Radioactive Nuclear Beams Research Articles

6Li breakup from 208Pb target at Coulomb barrier energies: doorway to reaction mechanism induced by loosely bound/halo nuclei

systemhave beendeduced. Comparisonoftheexperimentaldatawithtwodifferenttheoretical approaches strongly supports the direct breakup process description.1. INTRODUCTIONThe growing interest and effort of the nuclear physicists community for experimentsperformed with Radioactive Nuclear Beams (RIBs), has triggered several experimentsthat can be performed using stable beams and could give a first taste of what kind ofdifficulties and results we will face once RIBs will be available. In this perspective, it’snatural to choose stable beams that have characteristics very close to those of the RIBs.For example, if one considers the binding energy of the nuclei, it’s immediately clear thatsome stable light nuclei are weakly bound, like many light RIBs:

Multistrip silicon detectors for studies with low energy RNBs

Over the last decade, multistrip silicon detectors have had a major impact on experimental programmes using low-energy radioactive nuclear beams (RNBs). The development of silicon detectors and instrumentation for use at first and second generation RNB facilities will be discussed. The experimental requirements of prospective third generation RNB facilities will be discussed with particular emphasis on the development of custom integrated circuits and compatible multistrip silicon detectors.

Nuclear structure input for supernova modeling

Radioactive nuclear beams offer the possibility of studying the detailed properties of nuclei far away from stability. This manuscript gives a review of the main weak-interaction processes involving nuclei relevant for core collapse supernovae. Special emphasis is given to the necessity of constraining the theoretical models by experimental information. Examples of key experimental inputs are given.

Facilities and Methods: KEK-Jaeri Joint RNB Facility, TRIAC

Research and development on an isotope separator on-line (ISOL)-based radioactive nuclear beam (RNB) facility in Japan had mainly been carried out at the Institute for Nuclear Study (INS), University of Tokyo [1]. The first RNB acceleration was realized with the split-coaxial RFQ (SCRFQ) and interdigital-H (IH) type linacs in March 1997. A joint RNB facility, TRIAC (Tokai Radioactive Ion Accelerator Complex) facility, is partly based on the re-installation of the above INS-facility in Tokai site of the Japan Atomic Energy Research Institute (JAERI). It will open up the RNB science with 1.1 MeV/u RNBs from FY2005. The higher energetic (5-8 MeV/u) RNBs will be available in the near future.

RNB Facilities in Europe - Present and Future

A brief overview is given of present and future radioactive nuclear beam (RNB) facilities in Europe. Recent developments and extensions of RNB schemes and their uses are mentioned. The two major facilities planned for Europe employing, respectively, the in-flight and ISOL schemes are briefly presented.

The PX-AMS system and its applications at CIAE

The projectile X-ray detection method (PXD) has been set up in the China Institute of Atomic Energy AMS system. Using this method, the half-life of 79Se and 75Se have been measured, the intensity of 64Cu radioactive nuclear beams have been identified, and the upper limit of transition probability of the first excited state of 64Cu was obtained.

The PX-AMS system and its applications at CIAE

The projectile X-ray detection method (PXD) has been set up in the China Institute of Atomic Energy AMS system. Using this method, the half-life of 79 Se and 75 Se have been measured, the intensity of 64 Cu radioactive nuclear beams have been identified, and the upper limit of transition probability of the first excited state of 64 Cu was obtained.

Recent result from the nuclear moment measurements using a spin polarized radioactive beam

The first measurement of a magnetic moment of19N was performed by combining a β-NMR method with a spin-polarized radioactive nuclear beam from the fragmentation reaction. As a result, theg value for the19N ground state,g = 0.61 ± 0.03 (preliminary), was obtained. The value was compared with those of15N and17N. Contrary to shell-mode predictions that theg value should increase with increasing number of neutrons in thesd shell, the obtainedg for19Ng.s. is significantly smaller thang(17Ng.s.) previously obtained.

Recent result from the nuclear moment measurements using a spin polarized radioactive beam

The first measurement of a magnetic moment of 19N was performed by combining a β-NMR method with a spin-polarized radioactive nuclear beam from the fragmentation reaction. As a result, the g value for the 19N ground state, g = 0.61 ± 0.03 (preliminary), was obtained. The value was compared with those of 15N and 17N. Contrary to shell-mode predictions that the g value should increase with increasing number of neutrons in the sd shell, the obtained g for 19N g.s. is significantly smaller than g( 17N g.s.) previously obtained.

Giant resonance research: present interests and future perspectives

In the last decade extensive work has been done to explore and understand various giant resonance phenomena. The research involved the study of the giant dipole resonance as a function of temperature and angular momentum, the study of compressional modes - the isoscalar giant monopole and dipole resonances - and the investigation of their microscopic structures, the study of the charge-exchange modes both in the β + and β − directions, the establishment of the existence of double-phonon giant resonances, in particular those of the isovector GDR and the isoscalar GQR, etc.. A review of some of these advances is discussed and possible future directions in view of the operating and/or planned radioactive nuclear beam facilities will be delineated.

Giant resonance research: present interests and future perspectives

In the last decade extensive work has been done to explore and understand various giant resonance phenomena. The research involved the study of the giant dipole resonance as a function of temperature and angular momentum, the study of compressional modes - the isoscalar giant monopole and dipole resonances - and the investigation of their microscopic structures, the study of the charge-exchange modes both in the β + and β − directions, the establishment of the existence of double-phonon giant resonances, in particular those of the isovector GDR and the isoscalar GQR, etc.. A review of some of these advances is discussed and possible future directions in view of the operating and/or planned radioactive nuclear beam facilities will be delineated.

Giant resonance research: present interests and future perspectives

In the last decade extensive work has been done to explore and understand various giant resonance phenomena. The research involved the study of the giant dipole resonance as a function of temperature and angular momentum, the study of compressional modes - the isoscalar giant monopole and dipole resonances - and the investigation of their microscopic structures, the study of the charge-exchange modes both in the β + and β − directions, the establishment of the existence of double-phonon giant resonances, in particular those of the isovector GDR and the isoscalar GQR, etc.. A review of some of these advances is discussed and possible future directions in view of the operating and/or planned radioactive nuclear beam facilities will be delineated.

Fragmentation of 95 MeV/u 12C and 75 MeV/u 13C. Application to secondary-beam production

The fragmentation of 95 MeV/u 12C and 75 MeV/u 13C projectiles, interacting with natural targets of different elements (9Be, $^{\rm nat}$ Cu and 197Au for 12C, and 9Be, $^{\rm nat}$ Ni, and 181Ta for 13C) and of various thicknesses has been investigated at GANIL, using the doubly achromatic magnetic spectrometer LISE. The projectile-like fragments transmitted at 0 $^\circ$ have been analysed using a silicon $\Delta E$ -E telescope and the $\Delta E$ -time-of-flight method. The results obtained with the thinnest targets are discussed in the scope of radioactive nuclear beam production. The fragment momentum distributions can be fitted by Gaussian peaks associated with exponential tails towards low momentum values. The experimental production yields are compared with the results of the simulation code LISE. It appears that this code reproduces satisfactorily the yields of nuclei close to the stability line, but strongly overestimates the production of very neutron-deficient nuclei.

Energy-loss spectrometer for precise RIB experiments in the vicinity of the Coulumb barrier

Magnetic spectrometers of charged nuclear reaction products, properly matched with an accelerator beam line, have become a very effective setup for the performance of precise nuclear experiments involving ultrasensitive accelerator-based mass spectrometry and investigation of rare events, as well as experiments with radioactive nuclear beams. The procedure for increasing the efficiency and resolution of the available magnetic spectrometer at the Flerov Laboratory of Nuclear Reactions by a few orders of magnitude by means of its matching with the beam line is described.

Coulomb excitation with radioactive nuclear beam of 64Cu

The radioactive nuclear beam of 64Cu was obtained utilizing a two-stage method at the HI-13 tandem accelerator of China Institute of Atomic Energy. The B(E2) value of the first excitation state of 64Cu has been directly measured for the first time by Coulomb excitation method, using the radioactive nuclear beam of 64Cu. An upper limit of the B(E2;2 1 +→1 gs +) value from the first excitation state to the ground state of 64Cu is determined to be 49 W.u., which is significantly smaller than 250±170 W.u., the value adopted by Nuclear Data Sheets. The reliability of the experimental method was verified by simultaneously performing the Coulomb excitation experiment of 181Ta.

Simulation of radiotracer method for diffusion studies using short-lived radioactive nuclear beams

We have studied, by a computer simulation, the feasibility of the radiotracer method for diffusion studies using short-lived radioactive nuclear beams as tracers. We have considered two typical examples of radiotracers that will be available in KEK-JAERI RNB facility, 18F (half-life: 1.8 h, β +-emitter) and 8Li (half-life: 0.83 s, α-emitter). The sample is set on a given temperature and irradiated by the tracer beams for a time-duration. In the case of 18F, the serial sectioning technique by the ion-beam-sputtering device is assumed to obtain the concentration-depth profile of the tracer diffused during the irradiation time. In the case of 8Li, the simulation reveals that the time-dependent yields of α particles can be used as a measure of the diffusivity of the tracer in a non-destructive way. The present method could be applied to measure rather large diffusion coefficients of various radiotracers with a short measuring time.

Muon spectroscopy with unstable nuclei

The status of a new method to extend muonic atom spectroscopy to the use of radioactive isotope beams is being reported, including the progress of a feasibility study at RIKEN-RAL muon facility. This method would allow studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic x-ray method at facilities where both intense negative muon and radioactive nuclear beams would be available.

Generation and investigation of radioactive muonic atoms in solid hydrogen films

At RIKEN-RAL muon facility, a concept project is under way to extend the standard technique of muonic atom spectroscopy to the use of radioactive isotope beams. This new method would allow studies of the nuclear properties and nuclear sizes of very exotic nuclei at facilities where both intense negative muon and radioactive nuclear beams would be available. The present status of a feasibility study is being reported.

Spectroscopy of drip-line nuclei with fast and slow radioactive nuclear beams at the GANIL/SPIRAL facility

Several examples of recent results of experiments performed with the SPIRAL ISOL-type and GANIL high energy radioactive beams on the properties of nuclei in the vicinity of drip-lines and/or magic numbers are presented. Future plans of the GANIL/SPIRAL facility and in particular the SPIRAL II project are shortly discussed.

Direct measurements of (α, n) and (p, n) reaction cross sections using light neutron-rich radioactive nuclear beams

A project to acquire directly nuclear cross sections of (α, n) and (p, n) reactions using low energy light neutron-rich radioactive nuclear beams (RNB) is in progress at JAERI-Tandem facility. The method of the production of neutron-rich RNB, an improvement of a gas counter (MSTPC) in order to work effectively under the high RNB-injection rate, and the feasibility of our experiments are discussed.