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Ring Cyclotron Facility

At the cyclotron facility of RCNP, nuclear physics experiments are performed by using beams from two particle accelerators named AVF cyclotron and RING cyclotron.
These cyclotrons are used in a cascade mode to accelerate beams of protons and other particles up to 40-70% of the light velocity.
The keywords are high-resolution, spin, and isospin.
Various beams and experimental equipments are used. Here we only spot on some recent topics.

(1) Pi meson condensation, alpha condensation

How many particles can be put into a box of a fixed size? In the case of particles which mediate interactions (called Boson) such as light (photon), any number of particles can be placed in a box. This is called Bose-Einstein condensation. On the other hand, in the case of particles which construct the universe such as human body (called Fermion), the number is limited by a rule named Pauli exclusion principle. However, when two or four Fermions are tightly coupled, they start to behave as Bosons, and consequently the limitation on the number is removed. For example, an alpha particle which consists of two protons and two neutrons can be in a condensed state. Actually, we found candidates of such alpha-condensed states from experiments using an alpha beam at the RCNP. From another experiment using a proton beam, we obtained data which show that pi meson condensation might take place in a neutron star.

(2) Resonances in nuclei

Nuclei have a size of less than a millionth part of one nano-meter. How can we study properties of such tiny objects? The size is far-and-far smaller than the size which can be seen by the most powerful microscopes. When you hammer an object like xylophone you hear a sound from it. From the sound you can somehow estimate the size or material of the object. The method can be applied in the nuclear physics. We "hammer" nuclei by energetic particles and "hear" the sound from them. A nucleus is interesting material which is like gas, and simultaneously like liquid. If we appropriately hit a nucleus, we can make waves on its surface, crush the shape, or rotate it. Since much variety of states exists, you need to choose a proper hammer for your study. At RCNP we use various kinds of hammers, called spin and isospin, for studying resonances in nuclei.

(3) Astrophysics and nuclei

The sun shines by nuclear reactions. Various kinds of elements on the earth have been created in the early universe and in star explosions. We study their mechanism by reproducing the reactions in our laboratory. We hope to be able solve problems such that supernovae and explosions of star which are not yet explained by current theories.

(4) Applications

From recent developments and advancing density of integrated circuits, environmental radiation effects by neutrons are causing serious problems. RCNP has been supporting tests of integrated circuits by irradiating them with neutrons which are produced by a proton beam. We are also supporting chemical, biological, and medical researches requiring elements or isotopes which do not naturally exist.

The ''eyes'' for looking at nuclei,
high resolution spectrometer
''Grand Raiden'' (Left)
and large acceptance spectrometer
''LAS'' (Right)

A high-resolution spectrum of a silicon nucleus,
The horizontal axis corresponds to color of light or scale of sound. The vertical axis shows the strength.


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