Performance test of the MAIKo active target

TL;DR

The paper introduces MAIKo, a new active target system based on a TPC with a micro-pixel chamber, designed for inverse kinematics spectroscopy of unstable nuclei, demonstrating high resolution and stable operation at high beam intensities.

Contribution

Development and testing of MAIKo, a novel active target with high angular resolution and stability for nuclear physics experiments involving unstable nuclei.

Findings

Achieved 1.3° angular resolution for scattered helium particles.

Operated stably at beam intensities up to 1000 kcps.

Evaluated gas gain and resolution with alpha source and helium beam.

Abstract

A new active target named MAIKo (Mu-PIC based Active target for Inverse Kinematics$_{\circ}$) has been developed at Kyoto University and Research Center for Nuclear Physics (RCNP), Osaka University. MAIKo is suited for missing-mass spectroscopy of unstable nuclei at forward scattering angles in inverse kinematics. MAIKo consists of a time projection chamber (TPC), which incorporates a micro-pixel chamber ($\mu$-PIC) as the electron multiplication and collection system. In MAIKo, the medium gas also plays the role of a reaction target, thus allowing detection of low-energy recoil particles with high position resolution. The MAIKo TPC was commissioned with He(93%)+iso-C$_{4}$H$_{10}$(7%) and He(93%)+CO$_{2}$(7%) mixture gasses at 430 hPa. The gas gain and the angular resolution of MAIKo were evaluated with an alpha source and a $^{4}$He beam at 56 MeV. The TPC was stably operated up to 1000-kcps beam intensity. A tracking algorithm using the Hough transform method has been developed to analyze scattering events. An angular resolution of 1.3$^{\circ}$ was achieved for scattered $^{4}$He particles.