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아래와 같이 세미나를 개최하오니 많이 참석해 주시기 바랍니다.

 

아 래

 

제목: The rapid neutron capture nucleosynthesis: A hot topic in the Nuclear Astrophysics study

연사: 안 성 훈 박사 (JINA/NSCL)

일시: 2014 7 21() 16:00

장소: 삼성학술정보관 2층 프리젠테이션룸

초록:

As we understand properties of nuclei, we can explain many phenomena with the information in astrophysics.

For example, mass, excitation energies, spin and parities, cross sections and decay life times for any interesting nucleus can be applied to the astrophysics models such as nucleosynthesis calculation to explain the observed abundance pattern of elements in astrophysics. Among many nucleosynthesis processes, the rapid neutron capture process,

called r-process, is believed to be responsible for half of elements heavier than iron but still under the questions due to the absence of the observational sample as well as the involved nuclei are very neutron-rich and far from the stability which

have not studied much so far

In this talk, I will present two interesting cross sections measurements related to the r-process. One will be 80Ge(d,p)

neutron transfer reaction in inverse kinematics performed at Holifield Radioactive Ion Facility,

Oak Ridge National Laboratory. Recent sensitivity studies about the main r-process found that changes of reaction rates on only certain candidates of nuclei (all around neutron closed shells, e.g. 80Ge) produce a global effect on the abundance

pattern. This experimental result reduced the uncertainty of the reaction rates of 80Ge(n,g)81Ge reaction to help accurate

r-process calculations.

 

Another will be 75Ga(a,n)78As reaction in inverse kinematics. This will be performed at National Superconducting Cyclotron Laboratory, Michigan State University next year. Since the main r-process model could not reproduce a region of Z = 38 - 47 on the observed abundance pattern, a new possible model, called the weak r-process, was suggested as the charged

particle reactions such as (a,n) occurred in early stages of core collapse supernovae. However, due to experimental lack

of reaction rates on the involved nuclei the uncertainty of the model is still too big. This experiment was proposed to help

reducing its uncertainty. In this experiment, the new gas cell target, the new neutron long-counter and the position

sensitive ionization counter will be introduced as well as the NSCL Digital Data Acquisition System (DDAS).

 

Finally, many countries including the United States have invested in either upgrades to existing facilities or new facilities to make studies of neutron-rich nuclei possible and produce exciting results about the r-process. The Facility for Rare Isotope Beams (FRIB) in 2020, for example, will provide more than 1000 new isotopes at useful rates and 4500 isotopes available to study. Due to the advances in the beam production technique, more studies of the r-process will be performed resulting in better knowledge of the process.

 

 
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