Abstract
The neutron lifetime has been measured by comparing the decay rate with the reaction rate of $^3$He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton ...Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the $^3$He(n,p)$^3$H reaction using a gas chamber, the working gas of which contains diluted $^3$He. The measured neutron lifetime was $898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,$s.
The Shirakami Mountain range, including the largest primeval beech forest in East-Asia, is undergoing ecological change. Dissolved organic matter (DOM) plays an important role in nutrient and ...material cycling in forest ecosystems. Because the quality of DOM varies based on its origin and diagenetic and runoff processes, changes in the environment surrounding DOM can be rapidly detected by monitoring its quality. Herein, concentrations and fluorescence composition of DOM at 14 sites in 13 streams in the Shirakami Mountain range were monitored monthly for over 2 years, excluding winter (December–March), to gain insight into the catchment hydrological and soil characteristics affecting DOM concentrations and composition in stream water. Based on the pattern of temporal changes in fluorescent component composition, monitoring sites were categorized into four groups (streams with small catchments, large catchments, catchments facing the Sea of Japan, and open waters in the catchment) with similar catchment characteristics affecting DOM dynamics. Multiple linear regression analysis showed that DOM concentrations in each group could be attributed to rainfall on the survey date, short-term (1–2 days) rainfall, midterm (~1 month) accumulated rainfall, midterm (7–11 days) accumulated temperature, and catchment characteristics as explanatory variables. The degree of influence of these variables differed among the four groups. The results of this study show that grouping streams according to catchment hydrological characteristics can help identify the impact of climate and environmental change on DOM dynamics in stream water.
A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing ...considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with 6Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.
The Yet Another Rapid Readout (YARR) system is a DAQ system designed for pixel readout chips including the current generation ATLAS FE-I4 chip and the next generation RD53A chip, which is part of the ...development of new Pixel detector technology to be implemented in High-Luminosity Large Hadron Collider experiments. YARR utilises a PCI-e FPGA card which acts as a simple gateway to pipe all data from pixel readout chips via the high speed PCI-e connection into the host system's memory. All data processing is done on a software level in the host CPU(s), utilising a data-driven, multi-threaded, parallel processing paradigm. YARR has recently been upgraded to interface with software emulators of pixel readout chips. These emulators offer many benefits: quick development of DAQ software; expansion of the developer base to users without access to readout hardware; preparation of DAQ software for upcoming readout chips, such as RD53A; implementation of Continuous Integration and unit tests to ensure code quality and maintainability. The design and capabilities of the FE-I4 and RD53A software emulators will be presented.
On the basic mechanism of Pixelized Photon Detectors Otono, H.; Oide, H.; Yamashita, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2009, Letnik:
610, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A Pixelized Photon Detector (PPD) is a generic name for the semiconductor devices operated in the Geiger-mode, such as Silicon PhotoMultiplier and Multi-Pixel Photon Counter, which has high photon ...counting capability. While the internal mechanisms of the PPD have been intensively studied in recent years, the existing models do not include the avalanche process. We have simulated the multiplication and quenching of the avalanche process and have succeeded in reproducing the output waveform of the PPD. Furthermore our model predicts the existence of dead-time in the PPD which has never been numerically predicted. For searching the dead-time, we also have developed waveform analysis method using deconvolution which has the potential to distinguish neighboring pulses precisely. In this paper, we discuss our improved model and waveform analysis method.
Abstract
In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained ...by counting the protons emitted from the neutron absorption reaction of ^{3}{\rm He}$ gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of ^{3}{\rm He}$ in the mixture. In order to improve the accuracy of the number density of the ^{3}{\rm He}$ nuclei, we have suggested using the ^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ reaction as a reference because this reaction involves similar kinetic energy to the $^3$He(n,p)$^3$H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the $^{14}$N(n,p)$^{14}$C reaction at a neutron velocity of 2200 m s$^{-1}$, measured relative to the $^3$He(n,p)$^3$H reaction. The result was 1.868 $\pm$ 0.003 (stat.) $\pm$ 0.006 (sys.) b. Additionally, the cross section of the $^{17}$O(n,$\alpha$)$^{14}$C reaction at the neutron velocity is also redetermined as 249 $\pm$ 6 mb.
We measured the neutron beam polarization of the BL05/NOP (Neutron Optics and Physics) beamline at J-PARC with an accuracy of less than 10−3 using polarized 3He gas as a neutron spin analyzer. ...Precise polarimetry of the neutron beam is necessary to understand the beamline optics as well as for the asymmetry measurements of the neutron beta decay, which are planned in this beamline.
► We have measured neutron beam polarization with an accuracy of 0.03% using a 3He neutron spin filter. ► This accuracy was achieved by flipping the 3He polarization with adiabatic fast-passage (AFP) NMR. ► The 3He spin flipping canceled most of systematic uncertainties. ► Such accuracy is necessary for the precise neutron beta decay measurements planned at BL05 of the J-PARC spallation neutron source.
INFN-FBK developments of 3D sensors for High-Luminosity LHC Oide, H.; Alimonti, G.; Boscardin, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
924
Journal Article
Recenzirano
Odprti dostop
3D type of pixel sensors is a promising option for the innermost pixel layer at the High-Luminosity LHC. However, the required very high hit-rate capabilities, finer pixel granularity, extreme ...radiation hardness and reduced material budget call for a downscale of the pixel size as compared to existing 3D sensors, involving smaller pitch (e.g. 50 × 50 or 25×100μm2), shorter inter-electrode spacing (∼30μm), narrower electrodes (∼6μm diameter), and reduced active thickness (∼100–150μm). Within a joint R&D effort with INFN, FBK has produced a new generation of 3D pixel sensors with these challenging features. In this talk preliminary results from the electrical and functional characterisation of the first prototypes are reported, included their behaviour after large radiation fluence, close to the ones expected in the High Luminosity LHC environment. Prospects for the next prototypes are also presented.
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