Speaker
Description
We are developing a Low-Pressure Vertical Drift Chamber (LP-VDC) designed for high-rate particle measurements at around 10-MeV/u kinetic energy at RCNP. Although primarily optimized for the Large Acceptance Spectrometer (LAS) at RCNP, the design concepts, specifically prioritizing high-rate capability and cost-efficiency, are highly applicable to RIBF facilities such as the SHARAQ spectrometer and other large-acceptance systems like SAMURAI and ZD spectrometer.
Our physics goal is to experimentally quantify isoscalar proton-neutron pair correlations via systematic measurements of nucleon-pair transfer reactions. To separate isoscalar ($T=0$) and isovector ($T=1$) strengths, both ($d, \alpha$) and ($\alpha, {}^{6}\mathrm{Li}$) reactions are utilized. Typical product energies are below 15 MeV/u, with counting rates at the focal plane expected to reach 6 Mcps in a $2000 \times 500 \mathrm{mm}^2$ active area. In such high-rate environments, pileup is a critical limiting factor; therefore, a compact detector design along the drift direction to suppress event overlap is essential. Furthermore, for sustainable long-term operation, a cathode-wire configuration is considered instead of conventional foils to enhance maintainability and reduce costs.
Currently, the LP-VDC is designed for a focal plane tilted at 57 degrees. Using the Garfield++ simulation toolkit, detection efficiency and position resolution were estimated for various geometries (wire arrangement and plane spacing) assuming operation with 10-kPa isobutane gas. This poster discusses the details of these simulations.