A5017700204- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Radiation Detection and Scintillator Technologies
- Quantum, superfluid, helium dynamics
- Atmospheric and Environmental Gas Dynamics
- Electromagnetic Compatibility and Measurements
- Electrostatic Discharge in Electronics
- Advanced NMR Techniques and Applications
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Pulsars and Gravitational Waves Research
- Fault Detection and Control Systems
- Magnetic confinement fusion research
- Atmospheric Ozone and Climate
The University of Tokyo
2015-2022
RIKEN Nishina Center
2015
Abstract The helium standard of Japan, referred to as HESJ, is an interlaboratory for the 3 He/ 4 He ratio. While ratio and HESJ was previously determined by a relative comparison atmospheric helium, absolute value has not been directly yet. Therefore, it relies on early measurements that helium. accuracy ratios atmosphere other working standards including crucial in some applications isotopes, such tritium‐ dating, surface‐exposure age determination based cosmogenic He, accurate measurement...
The half-lives of 2 + 1 states were measured for 102,104 Zr and 106,108 Mo to test a new implementation LaBr 3 (Ce) array at the RIBF, RIKEN, Japan.The nuclei interest produced through fission
The neutron lifetime (τn) is one of the basic parameters in weak interaction, and used for predicting light element abundance early universe. Our group developed a new setup to measure τn with goal precision 0.1% at polarized beam branch BL05 MLF, J-PARC. commissioning data was acquired 2014 2015, first set evaluate 2016, which expected yield statistical uncertainty O(1)%. This paper presents current analysis results future plans achieve our precision.
The neutron lifetime has been measured by comparing the decay rate with reaction of $^3$He nuclei a pulsed beam from spallation source at Japan Proton Accelerator Research Complex (J-PARC). and were determined simultaneously detecting electrons protons $^3$He(n,p)$^3$H using gas chamber which working contains diluted $^3$He. was $898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,$s.
Abstract In a neutron lifetime measurement at the Japan Proton Accelerator Complex, is calculated from decay rate and incident flux. The flux obtained by counting protons emitted absorption reaction of ${}^{3}{\rm He}$ gas, which diluted in mixture working gas detector. Hence, it crucial to determine amount mixture. order improve accuracy number density nuclei, we have suggested using ${}^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ as reference because this involves similar kinetic energy...
The decay lifetime of free neutrons (∼880 s) is an important parameter the weak interaction and for Big Bang Nucleosynthesis. However, results measurements currently show discrepancies depending on method used. As most experiments nowadays employ ultra cold neutrons, we have developed a new cold-beam experiment which perform at Japan Proton Accelerator Research Complex. special feature, polarized neutron beam bunched by spin flip chopper. A time projection chamber operated with He CO 2 gas,...
The ``neutron lifetime puzzle'' arises from the discrepancy between neutron measurements obtained using beam method, which measures decay products, and bottle disappearance of neutrons. To resolve this puzzle, we conducted an experiment a pulsed cold at J-PARC. In experiment, is determined ratio counts to $^3$He(n,p)$^3$H reactions in gas detector. This belongs method but differs previous experiments that measured protons, as it instead detects electrons, enabling with distinct systematic...
A neutron lifetime measurement conducted at the Japan Proton Accelerator Research Complex (J-PARC) is counting number of electrons from decays with a time projection chamber (TPC). The $\gamma$ rays produced in TPC cause irreducible background events. To achieve precise measurement, inner walls consist $^6$Li-enriched lithium-fluoride ($^6$LiF) tiles to suppress amount rays. In order estimate $^{6}{\rm LiF}$ tile, prompt gamma ray analysis (PGA) measurements were performed using germanium...
A wire chamber often suffers significant saturation of the multiplication factor when electric field around its wires is strong. An analytical model this effect has previously been proposed [Y. Arimoto et al., Nucl. Instrum. Meth. Phys. Res. 799, 187 (2015)], in which was described by factor, energy deposit density per length, and one constant parameter. In order to confirm validity model, a multi-wire drift developed irradiated MeV-range proton beam at University Tsukuba. The compared for...
The neutron lifetime is one of the basic parameters in weak interaction, and used for predicting light element abundance early universe. Our group developed a new setup to measure with goal precision 0.1% at polarized beam branch BL05 MLF, J-PARC. commissioning data was acquired 2014 2015, first set evaluate 2016, which expected yield statistical uncertainty O(1)%. This paper presents current analysis results future plans achieve our precision.
"Neutron Optics and Physics (NOP/ BL05)" at MLF in J-PARC is a beamline for studies of fundamental physics. The divided into three branches so that different experiments can be performed parallel. These beam are being used to develop variety new projects. We developing an experimental project measure the neutron lifetime with total uncertainty 1 s (0.1%). important parameter elementary particle astrophysics. Thus far, has been measured by several groups; however, values obtained from...
In a neutron lifetime measurement at the Japan Proton Accelerator Complex, is calculated by decay rate and incident flux. The flux obtained due to counting protons emitted from absorption reaction of ${}^{3}{\rm He}$ gas, which diluted in mixture working gas detector. Hence, it crucial determine amount mixture. order improve accuracy number density nuclei, we suggested use ${}^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ as reference because this involves similar kinetic energy He}({\rm...
The neutron lifetime is one of the important parameters for particle physics and astrophysics. There a 4.6$\sigma$ (9.5 s) discrepancy between results two typical methods. To solve this discrepancy, new experiment with different method in progress at J-PARC, published first result 2020 $898 \pm 10 (\mathrm{stat.}) +15/-18 (\mathrm{syst.})\,\mathrm{s}$. We have performed improvements to reduce systematic uncertainties towards 1 s accuracy. methods measure amount $\mathrm{^3He}$ injected...