The T2K long-baseline neutrino oscillation experiment has been running since 2010; it collects data in both neutrino and anti-neutrino modes. The results presented here refer to a joint analysis of ...νμ disappearance and νe appearance for neutrino data giving the world-leading measurements of δcp, θ23 and Δm232. The first anti-neutrino beam results are also discussed here which allows for testing of CPT symmetry and an electron anti-neutrino appearance search.
Intrinsic energy resolution of NaI(Tl) Moszyński, M.; Zalipska, J.; Balcerzyk, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2002, Letnik:
484, Številka:
1
Journal Article
Recenzirano
The light output for ∅10 mm×10
mm and ∅75
mm×75
mm NaI(Tl) crystals and energy resolution were measured for γ-ray energies ranging from 16–1333
keV. These measurements enabled the observation of the ...light yield nonproportionality behavior and allowed the determination of the intrinsic resolution after correcting for the measured resolution for photomultiplier tube (PMT) statistics. The intrinsic resolution was then compared with the nonproportionality component. The latter was calculated using measured electron response, Monte Carlo
N Particle code (MCNP4B), and the simplified cascade sequence for NaI(Tl). This comparison allowed the identification of the intrinsic resolution component associated with δ-rays. Consequently, it was shown that the δ-ray component is the most dominant component of the NaI(Tl) intrinsic resolution.
First gadolinium loading to Super-Kamiokande Hiraide, K.; Imaizumi, S.; Moriyama, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2022, Letnik:
1027
Journal Article
Recenzirano
Odprti dostop
In order to improve Super-Kamiokande’s neutron detection efficiency and to thereby increase its sensitivity to the diffuse supernova neutrino background flux, 13 tons of Gd2(SO4)3⋅8H2O (gadolinium ...sulfate octahydrate) was dissolved into the detector’s otherwise ultrapure water from July 14 to August 17, 2020, marking the start of the SK-Gd phase of operations. During the loading, water was continuously recirculated at a rate of 60 m3/h, extracting water from the top of the detector and mixing it with concentrated Gd2(SO4)3⋅8H2O solution to create a 0.02% solution of the Gd compound before injecting it into the bottom of the detector. A clear boundary between the Gd-loaded and pure water was maintained through the loading, enabling monitoring of the loading itself and the spatial uniformity of the Gd concentration over the 35 days it took to reach the top of the detector. During the subsequent commissioning the recirculation rate was increased to 120 m3/h, resulting in a constant and uniform distribution of Gd throughout the detector and water transparency equivalent to that of previous pure-water operation periods. Using an Am–Be neutron calibration source the mean neutron capture time was measured to be 115±1 μs, which corresponds to a Gd concentration of 111±2 ppm, as expected for this level of Gd loading. This paper describes changes made to the water circulation system for this detector upgrade, the Gd loading procedure, detector commissioning, and the first neutron calibration measurements in SK-Gd.
The T2K Fine Grained Detector (FGD) is an active neutrino target that uses segmented scintillator bars to observe short-range particle tracks. 8448 multipixel photon counters (MPPCs) coupled to ...wavelength shifting fibres detect scintillator light. An application specific integrated circuit (ASIC) shapes the MPPC waveform and uses a switched capacitor array (SCA) to store up to 511 analog samples over 10.22 μs. High and low attenuation channels for each MPPC improve dynamic range. 12-bit serial quad-ADCs digitize ASIC analog output and interface with a field programmable gate array (FPGA). Each FPGA simultaneously reads out four ADCs and saves the synchronized samples in an external digital memory. The system produces 13.5 MB of uncompressed data with a target trigger rate of 20 Hz, and requires zero suppression to reduce data size and readout time. Firmware based data compression uses an online pulse-finder that decides whether to output pulse height information, a section of waveform, or to suppress all data. The front end FPGA transfers formatted data to data concentrator cards (DCCs) through a 2 Gb/s optical fiber interface using an efficient custom protocol. We have evaluated the performance of the FGD electronics system and the quality of its online data compression through the course of a physics data run. The average size of a compressed data acquisition is measured as 44 ~ kB.
Energy resolution of NaI(Tl), CsI(Tl), LSO and YAP crystals coupled to 16 mm diameter Large Area Avalanche Photodiodes (LAAPD) was studied for low energy gamma-rays. Energy resolutions of 11.3% and ...8.4% were obtained for 59.6 keV gamma-rays from (241)Am and 122 keV gamma-rays from (57)Co sources, respectively, as measured with a 10 mm diameter by 10 mm high NaI(Tl) crystal. The optimization of the LAAPD performance is presented, being essential for improvement of energy resolution at low energy gamma-rays. Measured numbers of primary electron-hole pairs produced in LAAPDs and evaluation of noise contribution of these devices allowed for quantitative discussion of the results. Particularly, the intrinsic energy resolution of the crystals vs. energy of gamma-rays has been evaluated. Obtained data for NaI(Tl) crystal showed a good agreement (within 30%) with calculated component due to nonproportional light yield for energies above 50 keV
We report a search for time variations of the solar B 8 neutrino flux using 5804 live days of Super-Kamiokande data collected between May 31, 1996, and May 30, 2018. Super-Kamiokande measured the ...precise time of each solar neutrino interaction over 22 calendar years to search for solar neutrino flux modulations with unprecedented precision. Periodic modulations are searched for in a dataset comprising five-day interval solar neutrino flux measurements with a maximum likelihood method. We also applied the Lomb-Scargle method to this dataset to compare it with previous reports. The only significant modulation found is due to the elliptic orbit of the Earth around the Sun. The observed modulation is consistent with astronomical data: we measured an eccentricity of ( 1.53 ± 0.35 ) % , and a perihelion shift of ( − 1.5 ± 13.5 ) days. Published by the American Physical Society 2024
We present a measurement of neutrino oscillation parameters with the Super-Kamiokande detector using atmospheric neutrinos from the complete pure-water SK I–V (April 1996–July 2020) dataset, ...including events from an expanded fiducial volume. The dataset corresponds to 6511.3 live days and an exposure of 484.2 kiloton-years. Measurements of the neutrino oscillation parameters Δ m 3 2 2 , sin 2 θ 2 3 , sin 2 θ 1 3 , δ CP , and the preference for the neutrino mass ordering are presented with atmospheric neutrino data alone, and with constraints on sin 2 θ 1 3 from reactor neutrino experiments. Our analysis including constraints on sin 2 θ 1 3 favors the normal mass ordering at the 92.3% level. Published by the American Physical Society 2024
PDF
