The SNO+ experiment is located at the SNOLAB underground laboratory and will employ 780 tons of liquid scintillator loaded, in its initial phase, with 800 kg of 130Te (0.3% by mass) for a ...low-background and high-isotope-mass search for neutrino-less double beta decay. SNO+ reuses the acrylic vessel and PMT array of the SNO detector, but several experimental upgrades and adaptations were necessary to allow for the use of liquid scintillator. The SNO+ technique allows a staged approach, and extensive R&D is ongoing to increase the loadings and improve the purification of Tellurium. The very good conditions of background and low energy threshold allow SNO+ to also have other physics topics in its program, including geo- and reactor neutrinos, Supernova and solar neutrinos. This talk will describe the main advantages and challenges of the SNO+ approach for the double-beta decay program, the current status of the experiment and its sensitivity prospects.
Neutrino oscillation experiments require a precise measurement of the neutrino energy. However, the kinematic detection of the final-state neutron in the neutrino interaction is missing in current ...neutrino oscillation experiments. The missing neutron kinematic detection results in a smaller detected neutrino energy than the true neutrino energy. A novel 3D-projection scintillator tracker, which consists of roughly ten million active cubes covered with an optical reflector, is capable of measuring the neutron kinetic energy and direction on an event-by-event basis using the time-of-flight technique thanks to the fast timing, fine granularity, and high light yield. The $\overline{v}$μ interactions tend to produce neutrons in the final state. By measuring the neutron kinetic energy, the $\overline{v}$μ energy can be reconstructed better, allowing a tighter incoming neutrino flux constraint. This article shows the detector's ability to reconstruct neutron kinetic energy and the $\overline{v}$μ flux constraint achieved by selecting the charged-current interactions without mesons or protons in the final state.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
3.
Calibration of the SNO+ experiment Maneira, J; Falk, E; Leming, E ...
Journal of physics. Conference series,
09/2017, Volume:
888, Issue:
1
Journal Article
Peer reviewed
Open access
The main goal of the SNO+ experiment is to perform a low-background and high-isotope-mass search for neutrinoless double-beta decay, employing 780 tonnes of liquid scintillator loaded with tellurium, ...in its initial phase at 0.5% by mass for a total mass of 1330 kg of 130Te. The SNO+ physics program includes also measurements of geo- and reactor neutrinos, supernova and solar neutrinos. Calibrations are an essential component of the SNO+ data-taking and analysis plan. The achievement of the physics goals requires both an extensive and regular calibration. This serves several goals: the measurement of several detector parameters, the validation of the simulation model and the constraint of systematic uncertainties on the reconstruction and particle identification algorithms. SNO+ faces stringent radiopurity requirements which, in turn, largely determine the materials selection, sealing and overall design of both the sources and deployment systems. In fact, to avoid frequent access to the inner volume of the detector, several permanent optical calibration systems have been developed and installed outside that volume. At the same time, the calibration source internal deployment system was re-designed as a fully sealed system, with more stringent material selection, but following the same working principle as the system used in SNO. This poster described the overall SNO+ calibration strategy, discussed the several new and innovative sources, both optical and radioactive, and covered the developments on source deployment systems.
Ion-pair formation in gaseous nitromethane (CH
3
NO
2
) induced by electron transfer has been studied by investigating the products of collisions between fast potassium atoms and nitromethane ...molecules using a crossed molecular-beam technique. The negative ions formed in such collisions were analysed using time-of-flight mass spectroscopy. The six most dominant product anions are NO
2
−
, O
−
, CH
3
NO
2
−
, OH
−
, CH
2
NO
2
−
and CNO
−
. By using nitromethane-d
3
(CD
3
NO
2
), we found that previous mass 17 amu assignment to O
−
delayed fragment, is in the present experiment may be unambiguously assigned to OH
−
. The formation of CH
2
NO
2
−
may be explained in terms of dissociative electron attachment to highly vibrationally excited molecules.
Electron transfer in K + CH
3
NO
2
collisions yields CH
3
NO
2
−
, CH
2
NO
2
−
, CNO
−
, NO
−
, CN
−
, OH
−
and H
−
.
SNO is being upgraded to SNO+, which has as its main goal the search for neutrinoless double-beta decay. The upgrade is defined by filling with a novel scintillator mixture containing 130Te. With a ...lower energy threshold than SNO, SNO+ will be sensitive to other exciting new physics. Here we are describing new optical calibration system that meets new, more stringent radiopurity requirements has been developed.
A light injection system using LEDs and optical fibres was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. Large volume, non-segmented, ...low-background detectors for rare event physics, such as the multi-purpose SNO+ experiment, need a calibration system that allow an accurate and regular measurement of the performance parameters of their photomultiplier arrays, while minimising the risk of radioactivity ingress. The design implemented for SNO+ uses a set of optical fibres to inject light pulses from external LEDs into the detector. The design, fabrication and installation of this light injection system, as well as the first commissioning tests, are described in this paper. Monte Carlo simulations were compared with the commissioning test results, confirming that the system meets the performance requirements.
A new external LED/fiber light injection calibration system was designed for the calibration and monitoring of the photomultiplier array of the SNO+ experiment at SNOLAB. The goal of the calibration ...system is to allow an accurate and regular measurement of the photomultiplier array's performance, while minimizing the risk of radioactivity ingress. The choice in SNO+ was to use a set of optical fiber cables to convey into the detector the light pulses produced by external LEDs. The quality control was carried out using a modified test bench that was used in QC of optical fibers for TileCal/ATLAS. The optical fibers were characterized for transmission, timing and angular dispersions. This article describes the setups used for the characterization and quality control of the system based on LEDs and optical fibers and their results.
The buildup of a poly1-4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido-1,2-ethanediyl, sodium salt (PAZO) layer adsorbed onto a already adsorbed layer of poly(allylamine hydrochloride) (PAH) was ...shown to be ruled by two processes, a nucleation process which occurs for short adsorption times and a process having longer characteristic times. During the nucleation process the adsorbed amount is seen to increase very rapidly and is dependent of PAZO concentration. The adsorbed PAZO molecules create a potential barrier that to make difficult that more molecules are adsorbed. However the presence of cations in the solution accounts for adsorption the continuation of adsorption in a second process, as they tend to be adsorbed lowering the potential barrier and allowing more PAZO molecules to be adsorbed. These processes are shown to be consistent with surface morphology evolution, it was observed an increase of roughness for short adsorption periods of time and a subsequent decrease of the surface roughness for longer adsorption times.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Here, a measurement of the 8B solar neutrino flux has been made using a 69.2 kt-day dataset acquired with the SNO+ detector during its water commissioning phase. At energies above 6 MeV the dataset ...is an extremely pure sample of solar neutrino elastic scattering events, owing primarily to the detector’s deep location, allowing an accurate measurement with relatively little exposure. In that energy region the best fit background rate is 0.25+0.09–0.07 events/kt–day, significantly lower than the measured solar neutrino event rate in that energy range, which is 1.03+0.13–0.12 events/kt–day. Also using data below this threshold, down to 5 MeV, fits of the solar neutrino event direction yielded an observed flux of 2.53+0.31–0.28(stat)+0.13–0.10(syst) × 106 cm–2 s–1, assuming no neutrino oscillations. This rate is consistent with matter enhanced neutrino oscillations and measurements from other experiments.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
PDF
