Yasukazu Yoshizawa

Precision measurements of gamma-ray intensities I. 56Co, 88Y, 110mAg, 134Cs and 207Bi

Abstract To determine relative intensities of gamma rays in the region of 280–2750 keV, Ge(Li) detectors were calibrated with eight kinds of standard sources and four kinds of cascade gamma-ray sources. The disintegration rates of the standard sources were determined by means of the coincidence method. Intensity measurements were performed with two Ge(Li) detector systems. Experimental conditions were improved, especially for source positions and the dead time. The total number of calibration measurements was 437. Gamma-ray spectra were carefully analyzed, and the sum effect was corrected. Relative gamma-ray intensities of 56Co, 88Y, 110mAg, 134Cs and 207Bi were obtained with errors less than 0.5% for strong gamma rays.

Precision measurements of gamma-ray intensities. II. 152Eu, 154Eu and 192Ir

Abstract Relative intensities of gamma rays in the decay of 152 Eu, 154 Eu and 192 Ir were measured precisely with a calibrated Ge(Li) detector. Errors of relative intensities for strong gamma rays are 0.3–0.5%. These multi-gamma-ray sources are useful for the calibration of the Ge(Li) detector. Gamma-ray intensities per decay of 192 Ir were derived from the relative intensities.

Precision measurements of gamma-ray intensities VI. 120Sb, 124Sb and 125Sb

Abstract Relative intensities of gamma rays in the decays of 120 Sb, 124 Sb and 125 Sb were measured precisely with a calibrated Ge(Li) detector. Experimental errors for strong gamma rays are (0.3–1)%. Relative intensities of gamma rays below 450 keV for 125 Eu, 154 Eu and 192 Ir were also measured. Gamma-ray intensities per decay of these nuclides were determined by using the relative intensities and other decay information.

Excitation functions of proton induced nuclear reactions on 85Rb

Abstract Excitation functions for the ( p , xn ) ( x =3−5), ( p , pxn ) ( x =1−4) and ( p , α 3 n ) reactions on 85 Rb with 14–70 MeV protons have been measured by means of the activation method. Enriched 85 RbCl targets were irradiated with energy-analyzed protons from the AVF cyclotron at Osaka University. Disintegration rates of product nuclides were obtained from intensities of selected γ-rays with calibrated Ge(Li) detectors. Thick target yields of 81 Rb for medical use and other radioactive products were calculated from measured excitation functions. The calculated thick target yield of 81 Rb was 31.2 mCi μA −1 h −1 at E p =70 MeV. The thick target yield of 81 Rb chemically separated from 81 Sr, by the reaction 85 Rb( p , 5 n ) 81 Sr( β + , EC) 81 Rb, was obtained to be 2.3 mCi μA −1 h −1 at 96.4 min.

Precision measurements of gamma-ray intensities IV. Low energy region: 75Se and 133Ba

Abstract Relative intensities of gamma rays were measured in Hiroshima and Nagoya in the region of 122–356 keV. Two Ge(Li) detectors were calibrated with four kinds of standard sources and a cascade gamma-ray source. The disintegration rates of the standard sources were determined by means of the coincidence method. Relative intensities of 75 Se and 133 Ba were obtained with estimated errors less than 1% for strong gamma rays. Gamma-ray intensities per decay were also extracted.

Excitation function of Ge(p,xnyp) reactions and production of 68Ge

Abstract Cross sections for the Ge(p,xn) 71–74As, (p,pxn) 68.69Ge, (p,αxn) 66.67Ga and (p,αpxn) 65Zn reactions were measured by the activation method in the proton energy range of 19–64 MeV. The thick target yields of product nuclides were estimated by using the observed excitation functions. The thick target yield of 68Ge at 64 MeV was 48 μCi/μA·h in the optimal irradiation condition (Ep = 64 → 28 MeV, target thickness of 1.8 g/cm2). As a result, the proton reaction on germanium is a useful reaction to produce a large amount of 68Ge for the positron computer tomograph in medical diagnosis.

Precision measurements of gamma-ray intensities V. 160Tb, 168Tm and 182Ta

Abstract Relative intensities of gamma rays in the decays of 160 Tb, 168 Tm and 182 Ta were precisely measured with a calibrated Ge(Li) detector. Experimental errors for strong gamma rays are 0.5–1%. A few new weak gamma rays for 168 Tm and 182 Ta were observed. Gamma-ray intensities per decay of three nuclides were derived from each of the relative intensities. These long-lived nuclides which emit multi-gamma-rays are useful for calibration of the gamma-ray spectrometer.

Precision measurement of gamma-ray energies in the range 450–600 KeV

Abstract Energies of five gamma rays were measured with Ge(Li) spectrometers which were calibrated by using gamma-ray energy standards of 198 Au and 192 Ir. Observed energies are 477.6064(26) KeV for 7 Be, 511.8562(23) KeV for 106 Ru, 514.0076(22) KeV for 85 Sr, 531.0329(24) KeV for 147 Nd and 569.7035(41) KeV for 207 Bi. These gamma rays are useful for energy standards, especially for the energy measurement of position annihilation radiation.

Precision energy measurement of the 106Ru 512 keV gamma ray compared with the position annihilation radiation

Abstract The energy of the 106 Ru 512 keV gamma ray is determined with a high resolution Ge(Li) detector in comparison with the energy of the positron annihilation in aluminum. The value is (511860.5±3.1) eV.

Precision measurements of gamma-ray intensities III: 52Mn, 90Nb and 198Au

Abstract Gamma rays in the decays of 52 Mn, 90 Nb and 198 Au were measured with a calibrated Ge(Li) detector, and weak gamma rays emitted from 46 Sc were searched for. Relative intensities were determined with accuracies of about 0.5% for strong gamma rays. Gamma-ray intensities per decays of 52 Mn, 90 Nb and 198 Au were obtained from the relative intensities, internal conversion coefficients and internal pair-formation coefficients. These nuclides are useful for calibration of gamma-ray spectrometers. No weak gamma rays were observed in the decay of 46 Sc.