92990894
COMMISSIONING OF THE SSRF STORAGE RING
The Shanghai Synchrotron Radiation Facility (SSRF) is a third generation light source with 3.5GeV beam energy. Its accelerator complex consists of a 150MeV linac, a full energy booster and a 3.5GeV storage ring. Commissioning of the storage ring on 3.0GeV beam energy began on Dec. 21st evening 2007 prior to the schedule. The first turn was observed after three hours with RF off. The beam was stored after twelve hours, and then cumulated up to 5 mA current. On Jan. 3, 2008, a beam with 100mA current is successfully obtained in the machine for the first time. Since then, the storage ring has been brought close to the designed specifications, and frequently operated with 100mA beam current for cleaning the vacuum chamber. In this paper, commissioning results of the storage ring is presented in details.
45940461
STATUS OF THE FERMI @ ELETTRA PHOTOINJECTOR
The new FERMI@Elettra photoinjector is presently undergoing high-power testing and characterization at MAXlab in Lund, Sweden. This effort is a collaboration between Sincrotrone Trieste, MAX-lab and UCLA. The 1.6-cell RF gun cavity and the focusing solenoid were successfully designed and built by the Particle Beam Physics Laboratory at UCLA, delivered to Sincrotrone Trieste at the beginning of 2008, and installed in the linac tunnel at MAX-lab. Use of the MAX-lab facility will allow the FERMI project to progress significantly with the photoinjector while waiting for the completion of the new linac building extension at Sincrotrone Trieste. We report here on the high-power conditioning of the RF cavity and the first beam tests. STATUS OF THE FERMI@ELETTRA PHOTOINJECTOR∗ M. Trovò† , L. Badano, S. Biedron, D. Castronovo, F. Cianciosi, P. Craievich, M.D. Danailov, G. D’Auria, M. Ferianis, S.V. Milton, G. Penco, L. Pivetta, L. Rumiz, D. Wang, Sincrotrone Trieste, Trieste, Italy M. Eriksson, D.Kumbaro, F. Lindau, MAX-lab, Lunds Universitet, Lund, Sweden H. Badakov, A. Fukasawa, B. O’Shea, J. Rosenzweig, UCLA Department of Physics and Astronomy, Los Angeles, CA 90095
55356715
PROGRESS OF THE eRHIC ELECTRON RING DESIGN
Over the past year, a baseline design of the electron ring for the eRHIC hadron-lepton collider has been developed. This site-specific design is based on the understanding of the existing RHIC machine performance and its possible upgrades. The design includes a full energy polarized electron beam injector to ensure operational reliability and to provide high integrated luminosity. The electron ring energy range is 5 to 10 GeV. The electron beam emittance, the electron beam path length, and the interaction region optics have to be adjustable over wide ranges depending on the ion species and energy for collisions. We describe the design features and expected machine performance. The results of recent beam polarization and beam-beam studies are also discussed.
124623797
HESYRL 200 MeV linac single bunch energy spectrum measurement
The HESYRL 200-MeV electron linac was completed in December 1987, and has been running well. A careful study of the single-bunch energy spectrum for the linac was done. The measurement shows that the energy spread of the linac is +or-0.4%. The energy spectrum is quite stable and repeatable, and the resolution and accuracy are found to be satisfactory.<<ETX>>
55429266
STUDY OF THE ENERGY CHIRP EFFECTS ON SEEDED FEL SCHEMES AT SDUV-FEL
In this paper, theoretical and simulation study of the energy chirp effects on the HGHG and EEHG schemes are present. It is found that the central wavelength and output bandwidth of EEHG can be nearly immune to the beam energy chirp by properly setting the strengths of the chicanes. Experimental studies for both these two schemes have been carried out at the SDUV-FEL to demonstrate the theoretical predictions.
120931097
Stripline beam position monitor for the MIT-Bates South Hall Ring
The MIT-Bates South Hall Ring (SHR) is an electron storage ring currently being commissioned. It is designed to operate at an RF frequency of 2856 MHz with all of the 1812 buckets filled and a circulating current of 80 mA or greater. This leads to a small charge per bunch and the requirement for beam position monitors. Since there will be 31 such monitors in the vacuum system, it is important to suppress trapped modes which may excite coupled bunch instabilities. The stripline monitor built for the SHR is a stainless steel structure, designed to be manufactured using standard machining techniques and commercial feedthroughs. With proper 50 Ohm matching and a geometry derived from insight from MAFIA calculations, the monitor was constructed having a nearly flat RF response up through 10 GHz over the range of measurement. The stripline electronics allows the measurements with 0.1 mm resolution, maintains orbital harmonics information past the 10th harmonic, and operates over a dynamic range of 1 mA to greater than 80 mA of beam current.<<ETX>>
111215607
Experiments and simulation of high current operation at CEBAF
The superconducting rf, cw electron accelerator at CEBAF has achieved the design energy of 4 GeV using 5-pass recirculation through a pair of 400 MeV linacs. Stable beam current of 35 {mu}A has been delivered to the Experimental Hall C. The total beam current that has been recirculated so far is 248 {mu}A. Measurements of the performance of the rf control system have been made in both pulsed and cw mode, and a numerical model has been developed which describes the beam-cavity interaction, includes a realistic representation of low level controls, klystron characteristics and microphonic noise. Experimental data and simulation results on transient beam loading, klystron saturation, a new technique for cavity phasing, and heavy beam loading tests are described; in conclusion, an outlook on full current operation is presented.
53867504
On the soliton solutions of the two-dimensional Toda lattice
The two-dimensional Toda lattice (2DTL) is a well-known (2+1)-dimensional integrable system that admits a large class of line-soliton solutions. We classify these soliton solutions by exploiting the structure of the Casoratian expression for its tau function. In general, these solutions consist of unequal numbers of 'incoming' and 'outgoing' line solitons. We classify the incoming and outgoing line solitons based on asymptotic analysis of the tau function of the 2DTL as the discrete variable tends to infinity. We also identify various subclasses of solutions and characterize some of them in terms of the amplitudes and directions of the interacting solitons. As a special case, we obtain the reduction in the soliton solutions of the one-dimensional Toda lattice. Throughout, we point out the similarities with—and the differences from—the corresponding results for the Kadomtsev–Petviashvili equation.
115467192
Dynamical breaking of supergauge symmetry and its restoration at high temperatures
The dynamical breaking of the supersymmetric Higgs model is discussed without adding the Fayet—Iliopoulos term to the Lagrangian. It is shown, in terms of the Nambu—Jona-Lasinio mechanism, that the supersymmetry breaking can be realized dynamically in the supersymmetric Higgs model. The supersymmetry behavior at finite temperatures is also investigated and it is shown that the supersymmetry broken dynamically at zero temperature can be restored at finite temperatures.
19297504
Very Short Bunches in MIT-Bates South Hall Ring
The ultra-short bunch is the key for producing strong terahertz coherent synchrotron radiation (CSR) and some other applications. A study is being conducted at MIT-Bates South Hall Ring to get 1 mm or shorter electron bunch length. A set of low momentum compaction lattice configurations have been designed. In first beam experiment in 2004, two of these configurations were successfully commissioned in which the momentum compaction was reduced by two orders of magnitude. About 1 mm rms bunch length was measured with a streak camera. It has been demonstrated that this storage ring machine has a great degree of flexibility and potential as an ideal test bed for various advanced beam physics studies.
119280465
Characterizing Temporal Structure of the Relativistic Electron Bunch
Using proper beam energy chirp and the undulator detuning effect, we propose a modified optical replica synthesizer scheme to characterize the temporal structure of a relativistic electron bunch, which predicts a 100-fs temporal resolution in numerical simulation. The proof of principle experiment demonstrates a peak current of 9 A and a slice energy spread of about 0.5 keV for the uncompressed electron beam of the Shanghai Deep UV Free Electron Laser Facility.