2017 Fiscal Year Research-status Report
Study of primary knock-on atoms from high-energy proton bombardment
| Project/Area Number |
17K14918
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
蔡 碧恩 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力基礎工学研究センター, 博士研究員 (50781671)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | primary knock-on atoms / time of flight / gas ionization chamber / PHITS |
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| Outline of Annual Research Achievements |
Experimental data of primary knock-on atoms (PKAs) produced from proton-induced reactions are demanding for the radiation damage assessment and validating nuclear physics models for various accelerator applications. This study proposed to measure the PKA data by a new measurement system, consisting of two ultra-fast timing detectors and one customized delta E-E gas ionization chamber.
The study was focused on the detector and hardware development of the measurement system in the first year. The timing detector, composed of a 15-nm thick C foil, an accelerating grid, an electrostatic mirror, and a microchannel plate detector, was assembled together with its detector holder and a voltage divider. Its test was conducted at the JAEA Tandem Facility by using a calibration alpha source, followed by the test at CYRIC at the Tohoku University by using 70-MeV protons bombarding a 300-nm carbon target. The test results indicated that (1) the electric fields of the accelerating grid and the electrostatic mirror might not be uniform enough and created a lot of noises, and (2) the two timing detectors and the Si detector might not be well-aligned, such that the triple coincidence rate of the three detectors was much lower than it was expected. Thus, the corresponding modifications started after the experiments. For the delta E-E gas ionization chamber, four low-noise preamplifiers were installed inside the chamber to reduce the noise level in this fiscal year. The gas flow and mass control system to maintain the constant gas pressure in the ionization chamber was also designed.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
For the detector development of the new measurement system, it was planned to finish the tests of each individual detector as well as the entire measurement system by the end of this fiscal year. The test of the timing detector was conducted as scheduled, though the performance of the prototype was not as good as we expected. However, for the gas ionization chamber, which was originally planned to be tested in FY2017, the schedule of installing the low-noise preamplifiers inside the chamber was delayed by the contracting company. There was also an unexpected delay with the contracting company for constructing the gas flow and mass control system to maintain a constant pressure within the gas ionization chamber. As a result, the test was performed for the timing detector assembly only, but the tests for the gas ionization chamber and for the entire measurement system need to be postponed to the next fiscal year.
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| Strategy for Future Research Activity |
The machine time of CYRIC at the Tohoku University has been granted and is scheduled in July 2018, with the beam condition of protons at 70 MeV and a 20-nA intensity. The tests that are planned to conduct before and during the CYRIC machine time include tests of the modified timing detector assembly, the gas ionization chamber along with its gas flow and mass control system, as well as the entire measurement system. The measurement of the energy- and mass-dependent PKA production cross sections at a forward direction for C and Si targets is planned to be performed in December 2018 at CYRIC with its 70-MeV proton beam.
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| Causes of Carryover |
1. The purchase of the pressure controller is supposed to close the case in FY2017, but the delivery was delayed to FY2018 and thus the payment was delayed.
2. Part of the budget was planned for purchasing different target materials if the detectors development and tests were performed as we expected. However, the schedule is slightly delayed, so more target materials will be purchased in FY2018.
3. Part of the budget will be spent on the travel expenses for the experiments at CYRIC of the Tohoku University.
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Research Products
(4 results)
