Origin of matter in the universe is one of the fundamental questions concerning the nature. "Elements" are useful not only as the ingredients to produce various materials used in our daily life but also as the probe for the astrophysical conditions where they wer synthesized.

We are studying the processes of the Big-bang nucleosynthesis and stellar nucleosynthesis by experimentally measureing the nuclear parameters which are needed to make theoretical predictions for the nucleosynthesis. One example of such parameters is the reaction rate of the 40Ca(a,g)44Ti reaction, which is considered as the main reaction to produce 44Ti, a radioactive isotope of titanium, which is known to make beta-decay with a half-life of 60 years, and the gamma-rays from the decay of 44Ti contained in the supernova remnants such as Cassiopeia A have been observed by the gamma-ray observatories in orbit.