1,245 research outputs found
Nuclear emulsions for the detection of micrometric-scale fringe patterns: an application to positron interferometry
Nuclear emulsions are capable of very high position resolution in the
detection of ionizing particles. This feature can be exploited to directly
resolve the micrometric-scale fringe pattern produced by a matter-wave
interferometer for low energy positrons (in the 10-20 keV range). We have
tested the performance of emulsion films in this specific scenario. Exploiting
silicon nitride diffraction gratings as absorption masks, we produced periodic
patterns with features comparable to the expected interferometer signal. Test
samples with periodicities of 6, 7 and 20 {\mu}m were exposed to the positron
beam, and the patterns clearly reconstructed. Our results support the
feasibility of matter-wave interferometry experiments with positrons.Comment: 15 pages, 10 figure
Towards the formation of a positronium coherent beam
Positronium (Ps) has emerged as a promising test particle within the QUPLAS
collaboration for investigating the gravitational effect. In this work, we
present a novel approach to generate a monoenergetic and highly coherent Ps
beam by creating a negative Ps ion (Ps, consisting of two electrons and one
positron). The necessary positron beam is formed by using a high flux electron
LINAC. Subsequently, we utilize a Fabry-Perot IR laser cavity operating at a
wavelength of 1560 nm to selectively remove the extra electron. An alternative
pulsed laser operating at a 3600 nm wavelength was studied to reduce broadening
due to recoil and excitation. Here, we provide a Monte Carlo simulation to
estimate the characteristics of the Ps beam, including its energy distribution
and intensity profiles. The results obtained from this study will provide
essential groundwork for future advancements in fundamental studies as Ps
gravity measurements by using a Mach-Zehnder interferometer.Comment: 16 pages, 4 figure
A large-momentum-transfer matter-wave interferometer to measure the effect of gravity on positronium
This paper reports the study of a new interferometric configuration to measure the effect of gravity on positronium. A Mach–Zehnder matter-wave interferometer has been designed to operate with single-photon transitions and to transfer high momentum to a 200 eV positronium beam. The work shows the results and methods used to simulate the interferometer and estimate the
operating parameters and the time needed to perform the experiment. It has been estimated that within less than 1 year, the acquisition time is sufficient to achieve a 10% accuracy level in measuring positronium gravitational acceleration, even with a poorly collimated beam, which is significant for theoretical models describing matter–antimatter symmetry. These results pave the way for single photon transition large momentum transfer interferometry with fast atomic beams, which is particularly useful for studies with antimatter and unstable atoms
High sensitivity double beta decay study of 116-Cd and 100-Mo with the BOREXINO Counting Test Facility (CAMEO project)
The unique features (super-low background and large sensitive volume) of the
CTF and BOREXINO set ups are used in the CAMEO project for a high sensitivity
study of 100-Mo and 116-Cd neutrinoless double beta decay. Pilot measurements
with 116-Cd and Monte Carlo simulations show that the sensitivity of the CAMEO
experiment (in terms of the half-life limit for neutrinoless double beta decay)
is (3-5) 10^24 yr with a 1 kg source of 100-Mo (116-Cd, 82-Se, and 150-Nd) and
about 10^26 yr with 65 kg of enriched 116-CdWO_4 crystals placed in the liquid
scintillator of the CTF. The last value corresponds to a limit on the neutrino
mass of less than 0.06 eV. Similarly with 1000 kg of 116-CdWO_4 crystals
located in the BOREXINO apparatus the neutrino mass limit can be pushed down to
m_nu<0.02 eV.Comment: 29 pages, LaTex, 9 eps figure
Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long-term growth reconstruction across a geographic gradient
In this study, we investigated the role of climatic variability and atmospheric nitrogen deposition in driving long-term tree growth in canopy beech trees along a geographic gradient in the montane belt of the Italian peninsula, from the Alps to the southern Apennines. We sampled dominant trees at different developmental stages (from young to mature tree cohorts, with tree ages spanning from 35 to 160 years) and used stem analysis to infer historic reconstruction of tree volume and dominant height. Annual growth volume (G V ) and height (G H ) variability were related to annual variability in model simulated atmospheric nitrogen deposition and site-specific climatic variables, (i.e. mean annual temperature, total annual precipitation, mean growing period temperature, total growing period precipitation, and standard precipitation evapotranspiration index) and atmospheric CO 2 concentration, including tree cambial age among growth predictors. Generalized additive models (GAM), linear mixed-effects models (LMM), and Bayesian regression models (BRM) were independently employed to assess explanatory variables. The main results from our study were as follows: (i) tree age was the main explanatory variable for long-term growth variability; (ii) GAM, LMM, and BRM results consistently indicated climatic variables and CO 2 effects on G V and G H were weak, therefore evidence of recent climatic variability influence on beech annual growth rates was limited in the montane belt of the Italian peninsula; (iii) instead, significant positive nitrogen deposition (N dep ) effects were repeatedly observed in G V and G H ; the positive effects of N dep on canopy height growth rates, which tended to level off at N dep values greater than approximately 1.0 g m −2 y −1 , were interpreted as positive impacts on forest stand above-ground net productivity at the selected study sites
Loss and revival of coherence in the interaction between a positron beam and a photon field
We study the interaction between a positron beam in the single-particle regime in an interferometric configuration and a microwave electromagnetic field. We discuss the conditions under which quantum interference can be affected by the field and we outline its possible experimental study in the framework of QUantum interferometry and gravitation
with Positrons and LASers (QUPLAS) experiment
Geoneutrinos in Borexino
This paper describes the Borexino detector and the high-radiopurity studies
and tests that are integral part of the Borexino technology and development.
The application of Borexino to the detection and studies of geoneutrinos is
discussed.Comment: Conference: Neutrino Geophysics Honolulu, Hawaii December 14-16, 200
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