• N. Vinogradov, P. Piot, C.R. Prokop
  Northern Illinois University, DeKalb, Illinois
• J.W. Lewellen, J. Noonan
  ANL, Argonne

Funding: Work supported by the Department of Education under contract P116Z010035 with Northern Illinois University.
A simple, inexpensive, and compact low-energy (~20 KeV) photoemission electron source was designed, built and recently commissioned. It uses a commercial ultraviolet photocathode drive laser producing 3 ns RMS pulse. The source will eventually be used to drive a table-top THz radiation source, based on the Smith-Purcell free-electron laser scheme, and could also have potential application to time-resolved electron microcopy. We present experimental measurements of the photoemitted electron beam and numerical simulations of the anticipated parameters. We also discuss the generation of flat beams required to efficiently drive the THz radiation source.

• S.A. Kondrashev, A. Barcikowski, B. Mustapha, P.N. Ostroumov
  ANL, Argonne
• N. Vinogradov
  Northern Illinois University, DeKalb, Illinois

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
We have developed a pepper pot - scintillator screen system to measure the emittance of low-energy dc beams extracted from an ECR ion source and post-accelerated to an energy of 75 - 90 keV/charge. Different scintillators have been tested and CsI (Tl) was chosen due to its high sensitivity, wide dynamic range and long life-time. The linearity of both the scintillator and the CCD camera has been studied. A LabVIEW code has been developed and used for on-line emittance measurements. Un-normalized rms emittances measured for 209Bi²⁰⁺ and 209Bi²¹⁺ beams with current of 1.0 - 1.5 pnA are usually ~30 π mm.mrad. A complicated structure of multiple images of individual holes has been observed. The innovative combination of a special type of scintillator, a CCD camera and a fast shutter allowed us to create a very efficient emittance meter for low-energy dc ion beams. Using on-line emittance measurements, it was possible to improve the beam quality by re-tuning the ion source conditions. Because of the two-dimensional array of holes in the pepper-pot, this emittance meter can be used to observe and study four-dimensional emittance correlations in beams from ECR ion sources.

• P.N. Ostroumov, A. Barcikowski, S.A. Kondrashev, B. Mustapha, R.H. Scott, S.I. Sharamentov
  ANL, Argonne
• N. Vinogradov
  Northern Illinois University, DeKalb, Illinois

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC-02-06CH11357.
A prototype injector capable to produce multiple-charge-state heavy-ion beams is being developed at ANL. The injector consists of an ECR ion source, a 100 kV platform and a Low Energy Beam Transport (LEBT). The latter comprises two 60-degree bending magnets, electrostatic triplets and beam diagnostics stations. Several charge states of bismuth ions from the ECR have been extracted, accelerated to an energy of 1.8 MeV, separated and then recombined into a high quality beam ready for further acceleration. This technique allows us to double heavy-ion beam intensity in high-power driver linac for future radioactive beam facility. The other application is the post-accelerators of radioactive ions based on charge breeders. The intensity of rare isotope beams can be doubled or even tripled by the extraction and acceleration of multiple charge state beams. We will report the results of emittance measurements of multiple-charge state beams after recombination.