The SNO+ experiment is the follow up of the SNO experiment, replacing the heavy water volume with about 780 tons of liquid scintillator (LAB) in order to shift the sensitive threshold to lower energy ...range. The 6000 m.w.e. natural rock shielding, and the use of ultra-clean materials makes the detector suitable for the detection of pep and CNO solar neutrinos, geo-neutrinos, reactor neutrinos and the possible observation of neutrinos from supernovae. Complementing this program, SNO+ will also search for 150Nd (5.6% abundance) neutrinoless double beta decay, loading the liquid scintillator with 0.1% of natural Neodymium. After a review of the general SNO+ setup, the physics of the solar neutrino phase will be presented.
The SNO+ experiment is the follow up of SNO. The detector is located 2 km underground in the Vale Canada Ltd.’s Creighton Mine near Sudbury, Ontario, Canada. The active volume of the detector ...consists of 780 tonnes of Linear Alkyl Benzene (LAB) in an acrylic vessel of 12 m diameter, surrounded by about 9500 PMTs. The main goal of the SNO+ experiment is the search for neutrinoless double beta decay of 130Te. With an initial loading of 0.3% of natural tellurium (nearly 800 kg of 130Te), it is expected to reach a sensitivity on the effective Majorana neutrino mass of about 100 meV after several years of data taking. Designed as a general purpose neutrino experiment, other exciting physical goals can be explored, like the measurement of reactor neutrino oscillations and geo-neutrinos in a geologically-interesting location, watch of supernova neutrinos and studies of solar neutrinos. A first commissioning phase with water filled detector will start at the end of 2013, while the double beta decay phase will start in 2015.
The effect of temperature changes on the light output of LAB based liquid scintillator is investigated in a range from
-
5
to
30
∘
C with
α
-particles and electrons in a small scale setup. Two PMTs ...observe the scintillator liquid inside a cylindrically shaped aluminum cuvette that is heated or cooled and the temperature dependent PMT sensitivity is monitored and corrected. The
α
-emitting isotopes in dissolved radon gas and in natural Samarium (bound to a LAB solution) excite the liquid scintillator mixtures and changes in light output with temperature variation are observed by fitting light output spectra. Furthermore, also changes in light output by compton electrons, which are generated from external calibration
γ
-ray sources, is analysed with varying temperature. Assuming a linear behaviour, a combined negative temperature coefficient of
(
-
0.29
±
0.01
)
%
/
∘
C
is found. Considering hints for a particle type dependency, electrons show
(
-
0.17
±
0.02
)
%
/
∘
C
, whereas the temperature dependency seems stronger for
α
-particles, with
(
-
0.35
±
0.03
)
%
/
∘
C
. Due to a high sampling rate, a pulse shape analysis can be performed and shows an enhanced slow decay component at lower temperatures, pointing to reduced non-radiative triplet state de-excitations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
SNO+ is a large multi-purpose liquid scintillator based experiment, with the main physics goal of searching for the neutrinoless double-beta decay of
130
Te. The first of the three SNO+ ...phases started in May 2017, with the detector filled with ultra-pure water. The deep underground location (6000 m.w.e.) and the low background levels allowed new physics searches, together with the measurement of the
8
B solar neutrino flux in the 5-15 MeV energy range. Recently, SNO+ has began the transition to the scintillator phase. The double-beta decay phase is expected to start in early 2020, when the ultra-pure liquid scintillator will be loaded with 3.9 tonnes of natural tellurium, for a half-life sensitivity larger than 2×10
26
years in 5 years of data taking. This article focuses on the low background measurement of the initial water phase.
Sn-124 is one of the double beta decay isotopes where no measurement of the 2νββ decay rate has been performed. The abundance of the isotope is 5.79%, fairly low, however it can be compensated for by ...the high loading potential of the natural isotope up to 10% into liquid scintillator without significant light quenching. This work presents results of the LAB based tin loaded liquid scintillator: stability, light yield and possible purification techniques.
SNO+ is a large scale liquid scintillator based experiment located 2 km underground in a mine near Sudbury, Ontario, Canada. The detector is reusing the Sudbury Neutrino Observatory facility to ...investigate the Majorana nature of neutrinos through the search for neutrinoless double-beta decay of 130Te. In the double-beta phase about 0.3% natural tellurium will be loaded in the 780 tonnes of liquid scintillator. This corresponds to nearly 800 kg of 130Te. After several years of data taking, it is expected to reach a sensitivity on the effective Majorana neutrino mass below 100 meV. Recent development has suggested that higher loadings, up to few percent, of natural tellurium are possible by which SNO+ could approach, in the near future, the bottom of the inverted hierarchy. Additionally, designed as a general purpose neutrino experiment, SNO+ can measure reactor anti-neutrino oscillations, geo anti-neutrinos in a geologically-interesting location, solar neutrinos and watch supernova neutrinos.
A first commissioning phase with the detector filled with water will start at the end of 2014, while the double-beta decay phase is foreseen for the beginning of 2016.
130Te is one of the candidates for the search for neutrinoless double beta decay. It is currently planned to be used in two experiments: CUORE and SNO+. In the CUORE experiment TeO2 crystals cooled ...at cryogenic temperatures will be used. In the SNO+ experiment natTe will be deployed up to 0.3% loading in the liquid scintillator volume. A possible background for the signal searched for, are the high Q-value, long-lived isotopes, produced by cosmogenic neutron and proton spallation reaction on the target material. A total of 18 isotopes with Q-value larger than 2MeV and T1/2>20days have been identified as potential backgrounds. In addition low Q-value, high rate isotopes can be problematic due to pile-up effects, specially in liquid scintillator based detectors. Production rates have been calculated using the ACTIVIA program, the TENDL library, and the cosmogenic neutron and proton flux parametrization at sea level from Armstrong and Gehrels for both long and short lived isotopes. The obtained values for the cross sections are compared with the existing experimental data and calculations. Good agreement has been generally found. The results have been applied to the SNO+ experiment for one year of exposure at sea level. Two possible cases have been considered: a two years of cooling down period deep underground, or a first purification on surface and 6 months of cooling down deep underground. Deep underground activation at the SNOLAB location has been considered.
Search for solar Axion Like Particles in the low energy range at CAST Cantatore, G.; Karuza, M.; Lozza, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Axion Like Particles (ALPs) could be continuously produced in the Sun via the Primakoff process. The ALP flux could be seen on Earth by observing the photons produced by the ALP decay. The expected ...energy distribution of reconverted photons is peaked at 3
keV. There could be, however, a low energy tail due to various processes active in the Sun. We report results of the first test measurements in the low energy range performed at CAST along with a description of the experimental setup. Future detector developments are discussed and preliminary results on a liquid nitrogen cooled Avalanche Photodiode are presented.
The presence of uterine myomas during pregnancy is considered a risk factor for gestation and delivery. In literature, myomas are related to spontaneous abortion, bleeding, PPROM, preterm delivery, ...placenta previa, placental abruption, fetal malpresentations, mechanical dystocia and high incidence of cesarean section. Laparotomic myomectomy done during pregnancy is indicated when symptoms related to uterine myomas, as acute pelvic pain or gastroenteric or urinary symptoms, persist despite the pharmacological therapy. The purpose of this study is to show a successful surgical management of uterine myomas at 15.5 weeks of pregnancy, which allowed the continuation of gestation and a delivery without major complications.
The birefringence of helium in the presence of a transverse magnetic field (Cotton–Mouton effect) is studied experimentally. A very sensitive ellipsometer, based on a high finesse Fabry–Perot cavity ...and coupled to a superconducting magnet, is used to detect this very tiny effect. Birefringence is measured varying the pressure of the sample.
We report a new precise measurement of the Cotton–Mouton effect in helium at
T
≃
290
K for the two wavelengths
λ
=
532
nm and
λ
=
1064
nm. The hypermagnetizability anisotropy Δ
η for helium is 0.92
±
0.07
au at the wavelength of 532
nm and 0.98
±
0.07
au at the wavelength of 1064
nm: these values agree well with the theoretical calculations.
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