J-PARC (Japan Proton Accelerator Research Complex) is a facility finishing construction as a joint venture of KEK and JAEA (Japan Atomic Energy Agency) in Tokai-mura, Ibaraki, Japan (see Fig. 12). Using a 50 GeV high-intensity proton synchrotron, secondary kaon beams of the highest intensity ever reached will become available from spring 2009. Fig. 13 shows the status of the hadron hall in spring 2008. Now everything is finished and first slow extracted beams have reached the experimental area in January 2009.

SMI joined two proposals, which were both approved as day-1 experiments:

E15: A search for deeply-bound kaonic nuclear states by in-flight ³He(K⁻, n) reaction.

E17: Precision spectroscopy of kaonic ³He 3d ® 2p X-rays.

 

Both experiments can be regarded as successors of the KEK experiments E471/549 and E570 in which we have already been involved. E15 will search for the simplest K-cluster K^–pp by in-flight (K^–,n) reactions. In-flight reactions have the advantage that the two-nucleon absorption of kaons, which is the largest background in experiments with stopped kaons, is strongly reduced. In addition to a missing-mass measurement as done so far, E15 will also allow invariant mass spectroscopy by detecting all charged particles originating from the decay of the K-cluster by using a cylindrical drift chamber in a solenoid magnet (see Fig. 14). This feature will be required from all next-generation experiments searching for deeply bound kaonic states. The experiment is already completely funded in Japan and construction is under way with the goal to be ready for the first beam from J-PARC in late 2009

 

Outlook

Both experiments are in preparation and expected to start data taking in 2009 and 2010. E17 can finish with 1-4 weeks of data taking depending on the initial performance of the accelerator, while E15 will require about 8 weeks of full phase-1 beam intensity