| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Research Abstract |
In FY2001, we developed an internal-conversion electron detector with nety silicon avalanche photodiodes (Si-APDs). The detector had two monolithic Si-APD arrays ofthitee pixels (3 mm in diameter), installed in a vacuum chamber. We tested the detector at beamline BL-14A of the Photon Factory using 8.4-keV x-rays. The results had a problem that the energy resolution ofthe Si-APD array was worse than that of a normal device due to a large difference of gains cn position in the detection area. Though we could not use the new Si-APDs, we tried to observe; the nuclear excitation by electrontransition (NEET) on ^<193>Ir, as we scheduled in our plan, with the detector that had one Si-APD in the vacuum chamber. The experiment was done at BL09XU of the SPring-8. We successfully observed NEET, of which probability was less than one tenth otfthat on ^<197>Au. Ourresult of the NEET probability was (2.8±0.2)×10^<-9>, while a recent calculation presented a value of 2.0×10^<-9>. The difference between the results will be discussed.
In FY2002, the Si-APD array was improved and tested again at BL-14A. The energy resolution became better and the arrays were installed in the detector. However, we did not have a chance for executing an experiment for NEET on ^<189>Os due to a delay of improving the Si-APD and due to atrouble in the accelerator within a period of our experiment at the SPring-8. After FY2002, in April 2003, we have tried to observe NEET on ^<I89>Os at BL09XU of the SPring-8. In the experiment, we used another Si-APDs because a signal-to-noise ratio of the Si-APD array was smaller than that we expected. With the detector, NEET on ^<189>Os was still not observed in the K-shell ionization. The improvement in the detector for a better signal-to-noise ratio will be continued.
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