Joint beam commissioning of the accelerators, target station and instruments started at the China Spallation Neutron Source (CSNS) on November 1, 2017. During the 10-day joint commissioning period, all three detector banks of the General Purpose Powder Diffractometer (GPPD), one of the first three instruments at CSNS, successfully obtained diffraction data, laying a good foundation for the next round of commissioning.

The working status of all GPPD components were carefully checked and confirmed after the neutron beam was available on November 1. The first experiment of NIST standard sample Si powder was started at 21:20, and the first diffraction peak was observed at 21:25 on the real-time data display screen.

In this commissioning, diffraction data for Si powder and vanadium were both collected. After preliminary reduction, diffraction patterns from the three detector banks were obtained (see figures). The instrument resolution of the high-angle detector bank is calculated to be 0.184%, which meets the acceptance requirements and is an important step towards project acceptance in 2018.

Diffraction pattern from the high-angle detector bank (Image by IHEP) 

 Diffraction pattern from the 90 degree detector bank (Image by IHEP) 

Diffraction pattern from the low-angle detector bank (Image by IHEP)

 Commissioning team members (Image by IHEP)