Mechanical design of multi-PMTs for IWCD Deshmukh, N; Chinchanikar, S; Garde, C ...
Journal of physics. Conference series,
11/2022, Letnik:
2374, Številka:
1
Journal Article
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Approximately 500 multi-PMTs (mPMTs) will be used as the photosensors for the Intermediate Water Cherenkov Detector (IWCD), a new near detector for the approved Hyper-Kamiokande experiment that will ...be built by 2025. The IWCD mPMT design has nineteen 3” PMTs enclosed in a water-tight pressure vessel, along with the associated electronics. The 3” PMTs provide excellent spatial imaging of the neutrino-induced Cherenkov light ring. This work will focus on the mechanical design of the mPMT vessel. In particular, design of the acrylic dome, use of optical gel to couple the dome to the PMTs, assembly procedures of dome and PMT sub-assembly (including the necessary jigs / fixtures), design of water-tight feed-through & plans for testing and results from several mPMT prototypes.
The Water Cherenkov Test Experiment (WCTE) is an experiment proposed at CERN to measure the response of a Water Cherenkov Detector for charged particles such as
π
±, p+, e±, etc. The data obtained ...from WCTE will be used in future neutrino experiments. WCTE consists of a sealed cylindrical tank filled with ultrapure water. 128 multi-PhotoMultiplier Tubes (mPMTs) are mounted on a cylindrical support structure facing inwards to map out the Cherenkov radiation with high granularity. This work presents the mechanical design and analysis of the support structure for WCTE. It is designed to sustain the load of 128 mPMTs, arrangement of Photogrammetry system Cameras & lights and Calibration arm without significant change in the position / geometry of the structure. SS304 is identified as a suitable material to ensure the compatibility with the ultrapure water and Gd-loaded water. The structure is robust against stresses during handling and subsequent transport with and without water.
Optical transition radiation monitor for the T2K experiment Bhadra, S.; Cadabeschi, M.; de Perio, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2013, Letnik:
703
Journal Article
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An optical transition radiation monitor has been developed for the proton beam-line of the T2K long baseline neutrino oscillation experiment. The monitor operates in the highly radioactive ...environment in proximity to the T2K target. It uses optical transition radiation, the light emitted from a thin metallic foil when the charged beam passes through it, to form a two-dimensional image of the 30GeV proton beam profile in the transverse plane. One of its key features is an optical system capable of transporting the light over a large distance out of the harsh environment near the target to a lower radiation area where it is possible to operate a camera to capture this light. The monitor measures the proton beam position and width with an accuracy better than 0.5mm, meeting the physics requirements of the T2K experiment.
•A metastable β Titanium alloy Ti-15V-3Cr-3Sn-3Al irradiated with 30 GeV protons to about 0.1 dpa was studied to evaluate radiation damage effects for high-intensity proton accelerator beam window ...and target application.•A high density nanometer-sized precipitate was observed by TEM, which would be martensite α and athermal ω formed during the solution-treatment process. They did not appear to change substantially after irradiation with protons.•No obvious signature of radiation damage, such as dislocation loops along the proton beam profile or radiation-induced hardening, was identified.•The metastable β alloy may exhibit radiation damage resistance due to the existence of nano-scale precipitates, acting as sinks for radiation-induced point defects.
A foil of a metastable β Titanium alloy Ti-15V-3Cr-3Sn-3Al was irradiated at the J-PARC neutrino experimental facility with 1.4 × 1020 30 GeV protons at low temperature (100–130 °C at most), and microstructural characterization and hardness testing were conducted as an initial study on the radiation damage effects of Titanium alloy by the high energy proton beam exposure. Expected radiation damage at the beam center is about 0.06–0.12 displacement per atom. A high density (> 1023 m−3) of a nanometer-sized precipitate was observed by TEM studies, which would be identified as martensite α-phase and athermal ω-phase formed during the solution-treatment process to fabricate metastable β alloy. They did not appear to change substantially after irradiation with protons. In the irradiated specimen, we could not identify an obvious signature of radiation damage distributed along the proton beam profile. Very small, nanometer-scale black dots were present at a low density in the most highly irradiated region, and may be small dislocation loops formed during irradiation. The micro-indentation test indicated that the radiation exposure led to tiny increase in Vickers micro-hardness of ΔHV = 20 at beam center. Atom probe tomography reveals compositional fluctuations that reach a maximum amplitude of 10 at% Ti within a space of < 5 nm both before and after irradiation, which may also indicate presence of rich precipitates. These experimental results suggest this specific β alloy may exhibit radiation damage resistance due to the existence of a high density of nano-scale precipitates, but further studies with higher exposure are required to explore this possibility.
Upgraded electronics, improved water system dynamics, better calibration and analysis techniques allowed Super-Kamiokande-IV to clearly observe very low-energy B8 solar neutrino interactions, with ...recoil electron kinetic energies as low as ∼3.5 MeV. Super-Kamiokande-IV data-taking began in September of 2008; this paper includes data until February 2014, a total livetime of 1664 days. The measured solar neutrino flux is (2.308±0.020(stat)−0.040+0.039(syst))×106/(cm2 sec) assuming no oscillations. The observed recoil electron energy spectrum is consistent with no distortions due to neutrino oscillations. An extended maximum likelihood fit to the amplitude of the expected solar zenith angle variation of the neutrino-electron elastic scattering rate in SK-IV results in a day/night asymmetry of (−3.6±1.6(stat)±0.6(syst))%. The SK-IV solar neutrino data determine the solar mixing angle as sin2θ12=0.327−0.031+0.026, all SK solar data (SK-I, SK-II, SK III and SK-IV) measures this angle to be sin2θ12=0.334−0.023+0.027, the determined mass-squared splitting is Δm212=4.8−0.8+1.5×10−5 eV2.
We have searched for proton decay via p → e+π0 and p → μ+π0 modes with the enlarged fiducial volume data of Super-Kamiokande from April 1996 to May 2018, which corresponds to 450 kton ⋅ years ...exposure. We have accumulated about 25% more livetime and enlarged the fiducial volume of the Super-Kamiokande detector from 22.5 kton to 27.2 kton for this analysis, so that 144 kton ⋅ years of data, including 78 kton ⋅ years of additional fiducial volume data, has been newly analyzed. No candidates have been found for p → e+π0 and one candidate remains for p → μ+π0 in the conventional 22.5 kton fiducial volume and it is consistent with the atmospheric neutrino background prediction. We set lower limits on the partial lifetime for each of these modes: τ/B(p → e+π0) > 2.4 × 1034 years and τ/B(p → μ+π0) > 1.6 × 1034 years at 90% confidence level.
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