ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The concept of an ultra-low transverse emittance injector operating in CW mode for an XFELO* was discussed at LINAC-08**. Here we will report the design optimization of the injector, which includes a 100 MHz RF-gun with thermionic cathode, an energy filter to produce short bunches (~0.5 nsec), a velocity bunching section, higher harmonic cavities to minimize longitudinal emittance, two bunch compressors and accelerating sections operating at 400 MHz and 1300 MHz to obtain 540 MeV electrons. The proposed design is capable of producing 40 pC bunches with 0.5 psec rms time width and 0.7 MeV rms energy spread. Most significantly, the transverse rms emittance is kept below 0.11 π μm. The longitudinal emittance and bunch time width can be substantially reduced for low-charge bunches of several pC.
*K.-J. Kim, Y. Shvyd’ko, and S. Reiche, Phys. Rev. Lett., 100 244802 (2008).
**P.N. Ostroumov, K.-J. Kim, Ph. Piot, Proceedings of the Linac-2008.
ANL, Argonne
GANIL, Caen
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
We have developed and tested an X-ray based Bunch Length Detector (XBLD) for application in ion accelerators. X-rays produced as a result of ion beam interactions with matter are used to generate photoelectrons. The photoelectrons are analyzed by an rf deflector synchronized with the master oscillator, similar to the BLDs based on secondary electrons. The expected time resolution is several picoseconds. The proposed XBLD is particularly useful for the measurement of cw heavy-ion beams passing through a stripper foil or film in a high-power driver accelerator. The results of the XBLD commissioning and beam bunch profile measurements at the ANL heavy-ion cw ATLAS accelerator will be presented.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The development of a uniform and stable high velocity, thin liquid lithium film stripper is essential for the Facility for Rare-Isotope Beams (FRIB) Project. The formation of such a film has been demonstrated recently at ANL. Film thickness should be measured, and its temporal and spatial stability under high power ion beam irradiation should be verified. Intense beams of light ions generated by the FRIB prototype injector can be used for this task. The injector consists of an ECR ion source followed by a LEBT. A DC 3.3 mA/75 kV proton beam has been generated at the LEBT output. Proton beam power will be brought to required level by adding the second acceleration tube. A low energy electron beams (LEEB) technique, based on the thickness-dependent scattering of the electrons by the film, has been proposed as a fast-response on-line film thickness monitoring. A LEEB test bench has been built to verify this technique. The transmission of electrons through the carbon foils of different thicknesses was measured and compared with results of CASINO simulations. Agreement between the experimental and numerical results allows quantitative measurements of film thickness using the LEEB.