The Production Of ～(64)Cu Radioactive Nuclide Beam And Experimental Study Of Coulomb Excitation

Most knowledge on nuclear physics has been based on the nuclear reactions induced by ion beams of stable isotopes. Since radioactive Nuclear Beams (RNBs) provide a new opportunity for studing nuclear phenomena in a wide degree of freedom of isospin, physics of RNB has rapidly become the frontier field of nuclear physics research. Under this circumstance, the project to construct Beijing RNB facility on the basis of HI-13 tandem accelerator has been proposed by China Institute of Atomic Energy (CIAE). Apart from carrying out some interesting experments in astrophysics using the secondary radioactive beam line in being, the research work about the off-line RNBs on HI-13 tandem accelerator can be also performed by making full use of CIAE's 101 heavy-water reactor (HWR) or Cyclone30 cyclotron.According to the off-line RNB's requirement of the radioactiveisotope, the doubly odd nucleus 64Cu produced by reactor was chosen as the first nuclide to carry out expermental research about the off-line RNB.Since the magic number 28, which is the first that requires the introduction of a strong spin-orbit interaction belongs to the If2p shell in the nuclear shell model. So the nuclei in the If2p shell have been a research hotspot in nuclear physics. The doubly odd nucleus 64Cu which is also in the If2p shell has been the subject of many experimental investigations previously via various type of nuclear reaction such as 64Ni(p,ny) and its excitation leveles have been already studied to about 8 MeV.But up to now, there is no direct experimental measurement result about the reduced transition probability of the first excitation state of 64Cu and only one experiment which had measured the lifetime of low-lying excitation state of 64Cu. The experiment populated the excitation state of 64Cu via 64Ni(p,ny)64Cu* reaction and the lifetime of low-lying excitation state of 64Cu were determined via the delayed coincidence method between pulse proton beam and de-excitation y rays detected by Ge(Li) detector. The lifetime of the first excitation state of 64Cu on the same experiment published was i=22?9ps and t=29.8?.4ps respectively. Multipole mixing ratio(8) of the first excitation state of 64Cu, that P. W. Green had studied through the angular distributions of de-excitation y rays following the 64Ni(p,ny) reaction was determined to be S=0.12?.04. But tracing back to experiments earlier than Green's, it can be found that the 8 value is much less than Green's. The adoped reduced transition probability of the first excitation state of 64Cu given in NTD in 1991 wasWhich were deduced from i=22?9ps and 6=0.l2?.04. So the uncertainty of B(E2) value is very large.The most direct and reliable method to determine the B(E2) value of excitation state of nuclei is to using the method of low-energy Coulomb excitation experiment. Thus the B(E2) value of the first excitation state of 64Cu has been directly measured for the first time with this method using 64Cu RNB in this work.The experiment was performed at the accelerator mass spectrometer (AMS) beam line on HI-13 tandem accelerator of CIAE using the 64Cu Off-line RNB, so the beam can be analysed and identified by static deflection technique of AMS. Limited by the deflection capacity of the electrostatic analyser of AMS, the maximum incident energy of 64Cu beam had to be restricted to 80 MeV in the Coulex experiment of 64Cu Off-line RNB.The natural copper pellet(3.5 mm in diameter, 3.5 mm in thickness, 99.99% purity) was irradiated under the thermal-neutron flux of 3xlO!3n/(cm2.s) in the No. 1 tunnel of CIAE's HWR. After 40 hour irradiation time, about 7 Ci of radioactive isotope 64Cu was produced via 63Cu(n,y)64Cu reaction. After simple disposal, the irradiated copper sample was installed in the high-intesity ion sputter source on the HI-13 tandem accelerator. Then 64Cu ions extracted from the high-intesity ion sputter source and injected into the tandem accelerator, 64Cu ions can be accelerated to an energy of 80 MeV and formed the Off-line RN...