosen in order to stop the ions inside the active zone. Starting from the energy loss calculation produced by the SRIM code, the experimental ion tracks have been simulated, taking into account the effect of the thermal diffusion of electrons during their drift towards the pad plane under the effect of a uniform electric field. The uncertainty in the geometry, mainly due to the thickness and deformation of the mylar interface window between the gas volume and the high vacuum line, has been taken into account. A good agreement is obtained between the experimental and simulated energy loss profiles.
The 4He(4He,4He)4He* inelastic scattering was investigated at the MAGNEX facility of INFN - LNS, aiming at shedding light on the characteristics of the isoscalar monopole resonance of 4He which lies ...at an energy slightly higher than the proton emission threshold and slightly lower than the neutron emission threshold. A complementary elastic scattering measurement was also performed to study the initial state interaction and set accurate coupled channel calculations. Here, the experimental setup, the data reduction and the theoretical interpretation strategy are briefly described.
Boron doped polysiloxane scintillators have been produced with different concentrations of boron and their scintillation yields have been studied as a function of the boron content under α, γ and ...fast and thermal neutrons irradiation. Their response has been compared with standard commercial plastic scintillators, namely EJ-212 as plastic scintillator and EJ-254 as boron doped scintillator. The produced samples exhibited a scintillation yield similar to EJ-212. The effect of boron on the energy transfer mechanism and on the polymer radiation hardness has been investigated by means of fluorescence and ion beam induced luminescence (IBIL) measurements. Detection efficiencies for thermal neutrons higher than commercial plastic scintillators have been attained with boron doped samples.
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