The China Spallation Neutron Source (CSNS) accelerator is designed to accelerate proton beam pulses to 1.6 GeV at 25 Hz repetition rate, striking a solid metal target to produce spallation neutrons. The accelerator provides a beam power of 100 kW on the target in the first phase and then 500 kW in the second phase by increasing the average beam intensity 5 times while raising the linac output energy. The project construction has been formally launched in 2011 and it is planned to complete the project in March 2018. It is one of the high intensity proton accelerator projects in the world and it imposes a great challenge to Chinese accelerator community. This presentation will cover the status and challenges of the CSNS project.

The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2 x 10(-5). The relative uncertainty of the beam's energy spread is about 6%. (C) 2011 Elsevier B.V. All rights reserved.

The performance of the vacuum system of storage ring depends critically on the synchrotron radiation induced gas desorption. The photo-desorption coefficient defined as the number of desorbed gas molecules per photon is a very important parameter for the design of the vacuum system. The experimental apparatus and measuring principle for photo-desorption coefficient were described, and the measuring results were also discussed.