Projectile X-ray Methods And Applications In Accelerator Mass Spectrometry

Some heavy nuclides such as ' Cu> Se< ""Sn 'Tc are important in the study of environment science, bio-medicine, radioactive waste deposit and radioactive nuclides beams. These nuclides could not be detected using AMS method with required sensitivity due to the limitation of ion energy. To expand the AMS research fields at the China Institute of Atomic Energy (C1AE). The projectile X-rays AMS(PX-AMS) method has been established. The PX-AMS method and the related scientific research work are described in this thesis.After eliminating the isotopic backgrounds using the AMS technique, the isobars can be distinguished with their emitted characteristic X-rays when the projectile ions collide with target. The isobars distinguishing method is nearly independent of the ion energies. A wide variety of new research work can be carried out using this method.In order to establish the PX-AMS method, the systematic studies on some physical phenomena in the heavy ion-atom collisions were carried out. The projectile ion and target X-ray production cross sections are related to the charge states of incident ions, target thickness and the incident energy. Especially, the projectile ion X-ray production cross sections are strongly related to the target materials. Due to the high stripping charge-states during heavy ion-atom collisions, the characteristic X-rays will be shifted upward and the X-ray line will be broadened, the fluorescence yields and the intensity ratio of Ka/Kp will be changed, and special X-ray will also produced. Moreover, the projectile X-rays have a Doppler shift and line broadening.The PX-AMS method is discussed in detail in this thesis. The PX-AMS system has been set up based on the CIAE AMS system. 79Se^ 75Se and "4Cu have been measured with the PX-AMS method. For the measurement of 7'Se, the chemical composition of sample and the target, detection direction and X-ray absorber were studied carefully. The detection sensitivity of Sc (79Se/Se) is 2x l(r".There are large differences in the published values of the half-life of wSe. The half-life of 79Se was measured again on the basis of direct detection with the PX-AMS method. So. It is more accurate and reliable than the previous measurements. The radioactivity was determined frommeasuring the |3-rays of 7ySe, and the number of 7ySe atoms was determined with PX-AMS method. Three samples were used for the determination of the half-life of 79Se, and each sample was measured repeatedly. The half-life of 7ySe from present work is (2.80?).40)xl()5y.In order to check the reliability of the result of 79Se half-life, the same method and procedure were used to measure the half-life of 75Se. The half-life of 75Se was obtained with the value of (115?2) days. It is in good agreement with the existing half-life value.The PX-AMS method is also useful for the radioactive nuclide beam (RNB). In the experiment of radioactive nuclide beam, it is needed to determine the intensity and the component of radioactive nuclide beam. The AMS technique can eliminate the interference of isotopes and improve the purity of RNB. Moreover, the intensity and the component of RNB can be determined using the projectile X-ray method. In present work, PX-AMS method has been used to determine the intensity and the component of the RNB of 64Cu.