• R.K. Li, H. Chen, Q. Du, T. Du, Y.-C. Du, W.-H. Huang, J. Shi, C.-X. Tang, L.X. Yan
  TUB, Beijing
• X.J. Wang
  BNL, Upton, Long Island, New York

Funding: Supported by National Natural Science Foundation of China (No.10735050, No.10875070) and National Basic Research Program of China (973 Program)(No.2007CB815102)

Time-resolved MeV ultra-fast electron diffraction (UED) is a promising tool for studying of structural dynamics on the fundamental temporal and spatial scales of atomic motion. To reach the desired temporal and spatial resolutions, precise control and measurement of ultra-short, low emittance electron pulses are required. A MeV UED system based on an S-band photocathode RF gun is built and optimized at Tsinghua University. We present the experiment results here.

• W. Liu, Y.-C. Du, W.-H. Huang, C.-X. Tang, D. Wu
  TUB, Beijing

The preliminary experiments and three-dimensional (3D) particle-in-cell (PIC) simulations of terahertz (THz) coherent transition radiation (CTR) performed at the Accelerator Laboratory of Tsinghua University are reported in this paper. THz radiation is generated from the interactions of Titanium foil with the ultrashort electron beam produced by the photocathode RF gun. The frequency and power of radiation are measured with the Martin-Pupllet interferometer and Gollay Cell detector, respectively. The radiation characteristics depending on the foil properties are preliminarily studied with the experiments and PIC simulations. On the other hand, the distribution of radiation field pattern and energy are studied by numerical calculated, and those results are in agreement with the PIC simulations.

• J. Wei, H. Chen, W.-H. Huang, C.-X. Tang, Q.Z. Xing
  TUB, Beijing
• S. Fu, J. Tao
  IHEP Beijing, Beijing
• X. Guan
  CIAE, Beijing
• C.-K. Loong
  ANL, Argonne
• H.M. Shimizu
  KEK, Tsukuba

Funding: Supported by the “985 Project” of the Minister of Education of China, CAS Bairen Init. (KJCX2-YW-N22), CAS Overseas Outstanding Youth Program, and the National Natural Science Foundation (10628510).

During the past decades, large-scale national neutron sources are developed in Asia, Europe, and USA. Complementing such efforts, compact hadron beam complexes and neutron sources intended for universities and industrial institutes are proposed and established. Responding to the demands in China for multidisciplinary researches and applications using pulsed neutrons and protons, hadron therapy and radiography, and accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we here propose a compact yet expandable accelerator complex based on a proton source, a 3 MeV RFQ linac, and a 22 MeV DTL linac. A Be target with solid methane and room-temperature water moderators serve 6 neutron stations for imaging/radiography, irradiation, SANS, engineering powder diffraction, instrumentation, and therapy. The proton platform serves multiple stations for bio-applications, fuel cell and nano-applications, and space irradiation and detection. A rapid cycling synchrotron subsequently accelerates the beam to up to 300 MeV for proton therapy and radiography. Following the DTL linac with a superconducting RF linac and a sub-critical reactor offers an ADS test facility.

• J. Shi, H. Chen, Q. Du, Y.-C. Du, W.-H. Huang, R.K. Li, C.-X. Tang, L.X. Yan
  TUB, Beijing
• D. Li
  LBNL, Berkeley, California

Funding: Supported by National Natural Science Foundation of China (No.10775080)

An S-band RF deflecting cavity has been developed and applied for measuring the bunch length at Tsinghua Thomson-Scattering X-ray Source (TTX). This paper briefly introduces the 3-cell pi-mode standing-wave deflecting cavity and reports the recent experiments of the beam diagnostics for the photo-cathode RF gun, which produces electron bunches with RMS length around 1-ps. It is also observed that the bunches are lengthened while the total charge increases, showing the strong space charge effect at a low beam energy.

• P.-CH. Yu, W.-H. Huang, X. Shen, C.-X. Tang
  TUB, Beijing

Funding: This work is supported by National Natural Science Foundation of China (Project 10735050) and National Basic Research Program of China (973 Program) (Grant No. 2007CB815102).

The feasibility study of optical stochastic cooling (OSC) utilizing a compact storage ring is presented in this paper. We present the general layout of the scheme, as well as the lattice design of the storage ring. The results of beam dynamics simulation are likewise presented.