| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
In early 90s, using the deuteron and alpha beams accelerated at the KEK-PS for the first time, we have carried out measurements of subthreshold antiproton productions in pA, dA and αA reactions, and found an enormous enhancement of the antiproton productions in the deuteron induced reactions. The production cross sections in dA reactions were three orders of magnitude larger than those in pA reactions at the incident energy of 3 GeV. A calculation base on a NN-collision model, in which the internal motion of nucleons in nuclei (Fermi motion) is taken into account, can well reproduce the antiproton production in pA reactions, but not reproduce those in dA reactions at lower incident energies. The calculation showed two orders of magnitude smaller cross sections than those in experiments.
In order to give an answer to the question why so many antiprotons are produced in dA reactions, we think the following measurements are importants from an experimental point of view ; (1) measure for si
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mple reaction systems such as p-d and d-d, (2) measure in wider angular and momentum ranges, (3) measure particles produced associated with an antiproton (coincidence measurements) (4) measure productions of particles other than antiprotons near and below its threshold energy.
We have studied the feasibility of an experiment of antiproton and K-meson production in p-d and d-d reactions at KEK-PS. The conventional liquid target technique can not be used in this case, because the small cross section requires very high beam intensity and consequently requires heavy radiation shields, which conflicts with the use of liquid hydrogen. Therefore we have to consider a new technique. We have heavily studied possibility to install a gas-jet or a liquid pellet target in the accelerator ring. The conclusion was that it is technically possible, but a bit expensive. Also the tight schedule of the KEK-PS operation makes it hard to install such a new device in a short period.
To continue this interesting physics topics, we decided to carry out experiments to measure subthreshold kaon productions at the heavy-ion accelerator at HOUIKEN. The first experiment showed that our detector has the capability of kaon identification in a high rate of background particles. Less
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