The Bgo System for Beam Background Monitoring in Beast Ii
Jing-Ge Shiu1*
1Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Jing-Ge Shiu,
The SuperKEKB collider in KEK Japan is designed to supply high luminosity of e+/e- collision for B physics study at Belle II experiment. It has started its first beam circulation in 2016, which announces a new era of precision measurements. The BEAST II project is dedicated to study the beam-induced backgrounds prior to the Belle II full installation and commissioning. This is very essential for the control practice of beam commissioning and protection the real Belle II detectors from unexpected high radiation.

The NTU-HEP group has developed a BGO system for beam background monitoring in BEAST II. Eight BGO scintillator crystals are installed near the designed interaction point of Belle II. The signals from BGO are conducted to one MAPMT via 37 m optical fibers with light-tight treatments. The readout electronics is equipped with a FPGA running at 40MHz clock to process the digitized signals in pipeline. The system sends the accumulated deposit energy in BGO to the central BEAST II DAQ system at 65 Hz rate without dead time. The monitoring data are also fed back to the accelerator group for comparison in real time.

This design has been proved working well during the BEAST II commissioning. We have studied the radiation background due to various beam conditions and the Touschek effect. Highlights of the design and preliminary results from BEAST II commissioning will be presented.

Keywords: SuperKEKB, Belle II, BEAST, beam background, BGO