Speaker
Description
The muon's anomalous magnetic moment (g-2) is a sensitive probe for new physics beyond the Standard Model, as it can be both experimentally measured and theoretically predicted with high precision. The consistency between experimental measurements and theoretical predictions is a subject of ongoing discussion, and validation from both sides is desired. The J-PARC muon g-2/EDM experiment aims to provide a new measurement of the muon g-2 based on an independent concept from previous experiments conducted at CERN, BNL, and FNAL. A $300\,\mathrm{MeV}$ low-emittance muon beam, generated using muon cooling and acceleration technology, is stored in a compact storage ring with a highly uniform $3\,\mathrm{T}$ magnetic field. The muon g-2 is measured from the muon's spin precession frequency, which is determined by detecting decay positrons within a specific momentum window. The muon EDM can also be searched for by measuring a tiny tilt of the spin precession axis relative to the storage B-field.
To achieve these goals, a positron tracking detector is being developed. It will be placed inside the muon storage orbit, which has a radius of $33\,\mathrm{cm}$. Forty silicon strip layers are arranged symmetrically around a central pole to measure the trajectories of approximately $200\,\mathrm{MeV}$ positrons. Each layer is composed of four detector sub-modules, known as quarter-vanes, each housing four $10 \times 10\,\mathrm{cm^2}$ silicon strip sensors (HPK S13804). To realize this, we have developed an assembly procedure for the quarter-vanes. Each component is glued using an adhesive dispensing robot and a dedicated jig. Wire bonding has also been performed to transfer silicon signals from sensors to ASICs. Prototypes of the quarter-vanes have been assembled and are currently undergoing operation tests.
Precise relative alignment between sensors is crucial for the muon EDM search to prevent any tilt of the measured spin precession axis caused by detector misalignment. Specifically, the rotation of each vane must be controlled with a precision of $10\,\mathrm{\mu rad}$, corresponding to a $1\,\mathrm{\mu m}$ alignment precision for each sensor. To achieve this, several complementary sensor alignment techniques are under development: precise sensor assembly using a coordinate measuring machine, a laser interferometer-based alignment monitor, and positron track-based alignment.
This paper reports on the developed quarter-vane assembly procedure and sensor alignment techniques.
| Position | Assistant Professor |
|---|---|
| Affiliation | KEK IPNS |
| Country | Japan |
