153 research outputs found
High density mapping systems for SRF cavities
20th International Conference on RF Superconductivity (SRF 2021)In order to evaluate the performance of a superconducting cavity, we are developing a mapping system to measure the distribution of cavity temperature, field emission X-rays, and trapped magnetic flux with high positional resolution. In order to construct a system with high positional resolution, a large number of sensors are required. However, as the number of sensors increases, so does the amount of wiring, which increases the complexity of the wiring in the cryogenic apparatus, and also increases the heat transfer through the wiring, which disturb efficient operation of cavity tests. We are developing an efficient mapping system with a multiplexer that scans the readout signal on the same circuit as the sensor in the cryogenic dewar where the cavity test is conducted. In this presentation, we report the outline and test results of the mapping system under developmen
The Stretcher Operation of KSR (NUCLEAR SCIENCE RESEARCH FACILITY-Particle and Photon Beams)
The electron ring KSR has been utilized as a pulse stretcher of the 100 MeV S-band electron linac. The duty factor of the electron beam has been increased drastically more than 90% from 2 10-5
High-pressure xenon gas time projection chamber with scalable design and its performance at around the Q value of Xe double-beta decay
We have been developing a high-pressure xenon gas time projection chamber
(TPC) to search for neutrinoless double beta () decay of
Xe. The unique feature of this TPC is in the detection part of
ionization electrons, called ELCC. ELCC is composed of multiple units, and one
unit covers 48.5 . A 180 L size prototype detector with 12
units, 672 channels, of ELCC was constructed and operated with 7.6 bar natural
xenon gas to evaluate the performance of the detector at around the Q value of
Xe . The obtained FWHM energy resolution is (0.73
0.11) % at 1836 keV. This corresponds to (0.60 0.03) % to (0.70
0.21) % of energy resolution at the Q value of .
This result shows the scalability of the AXEL detector with ELCC while
maintaining high energy resolution. Factors determining the energy resolution
were quantitatively evaluated and the result indicates further improvement is
feasible. Reconstructed track images show distinctive structures at the
endpoint of electron tracks, which will be an important feature to distinguish
signals from gamma-ray backgrounds.Comment: 33 pages, 24 figures, preprint accepted by PTE
Pigment Pattern in jaguar/obelix Zebrafish Is Caused by a Kir7.1 Mutation: Implications for the Regulation of Melanosome Movement
Many animals have a variety of pigment patterns, even within a species, and these patterns may be one of the driving forces of speciation. Recent molecular genetic studies on zebrafish have revealed that interaction among pigment cells plays a key role in pattern formation, but the mechanism of pattern formation is unclear. The zebrafish jaguar/obelix mutant has broader stripes than wild-type fish. In this mutant, the development of pigment cells is normal but their distribution is altered, making these fish ideal for studying the process of pigment pattern formation. Here, we utilized a positional cloning method to determine that the inwardly rectifying potassium channel 7.1 (Kir7.1) gene is responsible for pigment cell distribution among jaguar/obelix mutant fish. Furthermore, in jaguar/obelix mutant alleles, we identified amino acid changes in the conserved region of Kir7.1, each of which affected K(+) channel activity as demonstrated by patch-clamp experiments. Injection of a bacterial artificial chromosome containing the wild-type Kir7.1 genomic sequence rescued the jaguar/obelix phenotype. From these results, we conclude that mutations in Kir7.1 are responsible for jaguar/obelix. We also determined that the ion channel function defect of melanophores expressing mutant Kir7.1 altered the cellular response to external signals. We discovered that mutant melanophores cannot respond correctly to the melanosome dispersion signal derived from the sympathetic neuron and that melanosome aggregation is constitutively activated. In zebrafish and medaka, it is well known that melanosome aggregation and subsequent melanophore death increase when fish are kept under constant light conditions. These observations indicate that melanophores of jaguar/obelix mutant fish have a defect in the signaling pathway downstream of the α(2)-adrenoceptor. Taken together, our results suggest that the cellular defect of the Kir7.1 mutation is directly responsible for the pattern change in the jaguar/obelix mutant
Fundamental physics activities with pulsed neutron at J-PARC(BL05)
"Neutron Optics and Physics (NOP/ BL05)" at MLF in J-PARC is a beamline for
studies of fundamental physics. The beamline is divided into three branches so
that different experiments can be performed in parallel. These beam branches
are being used to develop a variety of new projects. We are developing an
experimental project to measure the neutron lifetime with total uncertainty of
1 s (0.1%). The neutron lifetime is an important parameter in elementary
particle and astrophysics. Thus far, the neutron lifetime has been measured by
several groups; however, different values are obtained from different
measurement methods. This experiment is using a method with different sources
of systematic uncertainty than measurements conducted to date. We are also
developing a source of pulsed ultra-cold neutrons (UCNs) produced from a
Doppler shifter are available at the unpolarized beam branch. We are developing
a time focusing device for UCNs, a so called "rebuncher", which can increase
UCN density from a pulsed UCN source. At the low divergence beam branch, an
experiment to search an unknown intermediate force with nanometer range is
performed by measuring the angular dependence of neutron scattering by noble
gases. Finally the beamline is also used for the research and development of
optical elements and detectors. For example, a position sensitive neutron
detector that uses emulsion to achieve sub-micrometer resolution is currently
under development. We have succeeded in detecting cold and ultra-cold neutrons
using the emulsion detector.Comment: 9 pages, 5 figures, Proceedings of International Conference on
Neutron Optics (NOP2017
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