Pulse shape discrimination is one of the more distinctive features of liquid scintillators. However, the optimum discrimination method to distinguish different types of particles, described in the ...seminal paper of Gatti and De Martini of more than 40 years ago, was not suitable for routine application until the recent development of adequately fast sampling techniques. In this work we present the features of a board explicitly designed and realized to exploit the performance of a fast, high resolution, 10-bit flash analog-to-digital converter (ADC) in order to sample with sufficient accuracy the integrated scintillation waveforms obtained under alpha or beta irradiation of a scintillator specimen. Data samples could then be processed according to the Gatti and De Martini method (modified following the prescription of Jordanov and Knoll in the case of integrated pulses) to quantify the optimum separation achievable. The board, besides providing the integration of the pulse within its analog portion and the digitization of the signal in the digital section, is also equipped with useful auxiliary functions that increase its versatility and practical operability. Using the same scintillator-phototube assembly, experimental pulse shape discrimination measurements were obtained with the new board and with the conventional charge technique and those results are illustrated here. Output from a Monte Carlo model allowed us to perform a numerical comparison of the performance of the optimum method versus the conventional one.
Borexino, a real-time device for low energy neutrino spectroscopy is nearing completion of construction in the underground laboratories at Gran Sasso, Italy (LNGS). The experiment's goal is the ...direct measurement of the flux of
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Be solar neutrinos of all flavors via neutrino–electron scattering in an ultra-pure scintillation liquid. Seeded by a series of innovations which were brought to fruition by large-scale operation of a 4-ton test detector at LNGS, a new technology has been developed for Borexino. It enables sub-MeV solar neutrino spectroscopy for the first time. This paper describes the design of Borexino, the various facilities essential to its operation, its spectroscopic and background suppression capabilities and a prognosis of the impact of its results towards resolving the solar neutrino problem. Borexino will also address several other frontier questions in particle physics, astrophysics and geophysics.
The work that has been performed since the beginning of 1993 in Milano in the INFN Group V experiment ASPIDE (Analogue Silicon PIxel DEtector) Italian partner (for the analogue readout development of ...hybrid pixel detectors) of the CERN RD19 collaboration is resumed. The aim of these experiments was to realize an analogue cell for the readout of hybrid pixel detectors. The Anapix cell has been successfully developed and tested, both alone and connected to a pixel detector. The main result is a noise of about 100 electrons r.m.s. on the cell alone, about 190 electrons r.m.s. with the cell connected via wire bonding to pixel detectors and a signal-noise ratio of about
120
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for minimum ionising particles.
Using a high statistics sample of photo-produced charm particles from the FOCUS experiment at Fermilab, we report results of a search for eight rare and Standard-Model-forbidden decays: D+, ...Ds+→h±μ∓μ+ (with h=π,K). Improvement over previous results by a factor of 1.7–14 is realized. Our branching ratio upper limit D+→π+μ−μ+ of 8.8×10−6 at the 90% C.L. is below the current MSSM R-parity violating constraint.
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