Change of nuclear decay constant under ultra high-pressure

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The experiments on a change of decay constant were made in the past 3 years as follows ; Site of the experiments : The RI research center of Kyoto University annex. Members : Y.Gono, Y.Isozumi, R.Katano, T.Kikegawa, A.Odahara, T.Kajino (With great helps by Mr. K.Saito and T.Tsutsumi : graduate students of Kyushu University)1st year (1998) ; Meeting to discuss when and how proceed this project. Then we started to buy necessary equipments using the grant given by JSPS.2nd year (1991) ; Blank test was made, i.g.a test of RI-source preparation and a measurement of a gamma-ray spectrum.3rd year (2000) ; Aull experiments was were made once with an ultra high-pressure (21 GPa).Results were analysed by using a differential method. However the result was Δλ/λ = (2.1 ±2.1) x 10^<-4> which was not consistent with previously reported ones. Then a run was made by using 2 sources both under normal pressures. The result was an enough accuracy to compare the results with those of the past. In the 1st … More run there were problems of back-grounds. Since we made experiments using two sources and one detector, we measured γ-ray spectra by moving lead shields located between sources and the detector. Then the background changed depending on the lead positions. Also a background changed depending on time in the first run though these problems were solved in the second run.We conclude that the experimental accuracy is enough to observe the previously reported Δλ/λ if all the conditions are reproduced when an ultra high-pressure is applied to one source. So we decided to continue this project even without a further financial support.The experiments on a change of decay constant were made in the past 3 years as follows ; Site of the experiments : The RI research center of Kyoto University annex.Members : Y.Gono, Y.Isozumi, R.Katano, T.Kikegawa, A.Odahara, T.Kajino (With great helps by Mr. K.Saito and T.Tsutsumi : graduate students of Kyushu University) 1st year (1998) ; Meeting to discuss when and how proceed this project. Then we started to buy necessary equipments using the grant given by JSPS.2nd year (1991) ; Blank test was made, i.g.a test of RI-source preparation and a measurement of a gamma-ray spectrum.3rd year (2000) ; Aull experiments was were made once with an ultra high-pressure (21 GPa).Results were analysed by using a differential method. However the result was Δλ/λ = (2.1 ±2.1) x 10^<-4> which was not consistent with previously reported ones. Then a run was made by using 2 sources both under normal pressures. The result was an enough accuracy to compare the results with those of the past. In the 1st run there were problems of back-grounds. Since we made experiments using two sources and one detector, we measured λ-ray spectra by moving lead shields located between sources and the detector. Then the background changed depending on the lead positions. Also a background changed depending on time in the first run though these problems were solved in the second run.We conclude that the experimental accuracy is enough to observe the previously reported Δλ/λ if all the conditions are reproduced when an ultra high-pressure is applied to one source. So we decided to continue this project even without a further financial support. Less