| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2022: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2021: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
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| Outline of Research at the Start |
This project aims at understanding the operating principle of a 4-CH delay line current-biased kinetic inductance detector (CB-KID) system. Since this detector is very different from any other existing neutron detectors, we need deeper understanding for the physical basis. The nuclear reaction 10B(n,alpha)7Li creates a hot spot in a superconducting Nb nanowire under the dc bias current. A coordinate (X,Y) of the hot spot is obtained by using time differences in signal arrival timestamps to obtain neutron image.
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| Outline of Annual Research Achievements |
We improved the stability of temperature of neutron detector better than 80uK at 5K, which gives an error in velocity lower than ±160 m/s (0.0002%) [1] under optimized PID conditions of two control loops using a Cryocon 54. This reduced the influence of velocity error to spatial resolution at near edges of detector [2]. Based on it, we built a new cryostat system to be able to mount room-temperature samples . This is in marked contrast with the former cryostat in conducting the experiments under pulsed neutrons. Especially, it performs a very high-resolution imaging because a sample is placed at the close vicinity of the CB-KID detector at a cryogenic temperature. Therefore, we can investigate various samples in a single beam time such as FeS2 ammonite, Fe2O3 ammonite, CaF2 [3], CuAl-glads, Li Grease, LiPS, etc.. This is also suitable to apply different conditions on sample during beam time, i.e., temperature, electrics, compression traction force, etc. to reveal many properties of material. We confirmed a sequential change in phase separations of low melting Wood’s metal by melting and re-solidification [1]. Neutron image becomes clearer by convenient open-beam normalization to avoid inhomogeneity beam condition and Boron conversion layer.
[1] T. D. Vu, et al., Journal of Physics: Conference Series in press.
[2] T. D. Vu, et al., The 3rd International Workshop on Engineering Physics, IC-MEMS-Sensors and Their Applications, HCM city, Viet Nam, November 25&26, 2022, Invited talk.
[3] H. Shishido, T. D. Vu et al., Journal of Physics: Conference Series in press.
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| Strategy for Future Research Activity |
Most of the research plans have been completed rather well so far. However, achievements have not been published thoroughly yet. We consider that our achievements should be published in the next fiscal year. We plan to present our results at the conferences in the field, too. Regarding the operation principle of the detector, we still have a difficulty that a spatial resolution is limited by a temporal resolution because the current readout circuit Kalliope-DC can not distinguish a repetition period of the meanderline 1.5um. This is simply due to a temporal resolution of 1ns. We plan to develop a readout circuit of tempral resolution of 30ps. This will improve the spatial resolution down to 1.5um.
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