# Highlights from SuperKEKB Phase 2 Commissioning

## TL;DR

SuperKEKB Phase 2 commissioning verified the nano-beam scheme and studied background levels, achieving key milestones towards higher luminosity for new physics searches in B-meson decays.

## Contribution

This paper reports the first verification of the nano-beam scheme and background studies during SuperKEKB Phase 2 commissioning.

## Key findings

- Successful verification of the nano-beam scheme.
- Reduced background levels at the Belle II detector.
- Progress towards achieving higher luminosity goals.

## Abstract

SuperKEKB is an electron-positron asymmetric-energy collider to search new physics phenomena appeared in B-meson decays. In order to accomplish this purpose, 40 times the luminosity as high as the KEKB collider is demanded. The strategy is that the vertical beta function at the IP is squeezed down to 1/20 and the beam currents double those of KEKB while keeping the same beam-beam parameter. The vertical beta function at the interaction point(IP) will be much smaller than the bunch length, however, the hourglass effect which degrades the luminosity will be reduced by adopting a novel "nano-beam" scheme. First of all, the Phase 2 commissioning was focused on the verification of nano-beam scheme. Secondary, beam related background at the Belle II detector was also studied for the preparation of the pixel vertex detector installed before the Phase 3 operation. The preliminary results and accomplishments of the commissioning in Phase 2 will be reported in this article.