Materials And Life Science Facility Research Articles

Measurement of residual [formula omitted] polarization in a LaF[formula omitted] scintillating material for a new [formula omitted] polarimeter system

A new experimental method to measure muon polarization using a scintillating material has been proposed. One of the key issues for this measurement is the choice of scintillation materials which can maintain the μ+ spin polarization for several μ+ lifetimes. Thus far, a CeF3 scintillating crystal has been known to be only a possible candidate and it is highly preferable to find other scintillators whose performance is nearly equivalent to CeF3. The residual μ+ polarization in a 2% cerium-doped LaF3 scintillating crystal was measured at the J-PARC Material and Life Science Facility (MLF) by applying the longitudinal field (LF) to the LaF3 material. The polarization was obtained to be 83 and 87 % with LF=100 and 140 Gauss, respectively, which is high enough to measure the μ+ polarization in various experiments.

Pulsed muon facility of J-PARC MUSE

J-PARC Muon Facility: MUSE (Muon Science Establishment) is responsible for the inter-university user program and the operation, maintenance, and construction of the muon beamlines, namely D-line, S-line, U-line, and H-line, along with the muon source at J-PARC Materials and Life Science Facility (MLF). In this paper, recent developments are briefly presented.

Measurement of muon spin relaxation time in various scintillating materials

A new experimental method to search for T-violating transverse muon polarization (PT ) in the K+ → π 0 μ + ν decay was recently proposed. In this new experiment, the measurements of the μ + momentum vector, the π 0 momentum vector, and the μ + polarization will be performed by the same segmented calorimeter. One of key issues is the choice of a scintillation material which can maintain the μ + spin polarization for several μ + lifetimes. A test experiment to measure the μ + spin relaxation time in various scintillating materials was carried out at J-PARC Material and Life Science Facility (MLF). It was concluded that the residual μ + polarization in CeF3 is high enough to perform the proposed T-violation experiment.

Measurement of residual [formula omitted] polarization in various scintillating materials to search for [formula omitted]-violating [formula omitted] polarization in [formula omitted] decay

A new experimental method to search for T-violating transverse muon polarization (PT) in the K+→π0μ+ν (Kμ3) decay using a segmented CeF3 calorimeter has been proposed. One of the key issues for this experiment is the choice of a scintillation material which can maintain the μ+ spin polarization for several μ+ lifetimes. The residual μ+ polarization in a CeF3 scintillating crystal was previously measured at the J-PARC Material and Life Science Facility (MLF). Unfortunately, due to the small size of the CeF3 material, beam backgrounds contributed significantly to the μSR spectra, and the absolute μ+ polarization could not be determined accurately. In order to solve this problem, a new experiment was performed at the MLF using a large CeF3 crystal, which successfully reduced the beam backgrounds to a negligible level. The residual μ+ polarization in CeF3 was measured by changing the strength of the applied longitudinal field (LF). The polarization was obtained to be 90 ± 2% with LF = 140 Gauss, which is high enough to perform the new T-violation experiment.

KeV-region analysis of the neutron capture cross-section of 237Np

ABSTRACT Neutron capture cross-section measurements for Np have been conducted with the Accurate Neutron Nucleus Reaction Measurement Instrument (ANNRI) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC) using neutrons with energy ranging from thermal energy to 1 MeV. A time-of-flight (TOF) method using a NaI(Tl) detector was employed and the data were analyzed based on the pulse-height weighting technique in order to derive the neutron capture cross-section. The absolute capture cross-section was determined using the first resonance from JENDL-4.0 together with the total neutron flux derived from a Au sample measurement in which the first resonance was completely saturated. Both normalization techniques present agreement within 1. The present results are also compared evaluated data libraries. There is a discrepancy of 10–25 discrepancy from 0.5 to 20 keV with JENDL-4.0. Nonetheless, above this energy JENDL-4.0 seems to reproduce the present data better as the results agree within uncertainties up to 500 keV. The cross-section results contain uncertainties below 4 from 0.5 to 30 keV. However, the total uncertainty increases to over 8 above 30 keV. Along with the cross-section measurement, theoretical calculations with the CCONE code were performed to reproduce the present results.

Toward the Suppression of the Release of Tritium Generated by Neutron Spallation Source at J-PARC

I am Shiho Takamiya, I am working at the neutron source section at the materials and life science facility (MLF) in J-PARC, where intense proton beam pulses from the accelerator are injected into t...

Current status and near future plan of neutron protein crystallography at J-PARC.

The IBARAKI Biological Crystal Diffractometer (iBIX) has been available for use at MLF (Material and Life Science Facility) in J-PARC (Japan Proton Accelerator Research Complex) since 2008. The development in state-of-the-art detector systems could enable iBIX to become one of the highest-performance neutron single-crystal diffractometers in the world. Here, together with other various developments, such as data reduction software, crystal growth, and new techniques in measurement coupled analysis, we provided new hydrogen and water structural data of several proteins and macromolecules. Although the proton power at MLF has not yet reached its planned maximum (1MW), a more powerful neutron source will be soon needed for neutron protein crystallography. A future idea is also proposed and discussed in this article.

A new experimental method to search for T-violation using a sequential CeF3 scintillating calorimeter

Abstract A new experimental method to search for T -violating transverse muon polarization ( P T ) in the K + → π 0 μ + ν ( K μ 3 ) decay is proposed. In this new experiment, the measurements of the μ + momentum vector, the π 0 momentum vector, and the μ + polarization will be performed by the same electro-magnetic calorimeter. One of key issues is the choice of a scintillation material which can preserve the μ + spin polarization for several μ + lifetimes. A test experiment to measure the residual μ + polarization in a Ce F 3 scintillating crystal was performed at J-PARC Material and Life Science Facility (MLF). We concluded that the residual μ + polarization in Ce F 3 is high enough to perform the new T -violation experiment.

Simulation of Surface Muon Beamline, UltraSlow Muon Production and Extraction for the J-PARC g-2/EDM Experiment

We have developed a ultraslow muon simulation for measurement of the muon anomalous magnetic moment at the Japan Proton Accelerator Research Complex (J-PARC). The experiment will be conducted at new muon beamline (H-line) at Materials and Life Science facility (MLF) in J-PARC. H-line provides surface muons that thermailizes in a silica aerogel target to form muonium. The generated muoniums are ionized by laser and ultraslow muons are generated. The ultraslow muons are extracted by an electrostatic accelerator and injecteced to a muon linac. This paper describes the simulation for the surface muons, muonium production, and electrostatic acceleration.

Determination Approach of Dislocation Density and Crystallite Size Using a Convolutional Multiple Whole Profile Software

Neutron diffraction profile analysis using the whole profile fitting method is useful for obtaining microscopic information on metallic materials. To determine an appropriate fitting approach for obtaining reasonable and non-arbitrary results, we applied diffraction line profile analyses using the Convolutional Multiple Whole Profile (CMWP) method to diffraction patterns obtained using the Engineering Materials Diffractometer (TAKUMI, BL19) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The tensile specimens of 780 MPa grade bainitic steel were uniaxially stretched until the plastic strain reached a value of 0.05. We performed CMWP analyses on the obtained diffraction patterns during tensile test with various initial parameters of dislocation density and crystallite size. These parameters were optimized in the fitting procedures to minimize the weighted sums of squared residuals (WSSRs). Following this approach, we found that unsuitable initial parameter values resulted in unreasonable convergence. Therefore, initial fitting parameters should be chosen to ensure that the initial profiles are as broad as possible. Reasonable results were obtained following this suggestive approach even when the strain anisotropy parameter is set to arbitrary values.

Characterization of germanium detectors for the measurement of the angular distribution of prompt γ-rays at the ANNRI in the MLF of the J-PARC

In this study, the germanium detector assembly, installed at the Accurate Neutron-Nuclear Reaction measurement Instruments (ANNRI) in the Material and Life Science Facility (MLF) operated by the Japan Proton Accelerator Research Complex (J-PARC), has been characterized for extension to the measurement of the angular distribution of individual γ-ray transitions from neutron-induced compound states. We have developed a Monte Carlo simulation code using the GEANT4 toolkit, which can reproduce the pulse-height spectra of γ-rays from radioactive sources and (n,γ) reactions. The simulation is applicable to the measurement of γ-rays in the energy region of 0.5–11.0 MeV.

Path to 1-MW at J-PARC Rapid Cycling Synchrotron

The accelerator system at Japan Proton Accelerator Research Complex (J-PARC) has been operational since May 2008 and has mainly been used to perform physics experiments. The accelerator system consists of a Linac, a Rapid Cycling Synchrotron (RCS), and a Main Ring Synchrotron. The originally designed RCS injection energy is 400MeV, but the first operation started at 181MeV. New acceleration cavities were installed in J-PARC Linac during the summer shutdown of 2013, and user operation by the Material and Life science Facility (MLF) at the injection energy of 400MeV was started from February 2014. Post beam commissioning of 400MeV injection energy, beam loss was small enough, and we established 300kW continuous operation. Subsequently, the peak current of the Linac was increased from 30mA to 50mA. This upgrade enabled us to try 1-MW beam acceleration. Finally, after some additional improvements, we successfully accelerated 1-MW equivalent protons.

J-PARC Accelerator Status

Japan Proton Accelerator Research Complex (J-PARC) has started the beam delivery at 2009 to the experimental facilities which are the neutrino experimental facility (T2K), the hadron experimental facility and the material and life science facility (MLF). However J-PARC had two big troubles during last three years: First one was induced by the Great East Japan Earthquake happened in March 2011 and the second one was caused by the radioactive material leakage from hadron experimental facility in May 2013. The damage to the accelerators from both troubles has been fixed by the effort of members. As a result J-PARC has resumed the beam delivery to users. The achieved beam power for T2K is 240 kW which is one third of design value of 750 kW. In this report, the status of the accelerator operation of J-PARC is described. Furthermore it is also described the measurement of the extinction level for the physics experiment.

Muonium in J-PARC; from fundamental to application

At J-PARC, the muon science facility (MUSE) was successfully constructed in the Materials and Life Science Facility (MLF), and three scientific activities is now ongoing related muonium (Mu) from fundamental to application; 1) Mu hyperfine structure measurement (MuSEUM), 2) Ultra Slow Muon Microscope (USMM) and 3) muon g-2 and EDM measurement. Here, we will report present status of each activity.

Current status of the J-PARC muon facility, MUSE

The muon science facility (MUSE), along with the neutron, hadron, and neutrino facilities, is one of the experimental areas of the J-PARC project. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Since the autumn of 2008, users operation is effective and making use of the pulsed muon beam particularly at the D-Line. Unfortunately, MUSE suffered severe damages from the earthquake on March 11, 2011, the so-called "Higashi-Nippon Dai-Shinsai". We managed to have a stable operation of the superconducting solenoid magnet with use of the on-line refrigerator on December, 2012, although we had to overcome a lot of difficulties against components not working properly. But we had to stop again the whole operations on May 2013, because of the radioactive materials leakage accident at the Hadron Hall Experimental Facility. Finally we restarted the users' runs on February 2014.

Optimal crossed overlap of coherent vacuum ultraviolet radiation and thermal muonium emission for μSR with the Ultra Slow Muon

For μSR with ultra slow muon, we are constructing U line in materials and life science facility (MLF), J-PARC at present. Generation of ultra slow muon requires thermal muonium generation and laser resonant ionization process with vacuum ultraviolet radiation (1S→2P) and 355-nm radiation (2P→unbound). For laser resonant ionization, the coherent radiations and the thermal muonium emission must be coincident in time and space. The radiations can be steered in a chamber for reasonable overlap in space, and they can be easily overlapped in time because they are generated from one laser source. The trigger signal of the accelerator is useful for stable overlap in time.

Development of a new special environment powder neutron diffractomter, SPICA

SPICA, a new special environment powder neutron diffractometer was built at BL09 in the Material and Life science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). This is the first instrument dedicated solely to the study of next-generation batteries in J-PARC and is optimized for in situ measurements to clarify the structural changes of battery materials at the atomic level. Our approach with this diffractometer is to reveal the reactions in batteries and to determine factors of safety and degradation over long periods in practical battery systems. To make in situ measurements of real batteries more fruitful, we need high Δd/d resolution with wider d ranges to detect many phases during chemical reaction, high neutron intensity to know the specific reaction process in high speed charge/discharge, low background and large sample area to install big sample environment and a dedicated chemistry area to carry out long-term scheduled experiments with many sets of on-beam measurements and off-beam charge-discharge measurements. The in situ measurements can be performed in realistic environment with external variables such as temperature, electric field (current density, pulsed current, and etc.), and high pressure in time-resolved conditions by the 2 m sample space. The reliability of the diffraction data has achieved a sufficiently high level for the structural analysis of materials using the Rietveld method. In the beginning stage of the commissioning, the structural changes of the materials, which are dependent on the lithium content in a commercialized Li-ion battery, were clearly observed. The lattice parameters for the anode and cathode materials as a function of the lithium content were extracted from the diffraction patterns. The current status of SPICA will be reported. ACKNOWLEDGEMENT: This work was predominantly supported by the RISING project of NEDO.

Field Measurement of Pulse Steering Magnet for J-PARC 3 GeV Rapid Cycling Synchrotron

J-PARC 3-GeV Rapid Cycling Synchrotron (RCS) has two functions: as a proton beam driver to the spallation neutron source at the Material and Life Science Facility (MLF) and also as an injector to the Main Ring (MR). However the required beam parameters for each facility are different. The pulse steering magnet (PSTR) was developed to satisfy these requirements by switching the painting area in each acceleration cycle of MLF and MR and to realize center injection at 400 MeV. Therefore there are two operation modes, painting injection and center injection, for operation of PSTR.

Development of SPICA, New Dedicated Neutron Powder Diffractometer for Battery Studies

SPICA, a new special environment powder neutron diffractometer was built at BL09 in the Material and Life science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). This is the first instrument dedicated solely to the study of next-generation batteries in J-PARC and is optimized for in situ measurements to clarify structural changes of materials in batteries. The basic design and instrumentation of SPICA have been completed. The highest Δd/d resolution achieved at the commissioning stage was 0.09% at the back scattering bank of SPICA. The reliability of the diffraction data has achieved a sufficiently high level for the structural analysis of materials using the Rietveld method. The air scattering banks with the blades made of B4C for in situ measurements also function very well.

Numerical simulation of BL06 neutron beamline for “VIN ROSE” at J-PARC/MLF

A new beam line for neutron resonance spin echo spectrometers is under construction at BL06 in the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). To design the radiation shielding in the setup for commissioning experiments we have performed the neutron beam transport calculation and dose evaluation via Monte Carlo method in the three-dimensional geometry. The radiation dose rates were kept below about 6 μSv/h outside of the thickness of 30 cm concrete shield surrounding the experimental area. We propose the conceptual design of radiation shielding of the beam line and simulation result playing an important role in determining engineering design and starting the construction.