Speaker
Description
A muon linear accelerator accelerating muons up to 212 MeV is being developed for the J-PARC muon g-2/EDM experiment. The beam intensity is estimated at only a few tens of muons per pulse, and the required transverse emittance is 1.5 π mm·mrad or less. The beam radius is expected to be σ ~ 1 mm, requiring a resolution of about 0.1 mm to resolve it. We are developing beam profile monitors at 40 MeV and 212 MeV satisfying this resolution. Conventional monitors are difficult to apply, since dark current electrons accompanying the beam make accurate measurement challenging. We exploit the difference in Cherenkov angle between muons and electrons to extract the muon signal alone; at 212 MeV, a silica aerogel is used as the Cherenkov medium.
Since the aerogel is irradiated by the beam during operation, its radiation hardness must be evaluated. Radiation-induced changes in refractive index alter the focal length of the optical system, affecting spatial resolution.
We irradiated the aerogel samples with electron beams under different conditions and measured transmittance and refractive index before and after irradiation, and report the results, discussing the feasibility of the monitor.
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| Supervisor's name | Fusashi Miyahara |
| Supervisor's email | fusashi.miyahara@kek.jp |
| Paper submission software | MSWord |