Seminar on Radio Active Ion Beam Nuruzzaman Under the guidance of Prof. A.K.Jain Department of Physics IIT Roorkee

Overview What is Radio Active Ion Beam ? Why It is Needed ? Experimental Methods and Its difficulties The Works Going on around the world Application of Radio Active Ion Beam Conclusion

What is Radio Active Ion Beam ? A collimated stream of accelerated radioactive nuclei, of sufficient intensity to be utilized for a variety of scientific enterprises such as studies of nuclear structure, nuclear astrophysics, and materials science

History The concept of radioactive ion beams was first mentioned by J. P. Bondorf in 1966. He pointed out “the rich field of information that would be opened by a future use of unstable targets and projectiles in nuclear reaction study” of nuclides far from the stability line

Why It is Needed ? In the mid-80s, experimental studies with radioactive ion beams have been widely expanded. The number of nuclei in the nuclear chart able to be accessed with these beams has been increased. Numerous experimental studies of far from stability nuclei with both stable and radioactive ion beams show many important differences in their structure from that of stable Nuclei. There are changes in the nuclear shell structure, for example the disappearance of the magic numbers known for stable nuclei and the appearance of new magic numbers in unstable nuclei. The importance of radioactive ion beams has been being well recognized in nuclear science, astrophysics, and other fundamental and applied fields

How RIB are Produced Two basic approaches in production of RIB ISOL( Isotope Separator On Line) Projectile Fragmentation

Experimental Methods ISOL: One approach to radioactive beam production is the isotope separator on-line (ISOL) technique. One accelerator bombards a target with a beam of stable nuclei, and a small number of the radioactive atoms of interest are produced through nuclear reactions. These atoms are transported, by various techniques, including thermal diffusion, to an ion source where they are ionized (removing or adding electrons to give atoms an electrical charge) and extracted. The radioactive ions are then mass-separated from other ions and accelerated to energies needed for nuclear physics experiments by a second accelerator. The ISOL technique can produce very high beam qualities, purities, and intensities; the disadvantages are that only a few radioactive beam species can be generated from each combination of production target and primary beam, and that beams with short lifetimes (less than 1 s) are difficult to produce

ISOL

Experimental Methods Projectile Fragmentation: A complementary radioactive beam production technique is projectile fragmentation. When a high-energy beam of stable heavy ions passes through a thin target, the beam particles (projectiles) can break up into fragments—some of which are the radioactive isotope of interest. The desired fragments are then mass-separated from other ions and steered toward a target to undergo the reaction of interest. The projectile fragmentation technique can produce beams of very short lifetimes (10^−6 s or less), and the same setup can be used to produce many different beam species; the disadvantages are that high beam quality, purity, and intensity are difficult to obtain

Projectile Fragmentation

RIB facilities using the ISOL method and a post-accelerator, either existing or under construction

RIB facilities using the PF method, existing or under construction

The Challenges of RIB Development In ISOL technique product produced for very short time and during this time it is to be ionized and accelerated to the target area and during diffusion RIB losses rapidly due to the propagation through the target. Efficiency is ~ 10^-2 to 10^-4. Sometimes acceleration is not desirable that due to short life time the whole process may be spoiled. RIBs at first positively ionized by plasma ion source and then charge exchanged in low density vapors to form negative ions for injection into the tandem accelerator. This process tends to have efficiencies ~10^-1 when suitable vapors are selected.

Our Focus Given the considerable radioactive atom losses and low initial production rates each target/ion source must therefore be designed to operate with the highest possible efficiency in order to provide enough RIB intensity for physics experiments: at least 10^5 ions per second is usually desired. The development and implementation of high efficiency target/ion source systems best suited to the specific chemical nature of each desired radioactive atom has therefore been a principle focus of our beam development efforts

Application of RAIB The properties of nuclei will be explored to answer key scientific questions about the origin of the elements To understand Cosmological Phenomenon The properties of nuclei with extreme ratios of neutrons to protons The equation of state of neutron-rich nuclear matter Physics beyond the standard model of particle physics

Understand Cosmological Phenomenon Phenomena in the cosmos such as novae, supernovae, X-ray bursts, and other stellar explosions. In the extremely high temperatures (greater than 108 K) of these astrophysical environments, the interaction times between nuclei can be so short (~ seconds) that unstable nuclei formed in a nuclear reaction can undergo subsequent reactions before they decay. Measurements of the structure and reactions of unstable nuclei are therefore required to improve our understanding of the astrophysical origin of atomic nuclei and the evolution of stars and their (sometimes explosive) deaths. We are utilizing a combination of experimental measurements, data evaluations, and astrophysical simulations to improve our understanding of these cosmic phenomena. At the Holifield Radioactive Ion Beam Facility (HRIBF), we are making some of the first precision measurements of reactions needed to probe the details of exploding stars [2-9]. We have used radioactive beams of 17F and 18F to study the 14O(alpha,p)17F, 17F(p,gamma)18Ne, 18F(p,alpha)15O, and 18F(p,gamma)19Ne reactions, and a stable beam to study the 25Al(p,gamma)26Si reaction [9]. We have successfully demonstrated that precision nuclear spectroscopy measurements can be made with impure radioactive ion beams of intensities as low as 103 pps. When possible, we have detected all reaction products in coincidence, removing any ambiguities from reactions off stable ion isobaric contaminants in the radioactive ion beam

Recent Measurements We have measured the following reactions at HRIBF to better understand stellar explosions such as novae, X-ray bursts, and supernovae: 17F(p,p)17F to determine the 17F(p,gamma)18Ne reaction rate D.W. Bardayan et al., Phys. Rev. C62 (2000) 055804 Abstract Article D.W. Bardayan et al., Phys. Rev. Lett. 83 (1999) 45 Abstract Article Physical Review Focus Article, July 1999 Article 17F(p,alpha)14O, 17F(p,p)17F, and 17F(p,p')17F to determine the 14O(alpha,p)17F reaction rate J.C. Blackmon et al., in preparation (2003) J.C. Blackmon et al., Nucl. Phys. A718 (2003) 127 Abstract Article J.C. Blackmon et al., Nucl. Phys. A688 (2001) 142 Abstract Article R. Brummitt et al., Bull. American Phys. Soc. (2001) Abstract 18F(p,p)18F to determine the 18F(p,gamma)19Ne and 18F(p,alpha)15O reaction rates D.W. Bardayan et al., in preparation (2003) D.W. Bardayan et al., Phys. Rev. C62 (2000) 042802(R) Abstract Article 18F(p,alpha)15O to determine this reaction rate directly D.W. Bardayan et al., Phys. Rev. Lett. 89 (2002) 262501 Abstract Article D.W. Bardayan et al., Nucl. Phys. A718 (2003) 590 Abstract Article D.W. Bardayan et al., Phys. Rev. C63 (2001) 065802 Abstract Article D.W. Bardayan et al., Nucl. Phys. A688 (2001) 475 Abstract Article

Recent Measurements 28Si(p,t)26Si to determine the 25Al(p,gamma)26Si reaction rate D.W. Bardayan et al., Nuc. Phys. A718 (2003) 505 Abstract Article D.W. Bardayan et al., Phys. Rev. C65 (2002) 032801 Abstract Article 18F(d,p)19F to determine the 18F(p,gamma)19Ne and 18F(p,alpha)15O reaction rates R.L. Kozub et al., in preparation (2003) R.L Kozub et al., Bull. American Phys. Soc. (2003) Abstract 124Sn(d,p)125Sn to determine the 124Sn(n,gamma)125Sn reaction rate R.L. Kozub et al., in preparation (2003) 17F(14N,13C)18Ne* to determine the direct capture 17F(p,gamma)18Ne reaction rate J.C. Blackmon et al., in preparation (2003) J.C. Blackmon et al., Nucl. Phys. A718 (2003) 587 Abstract Article 82Ge(d,p)83Ge to determine the level structure of 83Ge and the 82Ge(n,gamma)83Ge reaction rate J.L. Thomas et al., in preparation (2003) J.L. Thomas et al.,Bull. American Phys. Soc. (2003) Abstract

Planned Experiments A number of nuclear astrophysics experiments with radioactive ion beams have been approved or are planned for the near future: 17F(p,gamma)18Ne 7Be(p,gamma)8B 7Be(p,p)7Be 18F(p,alpha)15O 132Sn(d,p)133Sn

Conclusion Radioactive ion beams as a new technology bring unprecedented opportunities to nuclear physics, astrophysics, and other fields. The RIB facilities, either with the projectile fragmentation method or the Isotope Separation- On-Line method, or a hybridization of both, are providing, or are going to provide, exciting results for our improved understanding of nuclear matter

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