Narrow Results

The microbeam system at Tohoku University was upgraded to a triplet lens system aiming at applying to the analysis of sub-micron features. The triplet lens system has a higher demagnification than the existing doublet system. However, the introduction of the triplet system also resulted in larger chromatic and spherical aberration coefficients. To overcome these problems, the energy resolution of the accelerator was improved by developing a terminal voltage stabilization system. The energy resolution of the accelerator was improved to 1 × 10⁻⁵ ΔE/E, which resulted in an increase in the brightness of the beam. The beam brightness was 2.3 pA Δ μm⁻² Δ mrad⁻² Δ MeV⁻ and was higher in the central region. The effects of the increased chromatic and spherical aberration were mitigated by restricting the divergence angle without reducing the beam current. A beam spot size of 0.6 × 0.8 μm² was obtained with a beam current of 150 pA.

In the present study, we used a silicon drift detector (SDD) for the quantitative analysis of in-air PIXE. First, we examined the basic performances of the detector. We found that the shift of the peak position was less than 0.45 eV, and the energy resolution was 130–136 eV at 5.98 keV. We then used the SDD for a quantitative analysis. Physical parameters, such as the X-ray production cross-sections, values of the transmission of X-rays through absorbers and the detection efficiencies, which are required for quantification, were obtained theoretically and experimentally. We confirmed that many elements, from magnesium to barium, were able to be detected without using any special device. The results of the quantitative analyses of a few standard materials showed good agreement with the certified values. This method was also used to analyze practical samples, including bio-medical samples, and the results were in good agreement with the results obtained with in-vacuum PIXE.

A position-sensitive proportional counter with a carbon fiber anode, a goniometer and its associated electronics have been constructed to measure particle induced X-rays. The counter is easy to construct and its volume is about one order of magnitude smaller than a commercially available delay-line PSPC. This counter has good position linearity and uniform sensitivity distribution. Comparison is made between the new type of PSPC and an older one previously reported. It is shown that an enlargement of the X-ray window of the PSPC is effective for improving the detection efficiency.

The paper presents some preliminary results of PSS performances measured by using various exciting sources. The energy resolution of 25eV for MnKα and of ~ 15eV for TiKα is obtained, respectively, for various exciting sources. The satellite structure of SiKα has been clearly observed. The peak of CrKβ and of MnKα in a stainless steel sample has also been resolved and the detectable amount of Ti has been less than 10^-9 g. The comparisons of these results attempt to find more suitable exciting source for a different application of PSS and to discuss the possibility of application carried out by PSS combined with a new μ-X-ray exciting source.

A two-dimensional micro-strip Gas Chamber (MSGC) with a 20 × 20 mm² detection area had been developed. The MSGC had a thin diamond film of 10 μm deposited on a silicon wafer as substrate and lots of micro-strip anode and cathode electrodes made by multi-chip module technology. Energy resolution and pulse signal under 5.9 keV ⁵⁵Fe X-rays were measured by a multi-channel energy spectrometer with different voltage under room temperature in atmospheric pressure. Results indicated high signal-to-noise ratio, count rate ≥10³ Hz and stable gas gain of the MSGC were obtained. When Ar:CH₄=90:10, drift voltage, cathode voltage and anode voltage was -1000 V, -650 V and 0 V, respectively. However, the energy resolution of 12.3% for 5.9 keV ⁵⁵Fe X-rays was achieved. The effects of cathode voltage and drift voltage on energy resolution and count rate were also obtained.

The outstanding properties of diamond make it an ideal material for radiation detectors especially in the high temperature, high radiation and corrosion environments. For this purpose, electrical and irradiation properties of high quality CVD diamond detector were investigated at room temperature under irradiation conditions. For freestanding diamond films, dark current was in the order of 10^-10 A and photocurrent was in the order of 10^-8 A by 5.9 keV X-ray irradiation from a ⁵⁵Fe source with the applied voltage of 40 V. Pulse height spectrum acquired using a ²⁴¹Am alpha particle source show a full-energy peak at 820 channel which corresponded to an average charge collection efficiency of approximately 40.5%. However, a good signal-to-noise ratio and an energy resolution of 1.33% for alpha particles detecting were also obtained.

The RD52 (DREAM) collaboration is performing R&D on dual readout calorimetry techniques with the aim of improving hadronic energy resolution for future high energy physics experiments. The simultaneous detection of Cherenkov and scintillation light enables us to measure the electromagnetic fraction of hadron shower event-by-event. As a result, we could eliminate the main fluctuation which prevented from achieving precision energy measurement for hadrons. We have tested the performance of the lead and copper fiber prototypes calorimeters with various energies of electromagnetic particles and hadrons. During the beam test, we investigated the energy resolutions for electrons and pions as well as the identification of those particles in a longitudinally unsegmented calorimeter. Measurements were also performed on pure and doped PbWO₄ crystals, as well as BGO and BSO, with the aim of realizing a crystal based dual readout detector. We will describe our results, focusing on the more promising properties of homogeneous media for the technique. Guidelines for additional developments on crystals will be also given. Finally we discuss the construction techniques that we have used to assemble our prototypes and give an overview of the ones that could be industrialized for the construction of a full hermetic calorimeter.

In this paper, a monochromator (MC) with double cylindrical lenses (CLs) is evaluated. The MC achieved an energy resolution of 37 meV with high repeatability and stability. The double CLs realized the coincidence of the beam positions at the exit. The beam profiles were evaluated in a relative manner. Comparing two conditions with or without the MC, the beam kept equivalent sizes and showed sufficiently fine profiles. This is because the first-order aberration was a dominant factor under the experimental condition, where the second-order aberration was canceled by the middle plane symmetry of the MC optics and the beam was limited in small angles by the incident aperture. The experimental results mean that the MC with double CLs functioned properly as designed. The MC has the additional advantage of a simple structure. The results confirm that this MC has a high possibility for application to electron microscopy.

Parallel plate avalanche detectors (PPADs) are new gas detectors and are being extensively used to detect heavy ions, fission fragments and minimum ionizing particles. Due to their excellent timing characteristics and low cost, they are being widely used in different areas of science and technology, particularly as start and stop detectors in different experiments. These detectors are ideal for coincidence measurements and for photofission studies. Different characteristics; construction operation, performance, time resolution, energy resolution and experimental techniques based on PPADs are reviewed in this paper.

We are studying and designing a novel high pressure (~10bar, CF4 or Ne+TMA=95:5) gas TPC detector based on the thick-GEM or Micromegas to detect the neutrino energy spectrum of the reactor, which will provide an input for JUNO to determine the neutrino hierarchy. By detecting the energy and scattering angle of the elastic scattering electron, which happens between the reactor neutrino and gas, we will reconstruct the neutrino spectrum of the reactor. And the mainly physics motivation of the short baseline experiment is precisely measure the energy spectrum of reactor antineutrino with a 3% energy resolution. Providing the input for JUNO (Daya Bay ~8%; JUNO ~3%). So the high pressure gas TPC is a better option with a higher energy resolution and a better track reconstruction. We prepare design a 200kg’s detector, which is placed at 20m away from power plant, to study the neutrino energy spectrum, mixing angle, sterile neutrino and abnormal magnetic moment.

The RD52 (DREAM) collaboration is performing R&D on dual readout calorimetry techniques with the aim of improving hadronic energy resolution for future high energy physics experiments. The simultaneous detection of Cherenkov and scintillation light enables us to measure the electromagnetic fraction of hadron shower event-by-event. As a result, we could eliminate the main uctuation which prevented from achieving precision energy measurement for hadrons. We have tested the performance of the lead and copper fiber prototypes calorimeters with various energies of electromagnetic particles and hadrons. During the beam test, we investigated the energy resolutions for electrons and pions as well as the identification of those particles in a longitudinally unsegmented calorimeter. Measurements were also performed on pure and doped PbWO₄ crystals, as well as BGO and BSO, with the aim of realizing a crystal based dual readout detector. We will describe our results, focusing on the more promising properties of homogeneous media for the technique. Guidelines for additional developments on crystals will be also given. Finally we discuss the construction techniques that we have used to assemble our prototypes and give an overview of the ones that could be industrialized for the construction of a full hermetic calorimeter.