Speaker
Description
The COMET experiment at J-PARC aims to search for a lepton-flavour violating process of muon to electron conversion, with a branching-ratio sensitivity of 10$^{−17}$, to explore the region predicted by most of theoretical models beyond the Standard Model. The expected signal of this process is mono-energetic 105 MeV single electron. To distinguish such a low energy signal, a material budget of detector is essential since the detection accuracy is primarily limited by multiple scattering.
To realize the required low material detector, a vacuum-compatible ultra-thin-wall straw tracker has been designed, then 20$\mu$-thick Mylar straw with 70nm Al cathode has been developed employing ultrasonic-welding technique. This was reported in VCI2016, and the detector performances such as detection efficiency and intrinsic spacial resolutions were reported in VCI2019. After the previous VCI, a detector construction using this straw was performed. In parallel to this, thinner straw, i.e. 12$\mu$m-thick straw, has been developed with joint collaboration among KEK, JINR and CERN. During this R&D, it was noticed that the current technology cannot achieve much thinner/smaller tubes than the present one. Then, we launched a brand-new project to realize the graphite-textile straw which realizes an extremely low material tracker.
In VCI2022, a brief report on detector construction with 20$\mu$m-thick straw, R&D on 12$\mu$m-thick straw and a brand-new graphite straw will be provided.
| Primary experiment | COMET |
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